title: Optimization of human tendon tissue engineering:  synergistic effects of growth factors for use in tendon scaffold repopulation.
abstract: BACKGROUND
  Tissue-engineered flexor tendon grafts may allow reconstruction of severe tendon losses. One critical factor is the optimization of cell proliferation and reseeding. Use of growth factors--basic fibroblast growth factor (bFGF), insulin-like growth factor (IGF)-1, and platelet-derived growth factor (PDGF)-BB--may improve culture conditions for human fibroblasts, tenocytes, and adipose-derived stem cells and increase repopulation of a tendon scaffold.
  
  
  METHODS
  All cell types were plated at a density of 10,000 cells per well and cultured in F12 media supplemented with varying concentrations of bFGF, IGF-1, and PDGF-BB. After 72 hours, cell proliferation was determined using the CellTiter assay. Human flexor tendon segments were acellularized and reseeded in a cell suspension of 5 × 10(5) cells/ml. After 5 days, tendon repopulation was determined using the MTS assay and histology. Statistical significance was determined with analysis of variance and a t test.
  
  
  RESULTS
  For all cell types, there was enhanced proliferation with growth factors. Among single growth factors, PDGF-BB at 50 ng/ml was the most efficient stimulator of proliferation. With multiple growth factors, the optimal concentration was determined to be 5 ng/ml bFGF, 50 ng/ml IGF-1, and 50 ng/ml PDGF-BB (increase when compared with control: fibroblasts, 2.92-fold; tenocytes, 2.3-fold; and adipose-derived stem cells, 2.4-fold; p < 0.05). Tendons reseeded with this optimal combination of growth factors showed improved reseeding compared with the control group (fibroblasts, 2.01-fold; tenocytes, 1.78-fold; and adipose-derived stem cells, 1.76-fold; p < 0.05).
  
  
  CONCLUSIONS
  bFGF, IGF-1, and PDGF-BB can be used to improve cellular proliferation and repopulation of an acellularized scaffold. The use of growth factors may be an important step in the tissue engineering of human flexor tendons.
authors.affiliation: Palo Alto, Calif. From the Division of Plastic and Reconstructive Surgery, Stanford University Medical Center, and the Section of Plastic Surgery, Veterans Affairs Palo Alto Health Care System.
authors.forename: Shyam S
authors.initials: SS
authors.lastname: Raghavan
authors.forename: Colin Y L
authors.initials: CYL
authors.lastname: Woon
authors.forename: Armin
authors.initials: A
authors.lastname: Kraus
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* / Q000187:drug effects*; D000077214:Becaplermin; D002478:Cells, Cultured; D004357:Drug Synergism; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology*; D005347:Fibroblasts / Q000187:drug effects*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D020574:Proto-Oncogene Proteins c-sis / Q000494:pharmacology*; D013234:Stem Cells / Q000187:drug effects*; D013710:Tendons / Q000166:cytology* / Q000187:drug effects*; D023822:Tissue Engineering / Q000379:methods*; D054457:Tissue Scaffolds
chemical_list: D020574:Proto-Oncogene Proteins c-sis; D016222:Fibroblast Growth Factor 2; D000077214:Becaplermin; D007334:Insulin-Like Growth Factor I