RESOURCES

Abstract
Periodontitis is a chronic inflammatory condition that often causes serious damage to tooth-supporting tissues. The limited successful outcomes of clinically available approaches underscore the need for therapeutics that cannot only provide structural guidance to cells but can also modulate the local immune response. Here, three-dimensional melt electrowritten (i.e., poly(ε-caprolactone)) scaffolds with tissue-specific attributes were engineered to guide differentiation of human-derived periodontal ligament stem cells (hPDLSCs) and mediate macrophage polarization. The investigated tissue-specific scaffold attributes comprised fiber morphology (aligned vs. random) and highly-ordered architectures with distinct strand spacings (small 250 μm and large 500 μm). Macrophages exhibited an elongated morphology in aligned and highly-ordered scaffolds, while maintaining their round-shape on randomly-oriented fibrous scaffolds. Expressions of periostin and IL-10 were more pronounced on the aligned and highly-ordered scaffolds. While hPDLSCs on the scaffolds with 500 μm strand spacing show higher expression of osteogenic marker (Runx2) over 21 days, cells on randomly-oriented fibrous scaffolds showed upregulation of M1 markers. In an orthotopic mandibular fenestration defect model, findings revealed that the tissue-specific scaffolds (i.e., aligned fibers for periodontal ligament and highly-ordered 500 μm strand spacing fluorinated calcium phosphate [F/CaP]-coated fibers for bone) could enhance the mimicking of regeneration of natural periodontal tissues.

Abstract
Abstract Periodontitis is a chronic inflammatory, bacteria-triggered disorder affecting nearly half of American adults. Although some level of tissue regeneration is realized, its low success in complex cases demands superior strategies to amplify regenerative capacity. Herein, highly ordered scaffolds are engineered via Melt ElectroWriting (MEW), and the effects of strand spacing, as well as the presence of a nanostructured fluorinated calcium phosphate (F/CaP) coating on the adhesion/proliferation, and osteogenic differentiation of human-derived periodontal ligament stem cells, are investigated. Upon initial cell-scaffold interaction screening aimed at defining the most suitable design, MEW poly(ε-caprolactone) scaffolds with 500 µm strand spacing are chosen. Following an alkali treatment, scaffolds are immersed in a pre-established solution to allow for coating formation. The presence of a nanostructured F/CaP coating leads to a marked upregulation of osteogenic genes and attenuated bacterial growth. In vivo findings confirm that the F/CaP-coated scaffolds are biocompatible and lead to periodontal regeneration when implanted in a rat mandibular periodontal fenestration defect model. In aggregate, it is considered that this work can contribute to the development of personalized scaffolds capable of enabling tissue-specific differentiation of progenitor cells, and thus guide simultaneous and coordinated regeneration of soft and hard periodontal tissues, while providing antimicrobial protection.