title: Regulation of human adipose-derived stromal cell osteogenic differentiation by insulin-like growth factor-1 and platelet-derived growth factor-alpha.
abstract: BACKGROUND
  Human adipose-derived stromal cells possess a great potential for tissue engineering purposes. The authors' laboratory is interested in harnessing human adipose-derived stromal cells for skeletal tissue regeneration and identifying those factors that enhance human adipose-derived stromal cell osteogenic differentiation. The authors hypothesized that insulin-like growth factor (IGF) and platelet-derived growth factor (PDGF) would stimulate human adipose-derived stromal cell osteogenesis and that IGF would stimulate adipogenesis.
  
  
  METHODS
  Adipose-derived stromal cells were harvested from human lipoaspirate. Previously, a microarray analysis examined gene expression throughout osteogenic differentiation. In a candidate fashion, the authors added recombinant IGF-1 and PDGF-alpha individually and in combination. Osteogenesis and adipogenesis were assessed by alkaline phosphatase, alizarin red, and oil red O staining, and quantitative real-time polymerase chain reaction (RUNX2, ALP, OCN, IGF1, PPARG, LPL, AP2, and GCP1). Finally, intersection between IGF and PDGF signaling pathways was evaluated.
  
  
  RESULTS
  IGF-1 was observed to increase osteogenic differentiation by all markers (p < 0.01). However, PDGF-alpha when added alone primarily did not affect osteogenic markers. PDGF-alpha positively regulated transcription of IGF1. Addition of PDGF-alpha in combination with or before IGF-1 enhanced osteogenesis more than either alone. IGF-1 increased whereas PDGF-alpha diminished human adipose-derived stromal cell adipogenesis.
  
  
  CONCLUSIONS
  IGF signaling significantly increased osteogenesis in human adipose-derived stromal cells and may be used for tissue-engineering purposes. The combination of PDGF and IGF may be more beneficial than either alone in driving adipose-derived stromal cell osteogenesis. Future in vivo applications will focus on the combination of adipose-derived stromal cells, biomimetic scaffolds, and recombinant IGF.
authors.affiliation: Stanford, Calif. From the Hagey Pediatric Regenerative Research Laboratory, Department of Surgery, Plastic and Reconstructive Surgery Division, Stanford University School of Medicine.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Levi
authors.forename: Aaron W
authors.initials: AW
authors.lastname: James
authors.forename: Derrick C
authors.initials: DC
authors.lastname: Wan
authors.forename: Jason P
authors.initials: JP
authors.lastname: Glotzbach
authors.forename: George W
authors.initials: GW
authors.lastname: Commons
authors.forename: Michael T
authors.initials: MT
authors.lastname: Longaker
mesh_terms: D050156:Adipogenesis / Q000187:drug effects / Q000235:genetics; D000273:Adipose Tissue / Q000166:cytology*; D015153:Blotting, Western; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D005260:Female; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000494:pharmacology*; D008875:Middle Aged; D010011:Osteocytes / Q000166:cytology*; D010012:Osteogenesis / Q000187:drug effects* / Q000235:genetics; D010982:Platelet-Derived Growth Factor / Q000235:genetics / Q000494:pharmacology*; D016133:Polymerase Chain Reaction; D012313:RNA / Q000032:analysis; D015398:Signal Transduction / Q000235:genetics; D017154:Stromal Cells / Q000166:cytology* / Q000187:drug effects; D023822:Tissue Engineering / Q000379:methods*; D014158:Transcription, Genetic
chemical_list: D010982:Platelet-Derived Growth Factor; C075278:platelet-derived growth factor A; D012313:RNA; D007334:Insulin-Like Growth Factor I