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Zhuang, P., Ng, W.L., An, J., Chua, C.K. and Tan, L.P. Layer-by-layer ultraviolet assisted extrusion-based (UAE) bioprinting of hydrogel constructs with high aspect ratio for soft tissue engineering applications 2019 PLOS ONE
Vol. 14(6), pp. 1-21 
article DOI  
Abstract: One of the major challenges in the field of soft tissue engineering using bioprinting is fabricating complex tissue constructs with desired structure integrity and mechanical property. To accomplish such requirements, most of the reported works incorporated reinforcement materials such as poly(ϵ-caprolactone) (PCL) polymer within the 3D bioprinted constructs. Although this approach has made some progress in constructing soft tissue-engineered scaffolds, the mechanical compliance mismatch and long degradation period are not ideal for soft tissue engineering. Herein, we present a facile bioprinting strategy that combines the rapid extrusion-based bioprinting technique with an in-built ultraviolet (UV) curing system to facilitate the layer-by-layer UV curing of bioprinted photo-curable GelMA-based hydrogels to achieve soft yet stable cell-laden constructs with high aspect ratio for soft tissue engineering. GelMA is supplemented with a viscosity enhancer (gellan gum) to improve the bio-ink printability and shape fidelity while maintaining the biocompatibility before crosslinking via a layer-by-layer UV curing process. This approach could eventually fabricate soft tissue constructs with high aspect ratio (length to diameter) of ≥ 5. The effects of UV source on printing resolution and cell viability were also studied. As a proof-of-concept, small building units (3D lattice and tubular constructs) with high aspect ratio are fabricated. Furthermore, we have also demonstrated the ability to perform multi-material printing of tissue constructs with high aspect ratio along both the longitudinal and transverse directions for potential applications in tissue engineering of soft tissues. This layer-by-layer ultraviolet assisted extrusion-based (UAE) Bioprinting may provide a novel strategy to develop soft tissue constructs with desirable structure integrity.
BibTeX:
@article{Zhuang2019,
  author = {Zhuang, Pei AND Ng, Wei Long AND An, Jia AND Chua, Chee Kai AND Tan, Lay Poh},
  title = {Layer-by-layer ultraviolet assisted extrusion-based (UAE) bioprinting of hydrogel constructs with high aspect ratio for soft tissue engineering applications},
  journal = {PLOS ONE},
  publisher = {Public Library of Science},
  year = {2019},
  volume = {14},
  number = {6},
  pages = {1-21},
  doi = {https://doi.org/10.1371/journal.pone.0216776}
}
Noor, N., Shapira, A., Edri, R., Gal, I., Wertheim, L. and Dvir, T. 3D Printing of Personalized Thick and Perfusable Cardiac Patches and Hearts 2019 Advanced Science
Vol. 0(0), pp. 1900344 
article DOI  
Abstract: Abstract Generation of thick vascularized tissues that fully match the patient still remains an unmet challenge in cardiac tissue engineering. Here, a simple approach to 3D-print thick, vascularized, and perfusable cardiac patches that completely match the immunological, cellular, biochemical, and anatomical properties of the patient is reported. To this end, a biopsy of an omental tissue is taken from patients. While the cells are reprogrammed to become pluripotent stem cells, and differentiated to cardiomyocytes and endothelial cells, the extracellular matrix is processed into a personalized hydrogel. Following, the two cell types are separately combined with hydrogels to form bioinks for the parenchymal cardiac tissue and blood vessels. The ability to print functional vascularized patches according to the patient's anatomy is demonstrated. Blood vessel architecture is further improved by mathematical modeling of oxygen transfer. The structure and function of the patches are studied in vitro, and cardiac cell morphology is assessed after transplantation, revealing elongated cardiomyocytes with massive actinin striation. Finally, as a proof of concept, cellularized human hearts with a natural architecture are printed. These results demonstrate the potential of the approach for engineering personalized tissues and organs, or for drug screening in an appropriate anatomical structure and patient-specific biochemical microenvironment.
BibTeX:
@article{Noor2019,
  author = {Noor, Nadav and Shapira, Assaf and Edri, Reuven and Gal, Idan and Wertheim, Lior and Dvir, Tal},
  title = {3D Printing of Personalized Thick and Perfusable Cardiac Patches and Hearts},
  journal = {Advanced Science},
  year = {2019},
  volume = {0},
  number = {0},
  pages = {1900344},
  doi = {https://doi.org/10.1002/advs.201900344}
}
Markstedt, K., Håkansson, K., Toriz, G. and Gatenholm, P. Materials from trees assembled by 3D printing – Wood tissue beyond nature limits 2019 Applied Materials Today
Vol. 15, pp. 280 - 285 
article DOI URL 
Abstract: Materials from trees have the potential to replace fossil based and other non-sustainable materials in everyday products, thus transforming the society back to a bioeconomy. This paper presents a 3D printing platform which mimics wood biogenesis for the assembly of wood biopolymers into wood-like hierarchical composites. The genome was substituted with G-code, the programming language which controls how the 3D printer assembles material. The rosette was replaced by the printer head for extrusion of cellulose. Instead of microtubules guiding the alignment of cellulose, the printing direction was guided by an x/y stage, thus mimicking the microfibril angle. The printed structures were locked by an enzymatic crosslinking reaction similar to what occurs in the cell wall upon lignification. Hierarchical structures characteristic for wood were designed and printed with control of density, swelling and directional strength. Accelerating the development of the 3D printing technology helps realize the circular bioeconomy where garments, packaging, furniture and entire houses are manufactured by 3D printing wood.
BibTeX:
@article{Markstedt2019,
  author = {Kajsa Markstedt and Karl Håkansson and Guillermo Toriz and Paul Gatenholm},
  title = {Materials from trees assembled by 3D printing – Wood tissue beyond nature limits},
  journal = {Applied Materials Today},
  year = {2019},
  volume = {15},
  pages = {280 - 285},
  url = {http://www.sciencedirect.com/science/article/pii/S2352940718304918},
  doi = {https://doi.org/10.1016/j.apmt.2019.02.005}
}
Huang, B., Vyas, C., Roberts, I., Poutrel, Q.-A., Chiang, W.-H., Blaker, J.J., Huang, Z. and Bártolo, P. Fabrication and characterisation of 3D printed MWCNT composite porous scaffolds for bone regeneration 2019 Materials Science and Engineering: C
Vol. 98, pp. 266 - 278 
article DOI URL 
Abstract: Carbon nanotubes (CNTs) with exceptional physical and chemical properties are attracting significant interest in the field of tissue engineering. Several reports investigated CNTs biocompatibility and their impact in terms of cell attachment, proliferation and differentiation mainly using polymer/CNTs membranes. However, these 2D membranes are not able to emulate the complex in vivo environment. In this paper, additive manufacturing (3D printing) is used to create composite 3D porous scaffolds containing different loadings of multi-walled carbon nanotubes (MWCNT) (0.25, 0.75 and 3 wt%) for bone tissue regeneration. Pre-processed and processed materials were extensively characterised in terms of printability, morphological and topographic characteristics and thermal, mechanical and biological properties. Scaffolds with pore sizes ranging between 366 μm and 397 μm were successfully produced and able to sustain early-stage human adipose-derived mesenchymal stem cells attachment and proliferation. Results show that MWCNTs enhances protein adsorption, mechanical and biological properties. Composite scaffolds, particularly the 3 wt% loading of MWCNTs, seem to be good candidates for bone tissue regeneration.
BibTeX:
@article{Huang2019,
  author = {Boyang Huang and Cian Vyas and Iwan Roberts and Quentin-Arthur Poutrel and Wei-Hung Chiang and Jonny J. Blaker and Zhucheng Huang and Paulo Bártolo},
  title = {Fabrication and characterisation of 3D printed MWCNT composite porous scaffolds for bone regeneration},
  journal = {Materials Science and Engineering: C},
  year = {2019},
  volume = {98},
  pages = {266 - 278},
  url = {http://www.sciencedirect.com/science/article/pii/S0928493118317491},
  doi = {https://doi.org/10.1016/j.msec.2018.12.100}
}
Gonzalez-Fernandez, T., Rathan, S., Hobbs, C., Pitacco, P., Freeman, F., Cunniffe, G., Dunne, N., McCarthy, H., Nicolosi, V., O'Brien, F. and Kelly, D. Pore-forming bioinks to enable Spatio-temporally defined gene delivery in bioprinted tissues 2019 Journal of Controlled Release  article DOI URL 
Abstract: The regeneration of complex tissues and organs remains a major clinical challenge. With a view towards bioprinting such tissues, we developed a new class of pore-forming bioink to spatially and temporally control the presentation of therapeutic genes within bioprinted tissues. By blending sacrificial and stable hydrogels, we were able to produce bioinks whose porosity increased with time following printing. When combined with amphipathic peptide-based plasmid DNA delivery, these bioinks supported enhanced non-viral gene transfer to stem cells in vitro. By modulating the porosity of these bioinks, it was possible to direct either rapid and transient (pore-forming bioinks), or slower and more sustained (solid bioinks) transfection of host or transplanted cells in vivo. To demonstrate the utility of these bioinks for the bioprinting of spatially complex tissues, they were next used to zonally position stem cells and plasmids encoding for either osteogenic (BMP2) or chondrogenic (combination of TGF-β3, BMP2 and SOX9) genes within networks of 3D printed thermoplastic fibers to produce mechanically reinforced, gene activated constructs. In vivo, these bioprinted tissues supported the development of a vascularised, bony tissue overlaid by a layer of stable cartilage. When combined with multiple-tool biofabrication strategies, these gene activated bioinks can enable the bioprinting of a wide range of spatially complex tissues.
BibTeX:
@article{Gonzalez-Fernandez2019,
  author = {T. Gonzalez-Fernandez and S. Rathan and C. Hobbs and P. Pitacco and F.E. Freeman and G.M. Cunniffe and N.J. Dunne and H.O. McCarthy and V. Nicolosi and F.J. O'Brien and D.J. Kelly},
  title = {Pore-forming bioinks to enable Spatio-temporally defined gene delivery in bioprinted tissues},
  journal = {Journal of Controlled Release},
  year = {2019},
  url = {http://www.sciencedirect.com/science/article/pii/S0168365919301440},
  doi = {https://doi.org/10.1016/j.jconrel.2019.03.006}
}
Gloria, A., Frydman, B., Lamas, M.L., Serra, A.C., Martorelli, M., Coelho, J.F., Fonseca, A.C. and Domingos, M. The influence of poly(ester amide) on the structural and functional features of 3D additive manufactured poly(ε-caprolactone) scaffolds 2019 Materials Science and Engineering: C
Vol. 98, pp. 994 - 1004 
article DOI URL 
Abstract: The current research reports for the first time the use of blends of poly(ε-caprolactone) (PCL) and poly(ester amide) (PEA) for the fabrication of 3D additive manufactured scaffolds. Tailor made PEA was synthesized to afford fully miscible blends of PCL and PEA using different percentages (5, 10, 15 and 20% w/w). Stability, characteristic temperatures and material's compatibility were studied through thermal analyses (i.e., TGA, DSC). Even though DMTA and static compression tests demonstrated the possibility to improve the storage modulus, Young's modulus and maximum stress by increasing the amount of PEA, a decrease of hardness was found beyond a threshold concentration of PEA as the lowest values were achieved for PCL/PEA (20% w/w) scaffolds (from 0.39 ± 0.03 GPa to 0.21 ± 0.02 GPa in the analysed load range). The scaffolds presented a controlled morphology and a fully interconnected network of internal channels. The water contact angle measurements showed a clear increase of hydrophilicity resulting from the addition of PEA. This result was further corroborated with the improved adhesion and proliferation of human mesenchymal stem cells (hMSCs). The presence of PEA also influenced the cell morphology. Better cell spreading and a much higher and homogenous number of cells were observed for PCL/PEA scaffolds when compared to PCL ones.
BibTeX:
@article{Gloria2019,
  author = {Antonio Gloria and B. Frydman and Miguel L. Lamas and Armenio C. Serra and Massimo Martorelli and Jorge F.J. Coelho and Ana C. Fonseca and M. Domingos},
  title = {The influence of poly(ester amide) on the structural and functional features of 3D additive manufactured poly(ε-caprolactone) scaffolds},
  journal = {Materials Science and Engineering: C},
  year = {2019},
  volume = {98},
  pages = {994 - 1004},
  url = {http://www.sciencedirect.com/science/article/pii/S0928493118323944},
  doi = {https://doi.org/10.1016/j.msec.2019.01.063}
}
Apelgren, P., Karabulut, E., Amoroso, M., Mantas, A., Martínez Ávila, H., Kölby, L., Kondo, T., Toriz, G. and Gatenholm, P. In Vivo Human Cartilage Formation in Three-Dimensional Bioprinted Constructs with a Novel Bacterial Nanocellulose Bioink 2019 ACS Biomater. Sci. Eng.
Vol. 5(5), pp. 2482-2490 
article DOI  
Abstract: Bacterial nanocellulose (BNC) is a 3D network of nanofibrils exhibiting excellent biocompatibility. Here, we present the aqueous counter collision (ACC) method of BNC disassembly to create bioink with suitable properties for cartilage-specific 3D-bioprinting. BNC was disentangled by ACC, and fibril characteristics were analyzed. Bioink printing fidelity and shear-thinning properties were evaluated. Cell-laden bioprinted grid constructs (5 × 5 × 1 mm3) containing human nasal chondrocytes (10 M mL-1) were implanted in nude mice and explanted after 30 and 60 days. Both ACC and hydrolysis resulted in significantly reduced fiber lengths, with ACC resulting in longer fibrils and fewer negative charges relative to hydrolysis. Moreover, ACC-BNC bioink showed outstanding printability, postprinting mechanical stability, and structural integrity. In vivo, cell-laden structures were rapidly integrated, maintained structural integrity, and showed chondrocyte proliferation, with 32.8 ± 13.8 cells per mm2 observed after 30 days and 85.6 ± 30.0 cells per mm2 at day 60 (p = 0.002). Furthermore, a full-thickness skin graft was attached and integrated completely on top of the 3D-bioprinted construct. The novel ACC disentanglement technique makes BNC biomaterial highly suitable for 3D-bioprinting and clinical translation, suggesting cell-laden 3D-bioprinted ACC-BNC as a promising solution for cartilage repair.
Bacterial nanocellulose (BNC) is a 3D network of nanofibrils exhibiting excellent biocompatibility. Here, we present the aqueous counter collision (ACC) method of BNC disassembly to create bioink with suitable properties for cartilage-specific 3D-bioprinting. BNC was disentangled by ACC, and fibril characteristics were analyzed. Bioink printing fidelity and shear-thinning properties were evaluated. Cell-laden bioprinted grid constructs (5 × 5 × 1 mm3) containing human nasal chondrocytes (10 M mL-1) were implanted in nude mice and explanted after 30 and 60 days. Both ACC and hydrolysis resulted in significantly reduced fiber lengths, with ACC resulting in longer fibrils and fewer negative charges relative to hydrolysis. Moreover, ACC-BNC bioink showed outstanding printability, postprinting mechanical stability, and structural integrity. In vivo, cell-laden structures were rapidly integrated, maintained structural integrity, and showed chondrocyte proliferation, with 32.8 ± 13.8 cells per mm2 observed after 30 days and 85.6 ± 30.0 cells per mm2 at day 60 (p = 0.002). Furthermore, a full-thickness skin graft was attached and integrated completely on top of the 3D-bioprinted construct. The novel ACC disentanglement technique makes BNC biomaterial highly suitable for 3D-bioprinting and clinical translation, suggesting cell-laden 3D-bioprinted ACC-BNC as a promising solution for cartilage repair.
BibTeX:
@article{Apelgren2019,
  author = {Apelgren, Peter and Karabulut, Erdem and Amoroso, Matteo and Mantas, Athanasios and Martínez Ávila, Héctor and Kölby, Lars and Kondo, Tetsuo and Toriz, Guillermo and Gatenholm, Paul},
  title = {In Vivo Human Cartilage Formation in Three-Dimensional Bioprinted Constructs with a Novel Bacterial Nanocellulose Bioink},
  journal = {ACS Biomater. Sci. Eng.},
  publisher = {American Chemical Society},
  year = {2019},
  volume = {5},
  number = {5},
  pages = {2482--2490},
  doi = {https://doi.org/10.1021/acsbiomaterials.9b00157}
}
Mehrotra, S., Moses, J.C., Bandyopadhyay, A. and Mandal, B.B. 3D Printing/Bioprinting Based Tailoring of in Vitro Tissue Models: Recent Advances and Challenges 2019 ACS Appl. Bio Mater.
Vol. 2(4), pp. 1385-1405 
article DOI  
Abstract: Prodigious progress in the past decade has pronounced 3D printing as one of the most promising technique for assembling biological materials in a complex layout that mimics native human tissues. With the advent of technology, several improvements in printing techniques have facilitated the development of intricate strategies and designs that were imaginably distant due to the conventional top-down approaches. Most of these advanced strategies generally follow a thorough coordination and an elaborate biomimetic blueprint due to which it is now possible to fabricate in vitro tissue models with ease. However, much remains to be accomplished at several forefronts for utilizing this technology to its full potential. With several printing strategies at the lead, it has now become essential to systematically analyze and learn from several endeavors such that shortcomings can be understood and future efforts can be made toward negating them. Taking account of all the recent tissue specific developments in this field, this review serves as a framework for bringing together in discussion several strategies and constraints in developing small scaled in vitro tissues. Highlighting the growing popularity of the organ and body on chip platforms and their easy scale up using 3D printing, latest advancements, and the challenges in this field are also discussed.
Prodigious progress in the past decade has pronounced 3D printing as one of the most promising technique for assembling biological materials in a complex layout that mimics native human tissues. With the advent of technology, several improvements in printing techniques have facilitated the development of intricate strategies and designs that were imaginably distant due to the conventional top-down approaches. Most of these advanced strategies generally follow a thorough coordination and an elaborate biomimetic blueprint due to which it is now possible to fabricate in vitro tissue models with ease. However, much remains to be accomplished at several forefronts for utilizing this technology to its full potential. With several printing strategies at the lead, it has now become essential to systematically analyze and learn from several endeavors such that shortcomings can be understood and future efforts can be made toward negating them. Taking account of all the recent tissue specific developments in this field, this review serves as a framework for bringing together in discussion several strategies and constraints in developing small scaled in vitro tissues. Highlighting the growing popularity of the organ and body on chip platforms and their easy scale up using 3D printing, latest advancements, and the challenges in this field are also discussed.
BibTeX:
@article{Mehrotra2019,
  author = {Mehrotra, Shreya and Moses, Joseph Christakiran and Bandyopadhyay, Ashutosh and Mandal, Biman B.},
  title = {3D Printing/Bioprinting Based Tailoring of in Vitro Tissue Models: Recent Advances and Challenges},
  journal = {ACS Appl. Bio Mater.},
  publisher = {American Chemical Society},
  year = {2019},
  volume = {2},
  number = {4},
  pages = {1385--1405},
  doi = {https://doi.org/10.1021/acsabm.9b00073}
}
Allig, S., Mayer, M., Arrizabalaga, O., Ritter, S., Schroeder, I. and Thielemann, C. Effect of extrusion-based bioprinting on neurospheres 2019 GSI-FAIR SCIENTIFIC REPORT 2017  techreport URL 
BibTeX:
@techreport{Allig2019,
  author = {Allig, S and Mayer, Margot and Arrizabalaga, Onetsine and Ritter, Sylvia and Schroeder, Insa and Thielemann, Christiane},
  title = {Effect of extrusion-based bioprinting on neurospheres},
  booktitle = {GSI-FAIR SCIENTIFIC REPORT 2017},
  year = {2019},
  url = {https://www.researchgate.net/publication/332672473_Effect_of_extrusion-based_bioprinting_on_neurospheres}
}
Marques, C.F., Diogo, G.S., Pina, S., Oliveira, J.M., Silva, T.H. and Reis, R.L. Collagen-based bioinks for hard tissue engineering applications: a comprehensive review 2019 Journal of Materials Science: Materials in Medicine
Vol. 30(3), pp. 32 
article DOI  
Abstract: In the last few years, additive manufacturing (AM) has been gaining great interest in the fabrication of complex structures for soft-to-hard tissues regeneration, with tailored porosity, and boosted structural, mechanical, and biological properties. 3D printing is one of the most known AM techniques in the field of biofabrication of tissues and organs. This technique opened up opportunities over the conventional ones, with the capability of creating replicable, customized, and functional structures that can ultimately promote effectively different tissues regeneration. The uppermost component of 3D printing is the bioink, i.e. a mixture of biomaterials that can also been laden with different cell types, and bioactive molecules. Important factors of the fabrication process include printing fidelity, stability, time, shear-thinning properties, mechanical strength and elasticity, as well as cell encapsulation and cell-compatible conditions. Collagen-based materials have been recognized as a promising choice to accomplish an ideal mimetic bioink for regeneration of several tissues with high cell-activating properties. This review presents the state-of-art of the current achievements on 3D printing using collagen-based materials for hard tissue engineering, particularly on the development of scaffolds for bone and cartilage repair/regeneration. The ultimate aim is to shed light on the requirements to successfully print collagen-based inks and the most relevant properties exhibited by the so fabricated scaffolds. In this regard, the adequate bioprinting parameters are addressed, as well as the main materials properties, namely physicochemical and mechanical properties, cell compatibility and commercial availability, covering hydrogels, microcarriers and decellularized matrix components. Furthermore, the fabrication of these bioinks with and without cells used in inkjet printing, laser-assisted printing, and direct in writing technologies are also overviewed. Finally, some future perspectives of novel bioinks are given.
BibTeX:
@article{Marques2019,
  author = {Marques, C. F. and Diogo, G. S. and Pina, S. and Oliveira, J. M. and Silva, T. H. and Reis, R. L.},
  title = {Collagen-based bioinks for hard tissue engineering applications: a comprehensive review},
  journal = {Journal of Materials Science: Materials in Medicine},
  year = {2019},
  volume = {30},
  number = {3},
  pages = {32},
  doi = {https://doi.org/10.1007/s10856-019-6234-x}
}
Zhou, M., Lee, B.H., Tan, Y.J. and Tan, L.P. Microbial transglutaminase induced controlled crosslinking of gelatin methacryloyl to tailor rheological properties for 3D printing 2019 Biofabrication
Vol. 11(2), pp. 025011 
article DOI  
Abstract: Gelatin methacryloyl (GelMA) is a versatile biomaterial that has been shown to possess many advantages such as good biocompatibility, support for cell growth, tunable mechanical properties, photocurable capability, and low material cost. Due to these superior properties, much research has been carried out to develop GelMA as a bioink for bioprinting. However, there are still many challenges, and one major challenge is the control of its rheological properties to yield good printability. Herein, this study presents a strategy to control the rheology of GelMA through partial enzymatic crosslinking. Unlike other enzymatic crosslinking strategies where the rheological properties could not be controlled once reaction takes place, we could, to a large extent, keep the rheological properties stable by introducing a deactivation step after obtaining the optimized rheological properties. Ca2+-independent microbial transglutaminase (MTGase) was introduced to partially catalyze covalent bond formation between chains of GelMA. The enzyme was then deactivated to prevent further uncontrolled crosslinking that would render the hydrogel not printable. After printing, a secondary post-printing crosslinking step (photo crosslinking) was then introduced to ensure long-term stability of the printed structure for subsequent cell studies. Biocompatibility studies carried out using cells encapsulated in the printed structure showed excellent cell viability for at least 7 d. This strategy for better control of rheological properties of GelMA could more significantly enhance the usability of this material as bioink for bioprinting of cell-laden structures for soft tissue engineering.
BibTeX:
@article{Zhou2019,
  author = {Miaomiao Zhou and Bae Hoon Lee and Yu Jun Tan and Lay Poh Tan},
  title = {Microbial transglutaminase induced controlled crosslinking of gelatin methacryloyl to tailor rheological properties for 3D printing},
  journal = {Biofabrication},
  publisher = {IOP Publishing},
  year = {2019},
  volume = {11},
  number = {2},
  pages = {025011},
  doi = {https://doi.org/10.1088/1758-5090/ab063f}
}
Rotbaum, Y., Puiu, C., Rittel, D. and Domingos, M. Quasi-static and dynamic in vitro mechanical response of 3D printed scaffolds with tailored pore size and architectures 2019 Materials Science and Engineering: C
Vol. 96, pp. 176 - 182 
article DOI URL 
Abstract: Scaffold-based Tissue Engineering represents the most promising approach for the regeneration of load bearing skeletal tissues, in particular bone and cartilage. Scaffolds play major role in this process by providing a physical template for cells to adhere and proliferate whilst ensuring an adequate biomechanical support at the defect site. Whereas the quasi static mechanical properties of porous polymeric scaffolds are well documented, the response of these constructs under high strain compressive rates remain poorly understood. Therefore, this study investigates, for the first time, the influence of pore size and geometry on the mechanical behaviour of Polycaprolactone (PCL) scaffolds under quasi static and dynamic conditions. 3D printed scaffolds with varied pore sizes and geometries were obtained using different filament distances (FD) and lay-down patterns, respectively. In particular, by fixing the lay-down pattern at 0/90° and varying the FD between 480 and 980 μm it was possible to generate scaffolds with square pores with dimensions in the range of 150–650 μm and porosities of 59–79%. On the other hand, quadrangular, hexagonal, triangular and complex pore geometries with constant porosity (approx. 70%) were obtained at a fixed FD of 680 μm and imposing four different lay-down patterns of 0/90, 0/60/120, 0/45/90/135 and 0/30/60/90/120/150°, respectively. The mechanical response of printed scaffolds was assessed under two different compression loading regimes spanning five distinct strain rates, from 10−2 to 2000 s−1, using two different apparatus: a conventional screw-driven testing machine (Instron 4483) and a Split Hopkinson pressure bar (SHPB) equipped with a set of A201 Flexi-force™ (FF) force sensors and a pulse shaper. Our results show that the mechanical properties of PCL scaffolds are not strain rate sensitive between 1300 and 2000 s−1 and these strongly depend on the pore size (porosity) rather than pore geometry. Those findings are extremely relevant for the engineering of bone tissue scaffolds with enhanced mechanical stability by providing new data describing the mechanical response of these constructs at high strain rates as well as the at the transition between quasi static and dynamic regimes.
BibTeX:
@article{Rotbaum2019,
  author = {Y. Rotbaum and C. Puiu and D. Rittel and M. Domingos},
  title = {Quasi-static and dynamic in vitro mechanical response of 3D printed scaffolds with tailored pore size and architectures},
  journal = {Materials Science and Engineering: C},
  year = {2019},
  volume = {96},
  pages = {176 - 182},
  url = {http://www.sciencedirect.com/science/article/pii/S0928493118326651},
  doi = {https://doi.org/10.1016/j.msec.2018.11.019}
}
Pedrotty, D.M., Volodymyr, K., Erdem, K., Sugrue Alan, M., Christopher, L., Vaidya Vaibhav, R., McLeod Christopher, J., Asirvatham Samuel, J., Paul, G. and Suraj, K. Three-Dimensional Printed Biopatches With Conductive Ink Facilitate Cardiac Conduction When Applied to Disrupted Myocardium 2019 Circulation: Arrhythmia and Electrophysiology
Vol. 12(3), pp. e006920 
article DOI  
BibTeX:
@article{Pedrotty2019,
  author = {Pedrotty, Dawn M. and Volodymyr, Kuzmenko and Erdem, Karabulut and Sugrue Alan, M. and Christopher, Livia and Vaidya Vaibhav, R. and McLeod Christopher, J. and Asirvatham Samuel, J. and Paul, Gatenholm and Suraj, Kapa},
  title = {Three-Dimensional Printed Biopatches With Conductive Ink Facilitate Cardiac Conduction When Applied to Disrupted Myocardium},
  journal = {Circulation: Arrhythmia and Electrophysiology},
  publisher = {American Heart Association},
  year = {2019},
  volume = {12},
  number = {3},
  pages = {e006920},
  doi = {https://doi.org/10.1161/circep.118.006920}
}
Langer, E.M., Allen-Petersen, B.L., King, S.M., Kendsersky, N.D., Turnidge, M.A., Kuziel, G.M., Riggers, R., Samatham, R., Amery, T.S., Jacques, S.L., Sheppard, B.C., Korkola, J.E., Muschler, J.L., Thibault, G., Chang, Y.H., Gray, J.W., Presnell, S.C., Nguyen, D.G. and Sears, R.C. Modeling Tumor Phenotypes In Vitro with Three-Dimensional Bioprinting 2019 Cell Reports
Vol. 26(3), pp. 608-623.e6 
article DOI  
Abstract: The tumor microenvironment plays a critical role in tumor growth, progression, and therapeutic resistance, but interrogating the role of specific tumor-stromal interactions on tumorigenic phenotypes is challenging within in vivo tissues. Here, we tested whether three-dimensional (3D) bioprinting could improve in vitro models by incorporating multiple cell types into scaffold-free tumor tissues with defined architecture. We generated tumor tissues from distinct subtypes of breast or pancreatic cancer in relevant microenvironments and demonstrate that this technique can model patient-specific tumors by using primary patient tissue. We assess intrinsic, extrinsic, and spatial tumorigenic phenotypes in bioprinted tissues and find that cellular proliferation, extracellular matrix deposition, and cellular migration are altered in response to extrinsic signals or therapies. Together, this work demonstrates that multi-cell-type bioprinted tissues can recapitulate aspects of in vivo neoplastic tissues and provide a manipulable system for the interrogation of multiple tumorigenic endpoints in the context of distinct tumor microenvironments.
The tumor microenvironment plays a critical role in tumor growth, progression, and therapeutic resistance, but interrogating the role of specific tumor-stromal interactions on tumorigenic phenotypes is challenging within in vivo tissues. Here, we tested whether three-dimensional (3D) bioprinting could improve in vitro models by incorporating multiple cell types into scaffold-free tumor tissues with defined architecture. We generated tumor tissues from distinct subtypes of breast or pancreatic cancer in relevant microenvironments and demonstrate that this technique can model patient-specific tumors by using primary patient tissue. We assess intrinsic, extrinsic, and spatial tumorigenic phenotypes in bioprinted tissues and find that cellular proliferation, extracellular matrix deposition, and cellular migration are altered in response to extrinsic signals or therapies. Together, this work demonstrates that multi-cell-type bioprinted tissues can recapitulate aspects of in vivo neoplastic tissues and provide a manipulable system for the interrogation of multiple tumorigenic endpoints in the context of distinct tumor microenvironments.
BibTeX:
@article{Langer2019,
  author = {Langer, Ellen M. and Allen-Petersen, Brittany L. and King, Shelby M. and Kendsersky, Nicholas D. and Turnidge, Megan A. and Kuziel, Genevra M. and Riggers, Rachelle and Samatham, Ravi and Amery, Taylor S. and Jacques, Steven L. and Sheppard, Brett C. and Korkola, James E. and Muschler, John L. and Thibault, Guillaume and Chang, Young Hwan and Gray, Joe W. and Presnell, Sharon C. and Nguyen, Deborah G. and Sears, Rosalie C.},
  title = {Modeling Tumor Phenotypes In Vitro with Three-Dimensional Bioprinting},
  journal = {Cell Reports},
  publisher = {Elsevier},
  year = {2019},
  volume = {26},
  number = {3},
  pages = {608--623.e6},
  doi = {https://doi.org/10.1016/j.celrep.2018.12.090}
}
Jiang, T., Munguía López, J., Flores-Torres, S., Kort-Mascort, J. and Kinsella, J. Extrusion bioprinting of soft materials: An emerging technique for biological model fabrication 2019 Applied Physics Reviews
Vol. 6, pp. 011310 
article DOI  
BibTeX:
@article{Jiang2019,
  author = {Jiang, Tao and Munguía López, Jose and Flores-Torres, Salvador and Kort-Mascort, Jacqueline and Kinsella, Joseph},
  title = {Extrusion bioprinting of soft materials: An emerging technique for biological model fabrication},
  journal = {Applied Physics Reviews},
  year = {2019},
  volume = {6},
  pages = {011310},
  doi = {https://doi.org/10.1063/1.5059393}
}
Filardo, G., Petretta, M., Cavallo, C., Roseti, L., Durante, S., Albisinni, U. and Grigolo, B. Patient-specific meniscus prototype based on 3D bioprinting of human cell-laden scaffold 2019 Bone & Joint Research
Vol. 8(2), pp. 101-106 
article DOI  
Abstract: Objectives Meniscal injuries are often associated with an active lifestyle. The damage of meniscal tissue puts young patients at higher risk of undergoing meniscal surgery and, therefore, at higher risk of osteoarthritis. In this study, we undertook proof-of-concept research to develop a cellularized human meniscus by using 3D bioprinting technology. Methods A 3D model of bioengineered medial meniscus tissue was created, based on MRI scans of a human volunteer. The Digital Imaging and Communications in Medicine (DICOM) data from these MRI scans were processed using dedicated software, in order to obtain an STL model of the structure. The chosen 3D Discovery printing tool was a microvalve-based inkjet printhead. Primary mesenchymal stem cells (MSCs) were isolated from bone marrow and embedded in a collagen-based bio-ink before printing. LIVE/DEAD assay was performed on realized cell-laden constructs carrying MSCs in order to evaluate cell distribution and viability. Results This study involved the realization of a human cell-laden collagen meniscus using 3D bioprinting. The meniscus prototype showed the biological potential of this technology to provide an anatomically shaped, patient-specific construct with viable cells on a biocompatible material. Conclusion This paper reports the preliminary findings of the production of a custom-made, cell-laden, collagen-based human meniscus. The prototype described could act as the starting point for future developments of this collagen-based, tissue-engineered structure, which could aid the optimization of implants designed to replace damaged menisci. Cite this article: G. Filardo, M. Petretta, C. Cavallo, L. Roseti, S. Durante, U. Albisinni, B. Grigolo. Patient-specific meniscus prototype based on 3D bioprinting of human cell-laden scaffold. Bone Joint Res 2019;8:101–106. DOI: 10.1302/2046-3758.82.BJR-2018-0134.R1.
BibTeX:
@article{Filardo2019,
  author = {Filardo, G. and Petretta, M. and Cavallo, C. and Roseti, L. and Durante, S. and Albisinni, U. and Grigolo, B.},
  title = {Patient-specific meniscus prototype based on 3D bioprinting of human cell-laden scaffold},
  journal = {Bone & Joint Research},
  year = {2019},
  volume = {8},
  number = {2},
  pages = {101-106},
  doi = {https://doi.org/10.1302/2046-3758.82.BJR-2018-0134.R1}
}
Athanasiadis, M., Pak, A., Afanasenkau, D. and Minev, I.R. Direct Writing of Elastic Fibers with Optical, Electrical, and Microfluidic Functionality 2019 Advanced Materials Technologies
Vol. 0(0), pp. 1800659 
article DOI  
Abstract: Abstract Direct Ink Writing is an additive fabrication technology that allows the integration of a diverse range of functional materials into soft and bioinspired devices such as robots and human-machine interfaces. Typically, a viscoelastic ink is extruded from a nozzle as a continuous filament of circular cross section. Here it is shown that a careful selection of printing parameters such as nozzle height and speed can produce filaments with a range of cross-sectional geometries. Thus, elliptic cylinder-, ribbon-, or groove-shaped filaments can be printed. By using the nozzle as a stylus for postprint filament modification, even filaments with an embedded microfluidic channel can be produced. This strategy is applied to directly write freeform and elastic optical fibers, electrical interconnects, and microfluidics. The integration of these components into simple sensor-actuator systems is demonstrated. Prototypes of an optical fiber with steerable tip and a thermal actuation system for soft tissues are presented.
BibTeX:
@article{Athanasiadis2019,
  author = {Athanasiadis, Markos and Pak, Anna and Afanasenkau, Dzmitry and Minev, Ivan R.},
  title = {Direct Writing of Elastic Fibers with Optical, Electrical, and Microfluidic Functionality},
  journal = {Advanced Materials Technologies},
  year = {2019},
  volume = {0},
  number = {0},
  pages = {1800659},
  doi = {https://doi.org/10.1002/admt.201800659}
}
Sharma, A., Desando, G., Petretta, M., Chawla, S., Bartolotti, I., Manferdini, C., Paolella, F., Gabusi, E., Trucco, D., Ghosh, S. and Lisignoli, G. Investigating the Role of Sustained Calcium Release in Silk-Gelatin-Based Three-Dimensional Bioprinted Constructs for Enhancing the Osteogenic Differentiation of Human Bone Marrow Derived Mesenchymal Stromal Cells 2019 ACS Biomater. Sci. Eng.  article DOI  
BibTeX:
@article{Sharma2019,
  author = {Sharma, Aarushi and Desando, Giovanna and Petretta, Mauro and Chawla, Shikha and Bartolotti, Isabella and Manferdini, Cristina and Paolella, Francesca and Gabusi, Elena and Trucco, Diego and Ghosh, Sourabh and Lisignoli, Gina},
  title = {Investigating the Role of Sustained Calcium Release in Silk-Gelatin-Based Three-Dimensional Bioprinted Constructs for Enhancing the Osteogenic Differentiation of Human Bone Marrow Derived Mesenchymal Stromal Cells},
  journal = {ACS Biomater. Sci. Eng.},
  publisher = {American Chemical Society},
  year = {2019},
  doi = {https://doi.org/10.1021/acsbiomaterials.8b01631}
}
Pan, H.M., Chen, S., Jang, T.-S., Han, W.T., Jung, H.-d., Li, Y. and Song, J. Plant seed-inspired cell protection, dormancy, and growth for large-scale biofabrication 2019 Biofabrication
Vol. 11(2), pp. 025008 
article DOI  
Abstract: Biofabrication technologies have endowed us with the capability to fabricate complex biological constructs. However, cytotoxic biofabrication conditions have been a major challenge for their clinical application, leading to a trade-off between cell viability and scalability of biofabricated constructs. Taking inspiration from nature, we proposed a cell protection strategy which mimicks the protected and dormant state of plant seeds in adverse external conditions and their germination in response to appropriate environmental cues. Applying this bioinspired strategy to biofabrication, we successfully preserved cell viability and enhanced the seeding of cell-laden biofabricated constructs via a cytoprotective pyrogallol (PG)-alginate encapsulation system. Our cytoprotective encapsulation technology utilizes PG-triggered sporulation and germination processes to preserve cells, is mechanically robust, chemically resistant, and highly customizable to adequately match cell protectability with cytotoxicity of biofabrication conditions. More importantly, the facile and tunable decapsulation of our PG-alginate system allows for effective germination of dormant cells, under typical culture conditions. With this approach, we have successfully achieved a biofabrication process which is reproducible, scalable, and provided a practical solution for off-the-shelf availability, shipping and temporary storage of fabricated bio-constructs.
BibTeX:
@article{Pan2019,
  author = {Houwen Matthew Pan and Shengyang Chen and Tae-Sik Jang and Win Tun Han and Hyun-do Jung and Yaning Li and Juha Song},
  title = {Plant seed-inspired cell protection, dormancy, and growth for large-scale biofabrication},
  journal = {Biofabrication},
  publisher = {IOP Publishing},
  year = {2019},
  volume = {11},
  number = {2},
  pages = {025008},
  doi = {https://doi.org/10.1088/1758-5090/ab03ed}
}
Dooley, M., Prasopthum, A., Liao, Z., Sinjab, F., McLaren, J., Rose, F.R.A.J., Yang, J. and Notingher, I. Spatially-offset Raman spectroscopy for monitoring mineralization of bone tissue engineering scaffolds: feasibility study based on phantom samples 2019 Biomed. Opt. Express
Vol. 10(4), pp. 1678-1690 
article DOI URL 
Abstract: Using phantom samples, we investigated the feasibility of spatially-offset Raman spectroscopy (SORS) as a tool for monitoring non-invasively the mineralization of bone tissue engineering scaffold in-vivo. The phantom samples consisted of 3D-printed scaffolds of poly-caprolactone (PCL) and hydroxyapatite (HA) blends, with varying concentrations of HA, to mimic the mineralisation process. The scaffolds were covered by a 4 mm layer of skin to simulate the real in-vivo measurement conditions. At a concentration of HA approximately 1/3 that of bone ( 0.6 g/cm3), the characteristic Raman band of HA (960 cm&x2212;1) was detectable when the PCL:HA layer was located at 4 mm depth within the scaffold (i.e. 8 mm below the skin surface). For the layers of the PCL:HA immediately under the skin (i.e. top of the scaffold), the detection limit of HA was 0.18 g/cm3, which is approximately one order of magnitude lower than that of bone. Similar results were also found for the phantoms simulating uniform and inward gradual mineralisation of the scaffold, indicating the suitability of SORS to detect early stages of mineralisation. Nevertheless, the results also show that the contribution of the materials surrounding the scaffold can be significant and methods for subtraction need to be investigated in the future. In conclusion, these results indicate that spatially-offset Raman spectroscopy is a promising technique for in-vivo longitudinal monitoring scaffold mineralization and bone re-growth.
BibTeX:
@article{Dooley2019,
  author = {Max Dooley and Aruna Prasopthum and Zhiyu Liao and Faris Sinjab and Jane McLaren and Felicity R. A. J. Rose and Jing Yang and Ioan Notingher},
  title = {Spatially-offset Raman spectroscopy for monitoring mineralization of bone tissue engineering scaffolds: feasibility study based on phantom samples},
  journal = {Biomed. Opt. Express},
  publisher = {OSA},
  year = {2019},
  volume = {10},
  number = {4},
  pages = {1678--1690},
  url = {http://www.osapublishing.org/boe/abstract.cfm?URI=boe-10-4-1678},
  doi = {https://doi.org/10.1364/BOE.10.001678}
}
Zhang, D., Peng, E., Borayek, R. and Ding, J. Controllable Ceramic Green-Body Configuration for Complex Ceramic Architectures with Fine Features 2019 Advanced Functional Materials
Vol. 0(0), pp. 1807082 
article DOI  
Abstract: Abstract Fabrication of dense ceramic articles with intricate fine features and geometrically complex morphology by using a relatively simple and the cost-effective process still remains a challenge. Ceramics, either in its green- or sintered-form, are known for being hard yet brittle which limits further shape reconfiguration. In this work, a combinatorial process of ceramic robocasting and photopolymerization is demonstrated to produce either flexible and/or stretchable ceramic green-body (Flex-Body or Stretch-Body) that can undergo a postprinting reconfiguration process. Secondary shaping may proceed through: i) self-assembly-assisted shaping and ii) mold-assisted shaping process, which allows a well-controlled ceramic structure morphology. With a proposed well-controlled thermal heating process, the ceramic Sintered-Body can achieve >99.0% theoretical density with good mechanical rigidity. Complex and dense ceramic articles with fine features down to 65 μm can be fabricated. When combined with a multi-nozzle deposition process, i) self-shaping ceramic structures can be realized through anisotropic shrinkage induced by suspensions' composition variation and ii) technical and functional multiceramic structures can be fabricated. The simplicity of the proposed technique and its inexpensive processing cost make it an attractive approach for fabricating geometrically complex ceramic articles with unique macrostructures, which complements the existing state of-the-art ceramic additive manufacturing techniques.
BibTeX:
@article{Zhang2019,
  author = {Zhang, Danwei and Peng, Erwin and Borayek, Ramadan and Ding, Jun},
  title = {Controllable Ceramic Green-Body Configuration for Complex Ceramic Architectures with Fine Features},
  journal = {Advanced Functional Materials},
  year = {2019},
  volume = {0},
  number = {0},
  pages = {1807082},
  doi = {https://doi.org/10.1002/adfm.201807082}
}
Rathan, S., Dejob, L., Schipani, R., Haffner, B., Möbius, M.E. and Kelly, D.J. Fiber Reinforced Cartilage ECM Functionalized Bioinks for Functional Cartilage Tissue Engineering 2019 Advanced Healthcare Materials
Vol. 0(0), pp. 1801501 
article DOI  
Abstract: Abstract Focal articular cartilage (AC) defects, if left untreated, can lead to debilitating diseases such as osteoarthritis. While several tissue engineering strategies have been developed to promote cartilage regeneration, it is still challenging to generate functional AC capable of sustaining high load-bearing environments. Here, a new class of cartilage extracellular matrix (cECM)-functionalized alginate bioink is developed for the bioprinting of cartilaginous tissues. The bioinks are 3D-printable, support mesenchymal stem cell (MSC) viability postprinting and robust chondrogenesis in vitro, with the highest levels of COLLII and ACAN expression observed in bioinks containing the highest concentration of cECM. Enhanced chondrogenesis in cECM-functionalized bioinks is also associated with progression along an endochondral-like pathway, as evident by increases in RUNX2 expression and calcium deposition in vitro. The bioinks loaded with MSCs and TGF-β3 are also found capable of supporting robust chondrogenesis, opening the possibility of using such bioinks for direct “print-and-implant” cartilage repair strategies. Finally, it is demonstrated that networks of 3D-printed polycaprolactone fibers with compressive modulus comparable to native AC can be used to mechanically reinforce these bioinks, with no loss in cell viability. It is envisioned that combinations of such biomaterials can be used in multiple-tool biofabrication strategies for the bioprinting of biomimetic cartilaginous implants.
BibTeX:
@article{Rathan2019,
  author = {Rathan, Swetha and Dejob, Léa and Schipani, Rossana and Haffner, Benjamin and Möbius, Matthias E. and Kelly, Daniel J.},
  title = {Fiber Reinforced Cartilage ECM Functionalized Bioinks for Functional Cartilage Tissue Engineering},
  journal = {Advanced Healthcare Materials},
  year = {2019},
  volume = {0},
  number = {0},
  pages = {1801501},
  doi = {https://doi.org/10.1002/adhm.201801501}
}
Alison, L., Menasce, S., Bouville, F., Tervoort, E., Mattich, I., Ofner, A. and Studart, A.R. 3D printing of sacrificial templates into hierarchical porous materials 2019 Scientific Reports
Vol. 9(1), pp. 409 
article DOI  
Abstract: Hierarchical porous materials are widespread in nature and find an increasing number of applications as catalytic supports, biological scaffolds and lightweight structures. Recent advances in additive manufacturing and 3D printing technologies have enabled the digital fabrication of porous materials in the form of lattices, cellular structures and foams across multiple length scales. However, current approaches do not allow for the fast manufacturing of bulk porous materials featuring pore sizes that span broadly from macroscopic dimensions down to the nanoscale. Here, ink formulations are designed and investigated to enable 3D printing of hierarchical materials displaying porosity at the nano-, micro- and macroscales. Pores are generated upon removal of nanodroplets and microscale templates present in the initial ink. Using particles to stabilize the droplet templates is key to obtain Pickering nanoemulsions that can be 3D printed through direct ink writing. The combination of such self-assembled templates with the spatial control offered by the printing process allows for the digital manufacturing of hierarchical materials exhibiting thus far inaccessible multiscale porosity and complex geometries.
BibTeX:
@article{Alison2019,
  author = {Alison, Lauriane and Menasce, Stefano and Bouville, Florian and Tervoort, Elena and Mattich, Iacopo and Ofner, Alessandro and Studart, André R.},
  title = {3D printing of sacrificial templates into hierarchical porous materials},
  journal = {Scientific Reports},
  year = {2019},
  volume = {9},
  number = {1},
  pages = {409},
  doi = {https://doi.org/10.1038/s41598-018-36789-z}
}
Wang, W., Junior, J.R.P., Nalesso, P.R.L., Musson, D., Cornish, J., Mendonça, F., Caetano, G.F. and Bártolo, P. Engineered 3D printed poly(ɛ-caprolactone)/graphene scaffolds for bone tissue engineering 2019 Materials Science and Engineering: C
Vol. 100, pp. 759 - 770 
article DOI URL 
Abstract: Scaffolds are important physical substrates for cell attachment, proliferation and differentiation. Multiple factors could influence the optimal design of scaffolds for a specific tissue, such as the geometry, the materials used to modulate cell proliferation and differentiation, its biodegradability and biocompatibility. The optimal design of a scaffold for a specific tissue strongly depends on both materials and manufacturing processes. Previous studies of human adipose-derived stem cells (hADSCs) seeded on poly(ε-caprolactone) (PCL)/graphene scaffolds have proved that the addition of small concentrations of graphene to PCL scaffolds improves cell proliferation. Based on such results, this paper further investigates, for the first time, both in vitro and in vivo characteristics of 3D printed PCL/graphene scaffolds. Scaffolds were evaluated from morphological, biological and short term immune response points of view. Results show that the produced scaffolds induce an acceptable level of immune response, suggesting high potential for in vivo applications. Finally, the scaffolds were used to treat a rat calvaria critical size defect with and without applying micro electrical stimulation (10 μA). Quantification of connective and new bone tissue formation and the levels of ALP, RANK, RANKL, OPG were considered. Results show that the use of scaffolds containing graphene and electrical stimulation seems to increase cell migration and cell influx, leading to new tissue formation, well-organized tissue deposition and bone remodelling.
BibTeX:
@article{Wang2019a,
  author = {Weiguang Wang and José Roberto Passarini Junior and Paulo Roberto Lopes Nalesso and David Musson and Jillian Cornish and Fernanda Mendonça and Guilherme Ferreira Caetano and Paulo Bártolo},
  title = {Engineered 3D printed poly(ɛ-caprolactone)/graphene scaffolds for bone tissue engineering},
  journal = {Materials Science and Engineering: C},
  year = {2019},
  volume = {100},
  pages = {759 - 770},
  url = {http://www.sciencedirect.com/science/article/pii/S092849311930308X},
  doi = {https://doi.org/10.1016/j.msec.2019.03.047}
}
Wang, W., Huang, B., Byun, J.J. and Bártolo, P. Assessment of PCL/carbon material scaffolds for bone regeneration 2019 Journal of the Mechanical Behavior of Biomedical Materials
Vol. 93, pp. 52 - 60 
article DOI URL 
Abstract: Biomanufacturing is a relatively new research domain focusing on the use of additive manufacturing technologies, biomaterials, cells and biomolecular signals to produce tissue constructs for tissue engineering. For bone regeneration, researchers are focusing on the use of polymeric and polymer/ceramic scaffolds seeded with osteoblasts or mesenchymal stem cells. However, the design of high-performance scaffolds in terms of mechanical, cell-stimulation and biological performance is still required. This is the first paper investigating the use of an extrusion additive manufacturing system to produce poly(ε-caprolactone) (PCL), PCL/graphene nanosheet (GNS) and PCL/carbon nanotube (CNT) scaffolds for bone applications. Scaffolds with regular and reproducible architecture were produced and evaluated from chemical, physical and biological points of view. Results suggest that the addition of both graphene and CNT allow the fabrication of scaffolds with improved properties. It also shows that scaffolds containing graphene present better mechanical properties and high cell-affinity improving cell attachment, proliferation and differentiation.
BibTeX:
@article{Wang2019,
  author = {Weiguang Wang and Boyang Huang and Jae Jong Byun and Paulo Bártolo},
  title = {Assessment of PCL/carbon material scaffolds for bone regeneration},
  journal = {Journal of the Mechanical Behavior of Biomedical Materials},
  year = {2019},
  volume = {93},
  pages = {52 - 60},
  url = {http://www.sciencedirect.com/science/article/pii/S1751616118314759},
  doi = {https://doi.org/10.1016/j.jmbbm.2019.01.020}
}
Tondera, C., Akbar, T.F., Thomas, A.K., Lin, W., Werner, C., Busskamp, V., Zhang, Y. and Minev, I.R. Highly Conductive, Stretchable, and Cell-Adhesive Hydrogel by Nanoclay Doping 2019 Small
Vol. 0(0), pp. 1901406 
article DOI  
Abstract: Abstract Electrically conductive materials that mimic physical and biological properties of tissues are urgently required for seamless brain–machine interfaces. Here, a multinetwork hydrogel combining electrical conductivity of 26 S m−1, stretchability of 800 and tissue-like elastic modulus of 15 kPa with mimicry of the extracellular matrix is reported. Engineering this unique set of properties is enabled by a novel in-scaffold polymerization approach. Colloidal hydrogels of the nanoclay Laponite are employed as supports for the assembly of secondary polymer networks. Laponite dramatically increases the conductivity of in-scaffold polymerized poly(ethylene-3,4-diethoxy thiophene) in the absence of other dopants, while preserving excellent stretchability. The scaffold is coated with a layer containing adhesive peptide and polysaccharide dextran sulfate supporting the attachment, proliferation, and neuronal differentiation of human induced pluripotent stem cells directly on the surface of conductive hydrogels. Due to its compatibility with simple extrusion printing, this material promises to enable tissue-mimetic neurostimulating electrodes.
BibTeX:
@article{Tondera2019,
  author = {Tondera, Christoph and Akbar, Teuku Fawzul and Thomas, Alvin Kuriakose and Lin, Weilin and Werner, Carsten and Busskamp, Volker and Zhang, Yixin and Minev, Ivan R.},
  title = {Highly Conductive, Stretchable, and Cell-Adhesive Hydrogel by Nanoclay Doping},
  journal = {Small},
  year = {2019},
  volume = {0},
  number = {0},
  pages = {1901406},
  doi = {https://doi.org/10.1002/smll.201901406}
}
Tiwari, S. and Bahadur, P. Modified hyaluronic acid based materials for biomedical applications 2019 International Journal of Biological Macromolecules
Vol. 121, pp. 556 - 571 
article DOI URL 
Abstract: Hyaluronic acid (HA) is a high molecular weight, non-sulfated anionic polysaccharide from glycosamine glycan family. It is a versatile biomaterial that binds to specific cell receptor CD44 (frequently over-expressed on the tumor cell surface) and is useful in skin rejuvenation, drug delivery, tissue engineering and molecular imaging due to its biodegradable, non-toxic, biocompatible, non-immunogenic and non-inflammatory characteristics. It can be chemically modified by cross-linking, grafting, linking with hydrophobic substances and drugs, or through polyion complex formation with oppositely charged polysaccharides, proteins or surfactants. Its interpenetrating network produces self-assembled aggregates, nanoparticles and gels. The present review is aimed to provide recent updates on researches on HA, with an emphasis on different modification approaches. Various transformations in HA through covalent and non-covalent interactions and resulting applications in biomedical fields from the recent literature are described. Studies on stabilization of nanoparticles (NPs) and other colloidal carriers through layer-by-layer adsorption of HA are also highlighted. The article provides a greater visibility into the magnitude of HA application in the development of targeted drug vectors and implantable biomaterials.
BibTeX:
@article{Tiwari2019,
  author = {Sanjay Tiwari and Pratap Bahadur},
  title = {Modified hyaluronic acid based materials for biomedical applications},
  journal = {International Journal of Biological Macromolecules},
  year = {2019},
  volume = {121},
  pages = {556 - 571},
  url = {http://www.sciencedirect.com/science/article/pii/S0141813018342569},
  doi = {https://doi.org/10.1016/j.ijbiomac.2018.10.049}
}
Séon-Lutz, M., Couffin, A.-C., Vignoud, S., Schlatter, G. and Hébraud, A. Electrospinning in water and in situ crosslinking of hyaluronic acid / cyclodextrin nanofibers: Towards wound dressing with controlled drug release 2019 Carbohydrate Polymers
Vol. 207, pp. 276 - 287 
article DOI URL 
Abstract: Hyaluronic acid (HA) is widely investigated due to its high potential for wound dressing applications. The fabrication of biomimetic HA-based scaffolds by electrospinning is thus extensively studied. However, HA is often dissolved in toxic organic solvents to allow the efficient production of electrospun nanofibers. Indeed, although HA is soluble in water, its ionic nature leading to long-range electrostatic interactions and the presence of counter ions induce a dramatic increase of the viscosity of aqueous HA solutions without insuring enough chain entanglements necessary for a stable and efficient electrospinning. In this study, biocompatible insoluble HA-based nanofibers were fabricated by electrospinning in pure water. To this end, poly(vinyl alcohol) (PVA) was added as a carrier polymer and it was found that the addition of hydroxypropyl-βcyclodextrin (HPβCD) stabilized the process of electrospinning and led to the efficient formation of uniform nanofibrous scaffolds. An in situ crosslinking process of the scaffolds is also proposed, insuring a whole fabrication process without any toxicity. Furthermore, the beneficial presence of HPβCD in the HA-based scaffolds paves the way for wound dressing applications with controlled drug encapsulation-release properties. As a proof of concept, naproxen (NAP), a non-steroidal anti-inflammatory drug was chosen as a model drug. NAP was impregnated into the scaffolds either in aqueous solution or under supercritical CO2. The resulting functional scaffolds showed a regular drug release profile along several days without losing the fibrous structure. This study proposes a simple approach to form stable HA-based nanofibrous scaffolds embedding HPβCD using water as the only solvent, enabling the development of safe functional wound dressings.
BibTeX:
@article{Seon-Lutz2019,
  author = {Morgane Séon-Lutz and Anne-Claude Couffin and Séverine Vignoud and Guy Schlatter and Anne Hébraud},
  title = {Electrospinning in water and in situ crosslinking of hyaluronic acid / cyclodextrin nanofibers: Towards wound dressing with controlled drug release},
  journal = {Carbohydrate Polymers},
  year = {2019},
  volume = {207},
  pages = {276 - 287},
  url = {http://www.sciencedirect.com/science/article/pii/S0144861718314188},
  doi = {https://doi.org/10.1016/j.carbpol.2018.11.085}
}
Derr, K., Zou, J., Luo, K., Song, M.J., Sittampalam, G.S., Zhou, C., Michael, S., Ferrer, M. and Derr, P. Fully 3D Bioprinted Skin Equivalent Constructs with Validated Morphology and Barrier Function 2019 Tissue Engineering Part C: Methods
Vol. 0(ja), pp. null 
article DOI  
Abstract: Development of high throughput, reproducible, three-dimensional bioprinted skin equivalents that are morphologically and functionally comparable to native skin tissue is advancing research in skin diseases, and providing a physiologically relevant platform for the development of therapeutics, transplants for regenerative medicine, and testing of skin products like cosmetics. Current protocols for the production of engineered skin rafts are limited in their ability to control three dimensional geometry of the structure and contraction leading to variability of skin function between constructs. Here we describe a method for the biofabrication of skin equivalents that are fully bioprinted using an open market bioprinter, made with commercially available primary cells and natural hydrogels. The unique hydrogel formulation allows for the production of a human-like skin equivalent with minimal lateral tissue contraction in a multiwell plate format, thus making them suitable for high throughput bioprinting in a single print with fast print and relatively short incubation times. The morphology and barrier function of the fully three-dimensional bioprinted skin equivalents are validated by immunohistochemistry staining, optical coherence tomography, and permeation assays.
BibTeX:
@article{Derr2019,
  author = {Derr, Kristy and Zou, Jinyun and Luo, Keren and Song, Min Jae and Sittampalam, G. Sitta and Zhou, Chao and Michael, Samuel and Ferrer, Marc and Derr, Paige},
  title = {Fully 3D Bioprinted Skin Equivalent Constructs with Validated Morphology and Barrier Function},
  journal = {Tissue Engineering Part C: Methods},
  year = {2019},
  volume = {0},
  number = {ja},
  pages = {null},
  note = {PMID: 31007132},
  doi = {https://doi.org/10.1089/ten.TEC.2018.0318}
}
Daly, A.C. and Kelly, D.J. Biofabrication of spatially organised tissues by directing the growth of cellular spheroids within 3D printed polymeric microchambers 2019 Biomaterials
Vol. 197, pp. 194 - 206 
article DOI URL 
Abstract: Successful tissue engineering requires the generation of human scale implants that mimic the structure, composition and mechanical properties of native tissues. Here, we report a novel biofabrication strategy that enables the engineering of structurally organised tissues by guiding the growth of cellular spheroids within arrays of 3D printed polymeric microchambers. With the goal of engineering stratified articular cartilage, inkjet bioprinting was used to deposit defined numbers of mesenchymal stromal cells (MSCs) and chondrocytes into pre-printed microchambers. These jetted cell suspensions rapidly underwent condensation within the hydrophobic microchambers, leading to the formation of organised arrays of cellular spheroids. The microchambers were also designed to provide boundary conditions to these spheroids, guiding their growth and eventual fusion, leading to the development of stratified cartilage tissue with a depth-dependant collagen fiber architecture that mimicked the structure of native articular cartilage. Furthermore, the composition and biomechanical properties of the bioprinted cartilage was also comparable to the native tissue. Using multi-tool biofabrication, we were also able to engineer anatomically accurate, human scale, osteochondral templates by printing this microchamber system on top of a hypertrophic cartilage region designed to support endochondral bone formation and then maintaining the entire construct in long-term bioreactor culture to enhance tissue development. This bioprinting strategy provides a versatile and scalable approach to engineer structurally organised cartilage tissues for joint resurfacing applications.
BibTeX:
@article{Daly2019,
  author = {Andrew C. Daly and Daniel J. Kelly},
  title = {Biofabrication of spatially organised tissues by directing the growth of cellular spheroids within 3D printed polymeric microchambers},
  journal = {Biomaterials},
  year = {2019},
  volume = {197},
  pages = {194 - 206},
  url = {http://www.sciencedirect.com/science/article/pii/S0142961218308639},
  doi = {https://doi.org/10.1016/j.biomaterials.2018.12.028}
}
Creusen, G., Roshanasan, A., Garcia Lopez, J., Peneva, K. and Walther, A. Bottom-up design of model network elastomers and hydrogels from precise star polymers 2019 Polym. Chem., pp. -  article DOI  
Abstract: We introduce a platform for the simultaneous design of model network hydrogels and bulk elastomers based on well-defined water-soluble star polymers with a low glass transition temperature (Tg). This platform is enabled via the development of a synthetic route to a new family of 4-arm star polymers based on water-soluble poly(triethylene glycol methyl ether acrylate) (p(mTEGA)), which after quantitative introduction of functional end-groups can serve as suitable building blocks for model network formation. We first describe in detail the synthesis of highly defined star polymers using light and Cu-wire mediated Cu-based reversible deactivation radical polymerization. The resulting polymers exhibit narrow dispersities and controlled arm length at very high molecular weights, and feature a desirable low Tg of −55 °C. Subsequently, we elucidate the rational design of the stiffness and elasticity in covalent model network elastomers and hydrogels formed by fast photo-crosslinking for different arm lengths, and construct thermally reversible model network hydrogels based on dynamic supramolecular bonds. In addition, we describe preliminary 3D-printing applications. This work provides a key alternative to commonly used star-poly(ethylene glycol) (PEG) for model hydrogel networks, and demonstrates access to new main and side chain chemistries, thus chain stiffnesses and entanglement molecular weight, and, critically, enables the simultaneous study of the mechanical behavior of bulk network elastomers and swollen hydrogels with the same network topology. In a wider perspective, this work also highlights the need for advancing precision polymer chemistry to allow for an understanding of architectural control for the rational design of functional mechanical network materials.
BibTeX:
@article{Creusen2019,
  author = {Creusen, Guido and Roshanasan, Ardeshir and Garcia Lopez, Javier and Peneva, Kalina and Walther, Andreas},
  title = {Bottom-up design of model network elastomers and hydrogels from precise star polymers},
  journal = {Polym. Chem.},
  publisher = {The Royal Society of Chemistry},
  year = {2019},
  pages = {-},
  doi = {https://doi.org/10.1039/C9PY00731H}
}
Costa, P.F. Translating Biofabrication to the Market 2019 Trends in Biotechnology  article DOI URL 
Abstract: Biofabrication holds great potential to revolutionize important industries in the health, food, and textile sectors, but its translation to market is still challenging. I analyze the current state of innovation and commercialization in biofabrication and try to assess its limitations, strengths, and future progress.
BibTeX:
@article{Costa2019,
  author = {Pedro F. Costa},
  title = {Translating Biofabrication to the Market},
  journal = {Trends in Biotechnology},
  year = {2019},
  url = {http://www.sciencedirect.com/science/article/pii/S0167779919300915},
  doi = {https://doi.org/10.1016/j.tibtech.2019.04.013}
}
Cernencu, A.I., Lungu, A., Stancu, I.-C., Serafim, A., Heggset, E., Syverud, K. and Iovu, H. Bioinspired 3D printable pectin-nanocellulose ink formulations 2019 Carbohydrate Polymers
Vol. 220, pp. 12 - 21 
article DOI URL 
Abstract: The assessment of several ink formulations for 3D printing based on two natural macromolecular compounds is presented. In the current research we have exploited the fast crosslinking potential of pectin and the remarkable shear-thinning properties of carboxylated cellulose nanofibrils, which is known to induce a desired viscoelastic behavior. Prior to 3D printing, the viscoelastic properties of the polysaccharide inks were evaluated by rheological measurements and injectability tests. The reliance of the printing parameters on the ink composition was established through one-dimensional lines printing, the base units of 3D-structures. The performance of the 3D-printed structures after ionic cross-linking was evaluated in terms of mechanical properties and rehydration behavior. MicroCT was also used to evaluate the morphology of the 3D-printed objects regarding the effect of pectin/nanocellulose ratio on the geometrical features of scaffolds. The proportionality between the two polymers proved to be the determining factor for the firmness and strength of the printed objects.
BibTeX:
@article{Cernencu2019,
  author = {Alexandra I. Cernencu and Adriana Lungu and Izabela-Cristina Stancu and Andrada Serafim and Ellinor Heggset and Kristin Syverud and Horia Iovu},
  title = {Bioinspired 3D printable pectin-nanocellulose ink formulations},
  journal = {Carbohydrate Polymers},
  year = {2019},
  volume = {220},
  pages = {12 - 21},
  url = {http://www.sciencedirect.com/science/article/pii/S0144861719305314},
  doi = {https://doi.org/10.1016/j.carbpol.2019.05.026}
}
Altun, E., Aydogdu, M.O., Togay, S.O., Sengil, A.Z., Ekren, N., Haskoylu, M.E., Oner, E.T., Altuncu, N.A., Ozturk, G., Crabbe-Mann, M., Ahmed, J., Gunduz, O. and Edirisinghe, M. Bioinspired Scaffold Induced Regeneration of Neural Tissue 2019 European Polymer Journal  article DOI URL 
Abstract: In the last decade, nerve tissue engineering has attracted much attention due to the incapability of self-regeneration. Nerve tissue regeneration is mainly based on scaffold induced nanofibrous structures using both bio and synthetic polymers. The produced nanofibrous scaffolds have to be similar to the natural extracellular matrix and should provide an appropriate environment for cells to attach onto. Nanofibrous scaffolds can support or regenerate cells of tissue. Electrospinning is an ideal method for producing the nanofibrous scaffolds. In this study, Bacterial cellulose (BC)/ Poly (ε-caprolactone) (PCL) blend nanofibrous scaffolds were successfully prepared by electrospinning for nerve tissue induced repair. The produced nanofibrous scaffolds contain well defined interconnected nanofiber networks with hollow micro/nanobeads. Firstly, in-vitro biocompatibilities of nanofibrous scaffolds were tested with L2929 murine fibroblasts and improved cell adhesion and proliferation was observed with polymer blends compared with PCL only. The primary cell culture was performed with dorsal root ganglia (DRG) cells on nanofibrous samples and the samples were found suitable for enhancing neural growth and neurite outgrowth. Based on these results, the BC/PCL (50:50 wt. %) nanofibrous scaffolds exhibited nerve-like branching and are excellent candidate for potential biomimetic applications in nerve tissue engineering regeneration.
BibTeX:
@article{Altun2019,
  author = {Esra Altun and Mehmet O. Aydogdu and Sine O. Togay and Ahmet Z. Sengil and Nazmi Ekren and Merve E. Haskoylu and Ebru T. Oner and Nese A. Altuncu and Gurkan Ozturk and Maryam Crabbe-Mann and Jubair Ahmed and Oguzhan Gunduz and Mohan Edirisinghe},
  title = {Bioinspired Scaffold Induced Regeneration of Neural Tissue},
  journal = {European Polymer Journal},
  year = {2019},
  url = {http://www.sciencedirect.com/science/article/pii/S0014305718324765},
  doi = {https://doi.org/10.1016/j.eurpolymj.2019.02.008}
}
Khaled, S.A., Alexander, M.R., Irvine, D.J., Wildman, R.D., Wallace, M.J., Sharpe, S., Yoo, J. and Roberts, C.J. Extrusion 3D Printing of Paracetamol Tablets from a Single Formulation with Tunable Release Profiles Through Control of Tablet Geometry 2018 AAPS PharmSciTech
Vol. 19(8), pp. 3403-3413 
article DOI  
Abstract: An extrusion-based 3D printer was used to fabricate paracetamol tablets with different geometries (mesh, ring and solid) from a single paste-based formulation formed from standard pharmaceutical ingredients. The tablets demonstrate that tunable drug release profiles can be achieved from this single formulation even with high drug loading (>thinspace80% w/w). The tablets were evaluated for drug release using a USP dissolution testing type I apparatus. The tablets showed well-defined release profiles (from immediate to sustained release) controlled by their different geometries. The dissolution results showed dependency of drug release on the surface area/volume (SA/V) ratio and the SA of the different tablets. The tablets with larger SA/V ratios and SA had faster drug release. The 3D printed tablets were also evaluated for physical and mechanical properties including tablet dimension, drug content, weight variation and breaking force and were within acceptable range as defined by the international standards stated in the US Pharmacopoeia. X-ray powder diffraction, differential scanning calorimetry and attenuated total reflectance Fourier transform infrared spectroscopy were used to identify the physical form of the active and to assess possible drug-excipient interactions. These data again showed that the tablets meet USP requirement. These results clearly demonstrate the potential of 3D printing to create unique pharmaceutical manufacturing, and potentially clinical, opportunities. The ability to use a single unmodified formulation to achieve defined release profiles could allow, for example, relatively straightforward personalization of medicines for individuals with different metabolism rates for certain drugs and hence could offer significant development and clinical opportunities.
BibTeX:
@article{Khaled2018a,
  author = {Khaled, Shaban A. and Alexander, Morgan R. and Irvine, Derek J. and Wildman, Ricky D. and Wallace, Martin J. and Sharpe, Sonja and Yoo, Jae and Roberts, Clive J.},
  title = {Extrusion 3D Printing of Paracetamol Tablets from a Single Formulation with Tunable Release Profiles Through Control of Tablet Geometry},
  journal = {AAPS PharmSciTech},
  year = {2018},
  volume = {19},
  number = {8},
  pages = {3403--3413},
  doi = {https://doi.org/10.1208/s12249-018-1107-z}
}
Zamani, Y., Mohammadi, J., Amoabediny, G., Visscher, D.O., Helder, M.N., Zandieh-Doulabi, B. and Klein-Nulend, J. Enhanced osteogenic activity by MC3T3-E1 pre-osteoblasts on chemically surface-modified poly(upepsilon-caprolactone) 3D-printed scaffolds compared to RGD immobilized scaffolds 2018 Biomedical Materials
Vol. 14(1), pp. 015008 
article DOI  
Abstract: In bone tissue engineering, the intrinsic hydrophobicity and surface smoothness of three-dimensional (3D)-printed poly(ε-caprolactone) scaffolds hamper cell attachment, proliferation and differentiation. This intrinsic hydrophobicity of poly(ε-caprolactone) can be overcome by surface modifications, such as surface chemical modification or immobilization of biologically active molecules on the surface. Moreover, surface chemical modification may alter surface smoothness. Whether surface chemical modification or immobilization of a biologically active molecule on the surface is more effective to enhance pre-osteoblast proliferation and differentiation is currently unknown. Therefore, we aimed to investigate the osteogenic response of MC3T3-E1 pre-osteoblasts to chemically surface-modified and RGD-immobilized 3D-printed poly(ε-caprolactone) scaffolds. Poly(ε-caprolactone) scaffolds were 3D-printed consisting of strands deposited layer by layer with alternating 0°/90° lay-down pattern. 3D-printed poly(ε-caprolactone) scaffolds were surface-modified by either chemical modification using 3 M sodium hydroxide (NaOH) for 24 or 72 h, or by RGD-immobilization. Strands were visualized by scanning electron microscopy. MC3T3-E1 pre-osteoblasts were seeded onto the scaffolds and cultured up to 14 d. The strands of the unmodified poly(ε-caprolactone) scaffold had a smooth surface. NaOH treatment changed the scaffold surface topography from smooth to a honeycomb-like surface pattern, while RGD immobilization did not alter the surface topography. MC3T3-E1 pre-osteoblast seeding efficiency was similar (44%–54%) on all scaffolds after 12 h. Cell proliferation increased from day 1 to day 14 in unmodified controls (1.9-fold), 24 h NaOH-treated scaffolds (3-fold), 72 h NaOH-treated scaffolds (2.2-fold), and RGD-immobilized scaffolds (4.5-fold). At day 14, increased collagenous matrix deposition was achieved only on 24 h NaOH-treated (1.8-fold) and RGD-immobilized (2.2-fold) scaffolds compared to unmodified controls. Moreover, 24 h, but not 72 h, NaOH-treated scaffolds, increased alkaline phosphatase activity by 5-fold, while the increase by RGD immobilization was only 2.5-fold. Only 24 h NaOH-treated scaffolds enhanced mineralization (2.0-fold) compared to unmodified controls. In conclusion, RGD immobilization (0.011 μg mg−1 scaffold) on the surface and 24 h NaOH treatment of the surface of 3D-printed PCL scaffold both enhance pre-osteoblast proliferation and matrix deposition while only 24 h NaOH treatment results in increased osteogenic activity, making it the treatment of choice to promote bone formation by osteogenic cells.
BibTeX:
@article{Zamani2018,
  author = {Yasaman Zamani and Javad Mohammadi and Ghassem Amoabediny and Dafydd O Visscher and Marco N Helder and Behrouz Zandieh-Doulabi and Jenneke Klein-Nulend},
  title = {Enhanced osteogenic activity by MC3T3-E1 pre-osteoblasts on chemically surface-modified poly(upepsilon-caprolactone) 3D-printed scaffolds compared to RGD immobilized scaffolds},
  journal = {Biomedical Materials},
  publisher = {IOP Publishing},
  year = {2018},
  volume = {14},
  number = {1},
  pages = {015008},
  doi = {https://doi.org/10.1088/1748-605x/aaeb82}
}
Li, H., Tan, Y.J. and Li, L. A strategy for strong interface bonding by 3D bioprinting of oppositely charged κ-carrageenan and gelatin hydrogels 2018 Carbohydrate Polymers
Vol. 198, pp. 261-269 
article URL 
Abstract: A promising approach for improving the interfacial bonding of a three-dimensionally (3D) printed multilayered structure has been investigated by taking advantage of the electrostatic interactions between two hydrogels with oppositely charges. Here, two hydrogels namely gelatin and κ-carrageenan, which are the cationic and anionic hydrogels respectively, are used. It is found that the interfacial bonding strength between these two oppositely charged hydrogels is significantly higher than that of a bilayered gelatin or a bilayered κ-carrageenan. The bioprinted multilayered κ-carrageenan-gelatin hydrogel construct demonstrates a very good biocompatibility and a good structure integrity at 37 °C. Our strategy also overcomes the limitation of using gelatin for bio-fabrication at 37 °C, without further post crosslinking.
BibTeX:
@article{Li2018b,
  author = {Li, Huijun and Tan, Yu Jun and Li, Lin},
  title = {A strategy for strong interface bonding by 3D bioprinting of oppositely charged κ-carrageenan and gelatin hydrogels},
  journal = {Carbohydrate Polymers},
  year = {2018},
  volume = {198},
  pages = {261--269},
  url = {http://www.sciencedirect.com/science/article/pii/S0144861718307355}
}
Florczak, S., Lorson, T., Zheng, T., Mrlik, M., Hutmacher, D., Higgins, M., Luxenhofer, R. and Dalton, P. Melt Electrowriting of Electroactive Poly(vinylidene difluoride) Fibers 2018 ChemRxiv  article DOI URL 
BibTeX:
@article{Florczak2018,
  author = {Sammy Florczak and Thomas Lorson and Tian Zheng and Miroslav Mrlik and Dietmar Hutmacher and Michael Higgins and Robert Luxenhofer and Paul Dalton},
  title = {Melt Electrowriting of Electroactive Poly(vinylidene difluoride) Fibers},
  journal = {ChemRxiv},
  year = {2018},
  url = {https://chemrxiv.org/articles/Melt_Electrowriting_of_Electroactive_Poly_vinylidene_difluoride_Fibers/7195460},
  doi = {https://doi.org/10.26434/chemrxiv.7195460.v1}
}
Petta, D., Armiento, A.R., Grijpma, D., Alini, M., Eglin, D. and D'Este, M. 3D bioprinting of a hyaluronan bioink through enzymatic-and visible light-crosslinking 2018 Biofabrication
Vol. 10(4), pp. 044104 
article DOI  
Abstract: Extrusion-based three-dimensional bioprinting relies on bioinks engineered to combine viscoelastic properties for extrusion and shape retention, and biological properties for cytocompatibility and tissue regeneration. To satisfy these conflicting requirements, bioinks often utilize either complex mixtures or complex modifications of biopolymers. In this paper we introduce and characterize a bioink exploiting a dual crosslinking mechanism, where an enzymatic reaction forms a soft gel suitable for cell encapsulation and extrusion, while a visible light photo-crosslinking allows shape retention of the printed construct. The influence of cell density and cell type on the rheological and printability properties was assessed correlating the printing outcomes with the damping factor, a rheological characteristic independent of the printing system. Stem cells, chondrocytes and fibroblasts were encapsulated, and their viability was assessed up to 14 days with live/dead, alamar blue and trypan blue assays. Additionally, the impact of the printing parameters on cell viability was investigated. Owing to its straightforward preparation, low modification, presence of two independent crosslinking mechanisms for tuning shear-thinning independently of the final shape fixation, the use of visible green instead of UV light, the possibility of encapsulating and sustaining the viability of different cell types, the hyaluronan bioink here presented is a valid biofabrication tool for producing 3D printed tissue-engineered constructs.
BibTeX:
@article{Petta2018,
  author = {D Petta and A R Armiento and D Grijpma and M Alini and D Eglin and M D'Este},
  title = {3D bioprinting of a hyaluronan bioink through enzymatic-and visible light-crosslinking},
  journal = {Biofabrication},
  publisher = {IOP Publishing},
  year = {2018},
  volume = {10},
  number = {4},
  pages = {044104},
  doi = {https://doi.org/10.1088/1758-5090/aadf58}
}
García-Lizarribar, A., Fernández-Garibay, X., Velasco-Mallorquí, F., G. Castaño, A., Samitier, J. and Ramón-Azcón, J. Composite Biomaterials as Long-Lasting Scaffolds for 3D Bioprinting of Highly Aligned Muscle Tissue 2018 Macromolecular Bioscience
Vol. 18, pp. 1800167 
article DOI  
BibTeX:
@article{Garcia-Lizarribar2018,
  author = {García-Lizarribar, Andrea and Fernández-Garibay, Xiomara and Velasco-Mallorquí, Ferran and G. Castaño, Albert and Samitier, Josep and Ramón-Azcón, Javier},
  title = {Composite Biomaterials as Long-Lasting Scaffolds for 3D Bioprinting of Highly Aligned Muscle Tissue},
  journal = {Macromolecular Bioscience},
  year = {2018},
  volume = {18},
  pages = {1800167},
  doi = {https://doi.org/10.1002/mabi.201800167}
}
Gleadall, A., Visscher, D., Yang, J., Thomas, D. and Segal, J. Review of additive manufactured tissue engineering scaffolds: relationship between geometry and performance 2018 Burns & Trauma
Vol. 6(1), pp. 19 
article DOI  
Abstract: Material extrusion additive manufacturing has rapidly grown in use for tissue engineering research since its adoption in the year 2000. It has enabled researchers to produce scaffolds with intricate porous geometries that were not feasible with traditional manufacturing processes. Researchers can control the structural geometry through a wide range of customisable printing parameters and design choices including material, print path, temperature, and many other process parameters. Currently, the impact of these choices is not fully understood. This review focuses on how the position and orientation of extruded filaments, which sometimes referred to as the print path, lay-down pattern, or simply ``scaffold design'', affect scaffold properties and biological performance. By analysing trends across multiple studies, new understanding was developed on how filament position affects mechanical properties. Biological performance was also found to be affected by filament position, but a lack of consensus between studies indicates a need for further research and understanding. In most research studies, scaffold design was dictated by capabilities of additive manufacturing software rather than free-form design of structural geometry optimised for biological requirements. There is scope for much greater application of engineering innovation to additive manufacture novel geometries. To achieve this, better understanding of biological requirements is needed to enable the effective specification of ideal scaffold geometries.
BibTeX:
@article{Gleadall2018,
  author = {Gleadall, Andrew and Visscher, Dafydd and Yang, Jing and Thomas, Daniel and Segal, Joel},
  title = {Review of additive manufactured tissue engineering scaffolds: relationship between geometry and performance},
  journal = {Burns & Trauma},
  year = {2018},
  volume = {6},
  number = {1},
  pages = {19},
  doi = {https://doi.org/10.1186/s41038-018-0121-4}
}
Gullo, M.R., Koeser, J., Ruckli, O., Eigenmann, A. and Hradetzky, D. Rapid Prototyping Method for 3D Printed Biomaterial Constructs with Vascular Structures 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), pp. 5729-5732  inproceedings DOI  
Abstract: This paper presents a fabrication method for rapid prototyping of 3D biomaterial constructs with vascular structures. The method relies on poloxamer fugitive ink, which is over casted with a custom-made alginate based model extracellular matrix (ECM). The presented method is simple to implement and compatible with standard cell culture workflows used in biomedical research and pharmaceutical development. We present the material preparation, gelation properties and printing methods in detail. First experiments demonstrate the suitability of the ECM constructs for 3D tissue culture.
BibTeX:
@inproceedings{Gullo2018,
  author = {Gullo, Maurizio R. and Koeser, J. and Ruckli, O. and Eigenmann, A. and Hradetzky, D.},
  title = {Rapid Prototyping Method for 3D Printed Biomaterial Constructs with Vascular Structures},
  booktitle = {40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC)},
  year = {2018},
  pages = {5729-5732},
  doi = {https://doi.org/10.1109/EMBC.2018.8513630}
}
Gill, E.L., Li, X., Birch, M.A. and Huang, Y.Y.S. Multi-length scale bioprinting towards simulating microenvironmental cues 2018 Bio-Design and Manufacturing
Vol. 1(2), pp. 77-88 
article DOI  
Abstract: It is envisaged that the creation of cellular environments at multiple length scales, that recapitulate in vivo bioactive and structural roles, may hold the key to creating functional, complex tissues in the laboratory. This review considers recent advances in biofabrication and bioprinting techniques across different length scales. Particular focus is placed on 3D printing of hydrogels and fabrication of biomaterial fibres that could extend the feature resolution and material functionality of soft tissue constructs. The outlook from this review discusses how one might create and simulate microenvironmental cues in vitro. A fabrication platform that integrates the competencies of different biofabrication technologies is proposed. Such a multi-process, multiscale fabrication strategy may ultimately translate engineering capability into an accessible life sciences toolkit, fulfilling its potential to deliver in vitro disease models and engineered tissue implants.
BibTeX:
@article{Gill2018,
  author = {Gill, Elisabeth L. and Li, Xia and Birch, Mark A. and Huang, Yan Yan Shery},
  title = {Multi-length scale bioprinting towards simulating microenvironmental cues},
  journal = {Bio-Design and Manufacturing},
  year = {2018},
  volume = {1},
  number = {2},
  pages = {77--88},
  doi = {https://doi.org/10.1007/s42242-018-0014-1}
}
Choudhury, D., Anand, S. and Win Naing, M. The Arrival of Commercial Bioprinters - Towards 3D Bioprinting Revolution! 2018 International Journal of Bioprinting
Vol. 4 
article DOI  
BibTeX:
@article{Choudhury2018,
  author = {Choudhury, Deepak and Anand, Shivesh and Win Naing, May},
  title = {The Arrival of Commercial Bioprinters - Towards 3D Bioprinting Revolution!},
  journal = {International Journal of Bioprinting},
  year = {2018},
  volume = {4},
  doi = {https://doi.org/10.18063/IJB.v4i2.139}
}
Theiler, P.M., Lütolf, F. and Ferrini, R. Non-contact printing of optical waveguides using capillary bridges 2018 Opt. Express
Vol. 26(9), pp. 11934-11939 
article DOI URL 
Abstract: Non-contact printing methods such as inkjet, electro hydrodynamic, and aerosol printing have attracted attention for their precise deposition of functional materials that are needed in printed electronics, optoelectronics, photonics, biotechnology, and microfluidics. In this article, we demonstrate printing of tapered optical waveguides with losses of 0.61 &x00B1; 0.26 dB/cm, with the best performing structure achieving 0.19 dB/cm. Such continuous features are indispensable for successfully printing functional patterns, but they are often corrupted by capillary forces. The proposed inkjet printing method uses these forces to align liquid bridges into continuous features, enabling the printing of smooth lines on substrates with arbitrary contact angles.
BibTeX:
@article{Theiler2018,
  author = {Pius M. Theiler and Fabian Lütolf and Rolando Ferrini},
  title = {Non-contact printing of optical waveguides using capillary bridges},
  journal = {Opt. Express},
  publisher = {OSA},
  year = {2018},
  volume = {26},
  number = {9},
  pages = {11934--11939},
  url = {http://www.opticsexpress.org/abstract.cfm?URI=oe-26-9-11934},
  doi = {https://doi.org/10.1364/OE.26.011934}
}
Agarwala, S., Lee, J.M., Ng, W.L., Layani, M., Yeong, W.Y. and Magdassi, S. A novel 3D bioprinted flexible and biocompatible hydrogel bioelectronic platform 2018 Biosensors and Bioelectronics
Vol. 102(Supplement C), pp. 365 - 371 
article DOI URL 
Abstract: Abstract Bioelectronics platforms are gaining widespread attention as they provide a template to study the interactions between biological species and electronics. Decoding the effect of the electrical signals on the cells and tissues holds the promise for treating the malignant tissue growth, regenerating organs and engineering new-age medical devices. This work is a step forward in this direction, where bio- and electronic materials co-exist on one platform without any need for post processing. We fabricate a freestanding and flexible hydrogel based platform using 3D bioprinting. The fabrication process is simple, easy and provides a flexible route to print materials with preferred shapes, size and spatial orientation. Through the design of interdigitated electrodes and heating coil, the platform can be tailored to print various circuits for different functionalities. The biocompatibility of the printed platform is tested using C2C12 murine myoblasts cell line. Furthermore, normal human dermal fibroblasts (primary cells) are also seeded on the platform to ascertain the compatibility.
BibTeX:
@article{Agarwala2018,
  author = {Shweta Agarwala and Jia Min Lee and Wei Long Ng and Michael Layani and Wai Yee Yeong and Shlomo Magdassi},
  title = {A novel 3D bioprinted flexible and biocompatible hydrogel bioelectronic platform},
  journal = {Biosensors and Bioelectronics},
  year = {2018},
  volume = {102},
  number = {Supplement C},
  pages = {365 - 371},
  url = {http://www.sciencedirect.com/science/article/pii/S0956566317307698},
  doi = {https://doi.org/10.1016/j.bios.2017.11.039}
}
Monzón, M., Liu, C., Ajami, S., Oliveira, M., Donate, R., Ribeiro, V. and Reis, R.L. Functionally graded additive manufacturing to achieve functionality specifications of osteochondral scaffolds 2018 Bio-Design and Manufacturing
Vol. 1(1), pp. 69-75 
article DOI  
BibTeX:
@article{Monzon2018,
  author = {Monzón, Mario and Liu, Chaozong and Ajami, Sara and Oliveira, Miguel and Donate, Ricardo and Ribeiro, Viviana and Reis, Rui L.},
  title = {Functionally graded additive manufacturing to achieve functionality specifications of osteochondral scaffolds},
  journal = {Bio-Design and Manufacturing},
  year = {2018},
  volume = {1},
  number = {1},
  pages = {69--75},
  doi = {https://doi.org/10.1007/s42242-018-0003-4}
}
Tognato, R., Armiento, A.R., Bonfrate, V., Levato, R., Malda, J., Alini, M., Eglin, D., Giancane, G. and Serra, T. A Stimuli-Responsive Nanocomposite for 3D Anisotropic Cell-Guidance and Magnetic Soft Robotics 2018 Adv. Funct. Mater.
Vol. 29(9), pp. 1804647 
article DOI  
Abstract: Abstract Stimuli-responsive materials have the potential to enable the generation of new bioinspired devices with unique physicochemical properties and cell-instructive ability. Enhancing biocompatibility while simplifying the production methodologies, as well as enabling the creation of complex constructs, i.e., via 3D (bio)printing technologies, remains key challenge in the field. Here, a novel method is presented to biofabricate cellularized anisotropic hybrid hydrogel through a mild and biocompatible process driven by multiple external stimuli: magnetic field, temperature, and light. A low-intensity magnetic field is used to align mosaic iron oxide nanoparticles (IOPs) into filaments with tunable size within a gelatin methacryloyl matrix. Cells seeded on top or embedded within the hydrogel align to the same axes of the IOPs filaments. Furthermore, in 3D, C2C12 skeletal myoblasts differentiate toward myotubes even in the absence of differentiation media. 3D printing of the nanocomposite hydrogel is achieved and creation of complex heterogeneous structures that respond to magnetic field is demonstrated. By combining the advanced, stimuli-responsive hydrogel with the architectural control provided by bioprinting technologies, 3D constructs can also be created that, although inspired by nature, express functionalities beyond those of native tissue, which have important application in soft robotics, bioactuators, and bionic devices.
BibTeX:
@article{Tognato2018,
  author = {Tognato, Riccardo and Armiento, Angela R. and Bonfrate, Valentina and Levato, Riccardo and Malda, Jos and Alini, Mauro and Eglin, David and Giancane, Gabriele and Serra, Tiziano},
  title = {A Stimuli-Responsive Nanocomposite for 3D Anisotropic Cell-Guidance and Magnetic Soft Robotics},
  journal = {Adv. Funct. Mater.},
  publisher = {John Wiley & Sons, Ltd},
  year = {2018},
  volume = {29},
  number = {9},
  pages = {1804647},
  doi = {https://doi.org/10.1002/adfm.201804647}
}
De Smet, L., Vancoillie, G., Minshall, P., Lava, K., Steyaert, I., Schoolaert, E., Van De Walle, E., Dubruel, P., De Clerck, K. and Hoogenboom, R. Plasma dye coating as straightforward and widely applicable procedure for dye immobilization on polymeric materials 2018 Nature Communications
Vol. 9(1), pp. 1123 
article DOI  
Abstract: Here, we introduce a novel concept for the fabrication of colored materials with significantly reduced dye leaching through covalent immobilization of the desired dye using plasma-generated surface radicals. This plasma dye coating (PDC) procedure immobilizes a pre-adsorbed layer of a dye functionalized with a radical sensitive group on the surface through radical addition caused by a short plasma treatment. The non-specific nature of the plasma-generated surface radicals allows for a wide variety of dyes including azobenzenes and sulfonphthaleins, functionalized with radical sensitive groups to avoid significant dye degradation, to be combined with various materials including PP, PE, PA6, cellulose, and PTFE. The wide applicability, low consumption of dye, relatively short procedure time, and the possibility of continuous PDC using an atmospheric plasma reactor make this procedure economically interesting for various applications ranging from simple coloring of a material to the fabrication of chromic sensor fabrics as demonstrated by preparing a range of halochromic materials.
BibTeX:
@article{DeSmet2018,
  author = {De Smet, Lieselot and Vancoillie, Gertjan and Minshall, Peter and Lava, Kathleen and Steyaert, Iline and Schoolaert, Ella and Van De Walle, Elke and Dubruel, Peter and De Clerck, Karen and Hoogenboom, Richard},
  title = {Plasma dye coating as straightforward and widely applicable procedure for dye immobilization on polymeric materials},
  journal = {Nature Communications},
  year = {2018},
  volume = {9},
  number = {1},
  pages = {1123},
  doi = {https://doi.org/10.1038/s41467-018-03583-4}
}
Schaffner, M., Faber, J.A., Pianegonda, L., Rühs, P.A., Coulter, F. and Studart, A.R. 3D printing of robotic soft actuators with programmable bioinspired architectures 2018 Nature Communications
Vol. 9(1), pp. 878 
article DOI  
Abstract: Soft actuation allows robots to interact safely with humans, other machines, and their surroundings. Full exploitation of the potential of soft actuators has, however, been hindered by the lack of simple manufacturing routes to generate multimaterial parts with intricate shapes and architectures. Here, we report a 3D printing platform for the seamless digital fabrication of pneumatic silicone actuators exhibiting programmable bioinspired architectures and motions. The actuators comprise an elastomeric body whose surface is decorated with reinforcing stripes at a well-defined lead angle. Similar to the fibrous architectures found in muscular hydrostats, the lead angle can be altered to achieve elongation, contraction, or twisting motions. Using a quantitative model based on lamination theory, we establish design principles for the digital fabrication of silicone-based soft actuators whose functional response is programmed within the material's properties and architecture. Exploring such programmability enables 3D printing of a broad range of soft morphing structures.
BibTeX:
@article{Schaffner2018,
  author = {Schaffner, Manuel and Faber, Jakob A. and Pianegonda, Lucas and Rühs, Patrick A. and Coulter, Fergal and Studart, André R.},
  title = {3D printing of robotic soft actuators with programmable bioinspired architectures},
  journal = {Nature Communications},
  year = {2018},
  volume = {9},
  number = {1},
  pages = {878},
  doi = {https://doi.org/10.1038/s41467-018-03216-w}
}
Raghunath, M., Rimann, M., Kopanska, K. and Laternser, S. TEDD Annual Meeting with 3D Bioprinting Workshop 2018 CHIMIA
Vol. 72CHIMIA International Journal for Chemistry, pp. 76-79 
article URL 
Abstract: Bioprinting is the technology of choice for realizing functional tissues such as vascular system, muscle, cartilage and bone. In the future, bioprinting will influence the way we engineer tissues and bring it to a new level of physiological relevance. That was the topic of the 2017 TEDD Annual Meeting at ZHAW Waedenswil on 8th and 9th November. In an exciting workshop, the two companies regenHU Ltd. and CELLINK gave us an insight
into highly topical applications and collaborations in this domain.
BibTeX:
@article{Raghunath2018,
  author = {Raghunath, Michael and Rimann, Markus and Kopanska, Katarzyna and Laternser, Sandra},
  title = {TEDD Annual Meeting with 3D Bioprinting Workshop},
  booktitle = {CHIMIA International Journal for Chemistry},
  journal = {CHIMIA},
  year = {2018},
  volume = {72},
  pages = {76-79},
  url = { https://doi.org/10.2533/chimia.2018.76}
}
Ovsianikov, A., Khademhosseini, A. and Mironov, V. The Synergy of Scaffold-Based and Scaffold-Free Tissue Engineering Strategies 2018 Trends in Biotechnology
Vol. 36 
article DOI  
BibTeX:
@article{Ovsianikov2018,
  author = {Ovsianikov, Aleksandr and Khademhosseini, Ali and Mironov, Vladimir},
  title = {The Synergy of Scaffold-Based and Scaffold-Free Tissue Engineering Strategies},
  journal = {Trends in Biotechnology},
  year = {2018},
  volume = {36},
  doi = {https://doi.org/10.1016/j.tibtech.2018.01.005}
}
Lopa, S., Mondadori, C., Luca Mainardi, V., Talò, G., Costantini, M., Candrian, C., Święszkowski, W. and Moretti, M. Translational Application of Microfluidics and Bioprinting for Stem Cell-Based Cartilage Repair 2018 stem cells international
Vol. 2018Stem Cells International, pp. 1-14 
article DOI  
BibTeX:
@article{Lopa2018,
  author = {Lopa, Silvia and Mondadori, Carlotta and Luca Mainardi, Valerio and Talò, Giuseppe and Costantini, Marco and Candrian, Christian and Święszkowski, Wojciech and Moretti, Matteo},
  title = {Translational Application of Microfluidics and Bioprinting for Stem Cell-Based Cartilage Repair},
  booktitle = {Stem Cells International},
  journal = {stem cells international},
  year = {2018},
  volume = {2018},
  pages = {1-14},
  doi = {https://doi.org/10.1155/2018/6594841}
}
Yeo, M. and Kim, G.H. Anisotropically Aligned Cell-Laden Nanofibrous Bundle Fabricated via Cell Electrospinning to Regenerate Skeletal Muscle Tissue 2018 Small
Vol. 14(48), pp. 1803491 
article DOI  
Abstract: Abstract For muscle regeneration, a uniaxially arranged micropattern is important to mimic the structure of the natural extracellular matrix. Recently, cell electrospinning (CE) has been tested to fabricate cell-laden fibrous structures by embedding cells directly into micro/nanofibers. Although homogenous cell distribution and a reasonable cell viability of the cell-laden fibrous structure fabricated using the CE process are achieved, unique topographical cues formed by an aligned fibrous structure have not been applied. In this study, a CE process to achieve not only homogeneous cell distribution with a high cell viability, but also highly aligned cells, which are guided by aligned alginate fibers is employed. To attain the aligned cell-laden fibrous structure, various processing conditions are examined. The selected condition is applied using C2C12 myoblast cells to ensure the biocompatibility and guidance of cell elongation and alignment. As a control, a cell-printed scaffold using a 3D bioprinter is used to compare the efficiency of cell alignment and differentiation of myoblasts. Highly arranged, multinucleated cell morphology is confirmed in the CE scaffold, which successively facilitates myogenic differentiation. It is believed that this study will be a new platform for obtaining cell alignment and will significantly benefit the efforts on muscle regeneration.
BibTeX:
@article{Yeo2018,
  author = {Yeo, Miji and Kim, Geun Hyung},
  title = {Anisotropically Aligned Cell-Laden Nanofibrous Bundle Fabricated via Cell Electrospinning to Regenerate Skeletal Muscle Tissue},
  journal = {Small},
  publisher = {John Wiley & Sons, Ltd},
  year = {2018},
  volume = {14},
  number = {48},
  pages = {1803491},
  doi = {https://doi.org/10.1002/smll.201803491}
}
Prasopthum, A., Shakesheff, K.M. and Yang, J. Direct three-dimensional printing of polymeric scaffolds with nanofibrous topography 2018 Biofabrication
Vol. 10(2), pp. 025002 
article DOI  
Abstract: Three-dimensional (3D) printing is a powerful manufacturing tool for making 3D structures with well-defined architectures for a wide range of applications. The field of tissue engineering has also adopted this technology to fabricate scaffolds for tissue regeneration. The ability to control architecture of scaffolds, e.g. matching anatomical shapes and having defined pore size, has since been improved significantly. However, the material surface of these scaffolds is smooth and does not resemble that found in natural extracellular matrix (ECM), in particular, the nanofibrous morphology of collagen. This natural nanoscale morphology plays a critical role in cell behaviour. Here, we have developed a new approach to directly fabricate polymeric scaffolds with an ECM-like nanofibrous topography and defined architectures using extrusion-based 3D printing. 3D printed tall scaffolds with interconnected pores were created with disparate features spanning from nanometres to centimetres. Our approach removes the need for a sacrificial mould and subsequent mould removal compared to previous methods. Moreover, the nanofibrous topography of the 3D printed scaffolds significantly enhanced protein absorption, cell adhesion and differentiation of human mesenchymal stem cells when compared to those with smooth material surfaces. These 3D printed scaffolds with both defined architectures and nanoscale ECM-mimicking morphologies have potential applications in cartilage and bone regeneration.
BibTeX:
@article{Prasopthum2018,
  author = {Aruna Prasopthum and Kevin M Shakesheff and Jing Yang},
  title = {Direct three-dimensional printing of polymeric scaffolds with nanofibrous topography},
  journal = {Biofabrication},
  publisher = {IOP Publishing},
  year = {2018},
  volume = {10},
  number = {2},
  pages = {025002},
  doi = {https://doi.org/10.1088/1758-5090/aaa15b}
}
Castilho, M., Hochleitner, G., Wilson, W., van Rietbergen, B., Dalton, P.D., Groll, J., Malda, J. and Ito, K. Mechanical behavior of a soft hydrogel reinforced with three-dimensional printed microfibre scaffolds 2018 Scientific Reports
Vol. 8(1), pp. 1245 
article DOI  
Abstract: Reinforcing hydrogels with micro-fibre scaffolds obtained by a Melt-Electrospinning Writing (MEW) process has demonstrated great promise for developing tissue engineered (TE) constructs with mechanical properties compatible to native tissues. However, the mechanical performance and reinforcement mechanism of the micro-fibre reinforced hydrogels is not yet fully understood. In this study, FE models, implementing material properties measured experimentally, were used to explore the reinforcement mechanism of fibre-hydrogel composites. First, a continuum FE model based on idealized scaffold geometry was used to capture reinforcement effects related to the suppression of lateral gel expansion by the scaffold, while a second micro-FE model based on micro-CT images of the real construct geometry during compaction captured the effects of load transfer through the scaffold interconnections. Results demonstrate that the reinforcement mechanism at higher scaffold volume fractions was dominated by the load carrying-ability of the fibre scaffold interconnections, which was much higher than expected based on testing scaffolds alone because the hydrogel provides resistance against buckling of the scaffold. We propose that the theoretical understanding presented in this work will assist the design of more effective composite constructs with potential applications in a wide range of TE conditions.
BibTeX:
@article{Castilho2018a,
  author = {Castilho, Miguel and Hochleitner, Gernot and Wilson, Wouter and van Rietbergen, Bert and Dalton, Paul D. and Groll, Jürgen and Malda, Jos and Ito, Keita},
  title = {Mechanical behavior of a soft hydrogel reinforced with three-dimensional printed microfibre scaffolds},
  journal = {Scientific Reports},
  year = {2018},
  volume = {8},
  number = {1},
  pages = {1245},
  doi = {https://doi.org/10.1038/s41598-018-19502-y}
}
Allig, S., Mayer, M. and Thielemann, C. Workflow for bioprinting of cell-laden bioink 2018 Lekar a Technika
Vol. 48, pp. 46-51 
article  
BibTeX:
@article{Allig2018,
  author = {Allig, S and Mayer, Margot and Thielemann, Christiane},
  title = {Workflow for bioprinting of cell-laden bioink},
  journal = {Lekar a Technika},
  year = {2018},
  volume = {48},
  pages = {46-51}
}
Wang, H., das Neves Domingos, M.A. and Scenini, F. Advanced mechanical and thermal characterization of 3D bioextruded poly(ε-caprolactone)-based composites 2018 Rapid Prototyping Journal
Vol. 0(ja), pp. 00-00 
article DOI  
Abstract: Purpose The main purpose of the present work is to study the effect of nano hydroxyapatite (HA) and graphene oxide (GO) particles on thermal and mechanical performances of 3D printed poly(ε-caprolactone) (PCL) filaments used in Bone Tissue Engineering (BTE). Design/methodology/approach Raw materials were prepared by melt blending, followed by 3D printing via 3D Discovery (regenHU Ltd., CH) with all fabricating parameters kept constant. Filaments, including pure PCL, PCL/HA, and PCL/GO, were tested under the same conditions. Several techniques were used to mechanically, thermally, and microstructurally evaluate properties of these filaments, including Differential Scanning Calorimetry (DSC), tensile test, nano indentation, and Scanning Electron Microscope (SEM). Findings Results show that both HA and GO nano particles are capable of improving mechanical performance of PCL. Enhanced mechanical properties of PCL/HA result from reinforcing effect of HA, while a different mechanism is observed in PCL/GO, where degree of crystallinity plays an important role. In addition, GO is more efficient at enhancing mechanical performance of PCL compared with HA. Originality/value For the first time, a systematic study about effects of nano HA and GO particles on bioactive scaffolds produced by Additive Manufacturing (AM) for bone tissue engineering applications is conducted in this work. Mechanical and thermal behaviors of each sample, pure PCL, PCL/HA and PCL/GO, are reported, correlated, and compared with literature.
BibTeX:
@article{Wang2018,
  author = {Hanxiao Wang and Marco Andre das Neves Domingos and Fabio Scenini},
  title = {Advanced mechanical and thermal characterization of 3D bioextruded poly(ε-caprolactone)-based composites},
  journal = {Rapid Prototyping Journal},
  year = {2018},
  volume = {0},
  number = {ja},
  pages = {00-00},
  doi = {https://doi.org/10.1108/RPJ-10-2016-0165}
}
Visscher, D.O., Gleadall, A., Buskermolen, J.K., Burla, F., Segal, J., Koenderink, G.H., Helder, M.N. and van Zuijlen, P.P.M. Design and fabrication of a hybrid alginate hydrogel/poly(ε-caprolactone) mold for auricular cartilage reconstruction 2018 Journal of Biomedical Materials Research Part B: Applied Biomaterials
Vol. 0(0) 
article DOI  
Abstract: Abstract The aim of this study was to design and manufacture an easily assembled cartilage implant model for auricular reconstruction. First, the printing accuracy and mechanical properties of 3D-printed poly-ε-caprolactone (PCL) scaffolds with varying porosities were determined to assess overall material properties. Next, the applicability of alginate as cell carrier for the cartilage implant model was determined. Using the optimal outcomes of both experiments (in terms of (bio)mechanical properties, cell survival, neocartilage formation, and printing accuracy), a hybrid auricular implant model was developed. PCL scaffolds with 600 μm distances between strands exhibited the best mechanical properties and most optimal printing quality for further exploration. In alginate, chondrocytes displayed high cell survival ( 83% after 21 days) and produced cartilage-like matrix in vitro. Alginate beads cultured in proliferation medium exhibited slightly higher compressive moduli (6 kPa) compared to beads cultured in chondrogenic medium (3.5 kPa, p > .05). The final auricular mold could be printed with 300 μm pores and high fidelity, and the injected chondrocytes survived the culture period of 21 days. The presented hybrid auricular mold appears to be an adequate model for cartilage tissue engineering and may provide a novel approach to auricular cartilage regeneration for facial reconstruction. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res B Part B: Appl Biomater, 2018.
BibTeX:
@article{Visscher2018,
  author = {Visscher, D. O. and Gleadall, A. and Buskermolen, J. K. and Burla, F. and Segal, J. and Koenderink, G. H. and Helder, M. N. and van Zuijlen, P. P. M.},
  title = {Design and fabrication of a hybrid alginate hydrogel/poly(ε-caprolactone) mold for auricular cartilage reconstruction},
  journal = {Journal of Biomedical Materials Research Part B: Applied Biomaterials},
  year = {2018},
  volume = {0},
  number = {0},
  doi = {https://doi.org/10.1002/jbm.b.34264}
}
Shi, P., Tan, Y.S.E., Yeong, W.Y., Li, H.Y. and Laude, A. A bilayer photoreceptor‐retinal tissue model with gradient cell density design: A study of microvalve‐based bioprinting 2018 Journal of Tissue Engineering and Regenerative Medicine
Vol. 12(5), pp. 1297-1306 
article DOI  
Abstract: Abstract ARPE‐19 and Y79 cells were precisely and effectively delivered to form an in vitro retinal tissue model via 3D cell bioprinting technology. The samples were characterized by cell viability assay, haematoxylin and eosin and immunofluorescent staining, scanning electrical microscopy and confocal microscopy, and so forth. The bioprinted ARPE‐19 cells formed a high‐quality cell monolayer in 14 days. Manually seeded ARPE‐19 cells were poorly controlled during and after cell seeding, and they aggregated to form uneven cell layer. The Y79 cells were subsequently bioprinted on the ARPE‐19 cell monolayer to form 2 distinctive patterns. The microvalve‐based bioprinting is efficient and accurate to build the in vitro tissue models with the potential to provide similar pathological responses and mechanism to human diseases, to mimic the phenotypic endpoints that are comparable with clinical studies, and to provide a realistic prediction of clinical efficacy.
BibTeX:
@article{Shi2018,
  author = {Shi ,Pujiang and Tan, Yong Sheng Edgar and Yeong, Wai Yee and Li, Hoi Yeung and Laude, Augustinus},
  title = {A bilayer photoreceptor‐retinal tissue model with gradient cell density design: A study of microvalve‐based bioprinting},
  journal = {Journal of Tissue Engineering and Regenerative Medicine},
  year = {2018},
  volume = {12},
  number = {5},
  pages = {1297-1306},
  doi = {https://doi.org/10.1002/term.2661}
}
Serban, M.A. and Skardal, A. Hyaluronan chemistries for three-dimensional matrix applications 2018 Matrix Biology  article DOI URL 
Abstract: Hyaluronan is a ubiquitous constituent of mammalian extracellular matrices and, because of its excellent intrinsic biocompatibility and chemical modification versatility, has been widely employed in a multitude of biomedical applications. In this article, we will survey the approaches used to tailor hyaluronan to specific needs of tissue engineering, regenerative and reconstructive medicine and overall biomedical research. We will also describe recent examples of applications in these broader areas, such as 3D cell culture, bioprinting, organoid biofabrication, and precision medicine that are facilitated by the use of hyaluronan as a biomaterial.
BibTeX:
@article{Serban2018,
  author = {Monica A. Serban and Aleksander Skardal},
  title = {Hyaluronan chemistries for three-dimensional matrix applications},
  journal = {Matrix Biology},
  year = {2018},
  url = {http://www.sciencedirect.com/science/article/pii/S0945053X17304547},
  doi = {https://doi.org/10.1016/j.matbio.2018.02.010}
}
Schmieg, B., Schimek, A. and Franzreb, M. Development and performance of a 3D‐printable Polyethylenglycol‐Diacrylate hydrogel suitable for enzyme entrapment and long‐term biocatalytic applications 2018 Engineering in Life Sciences
Vol. 0(ja) 
article DOI URL 
Abstract: Physical entrapment of enzymes within a porous matrix is a fast and gentle process to immobilize biocatalysts to enable their recycling and long‐term use. This study introduces the development of a biocompatible 3D‐printing material suitable for enzyme entrapment, while having good rheological and UV‐hardening properties. Three different viscosity‐enhancing additives have been tested in combination with a polyethylenglycol‐diacrylate‐based hydrogel system. The addition of polyxanthan or hectorite clay particles results in hydrogels that degrade over hours or days, releasing entrapped compounds. In contrast, the addition of nanometer‐sized silicate particles ensures processability while preventing disintegration of the hydrogel. Lattice structures with a total height of 6 mm consisting of 40 layers were 3D‐printed with all materials and characterized by image analysis. Rheological measurements identified a shear stress window of 200 < τ < 500 Pa at shear rates of 25 s−1 and 25°C for well‐defined geometries with an extrusion‐based printhead. Enzymes immobilized in these long‐term stable hydrogel structures retained an effective activity of approximately 10% compared to the free enzyme in solution. It could be shown that the reduction of effective activity isn't caused by a significant reduction of the intrinsic enzyme activity but by mass transfer limitations within the printed hydrogel structures. This article is protected by copyright. All rights reserved
BibTeX:
@article{Schmieg2018,
  author = {Schmieg, Barbara and Schimek, Adrian and Franzreb, Matthias},
  title = {Development and performance of a 3D‐printable Polyethylenglycol‐Diacrylate hydrogel suitable for enzyme entrapment and long‐term biocatalytic applications},
  journal = {Engineering in Life Sciences},
  year = {2018},
  volume = {0},
  number = {ja},
  url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/elsc.201800030},
  doi = {https://doi.org/10.1002/elsc.201800030}
}
de Ruijter Mylène, Alexandre, R., Inge, D., Miguel, C. and Jos, M. Simultaneous Micropatterning of Fibrous Meshes and Bioinks for the Fabrication of Living Tissue Constructs 2018 Advanced Healthcare Materials
Vol. 0(0), pp. 1800418 
article DOI URL 
Abstract: Abstract Fabrication of biomimetic tissues holds much promise for the regeneration of cells or organs that are lost or damaged due to injury or disease. To enable the generation of complex, multicellular tissues on demand, the ability to design and incorporate different materials and cell types needs to be improved. Two techniques are combined: extrusion-based bioprinting, which enables printing of cell-encapsulated hydrogels; and melt electrowriting (MEW), which enables fabrication of aligned (sub)-micrometer fibers into a single-step biofabrication process. Composite structures generated by infusion of MEW fiber structures with hydrogels have resulted in mechanically and biologically competent constructs; however, their preparation involves a two-step fabrication procedure that limits freedom of design of microfiber architectures and the use of multiple materials and cell types. How convergence of MEW and extrusion-based bioprinting allows fabrication of mechanically stable constructs with the spatial distributions of different cell types without compromising cell viability and chondrogenic differentiation of mesenchymal stromal cells is demonstrated for the first time. Moreover, this converged printing approach improves freedom of design of the MEW fibers, enabling 3D fiber deposition. This is an important step toward biofabrication of voluminous and complex hierarchical structures that can better resemble the characteristics of functional biological tissues.
BibTeX:
@article{Ruijter2018,
  author = {de Ruijter Mylène and Ribeiro Alexandre and Dokter Inge and Castilho Miguel and Malda Jos},
  title = {Simultaneous Micropatterning of Fibrous Meshes and Bioinks for the Fabrication of Living Tissue Constructs},
  journal = {Advanced Healthcare Materials},
  year = {2018},
  volume = {0},
  number = {0},
  pages = {1800418},
  url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/adhm.201800418},
  doi = {https://doi.org/10.1002/adhm.201800418}
}
Romanazzo, S., Vedicherla, S., Moran, C. and Kelly, D.J. Meniscus ECM‐functionalised hydrogels containing infrapatellar fat pad‐derived stem cells for bioprinting of regionally defined meniscal tissue 2018 Journal of Tissue Engineering and Regenerative Medicine
Vol. 12(3), pp. e1826-e1835 
article DOI  
Abstract: Abstract Injuries to the meniscus of the knee commonly lead to osteoarthritis. Current therapies for meniscus regeneration, including meniscectomies and scaffold implantation, fail to achieve complete functional regeneration of the tissue. This has led to increased interest in cell and gene therapies and tissue engineering approaches to meniscus regeneration. The implantation of a biomimetic implant, incorporating cells, growth factors, and extracellular matrix (ECM)‐derived proteins, represents a promising approach to functional meniscus regeneration. The objective of this study was to develop a range of ECM‐functionalised bioinks suitable for 3D bioprinting of meniscal tissue. To this end, alginate hydrogels were functionalised with ECM derived from the inner and outer regions of the meniscus and loaded with infrapatellar fat pad‐derived stem cells. In the absence of exogenously supplied growth factors, inner meniscus ECM promoted chondrogenesis of fat pad‐derived stem cells, whereas outer meniscus ECM promoted a more elongated cell morphology and the development of a more fibroblastic phenotype. With exogenous growth factors supplementation, a more fibrogenic phenotype was observed in outer ECM‐functionalised hydrogels supplemented with connective tissue growth factor, whereas inner ECM‐functionalised hydrogels supplemented with TGFβ3 supported the highest levels of Sox‐9 and type II collagen gene expression and sulfated glycosaminoglycans (sGAG) deposition. The final phase of the study demonstrated the printability of these ECM‐functionalised hydrogels, demonstrating that their codeposition with polycaprolactone microfibres dramatically improved the mechanical properties of the 3D bioprinted constructs with no noticeable loss in cell viability. These bioprinted constructs represent an exciting new approach to tissue engineering of functional meniscal grafts.
BibTeX:
@article{Romanazzo2018,
  author = {Romanazzo S. and Vedicherla S. and Moran C. and Kelly D.J.},
  title = {Meniscus ECM‐functionalised hydrogels containing infrapatellar fat pad‐derived stem cells for bioprinting of regionally defined meniscal tissue},
  journal = {Journal of Tissue Engineering and Regenerative Medicine},
  year = {2018},
  volume = {12},
  number = {3},
  pages = {e1826-e1835},
  doi = {https://doi.org/10.1002/term.2602}
}
Rayate, A. and Jain, P.K. A Review on 4D Printing Material Composites and Their Applications 2018 Materials Today: Proceedings
Vol. 5(9, Part 3), pp. 20474 - 20484 
article DOI URL 
Abstract: 4D printing is an extension of 3D printing in which stimuli-responsive active smart materials are used to produce the static structure. This static structure then converts into another structure when it is exposed to the stimulus. Type of stimulus may be light, heat, pH, water, magnetic field etc. depending upon the material selected for 3D printing. In recent advances, these dynamic structures developed by 3D printing process are used for actuators, smart devices, aesthetic primitives, smart textiles, and also in biomedical applications. This paper is about the brief overview of the advanced materials for 4D printing and their applications.
BibTeX:
@article{Rayate2018,
  author = {Amol Rayate and Prashant K. Jain},
  title = {A Review on 4D Printing Material Composites and Their Applications},
  journal = {Materials Today: Proceedings},
  year = {2018},
  volume = {5},
  number = {9, Part 3},
  pages = {20474 - 20484},
  note = {Materials Processing and characterization, 16th – 18th March 2018},
  url = {http://www.sciencedirect.com/science/article/pii/S2214785318315542},
  doi = {https://doi.org/10.1016/j.matpr.2018.06.424}
}
Pereira, F.D.A.S., Parfenov, V., Khesuani, Y.D., Ovsianikov, A. and Mironov, V. Commercial 3D Bioprinters 2018 3D Printing and Biofabrication, pp. 535-549  inbook DOI  
Abstract: The bioprinters are robotic devices, which enable 3D bioprinting. In this chapter, we provide classification of already existing commercially available 3D bioprinters and outline basic principles of their construction and functionalities. The emerging trends in the design and development of 3D bioprinters, perspectives of creation of new types of commercial 3D bioprinters based on new physical principles, including in situ bioprinters, as well as completely integrated organ biofabrication lines or ``human organ factories'' will be also discussed.
BibTeX:
@inbook{Pereira2018,
  author = {Pereira, Frederico David A. S. and Parfenov, Vladislav and Khesuani, Yusef D. and Ovsianikov, Aleksandr and Mironov, Vladimir},
  title = {Commercial 3D Bioprinters},
  booktitle = {3D Printing and Biofabrication},
  publisher = {Springer International Publishing},
  year = {2018},
  pages = {535--549},
  doi = {https://doi.org/10.1007/978-3-319-45444-3_12}
}
Peiffer, Q.C. Biofabrication: Tools for new therapeutics in regenerative medicine and drug delivery 2018 School: Queensland University of Technology  mastersthesis DOI URL 
Abstract: This thesis highlights how 3D fabrications techniques could revolutionize modern medicine, notably in the field of regenerative medicine and drug delivery. Two potential therapeutic usages of 3D fabricated polycaprolactone scaffolds are presented, the first project focuses on the regeneration of auricular cartilage while the second focus on implantable drug delivery system. If this work gives a glimpse of the potential of new fabrication methods, it remains clear from the results that significant steps are still to be undertaken to produce functional scaffolds able to regenerate tissue or to deliver drugs efficiently over an extended period.
BibTeX:
@mastersthesis{Peiffer2018,
  author = {Quentin C. Peiffer},
  title = {Biofabrication: Tools for new therapeutics in regenerative medicine and drug delivery},
  school = {Queensland University of Technology},
  year = {2018},
  url = {https://eprints.qut.edu.au/119359/},
  doi = {https://doi.org/10.5204/thesis.eprints.119359}
}
Park, H.S., Lee, J.S., Jung, H., Kim, D.Y., Kim, S.W., Sultan, M.T. and Park, C.H. An omentum-cultured 3D-printed artificial trachea: in vivo bioreactor 2018 Artificial Cells, Nanomedicine, and Biotechnology
Vol. 46(sup3), pp. S1131-S1140 
article DOI  
Abstract: AbstractThe purpose of this study was to evaluate whether the prior implantation of a 3D-printed polycaprolactone (PCL) artificial trachea in the omentum is beneficial for revascularization of the scaffold and reduces associated complications in the reconstruction of a circumferential tracheal defect. Ten New Zealand rabbits were divided into 2 groups: (1) PCL-OC group (PCL scaffold cultured in omentum for 2 weeks before transplantation) and (2) PCL group. In the PCL-OC group, newly formed connective tissue completely covered the luminal surface of the scaffold with mild inflammation at 2 weeks postoperatively; a minor degree of stenosis was noted at 8 weeks postoperatively. The PCL group showed scaffold exposure without any tissue regeneration at 2 weeks postoperatively, and a moderate degree of luminal stenosis 6 weeks after implantation. Histology revealed highly organized regenerated tissue composed of ciliated respiratory epithelium, and submucosal layer in the PCL-OC group. Neo-cartilage regeneration was noted in part of the regenerated tissue. The PCL group demonstrated severe inflammation and an unorganized structure compared to that of the PCL-OC group. In vivo omentum culture of the tracheal scaffold before transplantation is beneficial for rapid re-epithelialization and revascularization of the scaffold. It also prevents postoperative luminal stenosis.
BibTeX:
@article{Park2018,
  author = {Hae Sang Park and Ji Seung Lee and Harry Jung and Do Yeon Kim and Sang Wook Kim and Md. Tipu Sultan and Chan Hum Park},
  title = {An omentum-cultured 3D-printed artificial trachea: in vivo bioreactor},
  journal = {Artificial Cells, Nanomedicine, and Biotechnology},
  publisher = {Taylor & Francis},
  year = {2018},
  volume = {46},
  number = {sup3},
  pages = {S1131-S1140},
  note = {PMID: 30451550},
  doi = {https://doi.org/10.1080/21691401.2018.1533844}
}
Ng, W.L., Qi, J.T.Z., Yeong, W.Y. and Naing, M.W. Proof-of-concept: 3D bioprinting of pigmented human skin constructs 2018 Biofabrication
Vol. 10(2), pp. 025005 
article URL 
Abstract: Three-dimensional (3D) pigmented human skin constructs have been fabricated using a 3D bioprinting approach. The 3D pigmented human skin constructs are obtained from using three different types of skin cells (keratinocytes, melanocytes and fibroblasts from three different skin donors) and they exhibit similar constitutive pigmentation (pale pigmentation) as the skin donors. A two-step drop-on-demand bioprinting strategy facilitates the deposition of cell droplets to emulate the epidermal melanin units (pre-defined patterning of keratinocytes and melanocytes at the desired positions) and manipulation of the microenvironment to fabricate 3D biomimetic hierarchical porous structures found in native skin tissue. The 3D bioprinted pigmented skin constructs are compared to the pigmented skin constructs fabricated by conventional a manual-casting approach; in-depth characterization of both the 3D pigmented skin constructs has indicated that the 3D bioprinted skin constructs have a higher degree of resemblance to native skin tissue in term of the presence of well-developed stratified epidermal layers and the presence of a continuous layer of basement membrane proteins as compared to the manually-cast samples. The 3D bioprinting approach facilitates the development of 3D in vitro pigmented human skin constructs for potential toxicology testing and fundamental cell biology research.
BibTeX:
@article{Ng2018,
  author = {Wei Long Ng and Jovina Tan Zhi Qi and Wai Yee Yeong and May Win Naing},
  title = {Proof-of-concept: 3D bioprinting of pigmented human skin constructs},
  journal = {Biofabrication},
  year = {2018},
  volume = {10},
  number = {2},
  pages = {025005},
  url = {http://stacks.iop.org/1758-5090/10/i=2/a=025005}
}
Ng, W.L., Goh, M.H., Yeong, W.Y. and Naing, M.W. Applying macromolecular crowding to 3D bioprinting: fabrication of 3D hierarchical porous collagen-based hydrogel constructs 2018 Biomater. Sci.
Vol. 6, pp. 562-574 
article DOI URL 
Abstract: Native tissues and/or organs possess complex hierarchical porous structures that confer highly-specific cellular functions. Despite advances in fabrication processes, it is still very challenging to emulate the hierarchical porous collagen architecture found in most native tissues. Hence, the ability to recreate such hierarchical porous structures would result in biomimetic tissue-engineered constructs. Here, a single-step drop-on-demand (DOD) bioprinting strategy is proposed to fabricate hierarchical porous collagen-based hydrogels. Printable macromolecule-based bio-inks (polyvinylpyrrolidone, PVP) have been developed and printed in a DOD manner to manipulate the porosity within the multi-layered collagen-based hydrogels by altering the collagen fibrillogenesis process. The experimental results have indicated that hierarchical porous collagen structures could be achieved by controlling the number of macromolecule-based bio-ink droplets printed on each printed collagen layer. This facile single-step bioprinting process could be useful for the structural design of collagen-based hydrogels for various tissue engineering applications.
BibTeX:
@article{Ng2018a,
  author = {Ng, Wei Long and Goh, Min Hao and Yeong, Wai Yee and Naing, May Win},
  title = {Applying macromolecular crowding to 3D bioprinting: fabrication of 3D hierarchical porous collagen-based hydrogel constructs},
  journal = {Biomater. Sci.},
  publisher = {The Royal Society of Chemistry},
  year = {2018},
  volume = {6},
  pages = {562-574},
  url = {http://dx.doi.org/10.1039/C7BM01015J},
  doi = {https://doi.org/10.1039/C7BM01015J}
}
Mouser, V.H.M., Levato, R., Mensinga, A., Dhert, W.J.A., Gawlitta, D. and Malda, J. Bio-ink development for three-dimensional bioprinting of hetero-cellular cartilage constructs 2018 Connective Tissue Research
Vol. 0(0), pp. 1-15 
article DOI  
Abstract: ABSTRACTBioprinting is a promising tool to fabricate organized cartilage. This study aimed to investigate the printability of gelatin-methacryloyl/gellan gum (gelMA/gellan) hydrogels with and without methacrylated hyaluronic acid (HAMA), and to explore (zone-specific) chondrogenesis of chondrocytes, articular cartilage progenitor cells (ACPCs), and multipotent mesenchymal stromal cells (MSCs) embedded in these bio-inks.The incorporating of HAMA in gelMA/gellan bio-ink increased filament stability, as measured using a filament collapse assay, but did not influence (zone-specific) chondrogenesis of any of the cell types. Highest chondrogenic potential was observed for MSCs, followed by ACPCs, which displayed relatively high proteoglycan IV mRNA levels. Therefore, two-zone constructs were printed with gelMA/gellan/HAMA containing ACPCs in the superficial region and MSCs in the middle/deep region. Chondrogenic differentiation was confirmed, however, printing influence cellular differentiation.ACPC- and MSC-laden gelMA/gellan/HAMA hydrogels are of interest for the fabrication of cartilage constructs. Nevertheless, this study underscores the need for careful evaluation of the effects of printing on cellular differentiation.
BibTeX:
@article{Mouser2018,
  author = {Vivian H. M. Mouser and Riccardo Levato and Anneloes Mensinga and Wouter J. A. Dhert and Debby Gawlitta and Jos Malda},
  title = {Bio-ink development for three-dimensional bioprinting of hetero-cellular cartilage constructs},
  journal = {Connective Tissue Research},
  publisher = {Taylor & Francis},
  year = {2018},
  volume = {0},
  number = {0},
  pages = {1-15},
  note = {PMID: 30526130},
  doi = {https://doi.org/10.1080/03008207.2018.1553960}
}
Moor, L.D., Merovci, I., Baetens, S., Verstraeten, J., Kowalska, P., Krysko, D.V., Vos, W.H.D. and Declercq, H. High-throughput fabrication of vascularized spheroids for bioprinting 2018 Biofabrication  article DOI  
Abstract: Abstract Overcoming the problem of vascularization remains the main challenge in the field of tissue engineering. As three-dimensional (3D) bioprinting is the rising technique for the fabrication of large tissue constructs, small prevascularized building blocks were generated that can be incorporated throughout a printed construct, answering the need for a microvasculature within the small micron range (&lt; 10 µm). &#13; Uniform spheroids with an ideal geometry and diameter for bioprinting were formed, using a high-throughput non-adhesive agarose microwell system. Since monoculture spheroids of endothelial cells were unable to remain stable, coculture spheroids combining endothelial cells with fibroblasts and/or adipose tissue derived mesenchymal stem cells (ADSC) as supporting cells, were created. When applying the favourable coculture ratio, viable spheroids were obtained and endothelial cells spontaneously formed a capillary like network and lumina, as shown by immunohistochemistry and transmission electron microscopy. Especially the presence of ADSC led to a higher vascularization and extracellular matrix (ECM) production of the microtissue. Moreover, spheroids were able to assemble at random in suspension and in a hydrogel, creating a macrotissue. During at random assembly, cells reorganized, creating a branched capillary network throughout the entire fused construct by inoculating with capillaries of adjacent spheroids. Combining the advantage of this natural capacity of microtissues to self-assemble and the controlled organization by bioprinting technologies, these prevascularized spheroids can be useful as building blocks for the engineering of large vascularized 3D tissues.&#13;
BibTeX:
@article{Moor2018,
  author = {Lise De Moor and Idriz Merovci and Sarah Baetens and Julien Verstraeten and Paulina Kowalska and Dmitri V Krysko and Winnok H De Vos and Heidi Declercq},
  title = {High-throughput fabrication of vascularized spheroids for bioprinting},
  journal = {Biofabrication},
  year = {2018},
  doi = {https://doi.org/10.1088/1758-5090/aac7e6}
}
Moldovan, N., Maldovan, L. and Raghunath, M. Of balls, inks and cages: Hybrid biofabrication of 3D tissue analogs 2018 International Journal of Bioprinting
Vol. 5(1) 
article DOI URL 
Abstract: The overarching principle of three-dimensional (3D) bioprinting is the placing of cells or cell clusters in the 3D space to generate a cohesive tissue microarchitecture that comes close to in vivo characteristics. To achieve this goal, several technical solutions are available, generating considerable combinatorial bandwidth: (i) Support structures are generated first, and cells are seeded subsequently; (ii) alternatively, cells are delivered in a printing medium, so-called “bioink,” that contains them during the printing process and ensures shape fidelity of the generated structure; and (iii) a “scaffold-free” version of bioprinting, where only cells are used and the extracellular matrix is produced by the cells themselves, also recently entered a phase of accelerated development and successful applications. However, the scaffold-free approaches may still benefit from secondary incorporation of scaffolding materials, thus expanding their versatility. Reversibly, the bioink-based bioprinting could also be improved by adopting some of the principles and practices of scaffold-free biofabrication. Collectively, we anticipate that combinations of these complementary methods in a “hybrid” approach, rather than their development in separate technological niches, will largely increase their efficiency and applicability in tissue engineering.
BibTeX:
@article{Moldovan2018,
  author = {Nicanor Moldovan and Leni Maldovan and Michael Raghunath},
  title = {Of balls, inks and cages: Hybrid biofabrication of 3D tissue analogs},
  journal = {International Journal of Bioprinting},
  year = {2018},
  volume = {5},
  number = {1},
  url = {http://ijb.whioce.com/index.php/int-j-bioprinting/article/view/167},
  doi = {https://doi.org/10.18063/ijb.v5i1.167}
}
McColl, E., Groll, J., Jungst, T. and Dalton, P.D. Design and fabrication of melt electrowritten tubes using intuitive software 2018 Materials & Design
Vol. 155, pp. 46 - 58 
article DOI URL 
Abstract: This study approaches the accurate continuous direct-writing onto a cylindrical collector from a mathematical perspective, taking into account the winding angle, cylinder diameter and length required for the final 3D printed tube. Using an additive manufacturing process termed melt electrowriting (MEW), porous tubes intended for tissue engineering applications are fabricated from medical-grade poly(ε-caprolactone) (PCL), validating the mathematically-derived method. For the fabricated tubes in this study, the pore size, winding angle and printed length can all be planned in advance and manufactured as designed. The physical dimensions of the tubes matched theoretical predictions and mechanical testing performed demonstrated that variations in the tubular morphology have a direct impact on their strength. MEWTubes, the web-based application developed and described here, is a particularly useful tool for planning the complex continuous direct writing path required for MEW onto a rotating, cylindrical build surface.
BibTeX:
@article{McColl2018,
  author = {Erin McColl and Jürgen Groll and Tomasz Jungst and Paul D. Dalton},
  title = {Design and fabrication of melt electrowritten tubes using intuitive software},
  journal = {Materials & Design},
  year = {2018},
  volume = {155},
  pages = {46 - 58},
  url = {http://www.sciencedirect.com/science/article/pii/S0264127518304210},
  doi = {https://doi.org/10.1016/j.matdes.2018.05.036}
}
Liu, F., Hinduja, S. and Bártolo, P. User interface tool for a novel plasma-assisted bio-additive extrusion system 2018 Rapid Prototyping Journal
Vol. 24(2), pp. 368-378 
article DOI  
Abstract: Purpose This paper aims to describe the control software of a novel manufacturing system called plasma-assisted bio-extrusion system (PABS), designed to produce complex multi-material and functionally graded scaffolds for tissue engineering applications. This fabrication system combines multiple pressure-assisted and screw-assisted printing heads and plasma jets. Control software allows the users to create single or multi-material constructs with uniform pore size or pore size gradients by changing the operation parameters, such as geometric parameters, lay-down pattern, filament distance, feed rate and layer thickness, and to produce functional graded scaffolds with different layer-by-layer coating/surface modification strategies by using the plasma modification system. Design/methodology/approach MATLAB GUI is used to develop the software, including the design of the user interface and the implementation of all mathematical programing for both multi-extrusion and plasma modification systems. Findings Based on the user definition, G programing codes are generated, enabling full integration and synchronization with the hardware of PABS. Single, multi-material and functionally graded scaffolds can be obtained by manipulating different materials, scaffold designs and processing parameters. The software is easy to use, allowing the efficient control of the PABS even for the fabrication of complex scaffolds. Originality/value This paper introduces a novel additive manufacturing system for tissue engineering applications describing in detail the software developed to control the system. This new fabrication system represents a step forward regarding the current state-of-the-art technology in the field of biomanufacturing, enabling the design and fabrication of more effective scaffolds matching the mechanical and surface characteristics of the surrounding tissue and enabling the incorporation of high number of cells uniformly distributed and the introduction of multiple cell types with positional specificity.
BibTeX:
@article{Liu2018,
  author = {Fengyuan Liu and Srichand Hinduja and Paulo Bártolo},
  title = {User interface tool for a novel plasma-assisted bio-additive extrusion system},
  journal = {Rapid Prototyping Journal},
  year = {2018},
  volume = {24},
  number = {2},
  pages = {368-378},
  doi = {https://doi.org/10.1108/RPJ-07-2016-0115}
}
Lim, S.H., Kathuria, H., Tan, J.J.Y. and Kang, L. 3D printed drug delivery and testing systems — a passing fad or the future? 2018 Advanced Drug Delivery Reviews
Vol. 132, pp. 139 - 168 
article DOI URL 
Abstract: The US Food and Drug Administration approval of the first 3D printed tablet in 2015 has ignited growing interest in 3D printing, or additive manufacturing (AM), for drug delivery and testing systems. Beyond just a novel method for rapid prototyping, AM provides key advantages over traditional manufacturing of drug delivery and testing systems. These includes the ability to fabricate complex geometries to achieve variable drug release kinetics; ease of personalising pharmacotherapy for patient and lowering the cost for fabricating personalised dosages. Furthermore, AM allows fabrication of complex and micron-sized tissue scaffolds and models for drug testing systems that closely resemble in vivo conditions. However, there are several limitations such as regulatory concerns that may impede the progression to market. Here, we provide an overview of the advantages of AM drug delivery and testing, as compared to traditional manufacturing techniques. Also, we discuss the key challenges and future directions for AM enabled pharmaceutical applications.
BibTeX:
@article{Lim2018,
  author = {Seng Han Lim and Himanshu Kathuria and Justin Jia Yao Tan and Lifeng Kang},
  title = {3D printed drug delivery and testing systems — a passing fad or the future?},
  journal = {Advanced Drug Delivery Reviews},
  year = {2018},
  volume = {132},
  pages = {139 - 168},
  note = {3D-Bioprinting and Micro-/Nano-Technology: Emerging Technologies in Biomedical Sciences},
  url = {http://www.sciencedirect.com/science/article/pii/S0169409X18301091},
  doi = {https://doi.org/10.1016/j.addr.2018.05.006}
}
Li, H., Tan, Y.J., Liu, S. and Li, L. Three-Dimensional Bioprinting of Oppositely Charged Hydrogels with Super Strong Interface Bonding 2018 ACS Applied Materials & Interfaces
Vol. 10(13), pp. 11164-11174 
article DOI  
Abstract: A novel strategy to improve the adhesion between printed layers of three-dimensional (3D) printed constructs is developed by exploiting the interaction between two oppositely charged hydrogels. Three anionic hydrogels [alginate, xanthan, and κ-carrageenan (Kca)] and three cationic hydrogels [chitosan, gelatin, and gelatin methacrylate (GelMA)] are chosen to find the optimal combination of two oppositely charged hydrogels for the best 3D printability with strong interface bonding. Rheological properties and printability of the hydrogels, as well as structural integrity of printed constructs in cell culture medium, are studied as functions of polymer concentration and the combination of hydrogels. Kca2 (2 wt % Kca hydrogel) and GelMA10 (10 wt % GelMA hydrogel) are found to be the best combination of oppositely charged hydrogels for 3D printing. The interfacial bonding between a Kca layer and a GelMA layer is proven to be significantly higher than that of the bilayered Kca or bilayered GelMA because of the formation of polyelectrolyte complexes between the oppositely charged hydrogels. A good cell viability of >96% is obtained for the 3D-bioprinted Kca–GelMA construct. This novel strategy has a great potential for 3D bioprinting of layered constructs with a strong interface bonding.
BibTeX:
@article{Li2018,
  author = {Li, Huijun and Tan, Yu Jun and Liu, Sijun and Li, Lin},
  title = {Three-Dimensional Bioprinting of Oppositely Charged Hydrogels with Super Strong Interface Bonding},
  journal = {ACS Applied Materials & Interfaces},
  year = {2018},
  volume = {10},
  number = {13},
  pages = {11164-11174},
  note = {PMID: 29517901},
  doi = {https://doi.org/10.1021/acsami.7b19730}
}
Li, H., Tan, C. and Li, L. Review of 3D printable hydrogels and constructs 2018 Materials & Design
Vol. 159, pp. 20 - 38 
article DOI URL 
Abstract: Three dimensional (3D) bioprinting technologies with appropriate bioinks are potentially able to fabricate artificial tissues or organs with precise control. A bioink is a mixture of biomaterial and living cells, which is a biomaterial for bioprinting. Hydrogels are the most appealing candidates of biomaterials because they have many similar features of the natural extracellular matrix and could also provide a highly hydrated environment for cell proliferation. In this field of bio-fabrication, particularly in bioprinting, the lack of suitable hydrogels remains a major challenge. Thus, choosing appropriate hydrogels for bioprinting is the key to print self-supporting 3D constructs. Most importantly, the considerations regarding the bioinks and the obtained constructs should be made clear. This review aims to provide the specific considerations regarding the important properties of a potential bioink and the generated 3D construct, including rheological, interfacial, structural, biological, and degradation properties, which are crucial for printing of complex and functional 3D structures. Among all of the above considerations, interfacial bonding is one of the important considerations of successfully obtaining a 3D structure. Unfortunately, it is rarely mentioned in the prior literature. This review also points out, for the first time, the characterization of a potential bioink from a rheological point of view. To provide readers with an understanding of the background, the review will first present current technologies for bioprinting and their limitations. Following this will be a summary and discussion of some frequently used hydrogels for bioprinting, and their respective limitations as well. The readers will be informed on the current limitations and achievements in 3D bioprinting. This review ultimately intends to help researchers to select or develop suitable bioinks for successfully bioprinting 3D constructs.
BibTeX:
@article{Li2018a,
  author = {Huijun Li and Cavin Tan and Lin Li},
  title = {Review of 3D printable hydrogels and constructs},
  journal = {Materials & Design},
  year = {2018},
  volume = {159},
  pages = {20 - 38},
  url = {http://www.sciencedirect.com/science/article/pii/S0264127518306385},
  doi = {https://doi.org/10.1016/j.matdes.2018.08.023}
}
Lee, M., Bae, K., Guillon, P., Chang, J., Arlov, Ø. and Zenobi-Wong, M. Exploitation of Cationic Silica Nanoparticles for Bioprinting of Large-Scale Constructs with High Printing Fidelity 2018 ACS Applied Materials & Interfaces
Vol. 10(44), pp. 37820-37828 
article DOI  
Abstract: Three-dimensional (3D) bioprinting allows the fabrication of 3D structures containing living cells whose 3D shape and architecture are matched to a patient. The feature is desirable to achieve personalized treatment of trauma or diseases. However, realization of this promising technique in the clinic is greatly hindered by inferior mechanical properties of most biocompatible bioink materials. Here, we report a novel strategy to achieve printing large constructs with high printing quality and fidelity using an extrusion-based printer. We incorporate cationic nanoparticles in an anionic polymer mixture, which significantly improves mechanical properties, printability, and printing fidelity of the polymeric bioink due to electrostatic interactions between the nanoparticles and polymers. Addition of cationic-modified silica nanoparticles to an anionic polymer mixture composed of alginate and gellan gum results in significantly increased zero-shear viscosity (1062 as well as storage modulus (486. As a result, it is possible to print a large (centimeter-scale) porous structure with high printing quality, whereas the use of the polymeric ink without the nanoparticles leads to collapse of the printed structure during printing. We demonstrate such a mechanical enhancement is achieved by adding nanoparticles within a certain size range (<100 nm) and depends on concentration and surface chemistry of the nanoparticles as well as the length of polymers. Furthermore, shrinkage and swelling of the printed constructs during cross-linking are significantly suppressed by addition of nanoparticles compared with the ink without nanoparticles, which leads to high printing fidelity after cross-linking. The incorporated nanoparticles do not compromise biocompatibility of the polymeric ink, where high cell viability (>90 and extracellular matrix secretion are observed for cells printed with nanocomposite inks. The design principle demonstrated can be applied for various anionic polymer-based systems, which could lead to achievement of 3D bioprinting-based personalized treatment.
BibTeX:
@article{Lee2018,
  author = {Lee, Mihyun and Bae, Kraun and Guillon, Pierre and Chang, Jin and Arlov, Øystein and Zenobi-Wong, Marcy},
  title = {Exploitation of Cationic Silica Nanoparticles for Bioprinting of Large-Scale Constructs with High Printing Fidelity},
  journal = {ACS Applied Materials & Interfaces},
  year = {2018},
  volume = {10},
  number = {44},
  pages = {37820-37828},
  doi = {https://doi.org/10.1021/acsami.8b13166}
}
Laternser, S., Keller, H., Leupin, O., Rausch, M., Graf-Hausner, U. and Rimann, M. A Novel Microplate 3D Bioprinting Platform for the Engineering of Muscle and Tendon Tissues 2018 SLAS TECHNOLOGY: Translating Life Sciences Innovation
Vol. 0(0), pp. 2472630318776594 
article DOI URL 
Abstract: Two-dimensional (2D) cell cultures do not reflect the in vivo situation, and thus it is important to develop predictive three-dimensional (3D) in vitro models with enhanced reliability and robustness for drug screening applications. Treatments against muscle-related diseases are becoming more prominent due to the growth of the aging population worldwide. In this study, we describe a novel drug screening platform with automated production of 3D musculoskeletal-tendon-like tissues. With 3D bioprinting, alternating layers of photo-polymerized gelatin-methacryloyl-based bioink and cell suspension tissue models were produced in a dumbbell shape onto novel postholder cell culture inserts in 24-well plates. Monocultures of human primary skeletal muscle cells and rat tenocytes were printed around and between the posts. The cells showed high viability in culture and good tissue differentiation, based on marker gene and protein expressions. Different printing patterns of bioink and cells were explored and calcium signaling with Fluo4-loaded cells while electrically stimulated was shown. Finally, controlled co-printing of tenocytes and myoblasts around and between the posts, respectively, was demonstrated followed by co-culture and co-differentiation. This screening platform combining 3D bioprinting with a novel microplate represents a promising tool to address musculoskeletal diseases.
BibTeX:
@article{Laternser2018,
  author = {Sandra Laternser and Hansjoerg Keller and Olivier Leupin and Martin Rausch and Ursula Graf-Hausner and Markus Rimann},
  title = {A Novel Microplate 3D Bioprinting Platform for the Engineering of Muscle and Tendon Tissues},
  journal = {SLAS TECHNOLOGY: Translating Life Sciences Innovation},
  year = {2018},
  volume = {0},
  number = {0},
  pages = {2472630318776594},
  note = {PMID: 29895208},
  url = { 

https://doi.org/10.1177/2472630318776594

}, doi = {https://doi.org/10.1177/2472630318776594} }
Kuzmenko, V., Karabulut, E., Pernevik, E., Enoksson, P. and Gatenholm, P. Tailor-made conductive inks from cellulose nanofibrils for 3D printing of neural guidelines 2018 Carbohydrate Polymers
Vol. 189, pp. 22 - 30 
article DOI URL 
Abstract: Neural tissue engineering (TE), an innovative biomedical method of brain study, is very dependent on scaffolds that support cell development into a functional tissue. Recently, 3D patterned scaffolds for neural TE have shown significant positive effects on cells by a more realistic mimicking of actual neural tissue. In this work, we present a conductive nanocellulose-based ink for 3D printing of neural TE scaffolds. It is demonstrated that by using cellulose nanofibrils and carbon nanotubes as ink constituents, it is possible to print guidelines with a diameter below 1 mm and electrical conductivity of 3.8 × 10−1 S cm−1. The cell culture studies reveal that neural cells prefer to attach, proliferate, and differentiate on the 3D printed conductive guidelines. To our knowledge, this is the first research effort devoted to using cost-effective cellulosic 3D printed structures in neural TE, and we suppose that much more will arise in the near future.
BibTeX:
@article{Kuzmenko2018,
  author = {Volodymyr Kuzmenko and Erdem Karabulut and Elin Pernevik and Peter Enoksson and Paul Gatenholm},
  title = {Tailor-made conductive inks from cellulose nanofibrils for 3D printing of neural guidelines},
  journal = {Carbohydrate Polymers},
  year = {2018},
  volume = {189},
  pages = {22 - 30},
  url = {http://www.sciencedirect.com/science/article/pii/S0144861718301231},
  doi = {https://doi.org/10.1016/j.carbpol.2018.01.097}
}
Kumari, S., Bargel, H., Anby, M.U., Lafargue, D. and Scheibel, T. Recombinant Spider Silk Hydrogels for Sustained Release of Biologicals 2018 ACS Biomaterials Science & Engineering
Vol. 4(5), pp. 1750-1759 
article DOI  
Abstract: Therapeutic biologics (i.e., proteins) have been widely recognized for the treatment, prevention, and cure of a variety of human diseases and syndromes. However, design of novel protein-delivery systems to achieve a nontoxic, constant, and efficient delivery with minimal doses of therapeutic biologics is still challenging. Here, recombinant spider silk-based materials are employed as a delivery system for the administration of therapeutic biologicals. Hydrogels made of the recombinant spider silk protein eADF4(C16) were used to encapsulate the model biologicals BSA, HRP, and LYS by direct loading or through diffusion, and their release was studied. Release of model biologicals from eADF4(C16) hydrogels is in part dependent on the electrostatic interaction between the biological and the recombinant spider silk protein variant used. In addition, tailoring the pore sizes of eADF4(C16) hydrogels strongly influenced the release kinetics. In a second approach, a particles-in-hydrogel system was used, showing a prolonged release in comparison with that of plain hydrogels (from days to week). The particle-enforced spider silk hydrogels are injectable and can be 3D printed. These initial studies indicate the potential of recombinant spider silk proteins to design novel injectable hydrogels that are suitable for delivering therapeutic biologics.
BibTeX:
@article{Kumari2018,
  author = {Kumari, Sushma and Bargel, Hendrik and Anby, Mette U. and Lafargue, David and Scheibel, Thomas},
  title = {Recombinant Spider Silk Hydrogels for Sustained Release of Biologicals},
  journal = {ACS Biomaterials Science & Engineering},
  year = {2018},
  volume = {4},
  number = {5},
  pages = {1750-1759},
  doi = {https://doi.org/10.1021/acsbiomaterials.8b00382}
}
Kokkinis, D., Bouville, F. and Studart, A.R. 3D Printing of Materials with Tunable Failure via Bioinspired Mechanical Gradients 2018 Advanced Materials
Vol. 30(19), pp. 1705808 
article DOI  
Abstract: Abstract Mechanical gradients are useful to reduce strain mismatches in heterogeneous materials and thus prevent premature failure of devices in a wide range of applications. While complex graded designs are a hallmark of biological materials, gradients in manmade materials are often limited to 1D profiles due to the lack of adequate fabrication tools. Here, a multimaterial 3D‐printing platform is developed to fabricate elastomer gradients spanning three orders of magnitude in elastic modulus and used to investigate the role of various bioinspired gradient designs on the local and global mechanical behavior of synthetic materials. The digital image correlation data and finite element modeling indicate that gradients can be effectively used to manipulate the stress state and thus circumvent the weakening effect of defect‐rich interfaces or program the failure behavior of heterogeneous materials. Implementing this concept in materials with bioinspired designs can potentially lead to defect‐tolerant structures and to materials whose tunable failure facilitates repair of biomedical implants, stretchable electronics, or soft robotics.
BibTeX:
@article{Kokkinis2018,
  author = {Dimitri Kokkinis and Florian Bouville and André R. Studart},
  title = {3D Printing of Materials with Tunable Failure via Bioinspired Mechanical Gradients},
  journal = {Advanced Materials},
  year = {2018},
  volume = {30},
  number = {19},
  pages = {1705808},
  doi = {https://doi.org/10.1002/adma.201705808}
}
Khaled, S.A., Alexander, M.R., Wildman, R.D., Wallace, M.J., Sharpe, S., Yoo, J. and Roberts, C.J. 3D extrusion printing of high drug loading immediate release paracetamol tablets 2018 International Journal of Pharmaceutics
Vol. 538(1), pp. 223 - 230 
article DOI URL 
Abstract: The manufacture of immediate release high drug loading paracetamol oral tablets was achieved using an extrusion based 3D printer from a premixed water based paste formulation. The 3D printed tablets demonstrate that a very high drug (paracetamol) loading formulation (80% w/w) can be printed as an acceptable tablet using a method suitable for personalisation and distributed manufacture. Paracetamol is an example of a drug whose physical form can present challenges to traditional powder compression tableting. Printing avoids these issues and facilitates the relatively high drug loading. The 3D printed tablets were evaluated for physical and mechanical properties including weight variation, friability, breaking force, disintegration time, and dimensions and were within acceptable range as defined by the international standards stated in the United States Pharmacopoeia (USP). X-ray Powder Diffraction (XRPD) was used to identify the physical form of the active. Additionally, XRPD, Attenuated Total Reflectance Fourier Transform Infrared spectroscopy (ATR-FTIR) and differential scanning calorimetry (DSC) were used to assess possible drug-excipient interactions. The 3D printed tablets were evaluated for drug release using a USP dissolution testing type I apparatus. The tablets showed a profile characteristic of the immediate release profile as intended based upon the active/excipient ratio used with disintegration in less than 60 s and release of most of the drug within 5 min. The results demonstrate the capability of 3D extrusion based printing to produce acceptable high-drug loading tablets from approved materials that comply with current USP standards.
BibTeX:
@article{Khaled2018,
  author = {Shaban A. Khaled and Morgan R. Alexander and Ricky D. Wildman and Martin J. Wallace and Sonja Sharpe and Jae Yoo and Clive J. Roberts},
  title = {3D extrusion printing of high drug loading immediate release paracetamol tablets},
  journal = {International Journal of Pharmaceutics},
  year = {2018},
  volume = {538},
  number = {1},
  pages = {223 - 230},
  url = {http://www.sciencedirect.com/science/article/pii/S037851731830036X},
  doi = {https://doi.org/10.1016/j.ijpharm.2018.01.024}
}
Kelder, C., Bakker, A.D., Klein-Nulend, J. and Wismeijer, D. The 3D Printing of Calcium Phosphate with K-Carrageenan under Conditions Permitting the Incorporation of Biological Components—A Method 2018 Journal of Functional Biomaterials
Vol. 9(4) 
article DOI URL 
Abstract: Critical-size bone defects are a common clinical problem. The golden standard to treat these defects is autologous bone grafting. Besides the limitations of availability and co-morbidity, autografts have to be manually adapted to fit in the defect, which might result in a sub-optimal fit and impaired healing. Scaffolds with precise dimensions can be created using 3-dimensional (3D) printing, enabling the production of patient-specific, &lsquo;tailor-made&rsquo; bone substitutes with an exact fit. Calcium phosphate (CaP) is a popular material for bone tissue engineering due to its biocompatibility, osteoconductivity, and biodegradable properties. To enhance bone formation, a bioactive 3D-printed CaP scaffold can be created by combining the printed CaP scaffold with biological components such as growth factors and cytokines, e.g., vascular endothelial growth factor (VEGF), bone morphogenetic protein-2 (BMP-2), and interleukin-6 (IL-6). However, the 3D-printing of CaP with a biological component is challenging since production techniques often use high temperatures or aggressive chemicals, which hinders/inactivates the bioactivity of the incorporated biological components. Therefore, in our laboratory, we routinely perform extrusion-based 3D-printing with a biological binder at room temperature to create porous scaffolds for bone healing. In this method paper, we describe in detail a 3D-printing procedure for CaP paste with K-carrageenan as a biological binder.
BibTeX:
@article{Kelder2018,
  author = {Kelder, Cindy and Bakker, Astrid Diana and Klein-Nulend, Jenneke and Wismeijer, Daniël},
  title = {The 3D Printing of Calcium Phosphate with K-Carrageenan under Conditions Permitting the Incorporation of Biological Components—A Method},
  journal = {Journal of Functional Biomaterials},
  year = {2018},
  volume = {9},
  number = {4},
  url = {http://www.mdpi.com/2079-4983/9/4/57},
  doi = {https://doi.org/10.3390/jfb9040057}
}
Jordahl, J., Solorio, L., Sun, H., Ramcharan, S., Teeple, C., Haley, H., Lee, K., Eyster, T., Luker, G., Krebsbach, P. and Lahann, J 3D Jet Writing: Functional microtissues based on tessellated scaffold architectures 2018 Advanced Materials  article DOI  
Abstract: The advent of adaptive manufacturing techniques supports a vision of cell-instructive materials that mimic biological tissues. 3D jet writing, a modified electrospinning process
discovered herein, yields three-dimensional structures with unprecedented precision and resolution offering customizable pore geometries and scalability to over tens of centimeters. These scaffolds support the 3D expansion and differentiation of human mesenchymal stem cells in vitro. Implantation of these constructs leads to the healing of critical bone defects in vivo without exogenous growth factors. When applied as a metastatic target site in mice, circulating cancer cells homed in to the osteogenic environment simulated on 3D jet writing scaffolds, despite implantation in an anatomically abnormal site. Through 3D jet writing, we demonstrate the formation of tessellated microtissues which serve as a versatile 3D cell culture platform in a range of biomedical applications including regenerative medicine, cancer biology, and stem cell biotechnology
BibTeX:
@article{Jordahl2018,
  author = {Jordahl, JH; Solorio, L; Sun, H; Ramcharan, S; Teeple, CB; Haley, HR; Lee, KJ; Eyster, TW; Luker, GD; Krebsbach, PH; Lahann J},
  title = {3D Jet Writing: Functional microtissues based on tessellated scaffold architectures},
  journal = {Advanced Materials},
  year = {2018},
  doi = {https://doi.org/10.1002/adma.201707196}
}
Huang, Y.-A., Ho, C.T., Lin, Y.-H., Lee, C.-J., Ho, S.-M., Li, M.-C. and Hwang, E. Nanoimprinted Anisotropic Topography Preferentially Guides Axons and Enhances Nerve Regeneration 2018 Macromolecular Bioscience
Vol. 0(0), pp. 1800335 
article DOI  
Abstract: Abstract Surface topography has a profound effect on the development of the nervous system, such as neuronal differentiation and morphogenesis. While the interaction of neurons and the surface topography of their local environment is well characterized, the neuron–topography interaction during the regeneration process remains largely unknown. To address this question, an anisotropic surface topography resembling linear grooves made from poly(ethylene-vinyl acetate) (EVA), a soft and biocompatible polymer, using nanoimprinting, is established. It is found that neurons from both the central and peripheral nervous system can survive and grow on this grooved surface. Additionally, it is observed that axons but not dendrites specifically align with these grooves. Furthermore, it is demonstrated that neurons on the grooved surface are capable of regeneration after an on-site injury. More importantly, these injured neurons have an accelerated and enhanced regeneration. Together, the data demonstrate that this anisotropic topography guides axon growth and improves axon regeneration. This opens up the possibility to study the effect of surface topography on regenerating axons and has the potential to be developed into a medical device for treating peripheral nerve injuries.
BibTeX:
@article{Huang2018,
  author = {Huang, Yun-An and Ho, Chris T. and Lin, Yu-Hsuan and Lee, Chen-Ju and Ho, Szu-Mo and Li, Ming-Chia and Hwang, Eric},
  title = {Nanoimprinted Anisotropic Topography Preferentially Guides Axons and Enhances Nerve Regeneration},
  journal = {Macromolecular Bioscience},
  year = {2018},
  volume = {0},
  number = {0},
  pages = {1800335},
  doi = {https://doi.org/10.1002/mabi.201800335}
}
Hrynevich, A., Elçi, B.Ş., Haigh, J.N., McMaster, R., Youssef, A., Blum, C., Blunk, T., Hochleitner, G., Groll, J. and Dalton, P.D. Dimension-Based Design of Melt Electrowritten Scaffolds 2018 Small
Vol. 14(22), pp. 1800232 
article DOI  
Abstract: Abstract The electrohydrodynamic stabilization of direct-written fluid jets is explored to design and manufacture tissue engineering scaffolds based on their desired fiber dimensions. It is demonstrated that melt electrowriting can fabricate a full spectrum of various fibers with discrete diameters (2–50 µm) using a single nozzle. This change in fiber diameter is digitally controlled by combining the mass flow rate to the nozzle with collector speed variations without changing the applied voltage. The greatest spectrum of fiber diameters was achieved by the simultaneous alteration of those parameters during printing. The highest placement accuracy could be achieved when maintaining the collector speed slightly above the critical translation speed. This permits the fabrication of medical-grade poly(ε-caprolactone) into complex multimodal and multiphasic scaffolds, using a single nozzle in a single print. This ability to control fiber diameter during printing opens new design opportunities for accurate scaffold fabrication for biomedical applications.
BibTeX:
@article{Hrynevich2018,
  author = {Hrynevich, Andrei and Elçi, Bilge Ş. and Haigh, Jodie N. and McMaster, Rebecca and Youssef, Almoatazbellah and Blum, Carina and Blunk, Torsten and Hochleitner, Gernot and Groll, Jürgen and Dalton, Paul D.},
  title = {Dimension-Based Design of Melt Electrowritten Scaffolds},
  journal = {Small},
  year = {2018},
  volume = {14},
  number = {22},
  pages = {1800232},
  doi = {https://doi.org/10.1002/smll.201800232}
}
Hochleitner, G., Chen, F., Blum, C., Dalton, P.D., Amsden, B. and Groll, J. Melt electrowriting below the critical translation speed to fabricate crimped elastomer scaffolds with non-linear extension behaviour mimicking that of ligaments and tendons 2018 Acta Biomaterialia
Vol. 72, pp. 110 - 120 
article DOI URL 
Abstract: Ligaments and tendons are comprised of aligned, crimped collagen fibrils that provide tissue-specific mechanical properties with non-linear extension behaviour, exhibiting low stress at initial strain (toe region behaviour). To approximate this behaviour, we report fibrous scaffolds with sinusoidal patterns by melt electrowriting (MEW) below the critical translation speed (CTS) by exploitation of the natural flow behaviour of the polymer melt. More specifically, we synthesised photopolymerizable poly(L-lactide-co-ε-caprolactone-co-acryloyl carbonate) (p(LLA-co-ε-CL-co-AC)) and poly(ε-caprolactone-co-acryloyl carbonate) (p(ε-CL-co-AC)) by ring-opening polymerization (ROP). Single fibre (fØ = 26.8 ± 1.9 µm) tensile testing revealed a customisable toe region with Young’s Moduli ranging from E = 29 ± 17 MPa for the most crimped structures to E = 314 ± 157 MPa for straight fibres. This toe region extended to scaffolds containing multiple fibres, while the sinusoidal pattern could be influenced by printing speed. The synthesized polymers were cytocompatible and exhibited a tensile strength of σ = 26 ± 7 MPa after 104 cycles of preloading at 10% strain while retaining the distinct toe region commonly observed in native ligaments and tendon tissue.
Statement of Significance
Damaged tendons and ligaments are serious and frequently occurring injuries worldwide. Recent therapies, including autologous grafts, still have severe disadvantages leading to a demand for synthetic alternatives. Materials envisioned to induce tendon and ligament regeneration should be degradable, cytocompatible and mimic the ultrastructural and mechanical properties of the native tissue. Specifically, we utilised photo-cross-linkable polymers for additive manufacturing (AM) with MEW. In this way, we were able to direct-write cytocompatible fibres of a few micrometres thickness into crimp-structured elastomer scaffolds that mimic the non-linear biomechanical behaviour of tendon and ligament tissue.
BibTeX:
@article{Hochleitner2018,
  author = {Gernot Hochleitner and Fei Chen and Carina Blum and Paul D. Dalton and Brian Amsden and Jürgen Groll},
  title = {Melt electrowriting below the critical translation speed to fabricate crimped elastomer scaffolds with non-linear extension behaviour mimicking that of ligaments and tendons},
  journal = {Acta Biomaterialia},
  year = {2018},
  volume = {72},
  pages = {110 - 120},
  url = {http://www.sciencedirect.com/science/article/pii/S1742706118301430},
  doi = {https://doi.org/10.1016/j.actbio.2018.03.023}
}
Gungor-Ozkerim, P.S., Inci, I., Zhang, Y.S., Khademhosseini, A. and Dokmeci, M.R. Bioinks for 3D bioprinting: an overview 2018 Biomater. Sci.
Vol. 6, pp. 915-946 
article DOI  
Abstract: Bioprinting is an emerging technology with various applications in making functional tissue constructs to replace injured or diseased tissues. It is a relatively new approach that provides high reproducibility and precise control over the fabricated constructs in an automated manner, potentially enabling high-throughput production. During the bioprinting process, a solution of a biomaterial or a mixture of several biomaterials in the hydrogel form, usually encapsulating the desired cell types, termed the bioink, is used for creating tissue constructs. This bioink can be cross-linked or stabilized during or immediately after bioprinting to generate the final shape, structure, and architecture of the designed construct. Bioinks may be made from natural or synthetic biomaterials alone, or a combination of the two as hybrid materials. In certain cases, cell aggregates without any additional biomaterials can also be adopted for use as a bioink for bioprinting processes. An ideal bioink should possess proper mechanical, rheological, and biological properties of the target tissues, which are essential to ensure correct functionality of the bioprinted tissues and organs. In this review, we provide an in-depth discussion of the different bioinks currently employed for bioprinting, and outline some future perspectives in their further development.
BibTeX:
@article{Gungor-Ozkerim2018,
  author = {Gungor-Ozkerim, P. Selcan and Inci, Ilyas and Zhang, Yu Shrike and Khademhosseini, Ali and Dokmeci, Mehmet Remzi},
  title = {Bioinks for 3D bioprinting: an overview},
  journal = {Biomater. Sci.},
  publisher = {The Royal Society of Chemistry},
  year = {2018},
  volume = {6},
  pages = {915-946},
  doi = {https://doi.org/10.1039/C7BM00765E}
}
Gretzinger, S., Beckert, N., Gleadall, A., Lee-Thedieck, C. and Hubbuch, J. 3D bioprinting – Flow cytometry as analytical strategy for 3D cell structures 2018 Bioprinting
Vol. 11, pp. e00023 
article DOI URL 
Abstract: The importance of 3D printing technologies increased significantly over the recent years. They are considered to have a huge impact in regenerative medicine and tissue engineering, since 3D bioprinting enables the production of cell-laden 3D scaffolds. Transition from academic research to pharmaceutical industry or clinical applications, however, is highly dependent on developing a robust and well-known process, while maintaining critical cell characteristics. Hence, a directed and systematic approach to 3D bioprinting process development is required, which also allows for the monitoring of these cell characteristics. This work presents the development of a flow cytometry-based analytical strategy as a tool for 3D bioprinting research. The development was based on a model process using a commercially available alginate-based bioink, the β-cell line INS-1E, and direct dispensing as 3D bioprinting method. We demonstrated that this set-up enabled viability and proliferation analysis. Additionally, use of an automated sampler facilitated high-throughput screenings. Finally, we showed that each process step, e.g. suspension of cells in bioink or 3D printing, cross-linking of the alginate scaffold after printing, has a crucial impact on INS-1E viability. This reflects the importance of process optimization in 3D bioprinting and the usefulness of the flow cytometry-based analytical strategy described here. The presented strategy has a great potential as a cell characterisation tool for 3D bioprinting and may contribute to a more directed process development.
BibTeX:
@article{Gretzinger2018,
  author = {Sarah Gretzinger and Nicole Beckert and Andrew Gleadall and Cornelia Lee-Thedieck and Jürgen Hubbuch},
  title = {3D bioprinting – Flow cytometry as analytical strategy for 3D cell structures},
  journal = {Bioprinting},
  year = {2018},
  volume = {11},
  pages = {e00023},
  url = {http://www.sciencedirect.com/science/article/pii/S2405886618300034},
  doi = {https://doi.org/10.1016/j.BPRINT.2018.e00023}
}
Gelber, M., Hurst, G., Comi, T. and Bhargava, R. Model-guided design and characterization of a high-precision 3D printing process for carbohydrate glass 2018 Additive Manufacturing
Vol. 22, pp. 38 - 50 
article DOI URL 
Abstract: Water-soluble glass patterned by 3D printing is a versatile tool for tissue engineering and microfluidics. Glasses can be patterned layer-by-layer as in conventional fused deposition modeling but also along 3D, “freeform” paths. In the latter approach, extruding heated material through a nozzle translating in 3D space allows for fabrication of sparse, freestanding networks of cylindrical filaments. These freeform structures are suitable for sacrificial molding with a variety of media, leaving complex microchannel networks. However, 3D printing carbohydrate glass in this way presents several unique challenges: 1) the material must resist degradation and crystallization during printing, 2) the glass must be hot enough to flow freely during extrusion and fuse to the printed construct, while cooling rapidly to retain its shape upon exiting the nozzle, 3) the extruder needs to apply high pressure, with rapid stop and start times and 4) the net force that acts on the filament during extrusion must be minimized so that the filament shape is predictable, i.e., coincides with the path taken by the nozzle. First, we review the properties of commercially available carbohydrate glasses and provide a guide for processing isomalt, our material of choice, to achieve the best printing performance. A pressure-controlled, piston-driven extruder is then described which allows for rapid responses and precise control over the material flow rate. We then analyze the heat transfer within the filament and the forces that contribute to the filament’s final shape. We find that the dominant force is due to the radial flow of the molten glass as it exits the nozzle. This analysis is validated on a purpose-built isomalt 3D printer, which we utilize to characterize relationships between extrusion pressure, translation speed, filament diameter, and viscous force. The insights of the physics of the printing process enable fabrication of intricate freeform prints as well as layer-by-layer designs. The practical and theoretical considerations should facilitate adoption of additive manufacturing of carbohydrate glasses with applications to a wide variety of fields, including tissue engineering and microfluidics.
BibTeX:
@article{Gelber2018,
  author = {M.K. Gelber and G. Hurst and T.J. Comi and R. Bhargava},
  title = {Model-guided design and characterization of a high-precision 3D printing process for carbohydrate glass},
  journal = {Additive Manufacturing},
  year = {2018},
  volume = {22},
  pages = {38 - 50},
  url = {http://www.sciencedirect.com/science/article/pii/S2214860418301088},
  doi = {https://doi.org/10.1016/j.addma.2018.04.026}
}
Fortunato, G.M., Maria, C.D., Eglin, D., Serra, T. and Vozzi, G. An ink-jet printed electrical stimulation platform for muscle tissue regeneration 2018 Bioprinting
Vol. 11, pp. e00035 
article DOI URL 
Abstract: Conducting polymeric materials have been used to modulate response of cells seeded on their surfaces. However, there is still major improvement to be made related to their biocompatibility, conductivity, stability in biological milieu, and processability toward truly tissue engineered functional device. In this work, conductive polymer, poly(3,4-ethylene-dioxythiophene):polystyrene-sulfonate (PEDOT:PSS), and its possible applications in tissue engineering were explored. In particular PEDOT:PSS solution was inkjet printed onto a gelatin substrate for obtaining a conductive structure. Mechanical and electrical characterizations, structural stability by swelling and degradation tests were carried out on different PEDOT-based samples obtained by varying the number of printed PEDOT layers from 5 to 50 on gelatin substrate. Biocompatibility of substrates was investigated on C2C12 myoblasts, through metabolic activity assay and imaging analysis during a 7-days culture period, to assess cell morphology, differentiation and alignment. The results of this first part allowed to proceed with the second part of the study in which these substrates were used for the design of an electrical stimulation device, with the aim of providing the external stimulus (3 V amplitude square wave at 1 and 2 Hz frequency) to guide myotubes alignment and enhance differentiation, having in this way promising applications in the field of muscle tissue engineering.
BibTeX:
@article{Fortunato2018,
  author = {Gabriele Maria Fortunato and Carmelo De Maria and David Eglin and Tiziano Serra and Giovanni Vozzi},
  title = {An ink-jet printed electrical stimulation platform for muscle tissue regeneration},
  journal = {Bioprinting},
  year = {2018},
  volume = {11},
  pages = {e00035},
  url = {http://www.sciencedirect.com/science/article/pii/S2405886618300344},
  doi = {https://doi.org/10.1016/j.bprint.2018.e00035}
}
Foresti, D., Kroll, K.T., Amissah, R., Sillani, F., Homan, K.A., Poulikakos, D. and Lewis, J.A. Acoustophoretic printing 2018 Science Advances
Vol. 4(8) 
article DOI URL 
Abstract: Droplet-based printing methods are widely used in applications ranging from biological microarrays to additive manufacturing. However, common approaches, such as inkjet or electrohydrodynamic printing, are well suited only for materials with low viscosity or specific electromagnetic properties, respectively. While in-air acoustophoretic forces are material-independent, they are typically weak and have yet to be harnessed for printing materials. We introduce an acoustophoretic printing method that enables drop-on-demand patterning of a broad range of soft materials, including Newtonian fluids, whose viscosities span more than four orders of magnitude (0.5 to 25,000 mPatextperiodcentereds) and yield stress fluids (τ0 &gt; 50 Pa). By exploiting the acoustic properties of a subwavelength Fabry-Perot resonator, we have generated an accurate, highly localized acoustophoretic force that can exceed the gravitational force by two orders of magnitude to eject microliter-to-nanoliter volume droplets. The versatility of acoustophoretic printing is demonstrated by patterning food, optical resins, liquid metals, and cell-laden biological matrices in desired motifs.
BibTeX:
@article{Foresti2018,
  author = {Foresti, Daniele and Kroll, Katharina T. and Amissah, Robert and Sillani, Francesco and Homan, Kimberly A. and Poulikakos, Dimos and Lewis, Jennifer A.},
  title = {Acoustophoretic printing},
  journal = {Science Advances},
  publisher = {American Association for the Advancement of Science},
  year = {2018},
  volume = {4},
  number = {8},
  url = {http://advances.sciencemag.org/content/4/8/eaat1659},
  doi = {https://doi.org/10.1126/sciadv.aat1659}
}
Firth, J., Basit, A.W. and Gaisford, S. The Role of Semi-Solid Extrusion Printing in Clinical Practice 2018 3D Printing of Pharmaceuticals, pp. 133-151  inbook DOI  
Abstract: Residing under the umbrella term of `material extrusion', semi-solid extrusion (SSE) 3D printing deposits gels or pastes in sequential layers to create a solid object. The physical nature of the feedstock allows SSE to print quickly at low temperatures with little compromise in accuracy. As a result, the technology has been extensively adopted in the field of bioprinting in which SSE can print living cells able to create large, complex structures of human tissue. In terms of pharmaceutical formulation, SSE is relatively unused. By building on the advancements made in other fields, the unique attributes of SSE printing are beginning to come to the fore. In particular, the ability of SSE to create complex tablets at a low heat means the technology has the potential to make on demand, personalised dosages within a clinical setting. As a result, the infancy of SSE in pharmaceutics should not be seen as a sign of inferiority but rather a real opportunity to bring 3D printing into the clinic.
BibTeX:
@inbook{Firth2018,
  author = {Firth, Jack and Basit, Abdul W. and Gaisford, Simon},
  title = {The Role of Semi-Solid Extrusion Printing in Clinical Practice},
  booktitle = {3D Printing of Pharmaceuticals},
  publisher = {Springer International Publishing},
  year = {2018},
  pages = {133--151},
  doi = {https://doi.org/10.1007/978-3-319-90755-0_7}
}
Daly, A.C., Pitacco, P., Nulty, J., Cunniffe, G.M. and Kelly, D.J. 3D printed microchannel networks to direct vascularisation during endochondral bone repair 2018 Biomaterials
Vol. 162, pp. 34 - 46 
article DOI URL 
Abstract: Bone tissue engineering strategies that recapitulate the developmental process of endochondral ossification offer a promising route to bone repair. Clinical translation of such endochondral tissue engineering strategies will require overcoming a number of challenges, including the engineering of large and often anatomically complex cartilage grafts, as well as the persistence of core regions of avascular cartilage following their implantation into large bone defects. Here 3D printing technology is utilized to develop a versatile and scalable approach to guide vascularisation during endochondral bone repair. First, a sacrificial pluronic ink was used to 3D print interconnected microchannel networks in a mesenchymal stem cell (MSC) laden gelatin-methacryloyl (GelMA) hydrogel. These constructs (with and without microchannels) were next chondrogenically primed in vitro and then implanted into critically sized femoral bone defects in rats. The solid and microchanneled cartilage templates enhanced bone repair compared to untreated controls, with the solid cartilage templates (without microchannels) supporting the highest levels of total bone formation. However, the inclusion of 3D printed microchannels was found to promote osteoclast/immune cell invasion, hydrogel degradation, and vascularisation following implantation. In addition, the endochondral bone tissue engineering strategy was found to support comparable levels of bone healing to BMP-2 delivery, whilst promoting lower levels of heterotopic bone formation, with the microchanneled templates supporting the lowest levels of heterotopic bone formation. Taken together, these results demonstrate that 3D printed hypertrophic cartilage grafts represent a promising approach for the repair of complex bone fractures, particularly for larger defects where vascularisation will be a key challenge.
BibTeX:
@article{Daly2018,
  author = {Andrew C. Daly and Pierluca Pitacco and Jessica Nulty and Gráinne M. Cunniffe and Daniel J. Kelly},
  title = {3D printed microchannel networks to direct vascularisation during endochondral bone repair},
  journal = {Biomaterials},
  year = {2018},
  volume = {162},
  pages = {34 - 46},
  url = {http://www.sciencedirect.com/science/article/pii/S0142961218300772},
  doi = {https://doi.org/10.1016/j.biomaterials.2018.01.057}
}
Couck, S., Saint-Remi, J.C., der Perre, S.V., Baron, G.V., Minas, C., Ruch, P. and Denayer, J.F. 3D-printed SAPO-34 monoliths for gas separation 2018 Microporous and Mesoporous Materials
Vol. 255(Supplement C), pp. 185 - 191 
article DOI URL 
Abstract: Abstract A 3D printing method (the Direct Ink writing, DIW, method) is applied to produce SAPO-34 zeolite based structured adsorbents with the shape of a honeycomb-like monolith. The use of the 3D printing technique gives this structure a well-defined and easily adaptable geometry. As binder material, methyl cellulose was used. The SAPO-34 monolith was characterized by SEM as well as Ar and Hg porosimetry. The CO2 adsorption affinity, capacity and heat of adsorption were determined by recording high pressure adsorption isotherms at different temperatures, using the gravimetric technique. The separation potential was investigated by means of breakthrough experiments with mixtures of CO2 and N2. The experimental selectivity of CO2/N2 separation was compared to the selectivity as predicted by the Ideal Adsorbed Solution Theory. A drop in capacity was noticed during the experiments and N2 capacities were close to zero or slightly negative due to the very low adsorption, meaning absolute selectivity values could not be determined. However, due to the low N2 capacity, experimental selectivity is estimated to be excellent as was predicted with IAST. While the 3D printing is found to be a practical, fast and flexible route to generate monolithic adsorbent structures, improvements in formulation are required in terms of sample robustness for handling purposes and heat transfer characteristics of the obtained monoliths during gas separation.
BibTeX:
@article{Couck2018,
  author = {Sarah Couck and Julien Cousin-Saint-Remi and Stijn Van der Perre and Gino V. Baron and Clara Minas and Patrick Ruch and Joeri F.M. Denayer},
  title = {3D-printed SAPO-34 monoliths for gas separation},
  journal = {Microporous and Mesoporous Materials},
  year = {2018},
  volume = {255},
  number = {Supplement C},
  pages = {185 - 191},
  url = {http://www.sciencedirect.com/science/article/pii/S1387181117304869},
  doi = {https://doi.org/10.1016/j.micromeso.2017.07.014}
}
Chlanda, A., Kijeńska, E., Rinoldi, C., Tarnowski, M., Wierzchoń, T. and Swieszkowski, W. Structure and physico-mechanical properties of low temperature plasma treated electrospun nanofibrous scaffolds examined with atomic force microscopy 2018 Micron
Vol. 107, pp. 79 - 84 
article DOI URL 
Abstract: Electrospun nanofibrous scaffolds are willingly used in tissue engineering applications due to their tunable mechanical, chemical and physical properties. Additionally, their complex openworked architecture is similar to the native extracellular matrix of living tissue. After implantation such scaffolds should provide sufficient mechanical support for cells. Moreover, it is of crucial importance to ensure sterility and hydrophilicity of the scaffold. For this purpose, a low temperature surface plasma treatment can be applied. In this paper, we report physico-mechanical evaluation of stiffness and adhesive properties of electrospun mats after their exposition to low temperature plasma. Complex morphological and mechanical studies performed with an atomic force microscope were followed by scanning electron microscope imaging and a wettability assessment. The results suggest that plasma treatment can be a useful method for the modification of the surface of polymeric scaffolds in a desirable manner. Plasma treatment improves wettability of the polymeric mats without changing their morphology.
BibTeX:
@article{Chlanda2018,
  author = {Adrian Chlanda and Ewa Kijeńska and Chiara Rinoldi and Michał Tarnowski and Tadeusz Wierzchoń and Wojciech Swieszkowski},
  title = {Structure and physico-mechanical properties of low temperature plasma treated electrospun nanofibrous scaffolds examined with atomic force microscopy},
  journal = {Micron},
  year = {2018},
  volume = {107},
  pages = {79 - 84},
  url = {http://www.sciencedirect.com/science/article/pii/S0968432818300015},
  doi = {https://doi.org/10.1016/j.micron.2018.01.012}
}
Chinga-Carrasco, G. Potential and Limitations of Nanocelluloses as Components in Biocomposite Inks for Three-Dimensional Bioprinting and for Biomedical Devices 2018 Biomacromolecules
Vol. 19(3), pp. 701-711 
article DOI  
Abstract: Three-dimensional (3D) printing has rapidly emerged as a new technology with a wide range of applications that includes biomedicine. Some common 3D printing methods are based on the suitability of biopolymers to be extruded through a nozzle to construct a 3D structure layer by layer. Nanocelluloses with specific rheological characteristics are suitable components to form inks for 3D printing. This review considers various nanocelluloses that have been proposed for 3D printing with a focus on the potential advantages, limitations, and requirements when used for biomedical devices and when used in contact with the human body.
BibTeX:
@article{Chinga-Carrasco2018,
  author = {Chinga-Carrasco, Gary},
  title = {Potential and Limitations of Nanocelluloses as Components in Biocomposite Inks for Three-Dimensional Bioprinting and for Biomedical Devices},
  journal = {Biomacromolecules},
  year = {2018},
  volume = {19},
  number = {3},
  pages = {701-711},
  note = {PMID: 29489338},
  doi = {https://doi.org/10.1021/acs.biomac.8b00053}
}
Castilho, M., Mil, A., Maher, M., Metz, C.H.G., Hochleitner, G., Groll, J., Doevendans, P.A., Ito, K., Sluijter, J.P.G. and Malda, J. Melt Electrowriting Allows Tailored Microstructural and Mechanical Design of Scaffolds to Advance Functional Human Myocardial Tissue Formation 2018 Advanced Functional Materials
Vol. 0(0), pp. 1803151 
article DOI  
Abstract: Abstract Engineering native-like myocardial muscle, recapitulating its fibrillar organization and mechanical behavior is still a challenge. This study reports the rational design and fabrication of ultrastretchable microfiber scaffolds with controlled hexagonal microstructures via melt electrowriting (MEW). The resulting structures exhibit large biaxial deformations, up to 40% strain, and an unprecedented compliance, delivering up to 40 times more elastic energy than rudimentary MEW fiber scaffolds. Importantly, when human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CM) are encapsulated in a collagen-based hydrogel and seeded on these microstructured and mechanically tailored fiber scaffolds, they show an increase in beating rate (1.5-fold), enhanced cell alignment, sarcomere content and organization as well as an increase in cardiac maturation-related marker expression (Cx43 1.8-fold, cardiac Actin 1.5-fold, SERCA2a 2.5-fold, KCNJ2 1.5-fold, and PPARGC1a 3.6-fold), indicative of enhanced iPSC-CM maturation, as compared to rudimentary fiber scaffolds. By combining these novel fiber scaffolds with clinically relevant human iPSC-CMs, a heart patch that allows further maturation of contractile myocytes for cardiac tissue engineering is generated. Moreover, the designed scaffold allows successful shape recovery after epicardial delivery on a beating porcine heart, without negative effects on the engineered construct and iPSC-CM viability.
BibTeX:
@article{Castilho2018,
  author = {Castilho, Miguel and Mil, Alain and Maher, Malachy and Metz, Corina H. G. and Hochleitner, Gernot and Groll, Jürgen and Doevendans, Pieter A. and Ito, Keita and Sluijter, Joost P. G. and Malda, Jos},
  title = {Melt Electrowriting Allows Tailored Microstructural and Mechanical Design of Scaffolds to Advance Functional Human Myocardial Tissue Formation},
  journal = {Advanced Functional Materials},
  year = {2018},
  volume = {0},
  number = {0},
  pages = {1803151},
  doi = {https://doi.org/10.1002/adfm.201803151}
}
Casquillas, GV, Houssin, T. and Durieux, L INTRODUCTION TO LAB-ON-A-CHIP : REVIEW, HISTORY AND FUTURE 2018 School: Elveflow  techreport URL 
BibTeX:
@techreport{Casquillas2018,
  author = {Casquillas GV; Houssin, T; Durieux L},
  title = {INTRODUCTION TO LAB-ON-A-CHIP : REVIEW, HISTORY AND FUTURE},
  school = {Elveflow},
  year = {2018},
  url = {https://www.elveflow.com/microfluidic-tutorials/microfluidic-reviews-and-tutorials/introduction-to-lab-on-a-chip-2015-review-history-and-future/}
}
Casquillas, GV and Houssin, T. PDMS: A REVIEW 2018 School: Elveflow  techreport URL 
BibTeX:
@techreport{Casquillas2018b,
  author = {Casquillas GV; Houssin, T},
  title = {PDMS: A REVIEW},
  school = {Elveflow},
  year = {2018},
  url = {Elveflow.com/microfluidic-tutorials/microfluidic-reviews-and-tutorials/the-poly-di-methyl-siloxane-pdms-and-microfluidics/

} }
Casquillas, G., Houssin, T. and Durieux, L. MICROFLUIDICS AND MICROFLUIDIC DEVICES: A REVIEW 2018 School: Elveflow  techreport URL 
BibTeX:
@techreport{Casquillas2018a,
  author = {Casquillas, GV; Houssin, T; Durieux, L},
  title = {MICROFLUIDICS AND MICROFLUIDIC DEVICES: A REVIEW},
  school = {Elveflow},
  year = {2018},
  url = {Elveflow.com/microfluidic-tutorials/microfluidic-reviews-and-tutorials/microfluidics-and-microfluidic-device-a-review/�}
}
Caetano, G.F., Wang, W., Chiang, W.-H., Cooper, G., Diver, C., Blaker, J.J., Frade, M.A. and Bártolo, P. 3D-Printed Poly(ɛ-caprolactone)/Graphene Scaffolds Activated with P1-Latex Protein for Bone Regeneration 2018 3D Printing and Additive Manufacturing
Vol. 0(0), pp. null 
article DOI URL 
Abstract: Abstract Biomanufacturing is a relatively new research domain focusing on the use of additive manufacturing technologies, biomaterials, cells, and biomolecular signals to produce tissue constructs for tissue engineering. For bone regeneration, researchers are focusing on the use of polymeric and polymer/ceramic scaffolds seeded with osteoblasts or mesenchymal stem cells. However, high-performance scaffolds in terms of mechanical, cell stimulation, and biological performance are still required. This article investigates the use of an extrusion additive manufacturing system to produce poly(ɛ-caprolactone) (PCL) and PCL/graphene nanosheet scaffolds for bone applications. Scaffolds with regular and reproducible architecture and uniform dispersion of graphene were produced and coated with P1-latex protein extracted from the Hevea brasiliensis rubber tree. Results show that the obtained scaffolds cultivated with human adipose-derived stem cells present no toxicity effects. The presence of graphene nanosheet and P1-latex protein in the scaffolds increased cell proliferation compared with PCL scaffolds. Moreover, the presence of P1-latex protein promotes earlier osteogenic differentiation, suggesting that PCL/graphene/P1-latex protein scaffolds are suitable for bone regeneration applications.
BibTeX:
@article{Caetano2018,
  author = {Caetano, Guilherme Ferreira and Wang, Weiguang and Chiang, Wei-Hung and Cooper, Glen and Diver, Carl and Blaker, Jonny James and Frade, Marco Andrey and Bártolo, Paulo},
  title = {3D-Printed Poly(ɛ-caprolactone)/Graphene Scaffolds Activated with P1-Latex Protein for Bone Regeneration},
  journal = {3D Printing and Additive Manufacturing},
  year = {2018},
  volume = {0},
  number = {0},
  pages = {null},
  url = { 

https://doi.org/10.1089/3dp.2018.0012

}, doi = {https://doi.org/10.1089/3dp.2018.0012} }
Béduer, A., Piacentini, N., Aeberli, L., Silva, A.D., Verheyen, C., Bonini, F., Rochat, A., Filippova, A., Serex, L., Renaud, P. and Braschler, T. Additive manufacturing of hierarchical injectable scaffolds for tissue engineering 2018 Acta Biomaterialia
Vol. 76, pp. 71 - 79 
article DOI URL 
Abstract: We present a 3D-printing technology allowing free-form fabrication of centimetre-scale injectable structures for minimally invasive delivery. They result from the combination of 3D printing onto a cryogenic substrate and optimisation of carboxymethylcellulose-based cryogel inks. The resulting highly porous and elastic cryogels are biocompatible, and allow for protection of cell viability during compression for injection. Implanted into the murine subcutaneous space, they are colonized with a loose fibrovascular tissue with minimal signs of inflammation and remain encapsulation-free at three months. Finally, we vary local pore size through control of the substrate temperature during cryogenic printing. This enables control over local cell seeding density in vitro and over vascularization density in cell-free scaffolds in vivo. In sum, we address the need for 3D-bioprinting of large, yet injectable and highly biocompatible scaffolds and show modulation of the local response through control over local pore size.
Statement of Significance
This work combines the power of 3D additive manufacturing with clinically advantageous minimally invasive delivery. We obtain porous, highly compressible and mechanically rugged structures by optimizing a cryogenic 3D printing process. Only a basic commercial 3D printer and elementary control over reaction rate and freezing are required. The porous hydrogels obtained are capable of withstanding delivery through capillaries up to 50 times smaller than their largest linear dimension, an as yet unprecedented compression ratio. Cells seeded onto the hydrogels are protected during compression. The hydrogel structures further exhibit excellent biocompatibility 3 months after subcutaneous injection into mice. We finally demonstrate that local modulation of pore size grants control over vascularization density in vivo. This provides proof-of-principle that meaningful biological information can be encoded during the 3D printing process, deploying its effect after minimally invasive implantation.
BibTeX:
@article{Beduer2018,
  author = {A. Béduer and N. Piacentini and L. Aeberli and A. Da Silva and C.A. Verheyen and F. Bonini and A. Rochat and A. Filippova and L. Serex and P. Renaud and T. Braschler},
  title = {Additive manufacturing of hierarchical injectable scaffolds for tissue engineering},
  journal = {Acta Biomaterialia},
  year = {2018},
  volume = {76},
  pages = {71 - 79},
  url = {http://www.sciencedirect.com/science/article/pii/S1742706118303350},
  doi = {https://doi.org/10.1016/j.actbio.2018.05.056}
}
Bastola, A., Paudel, M. and Li, L. Development of hybrid magnetorheological elastomers by 3D printing 2018 Polymer
Vol. 149, pp. 213 - 228 
article DOI URL 
Abstract: Intelligent or smart materials have one or more properties that can be significantly changed in a controlled fashion by external stimuli, such as temperature, pH, electric or magnetic fields, etc. Magnetorheological (MR) materials are a class of smart materials whose properties can be varied by applying an external magnetic field. In this work, the possibility of employing a suitable 3D printing technology for the development of one of the smart MR materials, the magnetorheological elastomer (MRE) has been explored. In order to achieve such 3D printing, a multi-material printing is implemented, where a controlled volume of MR fluid is encapsulated within an elastomer matrix in the layer-by-layer fashion. The choice of printing materials determines the final structure of the 3D printed hybrid MR elastomer. Printing with a vulcanizing MR suspension produces the solid MR structure inside the elastomer matrix while printing with a non-vulcanizing MR suspension (MR fluid) results in the structures that the MR fluid is encapsulated inside the elastomer matrix. The 3D printability of different materials has been studied by measuring their rheological properties and we found that the highly shear thinning and thixotropic properties are important for 3D printability. The quality of the printed filaments strongly depends on the key printing parameters such as extrusion pressure, initial height and feed rate. The experimental results from the forced vibration testing show that the 3D printed MR elastomers could change their elastic and damping properties when exposed to the external magnetic field. Furthermore, the 3D printed MR elastomer also exhibits the anisotropic behavior when the direction of the magnetic field is changed with respect to the orientation of the printed filaments. This study has demonstrated that the 3D printing is viable for fabrication of hybrid MR elastomers with controlled structures of magnetic particles or MR fluids.
BibTeX:
@article{Bastola2018,
  author = {A.K. Bastola and M. Paudel and L. Li},
  title = {Development of hybrid magnetorheological elastomers by 3D printing},
  journal = {Polymer},
  year = {2018},
  volume = {149},
  pages = {213 - 228},
  url = {http://www.sciencedirect.com/science/article/pii/S0032386118305809},
  doi = {https://doi.org/10.1016/j.polymer.2018.06.076}
}
Banerjee, H. and Ren, H. Electromagnetically Responsive Soft-Flexible Robots and Sensors for Biomedical Applications and Impending Challenges 2018 Electromagnetic Actuation and Sensing in Medical Robotics, pp. 43-72  inbook DOI  
Abstract: Advantages of flexible polymer materials with developments in refined magnetic actuation can be intertwined for a promising platform to work on a resilient, adaptable manipulator aimed at a range of biomedical applications. Moreover, soft magnetic material has an inherent property of high remanence like the permanent magnets which can be further refined to meet ever-increasing demands in untethered and safe-regulated medical environments. In this chapter, we focus mostly on different avenues and facets of flexible polymer materials in adaptable actuation and sensing in the context of magnetic field for range of biomedical applications.
BibTeX:
@inbook{Banerjee2018,
  author = {Banerjee, Hritwick and Ren, Hongliang},
  title = {Electromagnetically Responsive Soft-Flexible Robots and Sensors for Biomedical Applications and Impending Challenges},
  booktitle = {Electromagnetic Actuation and Sensing in Medical Robotics},
  publisher = {Springer Singapore},
  year = {2018},
  pages = {43--72},
  doi = {https://doi.org/10.1007/978-981-10-6035-9_3}
}
Aied, A., Song, W., Wang, W., Baki, A. and Sigen, A. 3D Bioprinting of stimuli-responsive polymers synthesised from DE-ATRP into soft tissue replicas 2018 Bioprinting  article DOI URL 
Abstract: Synthetic polymers possess more reproducible physical and chemical properties than their naturally occurring counterparts. They have also emerged as an important alternative for fabricating tissue substitutes because they can be molecularly tailored to have vast array of molecular weights, block structures, active functional groups, and mechanical properties. To this date however, there has been very few successful and fully functional synthetic tissue and organ substitutes and with the rapidly spreading 3D printing technology beginning to reshape the tissue engineering and regenerative field, the need for an effective, safe, and bio printable biomaterial is becoming more and more urgent. Here, we have developed a synthetic polymer from controlled living radical polymerisation that can be printed into well-defined structures. The polymer showed low cytotoxicity before and after printing. Additionally, the incorporation of gelatine-methacrylate coated PLGA microparticles within the hydrogel provided cell adhesion surfaces for cell proliferation. The results point to possible application of the microparticle seeded, synthetic hydrogel as a direct printable tissue or organ substitute.
BibTeX:
@article{Aied2018,
  author = {Ahmed Aied and Wenhui Song and Wenxin Wang and Abdulrahman Baki and A. Sigen},
  title = {3D Bioprinting of stimuli-responsive polymers synthesised from DE-ATRP into soft tissue replicas},
  journal = {Bioprinting},
  year = {2018},
  url = {http://www.sciencedirect.com/science/article/pii/S2405886617300210},
  doi = {https://doi.org/10.1016/j.bprint.2018.02.002}
}
Zhou, Y. The recent development and applications of fluidic channels by 3D printing 2017 Journal of Biomedical Science
Vol. 24 
article DOI  
Abstract: The technology of “Lab-on-a-Chip” allows the synthesis and analysis of chemicals and biological substance within a portable or handheld device. The 3D printed structures enable precise control of various geometries. The combination of these two technologies in recent years makes a significant progress. The current approaches of 3D printing, such as stereolithography, polyjet, and fused deposition modeling, are introduced. Their manufacture specifications, such as surface roughness, resolution, replication fidelity, cost, and fabrication time, are compared with each other. Finally, novel application of 3D printed channel in biology are reviewed, including pathogenic bacteria detection using magnetic nanoparticle clusters in a helical microchannel, cell stimulation by 3D chemical gradients, perfused functional vascular channels, 3D tissue construct, organ-on-a-chip, and miniaturized fluidic “reactionware” devices for chemical syntheses. Overall, the 3D printed fluidic chip is becoming a powerful tool in the both medical and chemical industries.
BibTeX:
@article{Zhou2017,
  author = {Zhou, Yufeng},
  title = {The recent development and applications of fluidic channels by 3D printing},
  journal = {Journal of Biomedical Science},
  year = {2017},
  volume = {24},
  doi = {https://doi.org/10.1186/s12929-017-0384-2%EF%BF%BD}
}
Wunner, F., Florczak, S., Mieszczanek, P., Bas, O., De Juan-Pardo, E. and Hutmacher, D. Electrospinning With Polymer Melts – State of the Art and Future Perspectives 2017 Reference Module in Materials Science and Materials Engineering  inbook DOI  
BibTeX:
@inbook{Wunner2017a,
  author = {Wunner, Felix and Florczak, Sammy and Mieszczanek, Pawel and Bas, Onur and De Juan-Pardo, Elena and Hutmacher, Dietmar},
  title = {Electrospinning With Polymer Melts – State of the Art and Future Perspectives},
  journal = {Reference Module in Materials Science and Materials Engineering},
  year = {2017},
  doi = {https://doi.org/10.1016/B978-0-12-803581-8.09318-8}
}
Woodfield, T., Lim, K., Morouço, P., Levato, R., Malda, J. and Melchels, F. Biofabrication in Tissue Engineering 2017 Reference Module in Materials Science and Materials Engineering  book DOI  
Abstract: Organ biofabrication techniques offer the potential to produce living 3D tissue constructs to repair or replace damaged or diseased human tissues and organs. Using these advanced Biofabrication techniques, constructs exhibiting spatial variation of cells, cellular building blocks, growth factors, and mechanical properties along multiple axes with high geometric complexity can be obtained. The level of control offered by these technologies to develop complex biofabricated tissues will allow tissue engineers to better study factors that modulate tissue formation and function, and provide a valuable tool to study graft performance as well as for high throughput screening of drug candidates in biofabricated tissue organoid models.
BibTeX:
@book{Woodfield2017,
  author = {Woodfield, Tim and Lim, Khoon and Morouço, Pedro and Levato, Riccardo and Malda, Jos and Melchels, Ferry},
  title = {Biofabrication in Tissue Engineering},
  journal = {Reference Module in Materials Science and Materials Engineering},
  year = {2017},
  doi = {https://doi.org/10.1016/B978-0-12-803581-8.10221-8}
}
Suntornnond, R., Tan, E., An, J. and Chua, C. A highly printable and biocompatible hydrogel composite for direct printing of soft and perfusable vasculature-like structures 2017 Scientific Reports
Vol. 7(16902) 
article DOI URL 
Abstract: Vascularization is one major obstacle in bioprinting and tissue engineering. In order to create thick tissues or organs that can function like original body parts, the presence of a perfusable vascular system is essential. However, it is challenging to bioprint a hydrogel-based three-dimensional vasculature-like structure in a single step. In this paper, we report a new hydrogel-based composite that offers impressive printability, shape integrity, and biocompatibility for 3D bioprinting of a perfusable complex vasculature-like structure. The hydrogel composite can be used on a non-liquid platform and is printable at human body temperature. Moreover, the hydrogel composite supports both cell proliferation and cell differentiation. Our results represent a potentially new vascularization strategy for 3D bioprinting and tissue engineering.
BibTeX:
@article{Suntornnond2017,
  author = {Suntornnond, R. and Tan, E.Y.S. and An, J. and Chua, C.K.},
  title = {A highly printable and biocompatible hydrogel composite for direct printing of soft and perfusable vasculature-like structures},
  journal = {Scientific Reports},
  year = {2017},
  volume = {7},
  number = {16902},
  url = {http://www.nature.com/articles/s41598-017-17198-0},
  doi = {https://doi.org/10.1038/s41598-017-17198-0}
}
Schroeder, T.B.H., Guha, A., Lamoureux, A., VanRenterghem, G., Sept, D., Shtein, M., Yang, J. and Mayer, M. An electric-eel-inspired soft power source from stacked hydrogels 2017 Nature
Vol. 552, pp. 214 
article DOI  
Abstract: Progress towards the integration of technology into livingo ganisms requires electrical power sources that are biocompatible, mechanically flexible, and able to harness the chemical energy available inside biological systems. Conventional batteries were not designed with these criteria in mind. The electric organ of the knifefish Electrophorus electricus (commonly known as the electric eel) is, however, an example of an electrical power source that operates within biological constraints while featuring power characteristics that include peak potential differences of 600 volts and currents of 1 ampere1,2. Here we introduce an electric eel-inspired power concept that uses gradients of ions between miniature polyacrylamide hydrogel compartments bounded by a repeating sequence of cation- and anion-selective hydrogel membranes. The system uses a scalable stacking or folding geometry
that generates 110 volts at open circuit or 27 milliwatts per square
metre per gel cell upon simultaneous, self-registered mechanical
contact activation of thousands of gel compartments in series while
circumventing power dissipation before contact. Unlike typical
batteries, these systems are soft, flexible, transparent, and potentially
biocompatible. These characteristics suggest that artificial electric
organs could be used to power next-generation implant materials
such as pacemakers, implantable sensors, or prosthetic devices in
hybrids of living and non-living systems3–6.�
BibTeX:
@article{Schroeder2017,
  author = {Schroeder, Thomas B. H. and Guha, Anirvan and Lamoureux, Aaron and VanRenterghem, Gloria and Sept, David and Shtein, Max and Yang, Jerry and Mayer, Michael},
  title = {An electric-eel-inspired soft power source from stacked hydrogels},
  journal = {Nature},
  publisher = {Macmillan Publishers Limited, part of Springer Nature. All rights reserved.},
  year = {2017},
  volume = {552},
  pages = {214},
  doi = {https://doi.org/10.1038/nature24670}
}
Nguyen, D., Hägg, D., Forsman, A., Ekholm, J., Nimkingratana, P., Brantsing, C., Kalogeropoulos, T., Zaunz, S., Concaro, S., Brittberg, M., Lindahl, A., Gatenholm, P., Enejder, A. and Simonsson, S. Cartilage Tissue Engineering by the 3D Bioprinting of iPS Cells in a Nanocellulose/Alginate Bioink 2017 Scientific Reports
Vol. 7Scientific Reports 
article DOI  
Abstract: Cartilage lesions can progress into secondary osteoarthritis and cause severe clinical problems in numerous patients. As a prospective treatment of such lesions, human-derived induced pluripotent stem cells (iPSCs) were shown to be 3D bioprinted into cartilage mimics using a nanofibrillated cellulose (NFC) composite bioink when co-printed with irradiated human chondrocytes. Two bioinks were investigated: NFC with alginate (NFC/A) or hyaluronic acid (NFC/HA). Low proliferation and phenotypic changes away from pluripotency were seen in the case of NFC/HA. However, in the case of the 3D-bioprinted NFC/A (60/40, dry weight % ratio) constructs, pluripotency was initially maintained, and after five weeks, hyaline-like cartilaginous tissue with collagen type II expression and lacking tumorigenic Oct4 expression was observed in 3D -bioprinted NFC/A (60/40, dry weight % relation) constructs. Moreover, a marked increase in cell number within the cartilaginous tissue was detected by 2-photon fluorescence microscopy, indicating the importance of high cell densities in the pursuit of achieving good survival after printing. We conclude that NFC/A bioink is suitable for bioprinting iPSCs to support cartilage production in co-cultures with irradiated chondrocytes.
BibTeX:
@article{Nguyen2017,
  author = {Nguyen, Duong and Hägg, Daniel and Forsman, Alma and Ekholm, Josefine and Nimkingratana, Puwapong and Brantsing, Camilla and Kalogeropoulos, Theodoros and Zaunz, Samantha and Concaro, Sebastian and Brittberg, Mats and Lindahl, Anders and Gatenholm, Paul and Enejder, Annika and Simonsson, Stina},
  title = {Cartilage Tissue Engineering by the 3D Bioprinting of iPS Cells in a Nanocellulose/Alginate Bioink},
  booktitle = {Scientific Reports},
  journal = {Scientific Reports},
  year = {2017},
  volume = {7},
  doi = {https://doi.org/10.1038/s41598-017-00690-y}
}
Han, Y. and Dong, J. Electrohydrodynamic (EHD) Printing of Molten Metal Ink for Flexible and Stretchable Conductor with Self-Healing Capability 2017 advanced material technologiesAdvanced Materials Technologies, pp. 1700268  article DOI  
Abstract: Direct printing of flexible and stretchable conductors provides a low-cost mask-less approach for the fabrication of next-generation electronics. Inthis work, an electrohydrodynamic (EHD) printing technology is studied to achieve high-resolution printing of low-melting-point metal alloys, which enables low-cost direct fabrication of metallic conductors with sub 50 μm resolution. The EHD printed microscale metallic conductors represent a promising way to create conductive paths with metallic conductivity and excellent flexibility and stretchability. A stable electrical response is achieved after hundreds of bending cycles and during stretching/releasing cycles in a large range of tensile strain (0–70%) for the printed conductors with properly designed 2D patterns. Due to the low melting point of the metal alloy ink, the printed conductor demonstrates self-healing capability that recovers from failure simply by heating the device above the eutectic temperature of the metal ink and applying slight pressure. A high-density touch sensor array is fabricated to demonstrate the high-resolution capability of the EHD printing for the direction fabrication of flexible and stretchable devices.
BibTeX:
@article{Han2017,
  author = {Han, Yiwei and Dong, Jingyan},
  title = {Electrohydrodynamic (EHD) Printing of Molten Metal Ink for Flexible and Stretchable Conductor with Self-Healing Capability},
  booktitle = {Advanced Materials Technologies},
  journal = {advanced material technologies},
  year = {2017},
  pages = {1700268},
  doi = {https://doi.org/10.1002/admt.201700268}
}
Freeman, F.E. and Kelly, D.J. Tuning Alginate Bioink Stiffness and Composition for Controlled Growth Factor Delivery and to Spatially Direct MSC Fate within Bioprinted Tissues 2017 Scientific Reports
Vol. 7(1), pp. 17042 
article DOI  
Abstract: Alginate is a commonly used bioink in 3D bioprinting. Matrix stiffness is a key determinant of mesenchymal stem cell (MSC) differentiation, suggesting that modulation of alginate bioink mechanical properties represents a promising strategy to spatially regulate MSC fate within bioprinted tissues. In this study, we define a printability window for alginate of differing molecular weight (MW) by systematically varying the ratio of alginate to ionic crosslinker within the bioink. We demonstrate that the MW of such alginate bioinks, as well as the choice of ionic crosslinker, can be tuned to control the mechanical properties (Young’s Modulus, Degradation Rate) of 3D printed constructs. These same factors are also shown to influence growth factor release from the bioinks. We next explored if spatially modulating the stiffness of 3D bioprinted hydrogels could be used to direct MSC fate inside printed tissues. Using the same alginate and crosslinker, but varying the crosslinking ratio, it is possible to bioprint constructs with spatially varying mechanical microenvironments. Moreover, these spatially varying microenvironments were found to have a significant effect on the fate of MSCs within the alginate bioinks, with stiffer regions of the bioprinted construct preferentially supporting osteogenesis over adipogenesis.
BibTeX:
@article{Freeman2017,
  author = {Freeman, Fiona E. and Kelly, Daniel J.},
  title = {Tuning Alginate Bioink Stiffness and Composition for Controlled Growth Factor Delivery and to Spatially Direct MSC Fate within Bioprinted Tissues},
  journal = {Scientific Reports},
  year = {2017},
  volume = {7},
  number = {1},
  pages = {17042},
  doi = {https://doi.org/10.1038/s41598-017-17286-1}
}
D. Graham, A., N. Olof, S., J. Burke, M., Armstrong, J., A. Mikhailova, E., G. Nicholson, J., J. Box, S., G. Szele, F., Perriman, A. and Bayley, H. High-Resolution Patterned Cellular Constructs by Droplet-Based 3D Printing 2017 Scientific Reports
Vol. 7 
article DOI  
Abstract: Bioprinting is an emerging technique for the fabrication of living tissues that allows cells to be arranged in predetermined three-dimensional (3D) architectures. However, to date, there are limited examples of bioprinted constructs containing multiple cell types patterned at high-resolution. Here we present a low-cost process that employs 3D printing of aqueous droplets containing mammalian cells to produce robust, patterned constructs in oil, which were reproducibly transferred to culture medium. Human embryonic kidney (HEK) cells and ovine mesenchymal stem cells (oMSCs) were printed at tissue-relevant densities (10⁷ cells mL⁻¹) and a high droplet resolution of 1 nL. High-resolution 3D geometries were printed with features of ≤200 μm; these included an arborised cell junction, a diagonal-plane junction and an osteochondral interface. The printed cells showed high viability (90% on average) and HEK cells within the printed structures were shown to proliferate under culture conditions. Significantly, a five-week tissue engineering study demonstrated that printed oMSCs could be differentiated down the chondrogenic lineage to generate cartilage-like structures containing type II collagen.
BibTeX:
@article{D.Graham2017,
  author = {D. Graham, Alexander and N. Olof, Sam and J. Burke, Madeline and Armstrong, James and A. Mikhailova, Ellina and G. Nicholson, James and J. Box, Stuart and G. Szele, Francis and Perriman, Adam and Bayley, Hagan},
  title = {High-Resolution Patterned Cellular Constructs by Droplet-Based 3D Printing},
  journal = {Scientific Reports},
  year = {2017},
  volume = {7},
  doi = {https://doi.org/10.1038/s41598-017-06358-x}
}
Chen, M.J., Kimpton, L., Whiteley, J., Castilho, M., Malda, J., Please, C., Waters, S. and Byrne, H. Multiscale modelling and homogensation of fibre-reinforced hydrogels for tissue engineering 2017 ArXiv e-prints  article URL 
Abstract: Tissue engineering aims to grow artificial tissues in vitro to replace those in the body that have been damaged through age, trauma or disease. A recent approach to engineer artificial cartilage involves seeding cells within a scaffold consisting of an interconnected 3D-printed lattice of polymer fibres combined with a cast or printed hydrogel, and subjecting the construct (cell-seeded scaffold) to an applied load in a bioreactor. A key question is to understand how the applied load is distributed throughout the construct. To address this, we employ homogenisation theory to derive equations governing the effective macroscale material properties of a periodic, elastic-poroelastic composite. We treat the fibres as a linear elastic material and the hydrogel as a poroelastic material, and exploit the disparate length scales (small inter-fibre spacing compared with construct dimensions) to derive macroscale equations governing the response of the composite to an applied load. This homogenised description reflects the orthotropic nature of the composite. To validate the model, solutions from finite element simulations of the macroscale, homogenised equations are compared to experimental data describing the unconfined compression of the fibre-reinforced hydrogels. The model is used to derive the bulk mechanical properties of a cylindrical construct of the composite material for a range of fibre spacings, and to determine the local mechanical environment experienced by cells embedded within the construct
BibTeX:
@article{Chen2017,
  author = {Chen, M. J. and Kimpton, L.S. and Whiteley, J.P. and Castilho, M. and Malda, J. and Please, C.P. and Waters, S.L. and Byrne, H.M.},
  title = {Multiscale modelling and homogensation of fibre-reinforced hydrogels for tissue engineering},
  journal = {ArXiv e-prints},
  year = {2017},
  url = {http://adsabs.harvard.edu/abs/2017arXiv171201099C}
}
Levato, R., Webb, W.R., Otto, I.A., Mensinga, A., Zhang, Y., van Rijen, M., van Weeren, R., Khan, I.M. and Malda, J. The bio in the ink: cartilage regeneration with bioprintable hydrogels and articular cartilage-derived progenitor cells 2017 Acta Biomaterialia
Vol. 61(Supplement C), pp. 41-53 
article URL 
BibTeX:
@article{Levato2017,
  author = {Levato, Riccardo and Webb, William R. and Otto, Iris A. and Mensinga, Anneloes and Zhang, Yadan and van Rijen, Mattie and van Weeren, René and Khan, Ilyas M. and Malda, Jos},
  title = {The bio in the ink: cartilage regeneration with bioprintable hydrogels and articular cartilage-derived progenitor cells},
  journal = {Acta Biomaterialia},
  year = {2017},
  volume = {61},
  number = {Supplement C},
  pages = {41--53},
  url = {http://www.sciencedirect.com/science/article/pii/S1742706117304956}
}
Bertlein, S., Brown, G., Lim, K., Jungst, T., Boeck, T., Blunk, T., Tessmar, J., J. Hooper, G., Woodfield, T. and Groll, J. Thiol-Ene Clickable Gelatin: A Platform Bioink for Multiple 3D Biofabrication Technologies 2017 Advanced Materials  article DOI  
Abstract: Bioprinting can be defined as the art of combining materials and cells to fabricate designed, hierarchical 3D hybrid constructs. Suitable materials, so called bioinks, have to comply with challenging rheological processing demands and rapidly form a stable hydrogel postprinting in a cytocompatible manner. Gelatin is often adopted for this purpose, usually modified with (meth-)acryloyl functionalities for postfabrication curing by free radical photopolymerization, resulting in a hydrogel that is cross-linked via nondegradable polymer chains of uncontrolled length. The application of allylated gelatin (GelAGE) as a thiol-ene clickable bioink for distinct biofabrication applications is reported. Curing of this system occurs via dimerization and yields a network with flexible properties that offer a wider biofabrication window than (meth-)acryloyl chemistry, and without additional nondegradable components. An in-depth analysis of GelAGE synthesis is conducted, and standard UV-initiation is further compared with a recently described visible-light-initiator system for GelAGE hydrogel formation. It is demonstrated that GelAGE may serve as a platform bioink for several biofabrication technologies by fabricating constructs with high shape fidelity via lithography-based (digital light processing) 3D printing and extrusion-based 3D bioprinting, the latter supporting long-term viability postprinting of encapsulated chondrocytes.
BibTeX:
@article{Bertlein2017a,
  author = {Bertlein, Sarah and Brown, Gabriella and Lim, Khoon and Jungst, Tomasz and Boeck, Thomas and Blunk, Torsten and Tessmar, Joerg and J. Hooper, Gary and Woodfield, Tim and Groll, Jürgen},
  title = {Thiol-Ene Clickable Gelatin: A Platform Bioink for Multiple 3D Biofabrication Technologies},
  journal = {Advanced Materials},
  year = {2017},
  doi = {https://doi.org/10.1002/adma.201703404}
}
Yang, T.-C., Chuang, J.-H., Buddhakosai, W., Wu, W.-J., Lee, C.-J., Chen, W.-S., Yang, Y.-P., Li, M.-C., Peng, C.-H. and Chen, S.-J. Elongation of Axon Extension for Human iPSC-Derived Retinal Ganglion Cells by a Nano-Imprinted Scaffold 2017 International Journal of Molecular Sciences
Vol. 18(PMC5618661), pp. 2013 
article URL 
Abstract: Optic neuropathies, such as glaucoma and Leber’s hereditary optic neuropathy (LHON) lead to retinal ganglion cell (RGC) loss and therefore motivate the application of transplantation technique into disease therapy. However, it is a challenge to direct the transplanted optic nerve axons to the correct location of the retina. The use of appropriate scaffold can promote the proper axon growth. Recently, biocompatible materials have been integrated into the medical field, such as tissue engineering and reconstruction of damaged tissues or organs. We, herein, utilized nano-imprinting to create a scaffold mimicking the in vitro tissue microarchitecture, and guiding the axonal growth and orientation of the RGCs. We observed that the robust, long, and organized axons of human induced pluripotent stem cell (iPSC)-derived RGCs projected axially along the scaffold grooves. The RGCs grown on the scaffold expressed the specific neuronal biomarkers indicating their proper functionality. Thus, based on our in vitro culture system, this device can be useful for the neurophysiological analysis and transplantation for ophthalmic neuropathy treatment.
BibTeX:
@article{Yang2017,
  author = {Yang, Tien-Chun and Chuang, Jen-Hua and Buddhakosai, Waradee and Wu, Wen-Ju and Lee, Chen-Ju and Chen, Wun-Syuan and Yang, Yi-Ping and Li, Ming-Chia and Peng, Chi-Hsien and Chen, Shih-Jen},
  title = {Elongation of Axon Extension for Human iPSC-Derived Retinal Ganglion Cells by a Nano-Imprinted Scaffold},
  journal = {International Journal of Molecular Sciences},
  publisher = {MDPI},
  year = {2017},
  volume = {18},
  number = {PMC5618661},
  pages = {2013},
  url = {http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5618661/}
}
Wagner, M., Chen, T. and Shea, K. Large Shape Transforming 4D Auxetic Structures 2017 3D Printing and Additive Manufacturing
Vol. 4(3), pp. 133-142 
article DOI  
Abstract: Abstract Three-dimensional (3D) printing of active materials is a rapidly growing research area over the last few years. Numerous works have shown potential to revolutionize the field of four-dimensional (4D) printing and active self-deploying structures. Conventional manufacturing technologies restrict the geometric complexity of active structures. 3D printing allows the fabrication of complex active structures with no assembly required. In this study, we propose active 3D printed auxetic meta-materials that are capable of achieving area changes up to 200%. With these meta-materials, we design geometrically complex active structures that can be programmed into versatile shapes and recover their original shape given an external stimulus. We simulate the proposed meta-materials based on thermoviscoelastic material properties obtained by experimental characterization. A reduced beam model is constructed to predict forces and deformations of complex active structures. Excellent correlation is found between finite element simulation and experimental data from a 3-point bending test. Rectilinear tiling of the proposed meta-materials achieves the desired shape transformation. To demonstrate versatile programming, a selected meta-material is tiled into a complex contour, programmed into an arbitrary shape, and recovers as predicted. Simulation results verify this behavior. Such programmability in conjunction with 3D printing may be further exploited for applications such as biomedical devices, civil structures, and aerospace.
Abstract Three-dimensional (3D) printing of active materials is a rapidly growing research area over the last few years. Numerous works have shown potential to revolutionize the field of four-dimensional (4D) printing and active self-deploying structures. Conventional manufacturing technologies restrict the geometric complexity of active structures. 3D printing allows the fabrication of complex active structures with no assembly required. In this study, we propose active 3D printed auxetic meta-materials that are capable of achieving area changes up to 200%. With these meta-materials, we design geometrically complex active structures that can be programmed into versatile shapes and recover their original shape given an external stimulus. We simulate the proposed meta-materials based on thermoviscoelastic material properties obtained by experimental characterization. A reduced beam model is constructed to predict forces and deformations of complex active structures. Excellent correlation is found between finite element simulation and experimental data from a 3-point bending test. Rectilinear tiling of the proposed meta-materials achieves the desired shape transformation. To demonstrate versatile programming, a selected meta-material is tiled into a complex contour, programmed into an arbitrary shape, and recovers as predicted. Simulation results verify this behavior. Such programmability in conjunction with 3D printing may be further exploited for applications such as biomedical devices, civil structures, and aerospace.
BibTeX:
@article{Wagner2017,
  author = {Wagner, Marius and Chen, Tian and Shea, Kristina},
  title = {Large Shape Transforming 4D Auxetic Structures},
  journal = {3D Printing and Additive Manufacturing},
  publisher = {Mary Ann Liebert, Inc., publishers},
  year = {2017},
  volume = {4},
  number = {3},
  pages = {133--142},
  doi = {https://doi.org/10.1089/3dp.2017.0027}
}
Somers, S.M., Spector, A.A., DiGirolamo, D.J. and Grayson, W.L. Biophysical Stimulation for Engineering Functional Skeletal Muscle 2017 Tissue Engineering Part B: Reviews
Vol. 23(4), pp. 362-372 
article DOI  
Abstract: Tissue engineering is a promising therapeutic strategy to regenerate skeletal muscle. However, ex vivo cultivation methods typically result in a low differentiation efficiency of stem cells as well as grafts that resemble the native tissues morphologically, but lack contractile function. The application of biomimetic tensile strain provides a potent stimulus for enhancing myogenic differentiation and engineering functional skeletal muscle grafts. We reviewed integrin-dependent mechanisms that potentially link mechanotransduction pathways to the upregulation of myogenic genes. Yet, gaps in our understanding make it challenging to use these pathways to theoretically determine optimal ex vivo strain regimens. A multitude of strain protocols have been applied to in vitro cultures for the cultivation of myogenic progenitors (adipose- and bone marrow-derived stem cells and satellite cells) and transformed murine myoblasts, C2C12s. Strain regimens are characterized by orientation, amplitude, and time-dependent factors (effective frequency, duration, and the rest period between successive strain cycles). Analysis of published data has identified possible minimum/maximum values for these parameters and suggests that uniaxial strains may be more potent than biaxial strains, possibly because they more closely mimic physiologic strain profiles. The application of these biophysical stimuli for engineering 3D skeletal muscle grafts is nontrivial and typically requires custom-designed bioreactors used in combination with biomaterial scaffolds. Consideration of the physical properties of these scaffolds is critical for effective transmission of the applied strains to encapsulated cells. Taken together, these studies demonstrate that biomimetic tensile strain generally results in improved myogenic outcomes in myogenic progenitors and differentiated myoblasts. However, for 3D systems, the optimization of the strain regimen may require the entire system including cells, biomaterials, and bioreactor, to be considered in tandem.
Tissue engineering is a promising therapeutic strategy to regenerate skeletal muscle. However, ex vivo cultivation methods typically result in a low differentiation efficiency of stem cells as well as grafts that resemble the native tissues morphologically, but lack contractile function. The application of biomimetic tensile strain provides a potent stimulus for enhancing myogenic differentiation and engineering functional skeletal muscle grafts. We reviewed integrin-dependent mechanisms that potentially link mechanotransduction pathways to the upregulation of myogenic genes. Yet, gaps in our understanding make it challenging to use these pathways to theoretically determine optimal ex vivo strain regimens. A multitude of strain protocols have been applied to in vitro cultures for the cultivation of myogenic progenitors (adipose- and bone marrow-derived stem cells and satellite cells) and transformed murine myoblasts, C2C12s. Strain regimens are characterized by orientation, amplitude, and time-dependent factors (effective frequency, duration, and the rest period between successive strain cycles). Analysis of published data has identified possible minimum/maximum values for these parameters and suggests that uniaxial strains may be more potent than biaxial strains, possibly because they more closely mimic physiologic strain profiles. The application of these biophysical stimuli for engineering 3D skeletal muscle grafts is nontrivial and typically requires custom-designed bioreactors used in combination with biomaterial scaffolds. Consideration of the physical properties of these scaffolds is critical for effective transmission of the applied strains to encapsulated cells. Taken together, these studies demonstrate that biomimetic tensile strain generally results in improved myogenic outcomes in myogenic progenitors and differentiated myoblasts. However, for 3D systems, the optimization of the strain regimen may require the entire system including cells, biomaterials, and bioreactor, to be considered in tandem.
BibTeX:
@article{Somers2017,
  author = {Somers, Sarah M. and Spector, Alexander A. and DiGirolamo, Douglas J. and Grayson, Warren L.},
  title = {Biophysical Stimulation for Engineering Functional Skeletal Muscle},
  journal = {Tissue Engineering Part B: Reviews},
  publisher = {Mary Ann Liebert, Inc., publishers},
  year = {2017},
  volume = {23},
  number = {4},
  pages = {362--372},
  doi = {https://doi.org/10.1089/ten.teb.2016.0444}
}
Mancini, I., Vindas Bolaños, R., Brommer, H., Castilho, M., Ribeiro, A., van Loon, J., Mensinga, A., Rijen, M., Malda, J. and van Weeren, P. Fixation of hydrogel constructs for cartilage repair in the equine model: a challenging issue 2017 Tissue Engineering Part C: Methods  article DOI  
Abstract: u> Objective To evaluate the use of commercial and autologous fibrin glue and of an alternative method based on a 3D-printed polycaprolactone (PCL) anchor for the fixation of hydrogel-based scaffolds in an equine model for cartilage repair. Methods In a first study, three different hydrogel-based materials were orthotopically implanted in nine horses for 1-4 weeks in 6mm diameter full thickness cartilage defects in the medial femoral trochlear ridge and fixated with commercially available fibrin glue (CFG). One defect was filled with CFG only as a control. In a second study, CFG and autologous fibrin glue (AFG) were compared in an ectopic equine model. The third study compared the efficacy of AFG and a 3D-printed PCL-based osteal anchor for fixation of PCL-reinforced hydrogels in 3 horses for 2 weeks, with a 4 week follow-up to evaluate integration of bone with the PCL anchor. Short-term scaffold integration and cell infiltration were evaluated by micro-CT and histology as outcome parameters. Results The first study showed signs of subchondral bone resorption in all defects, including the controls filled with CFG only, with significant infiltration of neutrophils. Ectopically, CFG induced clear inflammation with strong neutrophil accumulation, AFG was less reactive, showing fibroblast infiltration only. In the third study the fixation potential for PCL-reinforced hydrogels of AFG was inferior to the PCL anchor. PCL-reinforcement had disappeared from two defects and showed signs of dislodging in the remaining four. All 6 constructs fixated with the PCL anchor were still in place after 2 weeks. At 4 weeks, the PCL anchor showed good integration and signs of new bone formation. Conclusions The use of AFG should be preferred to xenogeneic products in the horse, but AFG is subject to individual variations and laborious to make. The PCL anchor provide the best fixation, however this technique involves the whole osteochondral unit, which entails a different conceptual approach to cartilage repair.
BibTeX:
@article{Mancini2017,
  author = {Mancini, Irina and Vindas Bolaños, Rafael and Brommer, Harold and Castilho, Miguel and Ribeiro, Alexandro and van Loon, Johannes and Mensinga, Anneloes and Rijen, Mattie and Malda, Jos and van Weeren, Paul},
  title = {Fixation of hydrogel constructs for cartilage repair in the equine model: a challenging issue},
  journal = {Tissue Engineering Part C: Methods},
  year = {2017},
  doi = {https://doi.org/10.1089/ten.TEC.2017.0200}
}
Cunniffe, G., Gonzalez-Fernandez, T., Daly, A., Nelson Sathy, B., Jeon, O., Alsberg, E. and J. Kelly, D. Three-Dimensional Bioprinting of Polycaprolactone Reinforced Gene Activated Bioinks for Bone Tissue Engineering 2017 Tissue Engineering Part ATissue Engineering Part A  article DOI  
Abstract: Regeneration of complex bone defects remains a significant clinical challenge. Multi-tool biofabrication has permitted the combination of various biomaterials to create multifaceted composites with tailorable mechanical properties and spatially controlled biological function. In this study we sought to use bioprinting to engineer nonviral
gene activated constructs reinforced by polymeric micro-filaments. A gene activated bioink was developed using RGD-g-irradiated alginate and nano-hydroxyapatite (nHA) complexed to plasmid DNA (pDNA). This ink was combined with bonemarrow-derived mesenchymal stemcells (MSCs) and then co-printed with a polycaprolactone supporting mesh to provide mechanical stability to the construct. Reporter genes were first used to demonstrate successful cell transfection using this system, with sustained expression of the transgene detected over 14 days postbioprinting. Delivery of a combination of therapeutic genes encoding for bone morphogenic protein and transforming growth factor promoted robust osteogenesis of encapsulated MSCs in vitro, with enhanced levels of matrix deposition and mineralization observed following the incorporation of therapeutic pDNA. Gene activated MSC-laden constructs were then implanted subcutaneously, directly postfabrication, and were found to support superior levels of vascularization andmineralization compared to cell-free controls. These results validate the use of a gene activated bioink to impart biological functionality to three-dimensional bioprinted constructs.
BibTeX:
@article{Cunniffe2017,
  author = {Cunniffe, Gráinne and Gonzalez-Fernandez, Tomas and Daly, Andrew and Nelson Sathy, Binulal and Jeon, Oju and Alsberg, Eben and J. Kelly, Daniel},
  title = {Three-Dimensional Bioprinting of Polycaprolactone Reinforced Gene Activated Bioinks for Bone Tissue Engineering},
  booktitle = {Tissue Engineering Part A},
  journal = {Tissue Engineering Part A},
  year = {2017},
  doi = {https://doi.org/10.1089/ten.tea.2016.0498}
}
Shin, D.-G., Kim, T.-H. and Kim, D.-E. Review of 4D printing materials and their properties 2017 International Journal of Precision Engineering and Manufacturing-Green Technology
Vol. 4(3), pp. 349-357 
article DOI  
Abstract: Since its introduction, the 3D printing technology has been widely used in fields such as design, rapid prototyping, and biomedical devices, owing to its advantages of inexpensive, facile embodiment of computer 3D files into physical objects. Later, 4D printing was introduced by adding the temporal dimension to 3D. Stimuli such as heat, humidity, pH, and light trigger the actuation of printed objects without motors or wires. Smart materials that respond to external stimuli are good candidates for 4D printing. In this paper, we review the recent research on 4D printing, and categorize it with respect to the activating stimuli. The mechanical properties of 4D printing materials are mentioned as well. Finally, the future of 4D printing is discussed.
BibTeX:
@article{Shin2017,
  author = {Shin, Dong-Gap and Kim, Tae-Hyeong and Kim, Dae-Eun},
  title = {Review of 4D printing materials and their properties},
  journal = {International Journal of Precision Engineering and Manufacturing-Green Technology},
  year = {2017},
  volume = {4},
  number = {3},
  pages = {349--357},
  doi = {https://doi.org/10.1007/s40684-017-0040-z}
}
Hendrikx, S., Kuzmenka, D., Köferstein, R., Flath, T., Uhlig, H., Enke, D., Schulze, F.P., Hacker, M.C. and Schulz-Siegmund, M. Effects of curing and organic content on bioactivity and mechanical properties of hybrid sol--gel glass scaffolds made by indirect rapid prototyping 2017 Journal of Sol-Gel Science and Technology
Vol. 83(1), pp. 143-154 
article DOI  
Abstract: We employed indirect rapid prototyping templating to fabricate bioactive and macroporous scaffolds for bone regeneration. This templating technique utilizes lost molds made of polycaprolactone by fused deposition modeling, in which the organic/ inorganic hybrid silica sol was filled and cured. Finally, the molds were dissolved and extracted, and the remaining macroporous hybrid glass constructs were recovered. The hybrid glass scaffolds offered a fully interconnected pore structure with 63--72% porosity measured by N2-pycnometry and Hg-intrusion. In bioactive sol--gel glasses one issue is the insufficient and inhomogeneous incorporation of calcium (II) ions. To address this problem we varied the curing conditions and tested the effect of the organic crosslinker on calcium retention. We strengthened the silica network by covalent crosslinking with trimethylolpropane ethoxylate which was functionalized with 3-(triethoxysilyl)propyl isocyanate. Those scaffolds showed compressive yield strengths of up to 12.7thinspaceMPa and compressive moduli between 18 and 288thinspaceMPa. Energy dispersive X-ray spectroscopy showed that a crosslinker content of 60% in the hybrids resulted in a homogeneous calcium distribution in the glass, in contrast to 40% where we found a layer of CaCl2 on the scaffold surface. The materials exhibited bioactivity in simulated body fluid which was monitored by scanning electron microscopy and X-ray powder diffraction.
BibTeX:
@article{Hendrikx2017,
  author = {Hendrikx, Stephan and Kuzmenka, Dzmitry and Köferstein, Roberto and Flath, Tobias and Uhlig, Hans and Enke, Dirk and Schulze, F. Peter and Hacker, Michael C. and Schulz-Siegmund, Michaela},
  title = {Effects of curing and organic content on bioactivity and mechanical properties of hybrid sol--gel glass scaffolds made by indirect rapid prototyping},
  journal = {Journal of Sol-Gel Science and Technology},
  year = {2017},
  volume = {83},
  number = {1},
  pages = {143--154},
  doi = {https://doi.org/10.1007/s10971-017-4395-y}
}
Sakaguchi, T., Nagano, S., Hara, M., Hyon, S.-H., Patel, M. and Matsumura, K. Facile preparation of transparent poly(vinyl alcohol) hydrogels with uniform microcrystalline structure by hot-pressing without using organic solvents 2017 Polym J
Vol. 49(7), pp. 535-542 
article DOI  
Abstract: Poly(vinyl alcohol) hydrogels (PVA-Hs) are promising materials for various biomedical applications and have been studied extensively. Low-temperature crystallization is the most popular method used to prepare PVA-Hs with excellent mechanical properties. However, this method uses dimethylsulfoxide (DMSO) as a solvent, which is toxic and difficult to handle. In this study, a novel hot-pressing method was developed for preparing transparent PVA-Hs in order to eliminate the need of DMSO for solubilizing PVA during gelation. Unlike the conventional methods, this method used high initial concentrations of PVA, which made the molding of the gels easy and enhanced their gelation. The hydrogels prepared by hot-pressing showed rapid gelation of the PVA molecules along with an enhanced crystallinity, unlike the hydrogels prepared by freezing and thawing. The efficiency of different solvents (water and DMSO/water mixtures) for the preparation of PVA-Hs by the hot-pressing method was tested. The total amount of crystallites was the same for all the gels irrespective of the solvent used. However, the gels solubilized in only water showed a decrease in the net crystal size. This method not only eliminates the use of DMSO in preparing PVA-Hs but also produces gels with high mechanical properties for future use.
BibTeX:
@article{Sakaguchi2017,
  author = {Sakaguchi, Tomoyo and Nagano, Shusaku and Hara, Mitsuo and Hyon, Suong-Hyu and Patel, Monika and Matsumura, Kazuaki},
  title = {Facile preparation of transparent poly(vinyl alcohol) hydrogels with uniform microcrystalline structure by hot-pressing without using organic solvents},
  journal = {Polym J},
  publisher = {The Society of Polymer Science, Japan The Society of Polymer Science, Japan (SPSJ)},
  year = {2017},
  volume = {49},
  number = {7},
  pages = {535--542},
  doi = {https://doi.org/10.1038/pj.2017.18}
}
Carina, V., Costa, V., Raimondi, L., Pagani, S., Sartori, M., Figallo, E., Setti, S., Alessandro, R., Fini, M. and Giavaresi, G. Effect of low-intensity pulsed ultrasound on osteogenic human mesenchymal stem cells commitment in a new bone scaffold 2017 Journal of Applied Biomaterials & Functional Materials
Vol. 15(3), pp. 0-0 
article URL 
Abstract: PurposeBone tissue engineering is helpful in finding alternatives to overcome surgery limitations. Bone growth and repair are under the control of biochemical and mechanical signals; therefore, in recent years several approaches to improve bone regeneration have been evaluated. Osteo-inductive biomaterials, stem cells, specific growth factors and biophysical stimuli are among those. The aim of the present study was to evaluate if low-intensity pulsed ultrasound stimulation (LIPUS) treatment would improve the colonization of an MgHA/Coll hybrid composite scaffold by human mesenchymal stem cells (hMSCs) and their osteogenic differentiation. LIPUS stimulation was applied to hMSCs cultured on MgHA/Coll hybrid composite scaffold in osteogenic medium, mimicking the microenvironment of a bone fracture.MethodshMSCs were seeded on MgHA/Coll hybrid composite scaffold in an osteo-inductive medium and exposed to LIPUS treatment for 20 min/day for different experimental times (7 days, 14 days). The investigation was focused on (i) the improvement of hMSCs to colonize the MgHA/Coll hybrid composite scaffold by LIPUS, in terms of cell viability and ultrastructural analysis; (ii) the activation of MAPK/ERK, osteogenic (ALPL,COL1A1,BGLAP,SPP1) and angiogenetic (VEGF, IL8) pathways, through gene expression and protein release analysis, after LIPUS stimuli.ResultsLIPUS exposure improved MgHA/Coll hybrid composite scaffold colonization and induced in vitro osteogenic differentiation of hMSCs seeded on the scaffold.ConclusionsThis work shows that the combined use of new biomimetic osteo-inductive composite and LIPUS treatment could be a useful therapeutic approach in order to accelerate bone regeneration pathways.
BibTeX:
@article{Carina2017,
  author = {Carina, Valeria and Costa, Viviana and Raimondi, Lavinia and Pagani, Stefania and Sartori, Maria and Figallo, Elisa and Setti, Stefania and Alessandro, Riccardo and Fini, Milena and Giavaresi, Gianluca},
  title = {Effect of low-intensity pulsed ultrasound on osteogenic human mesenchymal stem cells commitment in a new bone scaffold},
  journal = {Journal of Applied Biomaterials & Functional Materials},
  publisher = {Wichtig Publishing},
  year = {2017},
  volume = {15},
  number = {3},
  pages = {0--0},
  url = {http://www.jab-fm.com/article/75dbe876-f3b9-4dd9-b7b5-267cd2de87e9}
}
Abbadessa, A., Landín, M., Oude Blenke, E., Hennink, W.E. and Vermonden, T. Two-component thermosensitive hydrogels: Phase separation affecting rheological behavior 2017 European Polymer Journal
Vol. 92(Supplement C), pp. 13-26 
article URL 
Abstract: Abstract Extracellular matrices are mainly composed of a mixture of different biopolymers and therefore the use of two or more building blocks for the development of tissue-mimicking hydrogels is nowadays an attractive strategy in tissue-engineering. Multi-component hydrogel systems may undergo phase separation, which in turn can lead to new, unexpected material properties. The aim of this study was to understand the role of phase separation on the mechanical properties and 3D printability of hydrogels composed of triblock copolymers of polyethylene glycol (PEG) and methacrylated poly(N-(2-hydroxypropyl) methacrylamide-mono/dilactate) (pHPMAlac) blended with methacrylated hyaluronic acid (HAMA). To this end, hydrogels composed of different concentrations of PEG/pHPMAlac and HAMA, were analyzed for phase behavior and rheological properties. Subsequently, phase separation and rheological behavior as function of the two polymer concentrations were mathematically processed to generate a predictive model. Results showed that PEG/pHPMAlac/HAMA hydrogels were characterized by hydrophilic, HAMA-richer internal domains dispersed in a more hydrophobic continuous phase, composed of PEG/pHPMAlac, and that the volume fraction of the dispersed phase increased by increasing HAMA concentration. Storage modulus, yield stress and viscosity increased with increasing HAMA concentration for low/medium HAMA contents (≤0.75% w/w), while a further increase of HAMA resulted in a decrease of the mentioned properties. On the other hand, by increasing the concentration of PEG/pHPMAlac these rheological properties were enhanced. The generated models showed a good fitting with experimental data, and were used to identify an exemplary 3D printability window for PEG/pHPMAlac/HAMA hydrogels, which was verified by rheological characterization and preparation of 3D printed scaffolds. In conclusion, a clear relationship between phase separation and rheological behavior in these two-component hydrogels can be described by complex functions of the two polymer concentrations. The predictive model generated in this study can be used as a valid tool for the identification of hydrogel compositions with desired, selected characteristics.
BibTeX:
@article{Abbadessa2017,
  author = {Abbadessa, Anna and Landín, Mariana and Oude Blenke, Erik and Hennink, Wim E. and Vermonden, Tina},
  title = {Two-component thermosensitive hydrogels: Phase separation affecting rheological behavior},
  journal = {European Polymer Journal},
  year = {2017},
  volume = {92},
  number = {Supplement C},
  pages = {13--26},
  url = {http://www.sciencedirect.com/science/article/pii/S0014305716317086}
}
Gascón-Garrido, P., Mainusch, N., Militz, H., Viöl, W. and Mai, C. Copper and aluminium deposition by cold-plasma spray on wood surfaces: effects on natural weathering behaviour 2017 European Journal of Wood and Wood Products
Vol. 75(3), pp. 315-324 
article DOI  
Abstract: Atmospheric pressure plasma was used to deposit thin layers of copper and aluminium micro-particles on the surface of Scots pine sapwood (Pinus sylvestris L.) boards. Three different loadings of metal particles were established. Additional wood boards were topcoated with a commercial acrylic binder. Boards were exposed to natural weathering for 18 months. Discolouration of copper-treated boards was slowed down, and the treatment at highest loading displayed the best appearance. Aluminium treatment was not sufficient to prevent or reduce discolouration. The application of an acrylic binder as topcoating enhanced the general appearance of metal-treated boards. Evaluation of treated boards did not reveal any reduction in crack formation or water uptake due to the particle deposition. Infrared spectroscopy suggested that copper does not protect lignin from photo-degradation. Nevertheless, copper treatment reduced fungal infestation on wood; at highest copper loading, blue stain did not penetrate through the treated surface.
BibTeX:
@article{Gascon-Garrido2017,
  author = {Gascón-Garrido, P. and Mainusch, N. and Militz, H. and Viöl, W. and Mai, C.},
  title = {Copper and aluminium deposition by cold-plasma spray on wood surfaces: effects on natural weathering behaviour},
  journal = {European Journal of Wood and Wood Products},
  year = {2017},
  volume = {75},
  number = {3},
  pages = {315--324},
  doi = {https://doi.org/10.1007/s00107-016-1121-3}
}
Tourlomousis, F., Ding, H., Kalyon, D.M. and Chang, R.C. Melt Electrospinning Writing Process Guided by a “Printability Number” 2017 Journal of Manufacturing Science and Engineering
Vol. 139(8), pp. 081004-081004-15 
article DOI  
Abstract: The direct electrostatic printing of highly viscous thermoplastic polymers onto movable collectors, a process known as melt electrospinning writing (MEW), has significant potential as an additive biomanufacturing (ABM) technology. MEW has the hitherto unrealized potential of fabricating three-dimensional (3D) porous interconnected fibrous mesh-patterned scaffolds in conjunction with cellular-relevant fiber diameters and interfiber distances without the use of cytotoxic organic solvents. However, this potential cannot be readily fulfilled owing to the large number and complex interplay of the multivariate independent parameters of the melt electrospinning process. To overcome this manufacturing challenge, dimensional analysis is employed to formulate a “Printability Number” (NPR), which correlates with the dimensionless numbers arising from the nondimensionalization of the governing conservation equations of the electrospinning process and the viscoelasticity of the polymer melt. This analysis suggests that the applied voltage potential (Vp), the volumetric flow rate (Q), and the translational stage speed (UT) are the most critical parameters toward efficient printability. Experimental investigations using a poly(ε-caprolactone) (PCL) melt reveal that any perturbations arising from an imbalance between the downstream pulling forces and the upstream resistive forces can be eliminated by systematically tuning Vp and Q for prescribed thermal conditions. This, in concert with appropriate tuning of the translational stage speed, enables steady-state equilibrium conditions to be achieved for the printing of microfibrous woven meshes with precise and reproducible geometries.
BibTeX:
@article{Tourlomousis2017,
  author = {Tourlomousis, Filippos and Ding, Houzhu and Kalyon, Dilhan M. and Chang, Robert C.},
  title = {Melt Electrospinning Writing Process Guided by a “Printability Number”},
  journal = {Journal of Manufacturing Science and Engineering},
  publisher = {ASME},
  year = {2017},
  volume = {139},
  number = {8},
  pages = {081004--081004-15},
  doi = {https://doi.org/10.1115/1.4036348}
}
Keriquel, V., Oliveira, H., Rémy, M., Ziane, S., Delmond, S., Rousseau, B., Rey, S., Catros, S., Amédée, J., Guillemot, F. and Fricain, J.-C. In situ printing of mesenchymal stromal cells, by laser-assisted bioprinting, for in vivo bone regeneration applications 2017 Scientific Reports
Vol. 7(1), pp. 1778 
article DOI  
Abstract: Bioprinting has emerged as a novel technological approach with the potential to address unsolved questions in the field of tissue engineering. We have recently shown that Laser Assisted Bioprinting (LAB), due to its unprecedented cell printing resolution and precision, is an attractive tool for the in situ printing of a bone substitute. Here, we show that LAB can be used for the in situ printing of mesenchymal stromal cells, associated with collagen and nano-hydroxyapatite, in order to favor bone regeneration, in a calvaria defect model in mice. Also, by testing different cell printing geometries, we show that different cellular arrangements impact on bone tissue regeneration. This work opens new avenues on the development of novel strategies, using in situ bioprinting, for the building of tissues, from the ground up.
BibTeX:
@article{Keriquel2017,
  author = {Keriquel, Virginie and Oliveira, Hugo and Rémy, Murielle and Ziane, Sophia and Delmond, Samantha and Rousseau, Benoit and Rey, Sylvie and Catros, Sylvain and Amédée, Joelle and Guillemot, Fabien and Fricain, Jean-Christophe},
  title = {In situ printing of mesenchymal stromal cells, by laser-assisted bioprinting, for in vivo bone regeneration applications},
  journal = {Scientific Reports},
  year = {2017},
  volume = {7},
  number = {1},
  pages = {1778},
  doi = {https://doi.org/10.1038/s41598-017-01914-x}
}
Gershlak, J.R., Hernandez, S., Fontana, G., Perreault, L.R., Hansen, K.J., Larson, S.A., Binder, B.Y.K., Dolivo, D.M., Yang, T., Dominko, T., Rolle, M.W., Weathers, P.J., Medina-Bolivar, F., Cramer, C.L., Murphy, W.L. and Gaudette, G.R. Crossing kingdoms: Using decellularized plants as perfusable tissue engineering scaffolds. 2017 Biomaterials
Vol. 125, pp. 13-22 
article URL 
Abstract: Despite significant advances in the fabrication of bioengineered scaffolds for tissue engineering, delivery of nutrients in complex engineered human tissues remains a challenge. By taking advantage of the similarities in the vascular structure of plant and animal tissues, we developed decellularized plant tissue as a prevascularized scaffold for tissue engineering applications. Perfusion-based decellularization was modified for different plant species, providing different geometries of scaffolding. After decellularization, plant scaffolds remained patent and able to transport microparticles. Plant scaffolds were recellularized with human endothelial cells that colonized the inner surfaces of plant vasculature. Human mesenchymal stem cells and human pluripotent stem cell derived cardiomyocytes adhered to the outer surfaces of plant scaffolds. Cardiomyocytes demonstrated contractile function and calcium handling capabilities over the course of 21 days. These data demonstrate the potential of decellularized plants as scaffolds for tissue engineering, which could ultimately provide a cost-efficient, "green" technology for regenerating large volume vascularized tissue mass.
BibTeX:
@article{Gershlak2017,
  author = {Gershlak, Joshua R. and Hernandez, Sarah and Fontana, Gianluca and Perreault, Luke R. and Hansen, Katrina J. and Larson, Sara A. and Binder, Bernard Y. K. and Dolivo, David M. and Yang, Tianhong and Dominko, Tanja and Rolle, Marsha W. and Weathers, Pamela J. and Medina-Bolivar, Fabricio and Cramer, Carole L. and Murphy, William L. and Gaudette, Glenn R.},
  title = {Crossing kingdoms: Using decellularized plants as perfusable tissue engineering scaffolds.},
  journal = {Biomaterials},
  year = {2017},
  volume = {125},
  pages = {13-22},
  url = {https://doi.org/10.1016/j.biomaterials.2017.02.011

} }
D'Amora, U., D'Este, M., Eglin, D., Safari, F., Sprecher, C., Gloria, A., De Santis, R., Alini, M. and Ambrosio, L. Collagen Density Gradient on 3D Printed Poly(ε-Caprolactone) Scaffolds for Interface Tissue Engineering 2017 Journal of tissue engineering and regenerative medicine
Vol. 12 
article DOI  
BibTeX:
@article{DAmora2017,
  author = {D'Amora, Ugo and D'Este, Matteo and Eglin, David and Safari, Fatemeh and Sprecher, Christoph and Gloria, Antonio and De Santis, Roberto and Alini, Mauro and Ambrosio, Luigi},
  title = {Collagen Density Gradient on 3D Printed Poly(ε-Caprolactone) Scaffolds for Interface Tissue Engineering},
  journal = {Journal of tissue engineering and regenerative medicine},
  year = {2017},
  volume = {12},
  doi = {https://doi.org/10.1002/term.2457}
}
Zhu, W., Qu, X., Zhu, J., Ma, X., Patel, S., Liu, J., Wang, P., Lai, C.S.E., Gou, M., Xu, Y., Zhang, K. and Chen, S. Direct 3D bioprinting of prevascularized tissue constructs with complex microarchitecture. 2017 Biomaterials
Vol. 124, pp. 106-115 
article DOI  
Abstract: Living tissues rely heavily on vascular networks to transport nutrients, oxygen and metabolic waste. However, there still remains a need for a simple and efficient approach to engineer vascularized tissues. Here, we created prevascularized tissues with complex three-dimensional (3D) microarchitectures using a rapid bioprinting method - microscale continuous optical bioprinting (muCOB). Multiple cell types mimicking the native vascular cell composition were encapsulated directly into hydrogels with precisely controlled distribution without the need of sacrificial materials or perfusion. With regionally controlled biomaterial properties the endothelial cells formed lumen-like structures spontaneously in vitro. In vivo implantation demonstrated the survival and progressive formation of the endothelial network in the prevascularized tissue. Anastomosis between the bioprinted endothelial network and host circulation was observed with functional blood vessels featuring red blood cells. With the superior bioprinting speed, flexibility and scalability, this new prevascularization approach can be broadly applicable to the engineering and translation of various functional tissues.
BibTeX:
@article{Zhu2017,
  author = {Zhu, Wei and Qu, Xin and Zhu, Jie and Ma, Xuanyi and Patel, Sherrina and Liu, Justin and Wang, Pengrui and Lai, Cheuk Sun Edwin and Gou, Maling and Xu, Yang and Zhang, Kang and Chen, Shaochen},
  title = {Direct 3D bioprinting of prevascularized tissue constructs with complex microarchitecture.},
  journal = {Biomaterials},
  year = {2017},
  volume = {124},
  pages = {106-115},
  doi = {https://doi.org/10.1016/j.biomaterials.2017.01.042}
}
Lind, J.U., Busbee, T.A., Valentine, A.D., Pasqualini, F.S., Yuan, H., Yadid, M., Park, S.-J., Kotikian, A., Nesmith, A.P., Campbell, P.H., Vlassak, J.J., Lewis, J.A. and Parker, K.K. Instrumented cardiac microphysiological devices via multimaterial three-dimensional printing 2017 Nat Mater
Vol. 16(3), pp. 303-308 
article DOI  
Abstract: Biomedical research has relied on animal studies and conventional cell cultures for decades. Recently, microphysiological systems (MPS), also known as organs-on-chips, that recapitulate the structure and function of native tissues in vitro, have emerged as a promising alternative1. However, current MPS typically lack integrated sensors and their fabrication requires multi-step lithographic processes2. Here, we introduce a facile route for fabricating a new class of instrumented cardiac microphysiological devices via multimaterial three-dimensional (3D) printing. Specifically, we designed six functional inks, based on piezo-resistive, high-conductance, and biocompatible soft materials that enable integration of soft strain gauge sensors within micro-architectures that guide the self-assembly of physio-mimetic laminar cardiac tissues. We validated that these embedded sensors provide non-invasive, electronic readouts of tissue contractile stresses inside cell incubator environments. We further applied these devices to study drug responses, as well as the contractile development of human stem cell-derived laminar cardiac tissues over four weeks.
BibTeX:
@article{Lind2017,
  author = {Lind, Johan U. and Busbee, Travis A. and Valentine, Alexander D. and Pasqualini, Francesco S. and Yuan, Hongyan and Yadid, Moran and Park, Sung-Jin and Kotikian, Arda and Nesmith, Alexander P. and Campbell, Patrick H. and Vlassak, Joost J. and Lewis, Jennifer A. and Parker, Kevin K.},
  title = {Instrumented cardiac microphysiological devices via multimaterial three-dimensional printing},
  journal = {Nat Mater},
  publisher = {Nature Publishing Group},
  year = {2017},
  volume = {16},
  number = {3},
  pages = {303--308},
  doi = {https://doi.org/10.1038/nmat4782}
}
Hamazaki, T., El Rouby, N., Fredette, N.C., Santostefano, K.E. and Terada, N. Concise Review: Induced Pluripotent Stem Cell Research in the Era of Precision Medicine 2017 Stem cells (Dayton, Ohio)
Vol. 35(28100040), pp. 545-550 
article URL 
Abstract: Recent advances in DNA sequencing technologies are revealing how human genetic variations associate with differential health risks, disease susceptibilities, and drug responses. Such information is now expected to help evaluate individual health risks, design personalized health plans and treat patients with precision. It is still challenging, however, to understand how such genetic variations cause the phenotypic alterations in pathobiologies and treatment response. Human induced pluripotent stem cell (iPSC) technologies are emerging as a promising strategy to fill the knowledge gaps between genetic association studies and underlying molecular mechanisms. Breakthroughs in genome editing technologies and continuous improvement in iPSC differentiation techniques are particularly making this research direction more realistic and practical. Pioneering studies have shown that iPSCs derived from a variety of monogenic diseases can faithfully recapitulate disease phenotypes in vitro when differentiated into disease-relevant cell types. It has been shown possible to partially recapitulate disease phenotypes, even with late onset and polygenic diseases. More recently, iPSCs have been shown to validate effects of disease and treatment-related single nucleotide polymorphisms identified through genome wide association analysis. In this review, we will discuss how iPSC research will further contribute to human health in the coming era of precision medicine. Stem Cells 2017;35:545-550.
BibTeX:
@article{Hamazaki2017,
  author = {Hamazaki, Takashi and El Rouby, Nihal and Fredette, Natalie C. and Santostefano, Katherine E. and Terada, Naohiro},
  title = {Concise Review: Induced Pluripotent Stem Cell Research in the Era of Precision Medicine},
  journal = {Stem cells (Dayton, Ohio)},
  year = {2017},
  volume = {35},
  number = {28100040},
  pages = {545--550},
  edition = {2017/02/05},
  url = {https://www.ncbi.nlm.nih.gov/pmc/PMC5915333/}
}
Richards, D., Jia, J., Yost, M., Markwald, R. and Mei, Y. 3D Bioprinting for Vascularized Tissue Fabrication 2017 Annals of Biomedical Engineering
Vol. 45(1), pp. 132-147 
article DOI  
Abstract: 3D bioprinting holds remarkable promise for rapid fabrication of 3D tissue engineering constructs. Given its scalability, reproducibility, and precise multi-dimensional control that traditional fabrication methods do not provide, 3D bioprinting provides a powerful means to address one of the major challenges in tissue engineering: vascularization. Moderate success of current tissue engineering strategies have been attributed to the current inability to fabricate thick tissue engineering constructs that contain endogenous, engineered vasculature or nutrient channels that can integrate with the host tissue. Successful fabrication of a vascularized tissue construct requires synergy between high throughput, high-resolution bioprinting of larger perfusable channels and instructive bioink that promotes angiogenic sprouting and neovascularization. This review aims to cover the recent progress in the field of 3D bioprinting of vascularized tissues. It will cover the methods of bioprinting vascularized constructs, bioink for vascularization, and perspectives on recent innovations in 3D printing and biomaterials for the next generation of 3D bioprinting for vascularized tissue fabrication.
BibTeX:
@article{Richards2017,
  author = {Richards, Dylan and Jia, Jia and Yost, Michael and Markwald, Roger and Mei, Ying},
  title = {3D Bioprinting for Vascularized Tissue Fabrication},
  journal = {Annals of Biomedical Engineering},
  year = {2017},
  volume = {45},
  number = {1},
  pages = {132--147},
  doi = {https://doi.org/10.1007/s10439-016-1653-z}
}
Suntornnond, R., An, J. and Kai Chua, C. Roles of support materials in 3D bioprinting -- present and future 2017 International Journal of Bioprinting
Vol. 3 
article DOI  
Abstract: Bioprinting has been introduced as a new technique in tissue engineering for more than a decade. However, characteristics of bioprinted part are still distinct from native human tissue and organ in terms of both shape fidelity and functionality. Recently, the combination of at least two hydrogels or " multi-materials/multi-nozzles " bioprinting enables simultaneous deposition of both model and support materials, thus advancing the complexity of bioprinted shapes from 2.5D lattice into micro-channeled 3D structure. In this article, a perspective on the roles of second bioinks or support materials is presented and future outlook of sacrificial materials is discussed.
BibTeX:
@article{Suntornnond2017a,
  author = {Suntornnond, Ratima and An, Jia and Kai Chua, Chee},
  title = {Roles of support materials in 3D bioprinting -- present and future},
  journal = {International Journal of Bioprinting},
  year = {2017},
  volume = {3},
  doi = {https://doi.org/10.18063/IJB.2017.01.006}
}
Pabjańczyk-Wlazło, E., Krucińska, I., Chrzanowski, M., Szparaga, G., Chaberska, A., Kolesińska, B., Komisarczyk, A. and Boguń, M. Fabrication of pure electrospun materials from hyaluronic acid 2017 Fibres and Textiles in Eastern Europe
Vol. 25, pp. 45-52 
article DOI  
BibTeX:
@article{Pabjanczyk-Wlazlo2017,
  author = {Pabjańczyk-Wlazło, Ewelina and Krucińska, Izabella and Chrzanowski, Michał and Szparaga, G and Chaberska, A and Kolesińska, B and Komisarczyk, Agnieszka and Boguń, Maciej},
  title = {Fabrication of pure electrospun materials from hyaluronic acid},
  journal = {Fibres and Textiles in Eastern Europe},
  year = {2017},
  volume = {25},
  pages = {45-52},
  doi = {https://doi.org/10.5604/12303666.1237225}
}
Liu, W., Zhang, Y.S., Heinrich, M.A., De Ferrari, F., Jang, H.L., Bakht, S.M., Alvarez, M.M., Yang, J., Li, Y.-C., Trujillo-de Santiago, G., Miri, A.K., Zhu, K., Khoshakhlagh, P., Prakash, G., Cheng, H., Guan, X., Zhong, Z., Ju, J., Zhu, G.H., Jin, X., Shin, S.R., Dokmeci, M.R. and Khademhosseini, A. Rapid Continuous Multimaterial Extrusion Bioprinting 2017 Advanced materials (Deerfield Beach, Fla.)
Vol. 29(27859710), pp. 10.1002/adma.201604630 
article URL 
Abstract: The development of a multimaterial extrusion bioprinting platform is reported. This platform is capable of depositing multiple coded bioinks in a continuous manner with fast and smooth switching among different reservoirs for rapid fabrication of complex constructs, through digitally controlled extrusion of bioinks from a single printhead consisting of bundled capillaries synergized with programmed movement of the motorized stage.
BibTeX:
@article{Liu2017b,
  author = {Liu, Wanjun and Zhang, Yu Shrike and Heinrich, Marcel A. and De Ferrari, Fabio and Jang, Hae Lin and Bakht, Syeda Mahwish and Alvarez, Mario Moisés and Yang, Jingzhou and Li, Yi-Chen and Trujillo-de Santiago, Grissel and Miri, Amir K. and Zhu, Kai and Khoshakhlagh, Parastoo and Prakash, Gyan and Cheng, Hao and Guan, Xiaofei and Zhong, Zhe and Ju, Jie and Zhu, Geyunjian Harry and Jin, Xiangyu and Shin, Su Ryon and Dokmeci, Mehmet Remzi and Khademhosseini, Ali},
  title = {Rapid Continuous Multimaterial Extrusion Bioprinting},
  journal = {Advanced materials (Deerfield Beach, Fla.)},
  year = {2017},
  volume = {29},
  number = {27859710},
  pages = {10.1002/adma.201604630},
  edition = {2016/11/17},
  url = {https://www.ncbi.nlm.nih.gov/pmc/PMC5235978/}
}
Leberfinger, A.N., Ravnic, D.J., Dhawan, A. and Ozbolat, I.T. Concise Review: Bioprinting of Stem Cells for Transplantable Tissue Fabrication 2017 STEM CELLS Translational Medicine
Vol. 6(10), pp. 1940-1948 
article DOI  
Abstract: Abstract Bioprinting is a quickly progressing technology, which holds the potential to generate replacement tissues and organs. Stem cells offer several advantages over differentiated cells for use as starting materials, including the potential for autologous tissue and differentiation into multiple cell lines. The three most commonly used stem cells are embryonic, induced pluripotent, and adult stem cells. Cells are combined with various natural and synthetic materials to form bioinks, which are used to fabricate scaffold-based or scaffold-free constructs. Computer aided design technology is combined with various bioprinting modalities including droplet-, extrusion-, or laser-based bioprinting to create tissue constructs. Each bioink and modality has its own advantages and disadvantages. Various materials and techniques are combined to maximize the benefits. Researchers have been successful in bioprinting cartilage, bone, cardiac, nervous, liver, and vascular tissues. However, a major limitation to clinical translation is building large-scale vascularized constructs. Many challenges must be overcome before this technology is used routinely in a clinical setting. Stem Cells Translational Medicine 2017;6:1940?1948
BibTeX:
@article{Leberfinger2017,
  author = {Leberfinger, Ashley N. and Ravnic, Dino J. and Dhawan, Aman and Ozbolat, Ibrahim T.},
  title = {Concise Review: Bioprinting of Stem Cells for Transplantable Tissue Fabrication},
  journal = {STEM CELLS Translational Medicine},
  publisher = {John Wiley & Sons, Ltd},
  year = {2017},
  volume = {6},
  number = {10},
  pages = {1940--1948},
  doi = {https://doi.org/10.1002/sctm.17-0148}
}
Garreta, E., Oria, R., Tarantino, C., Pla-Roca, M., Prado, P., Fernández-Avilés, F., Campistol, J.M., Samitier, J. and Montserrat, N. Tissue engineering by decellularization and 3D bioprinting 2017 Materials Today  article URL 
Abstract: Discarded human donor organs have been shown to provide decellularized extracellular matrix (dECM) scaffolds suitable for organ engineering. The quest for appropriate cell sources to satisfy the need of multiple cells types in order to fully repopulate human organ-derived dECM scaffolds has opened new venues for the use of human pluripotent stem cells (hPSCs) for recellularization. In addition, three-dimensional (3D) bioprinting techniques are advancing towards the fabrication of biomimetic cell-laden biomaterial constructs. Here, we review recent progress in decellularization/recellularization and 3D bioprinting technologies, aiming to fabricate autologous tissue grafts and organs with an impact in regenerative medicine.
BibTeX:
@article{Garreta2017,
  author = {Garreta, Elena and Oria, Roger and Tarantino, Carolina and Pla-Roca, Mateu and Prado, Patricia and Fernández-Avilés, Francisco and Campistol, Josep Maria and Samitier, Josep and Montserrat, Nuria},
  title = {Tissue engineering by decellularization and 3D bioprinting},
  journal = {Materials Today},
  year = {2017},
  url = {//www.sciencedirect.com/science/article/pii/S1369702116304278}
}
Bastola, A.K., Hoang, V.T. and Li, L. A novel hybrid magnetorheological elastomer developed by 3D printing 2017 Materials & Design
Vol. 114(Supplement C), pp. 391-397 
article URL 
Abstract: Abstract In this study, a novel magnetorheological (MR) hybrid elastomer has been developed using a 3D printing method. In such an MR hybrid elastomer, a controlled volume of an MR fluid was encapsulated layer by layer into an elastomer matrix by means of a 3D printer and each layer was a composite structure consisting of an MR fluid and an elastomer. Similar to current MR fluids and MR elastomers, mechanical properties of 3D printed MR hybrid elastomers could be controlled via an externally applied magnetic field. The experimental results showed that the relative change in the damping capability of the new MR elastomer was more pronounced than the change in its stiffness when exposed to an external magnetic field. The study demonstrated that the 3D printing technique is feasible for fabrication of MR elastomers with controlled microstructures including magnetic particles or MR fluids. The 3D printed MR hybrid elastomer is also a potential material as a tunable spring-damper element.
BibTeX:
@article{Bastola2017,
  author = {Bastola, A. K. and Hoang, V. T. and Li, L.},
  title = {A novel hybrid magnetorheological elastomer developed by 3D printing},
  journal = {Materials & Design},
  year = {2017},
  volume = {114},
  number = {Supplement C},
  pages = {391--397},
  url = {http://www.sciencedirect.com/science/article/pii/S0264127516313922}
}
Zhang, X., Geven, M.A., Grijpma, D.W., Peijs, T. and Gautrot, J.E. Tunable and processable shape memory composites based on degradable polymers 2017 Polymer
Vol. 122(Supplement C), pp. 323 - 331 
article DOI URL 
Abstract: Abstract Biodegradable shape memory polymers are attractive materials for the design of biomedical scaffolds as they allow deploying implants remotely with minimal intervention, whilst allowing degradation and tissue repair. However, shape memory properties are difficult to design from common degradable polymers, without chemical modifications. Here were developed readily tunable processable shape memory polymer composites (SMPCs) based on established degradable polymers in the biomedical field (poly(trimethylene carbonate) (PTMC) and poly(lactic acid) (PLA) fibres). These SMPCs rely on the glass-rubber transition of the PLA network to trigger shape recovery, whilst the elastic PTMC matrix optimises the full recovery of the scaffold to permanent shape. We demonstrate the performance of SMPCs can be readily designed by adjusting the loading and processing of the fibre network, or through the addition of plasticizing poly(ethylene glycol) chains. Importantly, we demonstrate that the use of cut fibres allows the solution processing of SMPCs, which should enable the design of potentially degradable shape memory 3D scaffolds with complex shapes.
BibTeX:
@article{Zhang2017,
  author = {Xi Zhang and Mike A. Geven and Dirk W. Grijpma and Ton Peijs and Julien E. Gautrot},
  title = {Tunable and processable shape memory composites based on degradable polymers},
  journal = {Polymer},
  year = {2017},
  volume = {122},
  number = {Supplement C},
  pages = {323 - 331},
  url = {http://www.sciencedirect.com/science/article/pii/S0032386117306365},
  doi = {https://doi.org/10.1016/j.polymer.2017.06.066}
}
Yu, H.S., Park, J., Lee, H.-S., Park, S.A., Lee, D.-W. and Park, K. Feasibility of Polycaprolactone Scaffolds Fabricated by Three-Dimensional Printing for Tissue Engineering of Tunica Albuginea 2017 World J Mens Health
Vol. 35 
article URL 
Abstract: Purpose To investigate the feasibility of a polycaprolactone (PCL) scaffold fabricated by three-dimensional (3D) printing for tissue engineering applications for tunica albuginea.
BibTeX:
@article{Yu2017a,
  author = {Yu, Ho Song and Park, Jinju and Lee, Hyun-Suk and Park, Su A. and Lee, Dong-Weon and Park, Kwangsung},
  title = {Feasibility of Polycaprolactone Scaffolds Fabricated by Three-Dimensional Printing for Tissue Engineering of Tunica Albuginea},
  journal = {World J Mens Health},
  publisher = {Korean Society for Sexual Medicine and Andrology},
  year = {2017},
  volume = {35},
  url = {http://synapse.koreamed.org/DOIx.php?id=10.5534%2Fwjmh.17025}
}
Youssef, A., Hollister, S.J. and Dalton, P.D. Additive manufacturing of polymer melts for implantable medical devices and scaffolds 2017 Biofabrication
Vol. 9(1), pp. 012002 
article URL 
Abstract: Melt processing is routinely used to fabricate medical polymeric devices/implants for clinical reconstruction and can be incorporated into quality systems procedures for medical device manufacture. As additive manufacturing (AM) becomes increasingly used for biomaterials and biofabrication, the translation of new, customizable, medical devices to the clinic becomes paramount. Melt processing is therefore a distinguishable group within AM that provides an avenue to manufacture scaffolds/implants with a clinical end-point. Three key melt processing AM technologies are highlighted in this review: melt micro-extrusion, selective laser sintering and melt electrospinning writing. The in vivo (including clinical) outcomes of medical devices and scaffolds made with these processes are reviewed. Together, they encompass the melt AM of scaffold architectures with feature sizes and resolutions ranging from 800 nm up to 700 μ m.
BibTeX:
@article{Youssef2017,
  author = {Almoatazbellah Youssef and Scott J Hollister and Paul D Dalton},
  title = {Additive manufacturing of polymer melts for implantable medical devices and scaffolds},
  journal = {Biofabrication},
  year = {2017},
  volume = {9},
  number = {1},
  pages = {012002},
  url = {http://stacks.iop.org/1758-5090/9/i=1/a=012002}
}
Wu, Y., Fuh, J., Wong, Y.S. and Sun, J. A hybrid electrospinning and electrospraying 3D printing for tissue engineered scaffolds 2017 Rapid Prototyping Journal
Vol. 0(ja), pp. 00-00 
article DOI  
Abstract: Purpose Fabricating functionally graded scaffolds to mimic the complex spatial distributions of the composition, micro-structure, and functionality of native tissues, will be one of the key objectives for future tissue engineering research. We applied a hybrid process to incorporate electrospun polycaprolactone (PCL) and electrosprayed hydroxyapatite (HA) in a simple pathway, and aimed to create a scaffold to mimic functionally graded tissue. Design/methodology/approach The PCL and HA were dispensed simultaneously from different positions to form a layer on a rotational mandrel, and a gradient construct was achieved by adjusting dispensing rates of both materials. Findings The morphology of scaffolds changed gradually from one layer to another layer with the change of the dispensing conditions of the two materials. The elemental distribution analysis revealed that C/Ca ratio linearly increased with certain dispensing rate ratio of PCL:HA. In addition, the thickness, mechanical properties (i.e. ultimate tensile stress and Young’s modulus), surface roughness and water contact angle of each layer changed accordingly with the variation of dispensing rate of PCL and HA, and the diameter distributions of PCL fibers and HA particles did not vary significantly. Originality/value This study showed the hybrid process has a potential to be used in fabrication of scaffold with functionally graded structure for tissue engineering applications, especially for mimicking the nature of the native 3D tendon-bone interface.
BibTeX:
@article{Wu2017,
  author = {Yang Wu and Jerry Fuh and Yoke San Wong and Jie Sun},
  title = {A hybrid electrospinning and electrospraying 3D printing for tissue engineered scaffolds},
  journal = {Rapid Prototyping Journal},
  year = {2017},
  volume = {0},
  number = {ja},
  pages = {00-00},
  doi = {https://doi.org/10.1108/RPJ-08-2015-0111}
}
Thamm, C., DeSimone, E. and Scheibel, T. Characterization of Hydrogels Made of a Novel Spider Silk Protein eMaSp1s and Evaluation for 3D Printing 2017 Macromolecular Bioscience
Vol. 17(11), pp. 1700141-n/a 
article DOI URL 
Abstract: Recombinantly produced spider silk proteins have high potential for bioengineering and various biomedical applications because of their biocompatibility, biodegradability, and low immunogenicity. Here, the recently described small spider silk protein eMaSp1s is assembled into hydrogels, which can be 3D printed into scaffolds. Further, blending with a recombinantly produced MaSp2 derivative eADF4(C16) alters the mechanical properties of the resulting hydrogels. Different spider silk hydrogels also show a distinct recovery after a high shear stress deformation, exhibiting the tunability of their features for selected applications.
BibTeX:
@article{Thamm2017,
  author = {Thamm, Christopher and DeSimone, Elise and Scheibel, Thomas},
  title = {Characterization of Hydrogels Made of a Novel Spider Silk Protein eMaSp1s and Evaluation for 3D Printing},
  journal = {Macromolecular Bioscience},
  year = {2017},
  volume = {17},
  number = {11},
  pages = {1700141--n/a},
  note = {1700141},
  url = {http://dx.doi.org/10.1002/mabi.201700141},
  doi = {https://doi.org/10.1002/mabi.201700141}
}
Taylor, A.C., Beirne, S., Alici, G. and Wallace, G.G. System and process development for coaxial extrusion in fused deposition modelling 2017 Rapid Prototyping Journal
Vol. 23(3), pp. 543-550 
article DOI  
Abstract: Purpose This paper aims to design and test a system capable of coaxial fused deposition modelling (FDM) and assess the coaxial fibres produced for their coaxial concentricity. The goal is to achieve concentricity values below the literature standard of 15 per cent. Design/methodology/approach This research discusses the design of the coaxial nozzle internal geometry and validates the modelling process by using computational fluid dynamics to assess its flow profile. Sequentially, this paper discusses the abilities of current additive manufacturing (AM) technology in the production of the coaxial nozzle. Findings The methodology followed has produced coaxial fibres with concentricity values as low as 2.89 per cent and also identifies a clear speed suitable for coaxial printing using polylactic acid (PLA) as the internal and external materials. Research limitations/implications The concentricity of the printed fibres is heavily influenced by the feed rate for the thermoplastic feedstock. This in turn alters the viscosity of the material to be printed, implying that a relationship exists between feed rate and print temperature, which can be further optimised to potentially obtain higher concentricity values. Practical implications This paper adds reliability and repeatability to the production of coaxially printed structures, the likes of which has numerous potential applications for biological printing. Originality/value The outcomes of this study will provide an AM platform to alter the paradigm of biofabrication by introducing a new level of versatility to the construction of biofabricated structures.
BibTeX:
@article{Taylor2017,
  author = {Adam C. Taylor and Stephen Beirne and Gursel Alici and Gordon G. Wallace},
  title = {System and process development for coaxial extrusion in fused deposition modelling},
  journal = {Rapid Prototyping Journal},
  year = {2017},
  volume = {23},
  number = {3},
  pages = {543-550},
  doi = {https://doi.org/10.1108/RPJ-10-2015-0141}
}
Suntornnond, R., An, J. and Chua, C.K. Roles of support materials in 3D bioprinting 2017 International Journal of Bioprinting; Vol 3, No 1 (2017)  article URL 
Abstract:   Bioprinting has been introduced as a new technique in tissue engineering for more than a decade. However, characteristics of bioprinted part are still distinct from native human tissue and organ in terms of both shape fidelity and functionality. Recently, the combination of at least two hydrogels or “multi-materials/multi-nozzles” bioprinting enables simultaneous deposition of both model and support materials, thus advancing the complexity of bioprinted shapes from 2.5D lattice into micro-channeled 3D structure. In this article, a perspective on the roles of second bioinks or support materials is presented and future outlook of sacrificial materials is discussed.
BibTeX:
@article{Suntornnond2017b,
  author = {Suntornnond, Ratima and An, Jia and Chua, Chee Kai},
  title = {Roles of support materials in 3D bioprinting},
  journal = {International Journal of Bioprinting; Vol 3, No 1 (2017)},
  year = {2017},
  url = {http://ijb.whioce.com/index.php/int-j-bioprinting/article/view/91}
}
Sultan, S., Siqueira, G., Zimmermann, T. and Mathew, A.P. 3D printing of nano-cellulosic biomaterials for medical applications 2017 Current Opinion in Biomedical Engineering
Vol. 2(Supplement C), pp. 29 - 34 
article DOI URL 
Abstract: Abstract Nanoscaled versions of cellulose viz. cellulose nanofibers (CNF) or cellulose nanocrystals (CNC) isolated from natural resources are being used extensively since the past decade in the biomedical field e.g. for tissue engineering, implants, drug delivery systems, cardiovascular devices, and wound healing due to their remarkable mechanical, chemical and biocompatible properties. In the recent years, 3D printing of nanocellulose in combination with polymers is being studied as a viable route to future regenerative therapy. The printability of nanocellulose hydrogels owing to their shear thinning behavior and the possibility to support living cells allows 3D bioprinting using nanocellulose, a recent development which holds tremendous potential.
BibTeX:
@article{Sultan2017,
  author = {Sahar Sultan and Gilberto Siqueira and Tanja Zimmermann and Aji P. Mathew},
  title = {3D printing of nano-cellulosic biomaterials for medical applications},
  journal = {Current Opinion in Biomedical Engineering},
  year = {2017},
  volume = {2},
  number = {Supplement C},
  pages = {29 - 34},
  note = {Additive Manufacturing},
  url = {http://www.sciencedirect.com/science/article/pii/S2468451117300132},
  doi = {https://doi.org/10.1016/j.cobme.2017.06.002}
}
Stichler, S., Böck, T., Paxton, N.C., Bertlein, S., Levato, R., Schill, V., Smolan, W., Malda, J., Tessmar, J., Blunk, T. and Groll, J. Double printing of hyaluronic acid / poly(glycidol) hybrid hydrogels with poly(ε-caprolactone) for MSC chondrogenesis 2017 Biofabrication  article DOI  
Abstract: Abstract This study investigates the use of allyl-functionalized poly(glycidol)s (P(AGE-co-G)) as cytocompatible cross-linker for thiol-functionalized hyaluronic acid (HA-SH) and the optimization of this hybrid hydrogel as bioink for 3D bioprinting. Chemical cross-linking of gels with 10 wt.% overall polymer concentration was achieved by UV-induced radical thiol-ene coupling between the thiol and allyl groups. Addition of unmodified high molecular weight HA (1.36 MDa) allowed tuning of the rheology for extrusion based bioprinting. Incorporation of additional HA resulted in hydrogels with lower Young’s modulus and higher swelling ratio especially in the first 24 h, but a comparable equilibrium swelling for all gels after 24 h. Embedding of human and equine mesenchymal stem cells (MSCs) in the gels and subsequent in vitro culture showed promising chondrogenic differentiation after 21 d for cells from both origins. Moreover, cells could be printed with these gels, and embedded hMSCs showed good cell survival for at least 21 d in culture. To achieve mechanical stable and robust constructs for the envisioned application in articular cartilage, the formulations were adjusted for double printing with the thermoplastic poly--caprolactone (PCL).
BibTeX:
@article{Stichler2017,
  author = {Simone Stichler and Thomas Böck and Naomi Claire Paxton and Sarah Bertlein and Riccardo Levato and Verena Schill and Willi Smolan and Jos Malda and Joerg Tessmar and Torsten Blunk and Juergen Groll},
  title = {Double printing of hyaluronic acid / poly(glycidol) hybrid hydrogels with poly(ε-caprolactone) for MSC chondrogenesis},
  journal = {Biofabrication},
  year = {2017},
  doi = {https://doi.org/10.1088/1758-5090/aa8cb7}
}
Sommer, M.R., Alison, L., Minas, C., Tervoort, E., Ruhs, P.A. and Studart, A.R. 3D printing of concentrated emulsions into multiphase biocompatible soft materials 2017 Soft Matter
Vol. 13, pp. 1794-1803 
article DOI  
Abstract: 3D printing via direct ink writing (DIW) is a versatile additive manufacturing approach applicable to a variety of materials ranging from ceramics over composites to hydrogels. Due to the mild processing conditions compared to other additive manufacturing methods, DIW enables the incorporation of sensitive compounds such as proteins or drugs into the printed structure. Although emulsified oil-in-water systems are commonly used vehicles for such compounds in biomedical, pharmaceutical, and cosmetic applications, printing of such emulsions into architectured soft materials has not been fully exploited and would open new possibilities for the controlled delivery of sensitive compounds. Here, we 3D print concentrated emulsions into soft materials, whose multiphase architecture allows for site-specific incorporation of both hydrophobic and hydrophilic compounds into the same structure. As a model ink, concentrated emulsions stabilized by chitosan-modified silica nanoparticles are studied, because they are sufficiently stable against coalescence during the centrifugation step needed to create a bridging network of droplets. The resulting ink is ideal for 3D printing as it displays high yield stress, storage modulus and elastic recovery, through the formation of networks of droplets as well as of gelled silica nanoparticles in the presence of chitosan. To demonstrate possible architectures, we print biocompatible soft materials with tunable hierarchical porosity containing an encapsulated hydrophobic compound positioned in specific locations of the structure. The proposed emulsion-based ink system offers great flexibility in terms of 3D shaping and local compositional control, and can potentially help address current challenges involving the delivery of incompatible compounds in biomedical applications.
BibTeX:
@article{Sommer2017,
  author = {Sommer, Marianne R. and Alison, Lauriane and Minas, Clara and Tervoort, Elena and Ruhs, Patrick A. and Studart, Andre R.},
  title = {3D printing of concentrated emulsions into multiphase biocompatible soft materials},
  journal = {Soft Matter},
  publisher = {The Royal Society of Chemistry},
  year = {2017},
  volume = {13},
  pages = {1794-1803},
  doi = {https://doi.org/10.1039/C6SM02682F}
}
Siqueira, G., Kokkinis, D., Libanori, R., Hausmann, M.K., Gladman, A.S., Neels, A., Tingaut, P., Zimmermann, T., Lewis, J.A. and Studart, A.R. Cellulose Nanocrystal Inks for 3D Printing of Textured Cellular Architectures 2017 Advanced Functional Materials
Vol. 27(12), pp. 1604619-n/a 
article DOI  
Abstract: 3D printing of renewable building blocks like cellulose nanocrystals offers an attractive pathway for fabricating sustainable structures. Here, viscoelastic inks composed of anisotropic cellulose nanocrystals (CNC) that enable patterning of 3D objects by direct ink writing are designed and formulated. These concentrated inks are composed of CNC particles suspended in either water or a photopolymerizable monomer solution. The shear-induced alignment of these anisotropic building blocks during printing is quantified by atomic force microscopy, polarized light microscopy, and 2D wide-angle X-ray scattering measurements. Akin to the microreinforcing effect in plant cell walls, the alignment of CNC particles during direct writing yields textured composites with enhanced stiffness along the printing direction. The observations serve as an important step forward toward the development of sustainable materials for 3D printing of cellular architectures with tailored mechanical properties.
BibTeX:
@article{Siqueira2017,
  author = {Siqueira, Gilberto and Kokkinis, Dimitri and Libanori, Rafael and Hausmann, Michael K. and Gladman, Amelia Sydney and Neels, Antonia and Tingaut, Philippe and Zimmermann, Tanja and Lewis, Jennifer A. and Studart, André R.},
  title = {Cellulose Nanocrystal Inks for 3D Printing of Textured Cellular Architectures},
  journal = {Advanced Functional Materials},
  year = {2017},
  volume = {27},
  number = {12},
  pages = {1604619--n/a},
  note = {1604619},
  doi = {https://doi.org/10.1002/adfm.201604619}
}
Shi, P., Laude, A. and Yeong, W.Y. Investigation of cell viability and morphology in 3D bio-printed alginate constructs with tunable stiffness 2017 Journal of Biomedical Materials Research Part A
Vol. 105(4), pp. 1009-1018 
article DOI  
Abstract: In this article, mouse fibroblast cells (L929) were seeded on 2%, 5%, and 10% alginate hydrogels, and they were also bio-printed with 2%, 5%, and 10% alginate solutions individually to form constructs. The elastic and viscous moduli of alginate solutions, their interior structure and stiffness, interactions of cells and alginate, cell viability, migration and morphology were investigated by rheometer, MTT assay, scanning electron microscope (SEM), and fluorescent microscopy. The three types of bio-printed scaffolds of distinctive stiffness were prepared, and the seeded cells showed robust viability either on the alginate hydrogel surfaces or in the 3D bio-printed constructs. Majority of the proliferated cells in the 3D bio-printed constructs weakly attached to the surrounding alginate matrix. The concentration of alginate solution and hydrogel stiffness influenced cell migration and morphology, moreover the cells formed spheroids in the bio-printed 10% alginate hydrogel construct. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1009–1018, 2017.
BibTeX:
@article{Shi2017,
  author = {Shi, Pujiang and Laude, Augustinus and Yeong, Wai Yee},
  title = {Investigation of cell viability and morphology in 3D bio-printed alginate constructs with tunable stiffness},
  journal = {Journal of Biomedical Materials Research Part A},
  year = {2017},
  volume = {105},
  number = {4},
  pages = {1009--1018},
  doi = {https://doi.org/10.1002/jbm.a.35971}
}
Reitmaier, S., Kovtun, A., Schuelke, J., Kanter, B., Lemm, M., Hoess, A., Heinemann, S., Nies, B. and Ignatius, A. Strontium(II) and mechanical loading additively augment bone formation in calcium phosphate scaffolds 2017 Journal of Orthopaedic Research, pp. n/a-n/a  article DOI  
Abstract:
Calcium phosphate cements (CPCs) are widely used for bone-defect treatment. Current developments comprise the fabrication of porous scaffolds by three-dimensional plotting and doting using biologically active substances, such as strontium. Strontium is known to increase osteoblast activity and simultaneously to decrease osteoclast resorption. This study investigated the short- and long-term in vivo performances of strontium(II)-doted CPC (SrCPC) scaffolds compared to non-doted CPC scaffolds after implantation in unloaded or load-bearing trabecular bone defects in sheep. After 6 weeks, both CPC and SrCPC scaffolds exhibited good biocompatibility and osseointegration. Fluorochrome labeling revealed that both scaffolds were penetrated by newly formed bone already after 4 weeks. Neither strontium doting nor mechanical loading significantly influenced early bone formation. In contrast, after 6 months, bone formation was significantly enhanced in SrCPC compared to CPC scaffolds. Energy dispersive X-ray analysis demonstrated the release of strontium from the SrCPC into the bone. Strontium addition did not significantly influence material resorption or osteoclast formation. Mechanical loading significantly stimulated bone formation in both CPC and SrCPC scaffolds after 6 months without impairing scaffold integrity. The most bone was found in SrCPC scaffolds under load-bearing conditions. Concluding, these results demonstrate that strontium doting and mechanical loading additively stimulated bone formation in CPC scaffolds and that the scaffolds exhibited mechanical stability under moderate load, implying good clinical suitability. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res
BibTeX:
@article{Reitmaier2017,
  author = {Reitmaier, Sandra and Kovtun, Anna and Schuelke, Julian and Kanter, Britta and Lemm, Madlin and Hoess, Andreas and Heinemann, Sascha and Nies, Berthold and Ignatius, Anita},
  title = {Strontium(II) and mechanical loading additively augment bone formation in calcium phosphate scaffolds},
  journal = {Journal of Orthopaedic Research},
  year = {2017},
  pages = {n/a--n/a},
  doi = {https://doi.org/10.1002/jor.23623}
}
Peng, W., Datta, P., Ayan, B., Ozbolat, V., Sosnoski, D. and Ozbolat, I.T. 3D bioprinting for drug discovery and development in pharmaceutics 2017 Acta Biomaterialia
Vol. 57, pp. 26 - 46 
article DOI URL 
Abstract: Successful launch of a commercial drug requires significant investment of time and financial resources wherein late-stage failures become a reason for catastrophic failures in drug discovery. This calls for infusing constant innovations in technologies, which can give reliable prediction of efficacy, and more importantly, toxicology of the compound early in the drug discovery process before clinical trials. Though computational advances have resulted in more rationale in silico designing, in vitro experimental studies still require gaining industry confidence and improving in vitro-in vivo correlations. In this quest, due to their ability to mimic the spatial and chemical attributes of native tissues, three-dimensional (3D) tissue models have now proven to provide better results for drug screening compared to traditional two-dimensional (2D) models. However, in vitro fabrication of living tissues has remained a bottleneck in realizing the full potential of 3D models. Recent advances in bioprinting provide a valuable tool to fabricate biomimetic constructs, which can be applied in different stages of drug discovery research. This paper presents the first comprehensive review of bioprinting techniques applied for fabrication of 3D tissue models for pharmaceutical studies. A comparative evaluation of different bioprinting modalities is performed to assess the performance and ability of fabricating 3D tissue models for pharmaceutical use as the critical selection of bioprinting modalities indeed plays a crucial role in efficacy and toxicology testing of drugs and accelerates the drug development cycle. In addition, limitations with current tissue models are discussed thoroughly and future prospects of the role of bioprinting in pharmaceutics are provided to the reader. Present advances in tissue biofabrication have crucial role to play in aiding the pharmaceutical development process achieve its objectives. Advent of three-dimensional (3D) models, in particular, is viewed with immense interest by the community due to their ability to mimic in vivo hierarchical tissue architecture and heterogeneous composition. Successful realization of 3D models will not only provide greater in vitro-in vivo correlation compared to the two-dimensional (2D) models, but also eventually replace pre-clinical animal testing, which has their own shortcomings. Amongst all fabrication techniques, bioprinting- comprising all the different modalities (extrusion-, droplet- and laser-based bioprinting), is emerging as the most viable fabrication technique to create the biomimetic tissue constructs. Notwithstanding the interest in bioprinting by the pharmaceutical development researchers, it can be seen that there is a limited availability of comparative literature which can guide the proper selection of bioprinting processes and associated considerations, such as the bioink selection for a particular pharmaceutical study. Thus, this work emphasizes these aspects of bioprinting and presents them in perspective of differential requirements of different pharmaceutical studies like in vitro predictive toxicology, high-throughput screening, drug delivery and tissue-specific efficacies. Moreover, since bioprinting techniques are mostly applied in regenerative medicine and tissue engineering, a comparative analysis of similarities and differences are also expounded to help researchers make informed decisions based on contemporary literature.
BibTeX:
@article{Peng2017,
  author = {Weijie Peng and Pallab Datta and Bugra Ayan and Veli Ozbolat and Donna Sosnoski and Ibrahim T. Ozbolat},
  title = {3D bioprinting for drug discovery and development in pharmaceutics},
  journal = {Acta Biomaterialia},
  year = {2017},
  volume = {57},
  pages = {26 - 46},
  url = {http://www.sciencedirect.com/science/article/pii/S1742706117303069},
  doi = {https://doi.org/10.1016/j.actbio.2017.05.025}
}
Paxton, N.C., Smolan, W., Böck, T., Melchels, F.P.W., Groll, J. and Juengst, T. Proposal to Assess Printability of Bioinks for Extrusion-Based Bioprinting and Evaluation of Rheological Properties Governing Bioprintability 2017 Biofabrication  article DOI  
Abstract: Abstract The development and formulation of printable inks for extrusion-based 3D bioprinting has been a major challenge in the field of biofabrication. Inks, often polymer solutions with the addition of crosslinking to form hydrogels, must not only display adequate mechanical properties for the chosen application, but also show high biocompatibility as well as printability. Here we describe a reproducible two-step method for the assessment of the printability of inks for bioprinting, focussing firstly on screening ink formulations to assess fibre formation and the ability to form 3D constructs before presenting a method for the rheological evaluation of inks to characterise the yield point, shear thinning and recovery behaviour. In conjunction, a mathematical model was formulated to provide a theoretical understanding of the pressure-driven, shear thinning extrusion of inks through needles in a bioprinter. The assessment methods were trialled with a commercially-available crème, poloxamer 407, alginate-based inks and an alginate-gelatin composite material. Yield stress was investigated by applying a stress ramp to a number of inks, which demonstrated the necessity of high yield for printable materials. The shear thinning behaviour of the inks was then characterised by quantifying the degree of shear thinning and using the mathematical model to predict the window of printer operating parameters in which the materials could be printed. Furthermore, the model predicted high shear conditions and high residence times for cells at the walls of the needle and effects on cytocompatibility at different printing conditions. Finally, the ability of the materials to recover to their original viscosity after extrusion was examined using rotational recovery rheological measurements. Taken together, these assessment techniques revealed significant insights into the requirements for printable inks and shear conditions present during the extrusion process and allow the rapid and reproducible characterisation of a wide variety of inks for bioprinting.
BibTeX:
@article{Paxton2017,
  author = {Naomi Claire Paxton and Willi Smolan and Thomas Böck and Ferry P W Melchels and Juergen Groll and Tomasz Juengst},
  title = {Proposal to Assess Printability of Bioinks for Extrusion-Based Bioprinting and Evaluation of Rheological Properties Governing Bioprintability},
  journal = {Biofabrication},
  year = {2017},
  doi = {https://doi.org/10.1088/1758-5090/aa8dd8}
}
Ng, L.W., Yeong, Y.W. and Naing, W.M. Polyvinylpyrrolidone-Based Bio-Ink Improves Cell Viability and Homogeneity during Drop-On-Demand Printing 2017 Materials
Vol. 10(2) 
article URL 
Abstract: Drop-on-demand (DOD) bioprinting has attracted huge attention for numerous biological applications due to its precise control over material volume and deposition pattern in a contactless printing approach. 3D bioprinting is still an emerging field and more work is required to improve the viability and homogeneity of printed cells during the printing process. Here, a general purpose bio-ink was developed using polyvinylpyrrolidone (PVP) macromolecules. Different PVP-based bio-inks (0%-3% w/v) were prepared and evaluated for their printability; the short-term and long-term viability of the printed cells were first investigated. The Z value of a bio-ink determines its printability; it is the inverse of the Ohnesorge number (Oh), which is the ratio between the Reynolds number and a square root of the Weber number, and is independent of the bio-ink velocity. The viability of printed cells is dependent on the Z values of the bio-inks; the results indicated that the cells can be printed without any significant impairment using a bio-ink with a threshold Z value of ≤9.30 (2% and 2.5% w/v). Next, the cell output was evaluated over a period of 30 min. The results indicated that PVP molecules mitigate the cell adhesion and sedimentation during the printing process; the 2.5% w/v PVP bio-ink demonstrated the most consistent cell output over a period of 30 min. Hence, PVP macromolecules can play a critical role in improving the cell viability and homogeneity during the bioprinting process.
BibTeX:
@article{Ng2017,
  author = {Ng, L. Wei and Yeong, Y. Wai and Naing, W. May},
  title = {Polyvinylpyrrolidone-Based Bio-Ink Improves Cell Viability and Homogeneity during Drop-On-Demand Printing},
  journal = {Materials},
  year = {2017},
  volume = {10},
  number = {2},
  url = {https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5459162/}
}
Mistry, P., Aied, A., Alexander, M., Shakesheff, K., Bennett, A. and Yang, J. Bioprinting Using Mechanically Robust Core–Shell Cell-Laden Hydrogel Strands 2017 Macromolecular Bioscience
Vol. 17(6), pp. 1600472-n/a 
article DOI  
Abstract: The strand material in extrusion-based bioprinting determines the microenvironments of the embedded cells and the initial mechanical properties of the constructs. One unmet challenge is the combination of optimal biological and mechanical properties in bioprinted constructs. Here, a novel bioprinting method that utilizes core–shell cell-laden strands with a mechanically robust shell and an extracellular matrix-like core has been developed. Cells encapsulated in the strands demonstrate high cell viability and tissue-like functions during cultivation. This process of bioprinting using core–shell strands with optimal biochemical and biomechanical properties represents a new strategy for fabricating functional human tissues and organs.






BibTeX:
@article{Mistry2017,
  author = {Mistry, Pritesh and Aied, Ahmed and Alexander, Morgan and Shakesheff, Kevin and Bennett, Andrew and Yang, Jing},
  title = {Bioprinting Using Mechanically Robust Core–Shell Cell-Laden Hydrogel Strands},
  journal = {Macromolecular Bioscience},
  year = {2017},
  volume = {17},
  number = {6},
  pages = {1600472--n/a},
  note = {1600472},
  doi = {https://doi.org/10.1002/mabi.201600472}
}
Lorson, T., Jaksch, S., Lübtow, M.M., Jüngst, T., Groll, J., Lühmann, T. and Luxenhofer, R. A Thermogelling Supramolecular Hydrogel with Sponge-Like Morphology as a Cytocompatible Bioink 2017 Biomacromolecules
Vol. 18(7), pp. 2161-2171 
article DOI  
Abstract: Biocompatible polymers that form thermoreversible supramolecular hydrogels have gained great interest in biomaterials research and tissue engineering. When favorable rheological properties are achieved at the same time, they are particularly promising candidates as material that allow for the printing of cells, so-called bioinks. We synthesized a novel thermogelling block copolymer and investigated the rheological properties of its aqueous solution by viscosimetry and rheology. The polymers undergo thermogelation between room temperature and body temperature, form transparent hydrogels of surprisingly high strength (G′ > 1000 Pa) and show rapid and complete shear recovery after stress. Small angle neutron scattering suggests an unusual bicontinuous sponge-like gel network. Excellent cytocompatibility was demonstrated with NIH 3T3 fibroblasts, which were incorporated and bioplotted into predefined 3D hydrogel structures without significant loss of viability. The developed materials fulfill all criteria for future use as bioink for biofabrication.
BibTeX:
@article{Lorson2017,
  author = {Lorson, Thomas and Jaksch, Sebastian and Lübtow, Michael M. and Jüngst, Tomasz and Groll, Jürgen and Lühmann, Tessa and Luxenhofer, Robert},
  title = {A Thermogelling Supramolecular Hydrogel with Sponge-Like Morphology as a Cytocompatible Bioink},
  journal = {Biomacromolecules},
  year = {2017},
  volume = {18},
  number = {7},
  pages = {2161-2171},
  note = {PMID: 28653854},
  doi = {https://doi.org/10.1021/acs.biomac.7b00481}
}
Liao, Z., Sinjab, F., Nommeots-Nomm, A., Jones, J., Ruiz-Cantu, L., Yang, J., Rose, F. and Notingher, I. Feasibility of Spatially Offset Raman Spectroscopy for in Vitro and in Vivo Monitoring Mineralization of Bone Tissue Engineering Scaffolds 2017 Analytical Chemistry
Vol. 89(1), pp. 847-853 
article DOI  
Abstract: We investigated the feasibility of using spatially offset Raman spectroscopy (SORS) for nondestructive characterization of bone tissue engineering scaffolds. The deep regions of these scaffolds, or scaffolds implanted subcutaneously in live animals, are typically difficult to measure by confocal Raman spectroscopy techniques because of the limited depth penetration of light caused by the high level of light scattering. Layered samples consisting of bioactive glass foams (IEIC16), three-dimensional (3D)-printed biodegradable poly(lactic-co-glycolic acid) scaffolds (PLGA), and hydroxyapatite powder (HA) were used to mimic nondestructive detection of biomineralization for intact real-size 3D tissue engineering constructs. SORS spectra were measured with a new SORS instrument using a digital micromirror device (DMD) to allow software selection of the spatial offsets. The results show that HA can be reliably detected at depths of 0–2.3 mm, which corresponds to the maximum accessible spatial offset of the current instrument. The intensity ratio of Raman bands associated with the scaffolds and HA with the spatial offset depended on the depth at which HA was located. Furthermore, we show the feasibility for in vivo monitoring mineralization of scaffold implanted subcutaneously by demonstrating the ability to measure transcutaneously Raman signals of the scaffolds and HA (fresh chicken skin used as a top layer). The ability to measure spectral depth profiles at high speed (5 s acquisition time) and the ease of implementation make SORS a promising approach for noninvasive characterization of cell/tissue development in vitro, and for long-term in vivo monitoring the mineralization in 3D scaffolds subcutaneously implanted in small animals.
BibTeX:
@article{Liao2017,
  author = {Liao, Zhiyu and Sinjab, Faris and Nommeots-Nomm, Amy and Jones, Julian and Ruiz-Cantu, Laura and Yang, Jing and Rose, Felicity and Notingher, Ioan},
  title = {Feasibility of Spatially Offset Raman Spectroscopy for in Vitro and in Vivo Monitoring Mineralization of Bone Tissue Engineering Scaffolds},
  journal = {Analytical Chemistry},
  year = {2017},
  volume = {89},
  number = {1},
  pages = {847-853},
  note = {PMID: 27983789},
  doi = {https://doi.org/10.1021/acs.analchem.6b03785}
}
Lian, H. and Meng, Z. Melt electrospinning of daunorubicin hydrochloride-loaded poly (ε-caprolactone) fibrous membrane for tumor therapy 2017 Bioactive Materials
Vol. 2(2), pp. 96 - 100 
article DOI URL 
Abstract: Daunorubicin hydrochloride is a cell-cycle non-specific antitumor drug with a high therapeutic effect. The present study outlines the fabrication of daunorubicin hydrochloride-loaded poly (ε-caprolactone) (PCL) fibrous membranes by melt electrospinning for potential application in localized tumor therapy. The diameters of the drug-loaded fibers prepared with varying concentrations of daunorubicin hydrochloride (1, 5, and 10 wt%) were 2.48 ± 1.25, 2.51 ± 0.78, and 2.49 ± 1.58 μm, respectively. Fluorescence images indicated that the hydrophobic drug was dispersed in the hydrophilic PCL fibers in their aggregated state. The drug release profiles of the drug-loaded PCL melt electrospun fibrous membranes were approximately linear, with slow release rates and long-term release periods, and no observed burst release. The MTT assay was used to examine the cytotoxic effect of the released daunorubicin hydrochloride on HeLa and glioma cells (U87) in vitro. The inhibition ratios of HeLa and glioma cells following treatment with membranes prepared with 1, 5, and 10 wt% daunorubicin hydrochloride were 62.69%, 76.12%, and 85.07% and 62.50%, 77.27%, and 84.66%, respectively. Therefore, PCL melt electrospun fibrous membranes loaded with daunorubicin hydrochloride may be used in the local administration of oncotherapy.
BibTeX:
@article{Lian2017,
  author = {He Lian and Zhaoxu Meng},
  title = {Melt electrospinning of daunorubicin hydrochloride-loaded poly (ε-caprolactone) fibrous membrane for tumor therapy},
  journal = {Bioactive Materials},
  year = {2017},
  volume = {2},
  number = {2},
  pages = {96 - 100},
  url = {http://www.sciencedirect.com/science/article/pii/S2452199X16300561},
  doi = {https://doi.org/10.1016/j.bioactmat.2017.03.003}
}
Kyle, S., Jessop, Z.M., Al-Sabah, A. and Whitaker, I.S. ‘Printability' of Candidate Biomaterials for Extrusion Based 3D Printing: State-of-the-Art 2017 Advanced Healthcare Materials
Vol. 6(16), pp. 1700264-n/a 
article DOI  
Abstract: Regenerative medicine has been highlighted as one of the UK's 8 ‘Great Technologies' with the potential to revolutionize patient care in the 21st Century. Over the last decade, the concept of ‘3D bioprinting' has emerged, which allows the precise deposition of cell laden bioinks with the aim of engineering complex, functional tissues. For 3D printing to be used clinically, there is the need to produce advanced functional biomaterials, a new generation of bioinks with suitable cell culture and high shape/print fidelity, to match or exceed the physical, chemical and biological properties of human tissue. With the rapid increase in knowledge associated with biomaterials, cell-scaffold interactions and the ability to biofunctionalize/decorate bioinks with cell recognition sequences, it is important to keep in mind the ‘printability' of these novel materials. In this illustrated review, we define and refine the concept of ‘printability' and review seminal and contemporary studies to highlight the current ‘state of play' in the field with a focus on bioink composition and concentration, manipulation of nozzle parameters and rheological properties.
BibTeX:
@article{Kyle2017,
  author = {Kyle, Stuart and Jessop, Zita M. and Al-Sabah, Ayesha and Whitaker, Iain S.},
  title = {‘Printability' of Candidate Biomaterials for Extrusion Based 3D Printing: State-of-the-Art},
  journal = {Advanced Healthcare Materials},
  year = {2017},
  volume = {6},
  number = {16},
  pages = {1700264--n/a},
  note = {1700264},
  doi = {https://doi.org/10.1002/adhm.201700264}
}
Kuzmenko, V. Cellulose-derived conductive nanofibrous materials for energy storage and tissue engineering Applications 2017 School: Department of Microtechnology and Nanoscience CHALMERS UNIVERSITY OF TECHNOLOGY  phdthesis URL 
BibTeX:
@phdthesis{Kuzmenko2017,
  author = {Kuzmenko, Volodymyr},
  title = {Cellulose-derived conductive nanofibrous materials for energy storage and tissue engineering Applications},
  school = {Department of Microtechnology and Nanoscience CHALMERS UNIVERSITY OF TECHNOLOGY},
  year = {2017},
  url = {http://publications.lib.chalmers.se/publication/248980-cellulose-derived-conductive-nanofibrous-materials-for-energy-storage-and-tissue-engineering-applica}
}
Kirillova, A., Maxson, R., Stoychev, G., Gomillion, C.T. and Ionov, L. 4D Biofabrication Using Shape-Morphing Hydrogels 2017 Advanced Materials, pp. 1703443-n/a  article DOI  
Abstract: Despite the tremendous potential of bioprinting techniques toward the fabrication of highly complex biological structures and the flourishing progress in 3D bioprinting, the most critical challenge of the current approaches is the printing of hollow tubular structures. In this work, an advanced 4D biofabrication approach, based on printing of shape-morphing biopolymer hydrogels, is developed for the fabrication of hollow self-folding tubes with unprecedented control over their diameters and architectures at high resolution. The versatility of the approach is demonstrated by employing two different biopolymers (alginate and hyaluronic acid) and mouse bone marrow stromal cells. Harnessing the printing and postprinting parameters allows attaining average internal tube diameters as low as 20 µm, which is not yet achievable by other existing bioprinting/biofabrication approaches and is comparable to the diameters of the smallest blood vessels. The proposed 4D biofabrication process does not pose any negative effect on the viability of the printed cells, and the self-folded hydrogel-based tubes support cell survival for at least 7 d without any decrease in cell viability. Consequently, the presented 4D biofabrication strategy allows the production of dynamically reconfigurable architectures with tunable functionality and responsiveness, governed by the selection of suitable materials and cells.
BibTeX:
@article{Kirillova2017,
  author = {Kirillova, Alina and Maxson, Ridge and Stoychev, Georgi and Gomillion, Cheryl T. and Ionov, Leonid},
  title = {4D Biofabrication Using Shape-Morphing Hydrogels},
  journal = {Advanced Materials},
  year = {2017},
  pages = {1703443--n/a},
  note = {1703443},
  doi = {https://doi.org/10.1002/adma.201703443}
}
Kim, H.D., Jang, H.L., Ahn, H.-Y., Lee, H.K., Park, J., Lee, E.-s., Lee, E.A., Jeong, Y.-H., Kim, D.-G., Nam, K.T. and Hwang, N.S. Biomimetic whitlockite inorganic nanoparticles-mediated in situ remodeling and rapid bone regeneration 2017 Biomaterials
Vol. 112, pp. 31 - 43 
article DOI URL 
Abstract: Bone remodeling process relies on complex signaling pathway between osteoblasts and osteoclasts and control mechanisms to achieve homeostasis of their growth and differentiation. Despite previous achievements in understanding complicated signaling pathways between cells and bone extracellular matrices during bone remodeling process, a role of local ionic concentration remains to be elucidated. Here, we demonstrate that synthetic whitlockite (WH: Ca18Mg2(HPO4)2(PO4)12) nanoparticles can recapitulate early-stage of bone regeneration through stimulating osteogenic differentiation, prohibiting osteoclastic activity, and transforming into mechanically enhanced hydroxyapatite (HAP)-neo bone tissues by continuous supply of PO43− and Mg2+ under physiological conditions. In addition, based on their structural analysis, the dynamic phase transformation from WH into HAP contributed as a key factor for rapid bone regeneration with denser hierarchical neo-bone structure. Our findings suggest a groundbreaking concept of ‘living bone minerals’ that actively communicate with the surrounding system to induce self-healing, while previous notions about bone minerals have been limited to passive products of cellular mineralization.
BibTeX:
@article{Kim2017,
  author = {Hwan D. Kim and Hae Lin Jang and Hyo-Yong Ahn and Hye Kyoung Lee and Jungha Park and Eun-seo Lee and Eunjee A. Lee and Yong-Hoon Jeong and Do-Gyoon Kim and Ki Tae Nam and Nathaniel S. Hwang},
  title = {Biomimetic whitlockite inorganic nanoparticles-mediated in situ remodeling and rapid bone regeneration},
  journal = {Biomaterials},
  year = {2017},
  volume = {112},
  pages = {31 - 43},
  url = {http://www.sciencedirect.com/science/article/pii/S0142961216305518},
  doi = {https://doi.org/10.1016/j.biomaterials.2016.10.009}
}
Huang, Y., Zhang, X.-F., Gao, G., Yonezawa, T. and Cui, X. 3D bioprinting and the current applications in tissue engineering 2017 Biotechnology Journal
Vol. 12(8), pp. 1600734-n/a 
article DOI  
Abstract: Bioprinting as an enabling technology for tissue engineering possesses the promises to fabricate highly mimicked tissue or organs with digital control. As one of the biofabrication approaches, bioprinting has the advantages of high throughput and precise control of both scaffold and cells. Therefore, this technology is not only ideal for translational medicine but also for basic research applications. Bioprinting has already been widely applied to construct functional tissues such as vasculature, muscle, cartilage, and bone. In this review, the authors introduce the most popular techniques currently applied in bioprinting, as well as the various bioprinting processes. In addition, the composition of bioink including scaffolds and cells are described. Furthermore, the most current applications in organ and tissue bioprinting are introduced. The authors also discuss the challenges we are currently facing and the great potential of bioprinting. This technology has the capacity not only in complex tissue structure fabrication based on the converted medical images, but also as an efficient tool for drug discovery and preclinical testing. One of the most promising future advances of bioprinting is to develop a standard medical device with the capacity of treating patients directly on the repairing site, which requires the development of automation and robotic technology, as well as our further understanding of biomaterials and stem cell biology to integrate various printing mechanisms for multi-phasic tissue engineering.
BibTeX:
@article{Huang2017,
  author = {Huang, Ying and Zhang, Xiao-Fei and Gao, Guifang and Yonezawa, Tomo and Cui, Xiaofeng},
  title = {3D bioprinting and the current applications in tissue engineering},
  journal = {Biotechnology Journal},
  publisher = {WILEY-VCH Verlag},
  year = {2017},
  volume = {12},
  number = {8},
  pages = {1600734--n/a},
  note = {1600734},
  doi = {https://doi.org/10.1002/biot.201600734}
}
Hospodiuk, M., Dey, M., Sosnoski, D. and Ozbolat, I.T. The bioink: A comprehensive review on bioprintable materials 2017 Biotechnology Advances
Vol. 35(2), pp. 217 - 239 
article DOI URL 
Abstract: Abstract This paper discusses “bioink”, bioprintable materials used in three dimensional (3D) bioprinting processes, where cells and other biologics are deposited in a spatially controlled pattern to fabricate living tissues and organs. It presents the first comprehensive review of existing bioink types including hydrogels, cell aggregates, microcarriers and decellularized matrix components used in extrusion-, droplet- and laser-based bioprinting processes. A detailed comparison of these bioink materials is conducted in terms of supporting bioprinting modalities and bioprintability, cell viability and proliferation, biomimicry, resolution, affordability, scalability, practicality, mechanical and structural integrity, bioprinting and post-bioprinting maturation times, tissue fusion and formation post-implantation, degradation characteristics, commercial availability, immune-compatibility, and application areas. The paper then discusses current limitations of bioink materials and presents the future prospects to the reader.
BibTeX:
@article{Hospodiuk2017,
  author = {Monika Hospodiuk and Madhuri Dey and Donna Sosnoski and Ibrahim T. Ozbolat},
  title = {The bioink: A comprehensive review on bioprintable materials},
  journal = {Biotechnology Advances},
  year = {2017},
  volume = {35},
  number = {2},
  pages = {217 - 239},
  url = {http://www.sciencedirect.com/science/article/pii/S0734975016301719},
  doi = {https://doi.org/10.1016/j.biotechadv.2016.12.006}
}
Holmes, A.M., Charlton, A., Derby, B., Ewart, L., Scott, A. and Shu, W. Rising to the challenge: applying biofabrication approaches for better drug and chemical product development 2017 Biofabrication
Vol. 9(3), pp. 033001 
article URL 
Abstract: Many industrial sectors, from pharmaceuticals to consumer products, are required to provide data on their products to demonstrate their efficacy and that they are safe for patients, consumers and the environment. This period of testing typically requires the use of animal models, the validity of which has been called into question due to the high rates of attrition across many industries. There is increasing recognition of the limitations of animal models and demands for safety and efficacy testing paradigms which embrace the latest technological advances and knowledge of human biology. This perspective article highlights the potential for biofabrication approaches (encompassing bioprinting and bioassembly strategies) to meet these needs and provides case studies from three different industry sectors to demonstrate the potential for new markets in the bioprinting community. We also present a series of recommendations to create a thriving bioprinting environment. One that operates at the forefront of science, technology and innovation to deliver improved decision-making tools for the more rapid development of medicines, agrichemicals, chemicals and consumer products, and which may reduce our reliance on animals.
BibTeX:
@article{Holmes2017,
  author = {Anthony M Holmes and Alex Charlton and Brian Derby and Lorna Ewart and Andrew Scott and Wenmiao Shu},
  title = {Rising to the challenge: applying biofabrication approaches for better drug and chemical product development},
  journal = {Biofabrication},
  year = {2017},
  volume = {9},
  number = {3},
  pages = {033001},
  url = {http://stacks.iop.org/1758-5090/9/i=3/a=033001}
}
Gray, K.M. and Stroka, K.M. Vascular endothelial cell mechanosensing: New insights gained from biomimetic microfluidic models 2017 Seminars in Cell & Developmental Biology  article DOI URL 
Abstract: In vivo, cells of the vascular system are subjected to various mechanical stimuli and have demonstrated the ability to adapt their behavior via mechanotransduction. Recent advances in microfluidic and “on-chip” techniques have provided the technology to study these alterations in cell behavior. Contrary to traditional in vitro assays such as transwell plates and parallel plate flow chambers, these microfluidic devices (MFDs) provide the opportunity to integrate multiple mechanical cues (e.g. shear stress, confinement, substrate stiffness, vessel geometry and topography) with in situ quantification capabilities. As such, MFDs can be used to recapitulate the in vivo mechanical setting and systematically vary microenvironmental conditions for improved mechanobiological studies of the endothelium. Additionally, adequate modelling provides for enhanced understanding of disease progression, design of cell separation and drug delivery systems, and the development of biomaterials for tissue engineering applications. Here, we will discuss the advances in knowledge about endothelial cell mechanosensing resulting from the design and application of biomimetic on-chip and microfluidic platforms.
BibTeX:
@article{Gray2017,
  author = {Kelsey M. Gray and Kimberly M. Stroka},
  title = {Vascular endothelial cell mechanosensing: New insights gained from biomimetic microfluidic models},
  journal = {Seminars in Cell & Developmental Biology},
  year = {2017},
  url = {http://www.sciencedirect.com/science/article/pii/S108495211630297X},
  doi = {https://doi.org/10.1016/j.semcdb.2017.06.002}
}
Elamparithi, A., Punnoose, A.M., Paul, S.F.D. and Kuruvilla, S. Gelatin electrospun nanofibrous matrices for cardiac tissue engineering applications 2017 International Journal of Polymeric Materials and Polymeric Biomaterials
Vol. 66(1), pp. 20-27 
article DOI  
Abstract: ABSTRACTThe generation of in vitro tissue constructs using biomaterials and cardiac cells is a promising strategy for screening novel therapeutics and their effects on cardiac regeneration. Current cardiac mimetic tissue constructs are unable to stably maintain functional characteristics of cardiomyocytes for long-term cultures. The objective of our study was to fabricate and characterize nanofibrous matrices of gelatin for prolonged cultures of primary cardiomyocytes which previously has been used as copolymer or hydrogels. Gelatin nanofibrous matrices were successfully electrospun using a benign binary solvent, cross-linked without swelling and fusing and evaluated by scanning electron microscopy (SEM) and uniaxial tensile measurement. Scaffolds exhibited modulus 19.6 ± 3.6 kPa similar to native human myocardium tissue with fiber diameters of 200–600 nm and average porosity percentage of 49.9 ± 5.6. Myoblasts showed good cell adhesion and proliferation. Neonatal rat cardiomyocytes cultured on gelatin nanofibrous matrices showing synchronized contracting cardiomyocytes (beating) for 27 days were studied by video microscopy. Confocal microscopic analysis of immunofluorescence stained sections indicated the presence of cardiac specific Troponin T in long-term cultures. Semiquantitative RT-PCR analysis of 3D versus 2D cultures revealed enhanced expression of contractile protein desmin. Our studies show that the biophysical and mechanical properties of electrospun gelatin nanofibers are ideal for in vitro engineered cardiac constructs (ECC), to explore cardiac function in drug testing and tissue replacement. Together with stem cell techniques, they may be an ideal platform for prolongedin vitro studies in alternatives to animal usage for the pharmaceutical industry.
BibTeX:
@article{Elamparithi2017,
  author = {Anuradha Elamparithi and Alan M. Punnoose and Solomon F. D. Paul and Sarah Kuruvilla},
  title = {Gelatin electrospun nanofibrous matrices for cardiac tissue engineering applications},
  journal = {International Journal of Polymeric Materials and Polymeric Biomaterials},
  year = {2017},
  volume = {66},
  number = {1},
  pages = {20-27},
  doi = {https://doi.org/10.1080/00914037.2016.1180616}
}
Dalton, P.D. Melt electrowriting with additive manufacturing principles 2017 Current Opinion in Biomedical Engineering
Vol. 2(Supplement C), pp. 49 - 57 
article DOI URL 
Abstract: Abstract The recent development of electrostatic writing (electrowriting) with molten jets provides an opportunity to tackle some significant challenges within tissue engineering. The process uses an applied voltage to generate a stable fluid jet with a predictable path, that is continuously deposited onto a collector. The fiber diameter is variable during the process, and is applicable to polymers with a history of clinical use. Melt electrowriting therefore has potential for clinical translation if the biological efficacy of the implant can be improved over existing gold standards. It provides a unique opportunity for laboratories to perform low-cost, high resolution, additive manufacturing research that is well positioned for clinical translation, using existing regulatory frameworks.
BibTeX:
@article{Dalton2017,
  author = {Paul D. Dalton},
  title = {Melt electrowriting with additive manufacturing principles},
  journal = {Current Opinion in Biomedical Engineering},
  year = {2017},
  volume = {2},
  number = {Supplement C},
  pages = {49 - 57},
  note = {Additive Manufacturing},
  url = {http://www.sciencedirect.com/science/article/pii/S2468451117300156},
  doi = {https://doi.org/10.1016/j.cobme.2017.05.007}
}
Cui, H., Nowicki, M., Fisher, J.P. and Zhang, L.G. 3D Bioprinting for Organ Regeneration 2017 Advanced Healthcare Materials
Vol. 6(1), pp. 1601118-n/a 
article DOI  
Abstract: Regenerative medicine holds the promise of engineering functional tissues or organs to heal or replace abnormal and necrotic tissues/organs, offering hope for filling the gap between organ shortage and transplantation needs. Three-dimensional (3D) bioprinting is evolving into an unparalleled biomanufacturing technology due to its high-integration potential for patient-specific designs, precise and rapid manufacturing capabilities with high resolution, and unprecedented versatility. It enables precise control over multiple compositions, spatial distributions, and architectural accuracy/complexity, therefore achieving effective recapitulation of microstructure, architecture, mechanical properties, and biological functions of target tissues and organs. Here we provide an overview of recent advances in 3D bioprinting technology, as well as design concepts of bioinks suitable for the bioprinting process. We focus on the applications of this technology for engineering living organs, focusing more specifically on vasculature, neural networks, the heart and liver. We conclude with current challenges and the technical perspective for further development of 3D organ bioprinting.
BibTeX:
@article{Cui2017,
  author = {Cui, Haitao and Nowicki, Margaret and Fisher, John P. and Zhang, Lijie Grace},
  title = {3D Bioprinting for Organ Regeneration},
  journal = {Advanced Healthcare Materials},
  year = {2017},
  volume = {6},
  number = {1},
  pages = {1601118--n/a},
  note = {1601118},
  doi = {https://doi.org/10.1002/adhm.201601118}
}
Choi, Y., Yi, H., Kim, S. and Cho, D. 3D Cell Printed Tissue Analogues: A New Platform for Theranostics 2017 Theranostics  article URL 
Abstract: Stem cell theranostics has received much attention for noninvasively monitoring and tracing transplanted therapeutic stem cells through imaging agents and imaging modalities. Despite the excellent regenerative capability of stem cells, their efficacy has been limited due to low cellular retention, low survival rate, and low engraftment after implantation. Three-dimensional (3D) cell printing provides stem cells with the similar architecture and microenvironment of the native tissue and facilitates the generation of a 3D tissue-like construct that exhibits remarkable regenerative capacity and functionality as well as enhanced cell viability. Thus, 3D cell printing can overcome the current concerns of stem cell therapy by delivering the 3D construct to the damaged site. Despite the advantages of 3D cell printing, the in vivo and in vitro tracking and monitoring of the performance of 3D cell printed tissue in a noninvasive and real-time manner have not been thoroughly studied. In this review, we explore the recent progress in 3D cell technology and its applications. Finally, we investigate their potential limitations and suggest future perspectives on 3D cell printing and stem cell theranostics.
BibTeX:
@article{Choi2017,
  author = {Choi, Y.J. and Yi, H.G. and Kim, S.W. and Cho, D.W.},
  title = {3D Cell Printed Tissue Analogues: A New Platform for Theranostics},
  journal = {Theranostics},
  year = {2017},
  url = {http://www.thno.org/v07p3118}
}
Chen, H., Malheiro, A.d.B.F.B., van Blitterswijk, C., Mota, C., Wieringa, P.A., Moroni, L., Chen, H., Malheiro, A.d.B.F.B., Van Blitterswijk, C., Mota, C., Wieringa, P.A. and Moroni, L. Direct Writing Electrospinning of Scaffolds with Multidimensional Fiber Architecture for Hierarchical Tissue Engineering 2017 ACS Applied Materials & Interfaces
Vol. 0(0), pp. null 
article DOI  
Abstract: Nanofibrous structures have long been used as scaffolds for tissue engineering (TE) applications, due to their favorable characteristics, such as high porosity, flexibility, high cell attachment and enhanced proliferation, and overall resemblance to native extracellular matrix (ECM). Such scaffolds can be easily produced at a low cost via electrospinning (ESP), but generally cannot be fabricated with a regular and/or complex geometry, characterized by macropores and uniform thickness. We present here a novel technique for direct writing (DW) with solution ESP to produce complex three-dimensional (3D) multiscale and ultrathin (∼1 μm) fibrous scaffolds with desirable patterns and geometries. This technique was simply achieved via manipulating technological conditions, such as spinning solution, ambient conditions, and processing parameters. Three different regimes in fiber morphologies were observed, including bundle with dispersed fibers, bundle with a core of aligned fibers, and single fibers. The transition between these regimes depended on tip to collector distance (Wd) and applied voltage (V), which could be simplified as the ratio V/Wd. Using this technique, a scaffold mimicking the zonal organization of articular cartilage was further fabricated as a proof of concept, demonstrating the ability to better mimic native tissue organization. The DW scaffolds directed tissue organization and fibril matrix orientation in a zone-dependent way. Comparative expression of chondrogenic markers revealed a substantial upregulation of Sox9 and aggrecan (ACAN) on these structures compared to conventional electrospun meshes. Our novel method provides a simple way to produce customized 3D ultrathin fibrous scaffolds, with great potential for TE applications, in particular those for which anisotropy is of importance.
BibTeX:
@article{Chen2017a,
  author = {Chen, Honglin and Malheiro, Afonso de Botelho Ferreira Braga and van Blitterswijk, Clemens and Mota, Carlos and Wieringa, Paul Andrew and Moroni, Lorenzo and Chen, H. and Malheiro, A. de Botelho Ferreira Braga and Van Blitterswijk, C. and Mota, C. and Wieringa, P. A. and Moroni, L.},
  title = {Direct Writing Electrospinning of Scaffolds with Multidimensional Fiber Architecture for Hierarchical Tissue Engineering},
  journal = {ACS Applied Materials & Interfaces},
  year = {2017},
  volume = {0},
  number = {0},
  pages = {null},
  note = {PMID: 29043781},
  doi = {https://doi.org/10.1021/acsami.7b07151}
}
Chadwick, K.P., Shefelbine, S.J., Pitsillides, A.A. and Hutchinson, J.R. Finite-element modelling of mechanobiological factors influencing sesamoid tissue morphology in the patellar tendon of an ostrich 2017 Open Science
Vol. 4(6) 
article DOI URL 
Abstract: The appearance and shape of sesamoid bones within a tendon or ligament wrapping around a joint are understood to be influenced by both genetic and epigenetic factors. Ostriches (Struthio camelus) possess two sesamoid patellae (kneecaps), one of which (the distal patella) is unique to their lineage, making them a good model for investigating sesamoid tissue development and evolution. Here we used finite-element modelling to test the hypothesis that specific mechanical cues in the ostrich patellar tendon favour the formation of multiple patellae. Using three-dimensional models that allow application of loading conditions in which all muscles, or only distal or only proximal muscles to be activated, we found that there were multiple regions within the tendon where transformation from soft tissue to fibrocartilage was favourable and therefore a potential for multiple patellae based solely upon mechanical stimuli. While more studies are needed to better understand universal mechanobiological principles as well as full developmental processes, our findings suggest that a tissue differentiation algorithm using shear strain and compressive strain as inputs may be a roughly effective predictor of the tissue differentiation required for sesamoid development.
BibTeX:
@article{Chadwick2017,
  author = {Chadwick, Kyle P. and Shefelbine, Sandra J. and Pitsillides, Andrew A. and Hutchinson, John R.},
  title = {Finite-element modelling of mechanobiological factors influencing sesamoid tissue morphology in the patellar tendon of an ostrich},
  journal = {Open Science},
  publisher = {The Royal Society},
  year = {2017},
  volume = {4},
  number = {6},
  url = {http://rsos.royalsocietypublishing.org/content/4/6/170133},
  doi = {https://doi.org/10.1098/rsos.170133}
}
Castilho, M., Feyen, D., Flandes-Iparraguirre, M., Hochleitner, G., Groll, J., Doevendans, P.A.F., Vermonden, T., Ito, K., Sluijter, J.P.G. and Malda, J. Melt Electrospinning Writing of Poly-Hydroxymethylglycolide-co-ε-Caprolactone-Based Scaffolds for Cardiac Tissue Engineering 2017 Advanced Healthcare Materials
Vol. 6(18), pp. 1700311-n/a 
article DOI  
Abstract: Current limitations in cardiac tissue engineering revolve around the inability to fully recapitulate the structural organization and mechanical environment of native cardiac tissue. This study aims at developing organized ultrafine fiber scaffolds with improved biocompatibility and architecture in comparison to the traditional fiber scaffolds obtained by solution electrospinning. This is achieved by combining the additive manufacturing of a hydroxyl-functionalized polyester, (poly(hydroxymethylglycolide-co-ε-caprolactone) (pHMGCL), with melt electrospinning writing (MEW). The use of pHMGCL with MEW vastly improves the cellular response to the mechanical anisotropy. Cardiac progenitor cells (CPCs) are able to align more efficiently along the preferential direction of the melt electrospun pHMGCL fiber scaffolds in comparison to electrospun poly(ε-caprolactone)-based scaffolds. Overall, this study describes for the first time that highly ordered microfiber (4.0–7.0 µm) scaffolds based on pHMGCL can be reproducibly generated with MEW and that these scaffolds can support and guide the growth of CPCs and thereby potentially enhance their therapeutic potential.
BibTeX:
@article{Castilho2017,
  author = {Castilho, Miguel and Feyen, Dries and Flandes-Iparraguirre, María and Hochleitner, Gernot and Groll, Jürgen and Doevendans, Pieter A. F. and Vermonden, Tina and Ito, Keita and Sluijter, Joost P. G. and Malda, Jos},
  title = {Melt Electrospinning Writing of Poly-Hydroxymethylglycolide-co-ε-Caprolactone-Based Scaffolds for Cardiac Tissue Engineering},
  journal = {Advanced Healthcare Materials},
  year = {2017},
  volume = {6},
  number = {18},
  pages = {1700311--n/a},
  note = {1700311},
  doi = {https://doi.org/10.1002/adhm.201700311}
}
ten Bosch, L., Pfohl, K., Avramidis, G., Wieneke, S., Viöl, W. and Karlovsky, P. Plasma-Based Degradation of Mycotoxins Produced by Fusarium, Aspergillus and Alternaria Species 2017 Toxins
Vol. 9(3), pp. 97 
article URL 
Abstract: The efficacy of cold atmospheric pressure plasma (CAPP) with ambient air as working gas
for the degradation of selected mycotoxins was studied. Deoxynivalenol, zearalenone, enniatins,
fumonisin B1, and T2 toxin produced by Fusarium spp., sterigmatocystin produced by Aspergillus spp. and AAL toxin produced by Alternaria alternata were used. The kinetics of the decay of mycotoxins exposed to plasma discharge was monitored. All pure mycotoxins exposed to CAPP were degraded almost completely within 60 s. Degradation rates varied with mycotoxin structure: fumonisin B1
and structurally related AAL toxin were degraded most rapidly while sterigmatocystin exhibited
the highest resistance to degradation. As compared to pure compounds, the degradation rates
of mycotoxins embedded in extracts of fungal cultures on rice were reduced to a varying extent.
Our results show that CAPP efficiently degrades pure mycotoxins, the degradation rates vary with
mycotoxin structure, and the presence of matrix slows down yet does not prevent the degradation.
CAPP appears promising for the decontamination of food commodities with mycotoxins confined to
or enriched on surfaces such as cereal grains.
BibTeX:
@article{Bosch2017,
  author = {ten Bosch, Lars and Pfohl, Katharina and Avramidis, Georg and Wieneke, Stephan and Viöl, Wolfgang and Karlovsky, Petr},
  title = {Plasma-Based Degradation of Mycotoxins Produced by Fusarium, Aspergillus and Alternaria Species},
  journal = {Toxins},
  year = {2017},
  volume = {9},
  number = {3},
  pages = {97},
  url = {https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5371852/}
}
Borovjagin, A.V., Ogle, B.M., Berry, J.L. and Zhang, J. From Microscale Devices to 3D Printing 2017 Circulation Research
Vol. 120(1), pp. 150-165 
article DOI URL 
Abstract: Current strategies for engineering cardiovascular cells and tissues have yielded a variety of sophisticated tools for studying disease mechanisms, for development of drug therapies, and for fabrication of tissue equivalents that may have application in future clinical use. These efforts are motivated by the need to extend traditional 2-dimensional (2D) cell culture systems into 3D to more accurately replicate in vivo cell and tissue function of cardiovascular structures. Developments in microscale devices and bioprinted 3D tissues are beginning to supplant traditional 2D cell cultures and preclinical animal studies that have historically been the standard for drug and tissue development. These new approaches lend themselves to patient-specific diagnostics, therapeutics, and tissue regeneration. The emergence of these technologies also carries technical challenges to be met before traditional cell culture and animal testing become obsolete. Successful development and validation of 3D human tissue constructs will provide powerful new paradigms for more cost effective and timely translation of cardiovascular tissue equivalents.
BibTeX:
@article{Borovjagin2017,
  author = {Borovjagin, Anton V. and Ogle, Brenda M. and Berry, Joel L. and Zhang, Jianyi},
  title = {From Microscale Devices to 3D Printing},
  journal = {Circulation Research},
  publisher = {American Heart Association, Inc.},
  year = {2017},
  volume = {120},
  number = {1},
  pages = {150--165},
  url = {http://circres.ahajournals.org/content/120/1/150},
  doi = {https://doi.org/10.1161/CIRCRESAHA.116.308538}
}
Bégin-Drolet, A., Dussault, M.-A., Fernandez, S.A., Larose-Dutil, J., Leask, R.L., Hoesli, C.A. and Ruel, J. Design of a 3D printer head for additive manufacturing of sugar glass for tissue engineering applications 2017 Additive Manufacturing
Vol. 15, pp. 29 - 39 
article DOI URL 
Abstract: Additive manufacturing is now considered as a new paradigm that is foreseen to improve progress in many fields. The field of tissue engineering has been facing the need for tissue vascularization when producing thick tissues. The use of sugar glass as a fugitive ink to produce vascular networks through rapid casting may offer the key to vascularization of thick tissues produced by tissue engineering. Here, a 3D printer head capable of producing complex structures out of sugar glass is presented. This printer head uses a motorized heated syringe fitted with a custom made nozzle. The printer head was adapted to be mounted on a commercially available 3D printer. A mathematical model was derived to predict the diameter of the filaments based on the printer head feed rate and extrusion rate. Using a 1mm diameter nozzle, the printer accurately produced filaments ranging from 0.3mm to 3.2mm in diameter. One of the main advantages of this manufacturing method is the self-supporting behaviour of sugar glass that allows the production of long, horizontal, curved, as well as overhanging filaments needed to produce complex vascular networks. Finally, to establish a proof of concept, polydimethylsiloxane was used as the gel matrix during the rapid casting to produce various “vascularized” constructs that were successfully perfused, which suggests that this new fabrication method can be used in a number of tissue engineering applications, including the vascularization of thick tissues.
BibTeX:
@article{Begin-Drolet2017,
  author = {André Bégin-Drolet and Marc-André Dussault and Stephanie A. Fernandez and Jeanne Larose-Dutil and Richard L. Leask and Corinne A. Hoesli and Jean Ruel},
  title = {Design of a 3D printer head for additive manufacturing of sugar glass for tissue engineering applications},
  journal = {Additive Manufacturing},
  year = {2017},
  volume = {15},
  pages = {29 - 39},
  url = {http://www.sciencedirect.com/science/article/pii/S2214860416301622},
  doi = {https://doi.org/10.1016/j.addma.2017.03.006}
}
Baumann, B., Jungst, T., Stichler, S., Feineis, S., Wiltschka, O., Kuhlmann, M., Lindén, M. and Groll, J. Control of Nanoparticle Release Kinetics from 3D Printed Hydrogel Scaffolds 2017 Angewandte Chemie International Edition, pp. n/a-n/a  article DOI  
Abstract: The convergence of biofabrication with nanotechnology is largely unexplored but enables geometrical control of cell-biomaterial arrangement combined with controlled drug delivery and release. As a step towards integration of these two fields of research, this study demonstrates that modulation of electrostatic nanoparticle–polymer and nanoparticle–nanoparticle interactions can be used for tuning nanoparticle release kinetics from 3D printed hydrogel scaffolds. This generic strategy can be used for spatiotemporal control of the release kinetics of nanoparticulate drug vectors in biofabricated constructs.
BibTeX:
@article{Baumann2017,
  author = {Baumann, Bernhard and Jungst, Tomasz and Stichler, Simone and Feineis, Susanne and Wiltschka, Oliver and Kuhlmann, Matthias and Lindén, Mika and Groll, Jürgen},
  title = {Control of Nanoparticle Release Kinetics from 3D Printed Hydrogel Scaffolds},
  journal = {Angewandte Chemie International Edition},
  year = {2017},
  pages = {n/a--n/a},
  doi = {https://doi.org/10.1002/anie.201700153}
}
Baumann, B., Jungst, T., Stichler, S., Feineis, S., Wiltschka, O., Kuhlmann, M., Lindén, M. and Groll, J. Kontrolle der Freisetzungskinetik von Nanopartikeln aus 3D-gedruckten Hydrogelgerüsten 2017 Angewandte Chemie, pp. n/a-n/a  article DOI  
Abstract: Die bisher größtenteils unerforschte Kombination aus Biofabrikation und Nanotechnologie ermöglicht eine örtlich und zeitlich aufgelöste Freisetzung von Wirkstoffen aus hierarchischen, zellbeladenen Biomaterialien. Als ein erster Schritt in Richtung der Verknüpfung dieser beiden Forschungsgebiete wird hier gezeigt, dass die Einstellung der elektrostatischen Nanopartikel-Polymer- und Nanopartikel-Nanopartikel-Wechselwirkungen verwendet werden kann, um die Freisetzungskinetik von Nanopartikeln aus gedruckten 3D Hydrogelgerüsten zu steuern. Diese grundlegende Strategie kann für die räumliche und zeitliche Kontrolle der Freisetzungskinetik von nanopartikulären Wirkstoffträgern in biofabrizierten Konstrukten verwendet werden.
BibTeX:
@article{Baumann2017a,
  author = {Baumann, Bernhard and Jungst, Tomasz and Stichler, Simone and Feineis, Susanne and Wiltschka, Oliver and Kuhlmann, Matthias and Lindén, Mika and Groll, Jürgen},
  title = {Kontrolle der Freisetzungskinetik von Nanopartikeln aus 3D-gedruckten Hydrogelgerüsten},
  journal = {Angewandte Chemie},
  year = {2017},
  pages = {n/a--n/a},
  doi = {https://doi.org/10.1002/ange.201700153}
}
Aljohani, W., Ullah, M.W., Zhang, X. and Yang, G. Bioprinting and its applications in tissue engineering and regenerative medicine 2017 International Journal of Biological Macromolecules  article DOI URL 
Abstract: Abstract Bioprinting of three-dimensional constructs mimicking natural-like extracellular matrix has revolutionized biomedical technology. Bioprinting technology circumvents various discrepancies associated with current tissue engineering strategies by providing an automated and advanced platform to fabricate various biomaterials through precise deposition of cells and polymers in a premeditated fashion. However, few obstacles associated with development of 3D scaffolds including varied properties of polymers used and viability, controlled distribution, and vascularization, etc. of cells hinder bioprinting of complex structures. Therefore, extensive efforts have been made to explore the potential of various natural polymers (e.g. cellulose, gelatin, alginate, and chitosan, etc.) and synthetic polymers in bioprinting by tuning their printability and cross-linking features, mechanical and thermal properties, biocompatibility, and biodegradability, etc. This review describes the potential of these polymers to support adhesion and proliferation of viable cells to bioprint cell laden constructs, bone, cartilage, skin, and neural tissues, and blood vessels, etc. for various applications in tissue engineering and regenerative medicines. Further, it describes various challenges associated with current bioprinting technology and suggests possible solutions. Although at early stage of development, the potential benefits of bioprinting technology are quite clear and expected to open new gateways in biomedical, pharmaceutics and several other fields in near future.
BibTeX:
@article{Aljohani2017,
  author = {Waeljumah Aljohani and Muhammad Wajid Ullah and Xianglin Zhang and Guang Yang},
  title = {Bioprinting and its applications in tissue engineering and regenerative medicine},
  journal = {International Journal of Biological Macromolecules},
  year = {2017},
  url = {http://www.sciencedirect.com/science/article/pii/S0141813017325862},
  doi = {https://doi.org/10.1016/j.ijbiomac.2017.08.171}
}
Albritton, J.L. and Miller, J.S. 3D bioprinting: improving in vitro models of metastasis with heterogeneous tumor microenvironments 2017 Disease Models & Mechanisms
Vol. 10(1), pp. 3-14 
article DOI URL 
Abstract: Even with many advances in treatment over the past decades, cancer still remains a leading cause of death worldwide. Despite the recognized relationship between metastasis and increased mortality rate, surprisingly little is known about the exact mechanism of metastatic progression. Currently available in vitro models cannot replicate the three-dimensionality and heterogeneity of the tumor microenvironment sufficiently to recapitulate many of the known characteristics of tumors in vivo. Our understanding of metastatic progression would thus be boosted by the development of in vitro models that could more completely capture the salient features of cancer biology. Bioengineering groups have been working for over two decades to create in vitro microenvironments for application in regenerative medicine and tissue engineering. Over this time, advances in 3D printing technology and biomaterials research have jointly led to the creation of 3D bioprinting, which has improved our ability to develop in vitro models with complexity approaching that of the in vivo tumor microenvironment. In this Review, we give an overview of 3D bioprinting methods developed for tissue engineering, which can be directly applied to constructing in vitro models of heterogeneous tumor microenvironments. We discuss considerations and limitations associated with 3D printing and highlight how these advances could be harnessed to better model metastasis and potentially guide the development of anti-cancer strategies.
BibTeX:
@article{Albritton2017,
  author = {Albritton, Jacob L. and Miller, Jordan S.},
  title = {3D bioprinting: improving in vitro models of metastasis with heterogeneous tumor microenvironments},
  journal = {Disease Models & Mechanisms},
  publisher = {The Company of Biologists Ltd},
  year = {2017},
  volume = {10},
  number = {1},
  pages = {3--14},
  url = {http://dmm.biologists.org/content/10/1/3},
  doi = {https://doi.org/10.1242/dmm.025049}
}
Chen, X.B., Shoenau, G. and Zhang, W.J. Modeling of time-pressure fluid dispensing processes Oct IEEE Transactions on Electronics Packaging Manufacturing
Vol. 23(4), pp. 300-305 
article DOI  
Abstract: The process of time-pressure fluid dispensing has been widely employed in the semiconductor industry, where the fluid is applied to boards or substrates. In such a process, the flow rate of fluid dispensed and the shape of fluid formed on the board are the two most critical performance indexes, yet extremely difficult to represent because of their complex behavior. This paper presents the development of a model for the time-pressure fluid dispensing process, by which the flow rate and shape can be established. Experiments have been performed to validate the model developed
BibTeX:
@article{ChenOct,
  author = {Chen, X. B. and Shoenau, G. and Zhang, W. J.},
  title = {Modeling of time-pressure fluid dispensing processes},
  journal = {IEEE Transactions on Electronics Packaging Manufacturing},
  year = {Oct},
  volume = {23},
  number = {4},
  pages = {300--305},
  doi = {https://doi.org/10.1109/6104.895075}
}
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