title: In Vitro Characteristics of Porcine Tendon Hydrogel for Tendon Regeneration.
abstract: OBJECTIVE
  Previous work has characterized the development of a human tendon hydrogel capable of improving mechanical strength after tendon injury. Animal tendon hydrogel has not yet been described, but would prove beneficial due to the cost and ethical concerns associated with the use of human cadaveric tendon. This study details the manufacture and assesses the biocompatibility of porcine tendon hydrogel seeded with human adipoderived stem cells (ASCs).
  
  
  METHODS
  Porcine tendon was dissected from surrounding connective and muscle tissue and decellularized via 0.2% sodium dodecyl sulfate and 0.2% sodium dodecyl sulfate/ethylenediaminetetraacetic acid wash solutions before lyophilization. Tendon was milled and reconstituted by previously described methods. Decellularization was confirmed by hematoxylin-eosin staining, SYTO Green 11 nucleic acid dye, and DNeasy assay. The protein composition of milled tendon matrix before and after digestion was identified by mass spectrometry. Rheological properties were determined using an ARG2 rheometer. Biocompatibility was assessed by live/dead assay. The proliferation of human ASCs seeded in porcine and human hydrogel was measured by MTS assay. All experimental conditions were performed in triplicate.
  
  
  RESULTS
  Decellularization of porcine tendon was successful. Mass spectrometry showed that collagen composes one third of milled porcine tendon before and after pepsin digestion. Rheology demonstrated that porcine hydrogel maintains a fluid consistency over a range of temperatures, unlike human hydrogel, which tends to solidify. Live/dead staining revealed that human ASCs survive in hydrogel 7 days after seeding and retain spindle-like morphology. MTS assay at day 3 and day 5 showed that human ASC proliferation was marginally greater in human hydrogel.
  
  
  CONCLUSIONS
  After reconstitution and digestion, porcine hydrogel was capable of supporting growth of human ASCs. The minimal difference in proliferative capacity suggests that porcine tendon hydrogel may be an effective and viable alternative to human hydrogel for the enhancement of tendon healing.
authors.affiliation: From the *Division of Plastic and Reconstructive Surgery, Stanford University Medical Center, Stanford; †Section of Plastic Surgery, VA Palo Alto Health Care System, Palo Alto; and ‡Department of Chemical Engineering, Stanford University, Stanford, CA.
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Crowe
authors.forename: Grace
authors.initials: G
authors.lastname: Chiou
authors.forename: Rory
authors.initials: R
authors.lastname: McGoldrick
authors.forename: Kenneth
authors.initials: K
authors.lastname: Hui
authors.forename: Hung
authors.initials: H
authors.lastname: Pham
authors.forename: Emily
authors.initials: E
authors.lastname: Hollenbeck
authors.forename: James
authors.initials: J
authors.lastname: Chang
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D048091:Guided Tissue Regeneration / Q000379:methods*; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D045164:Mesenchymal Stem Cell Transplantation; D012038:Regeneration / Q000502:physiology*; D013552:Swine; D013708:Tendon Injuries / Q000601:surgery*; D013710:Tendons / Q000502:physiology* / Q000601:surgery; D054457:Tissue Scaffolds
chemical_list: D001672:Biocompatible Materials; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate