title: Multilayered polycaprolactone/gelatin fiber-hydrogel composite for tendon tissue engineering.
abstract: Regeneration of injured tendon and ligament (T&L) remains a clinical challenge due to their poor intrinsic healing capacity. Tissue engineering provides a promising alternative treatment approach to facilitate T&L healing and regeneration. Successful tendon tissue engineering requires the use of three-dimensional (3D) biomimetic scaffolds that possess the physical and biochemical features of native tendon tissue. We report here the development and characterization of a novel composite scaffold fabricated by co-electrospinning of poly-ε-caprolactone (PCL) and methacrylated gelatin (mGLT). We found that photocrosslinking retained mGLT, resulted in a uniform distribution of mGLT throughout the depth of scaffold and also preserved scaffold mechanical strength. Moreover, photocrosslinking was able to integrate stacked scaffold sheets to form multilayered constructs that mimic the structure of native tendon tissues. Importantly, cells impregnated into the constructs remained responsive to topographical cues and exogenous tenogenic factors, such as TGF-β3. The excellent biocompatibility and highly integrated structure of the scaffold developed in this study will allow the creation of a more advanced tendon graft that possesses the architecture and cell phenotype of native tendon tissues.
  
  
  CONCLUSIONS
  The clinical challenges in tendon repair have spurred the development of tendon tissue engineering approaches to create functional tissue replacements. In this study, we have developed a novel composite scaffold as a tendon graft consisting of aligned poly-ε-caprolactone (PCL) microfibers and methacrylated gelatin (mGLT). Cell seeding and photocrosslinking between scaffold layers can be performed simultaneously to create cell impregnated multilayered constructs. This cell-scaffold construct combines the advantages of PCL nanofibrous scaffolds and photocrosslinked gelatin hydrogels to mimic the structure, mechanical anisotropy, and cell phenotype of native tendon tissue. The scaffold engineered here as a building block for multilayer constructs should have applications beyond tendon tissue engineering in the fabrication of tissue grafts that consist of both fibrous and hydrogel components.
authors.affiliation: Center for Cellular and Molecular Engineering, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA; Department of Orthopaedic Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA; McGowan Institute for Regenerative Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA; Department of Bioengineering, University of Pittsburgh Swanson School of Engineering, Pittsburgh, PA 15219, USA. Electronic address: guy9@pitt.edu.
authors.forename: Guang
authors.initials: G
authors.lastname: Yang
authors.affiliation: Center for Cellular and Molecular Engineering, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA; Department of Orthopaedic Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA; McGowan Institute for Regenerative Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA. Electronic address: hal46@pitt.edu.
authors.forename: Hang
authors.initials: H
authors.lastname: Lin
authors.affiliation: Center for Cellular and Molecular Engineering, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA; Department of Orthopaedic Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA; McGowan Institute for Regenerative Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA. Electronic address: bbr4@pitt.edu.
authors.forename: Benjamin B
authors.initials: BB
authors.lastname: Rothrauff
authors.affiliation: Center for Cellular and Molecular Engineering, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA; School of Medicine, Tsinghua University, Beijing 100083, China. Electronic address: shy39@pitt.edu.
authors.forename: Shuting
authors.initials: S
authors.lastname: Yu
authors.affiliation: Center for Cellular and Molecular Engineering, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA; Department of Orthopaedic Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA; McGowan Institute for Regenerative Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA; Department of Bioengineering, University of Pittsburgh Swanson School of Engineering, Pittsburgh, PA 15219, USA. Electronic address: rst13@pitt.edu.
authors.forename: Rocky S
authors.initials: RS
authors.lastname: Tuan
mesh_terms: D000273:Adipose Tissue / Q000166:cytology; D000328:Adult; D003432:Cross-Linking Reagents / Q000494:pharmacology; D005260:Female; D005780:Gelatin / Q000494:pharmacology*; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000494:pharmacology*; D008027:Light; D008297:Male; D011091:Polyesters / Q000494:pharmacology*; D013234:Stem Cells / Q000166:cytology / Q000187:drug effects; D013710:Tendons / Q000187:drug effects / Q000502:physiology*; D023822:Tissue Engineering / Q000379:methods*; D054457:Tissue Scaffolds / Q000737:chemistry
chemical_list: D003432:Cross-Linking Reagents; D011091:Polyesters; C016240:polycaprolactone; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D005780:Gelatin
keywords: Adipose stem cells; Aligned fibrous scaffold; Photocrosslinked hydrogel; Tendon regeneration