title: Co-culture of human adipose-derived stem cells with tenocytes increases proliferation and induces differentiation into a tenogenic lineage.
abstract: BACKGROUND
  Seeding acellularized tendons with cells is an approach for creating tissue-engineered tendon grafts with favorable biomechanical properties. It was the authors' aim to evaluate whether human adipose-derived stem cells could replace tenocytes for scaffold seeding.
  
  
  METHODS
  Adipose-derived stem cells and tenocytes were co-cultured in different ratios (3:1, 1:1, and 1:3) and with three different methods: (1) direct co-culture, (2) tenocyte-conditioned media on adipose-derived stem cells, and (3) an insert system to keep both cell types in the same media without contact. Proliferation, collagen production, and tenogenic marker expression were measured by hematocytometry, immunocytochemistry, enzyme-linked immunosorbent assay, and real-time polymerase chain reaction.
  
  
  RESULTS
  Proliferation and collagen production were similar for tenocytes and adipose-derived stem cells alone. Phenotype difference between adipose-derived stem cells and tenocytes was indicated by higher tenascin C and scleraxis expression in tenocytes. Proliferation was increased in direct co-cultures, especially at an adipose-derived stem cells-to-tenocyte ratio of 3:1, and for tenocytes in adipose-derived stem cell-conditioned media. Direct co-culture caused significant up-regulation in tenascin C expression in adipose-derived stem cells (4.0-fold; p<005). In tenocyte-conditioned media, tenascin C expression was up-regulated 2.5-fold (p<0.05). In the insert system, tenascin C expression was up-regulated 2.3-fold (p<0.05).
  
  
  CONCLUSIONS
  Adipose-derived stem cells are good candidates for tendon tissue engineering because they are similar to tenocytes in proliferation and collagen production. With an optimal ratio of 3:1, they increase proliferation in co-culture and change their phenotype toward a tenogenic direction.
authors.affiliation: Palo Alto, Calif.; and Magdeburg, Germany From the Division of Plastic and Reconstructive Surgery, Stanford University Medical Center; the Section of Plastic Surgery, Veterans Affairs Palo Alto Health Care System; and the Department of Plastic, Aesthetic, and Hand Surgery, Otto-von-Guericke University.
authors.forename: Armin
authors.initials: A
authors.lastname: Kraus
authors.forename: Colin
authors.initials: C
authors.lastname: Woon
authors.forename: Shyam
authors.initials: S
authors.lastname: Raghavan
authors.forename: Kai
authors.initials: K
authors.lastname: Megerle
authors.forename: Hung
authors.initials: H
authors.lastname: Pham
authors.forename: James
authors.initials: J
authors.lastname: Chang
mesh_terms: D000273:Adipose Tissue / Q000166:cytology*; D002454:Cell Differentiation; D049109:Cell Proliferation; D002478:Cells, Cultured; D018920:Coculture Techniques; D003094:Collagen / Q000096:biosynthesis*; D006801:Humans; D013234:Stem Cells / Q000502:physiology*; D013710:Tendons / Q000166:cytology* / Q000502:physiology; D023822:Tissue Engineering; D054457:Tissue Scaffolds
chemical_list: D003094:Collagen