title: In vitro osteoinductive effects of hydroxycholesterol on human adipose-derived stem cells are mediated through the hedgehog signaling pathway.
abstract: BACKGROUND
  Human adipose-derived stem cells have been identified as a potential source of cells for use in bone tissue engineering because of their ready availability, ease of harvest, and susceptibility to osteogenic induction. The authors have previously demonstrated the ability of an osteogenic molecule called hydroxycholesterol, an oxidative derivative of cholesterol, to induce osteogenic differentiation in pluripotent murine and rabbit bone marrow stromal cells. In this study, the authors examine the ability of hydroxycholesterol to induce osteogenesis in human adipose-derived stem cells.
  
  
  METHODS
  Human adipose-derived stem cells were isolated from raw human lipoaspirates through standard isolation and expansion of the stromal vascular fraction. Cells were plated onto tissue culture plates in control medium and harvested between passages 2 and 3, incubated with conventional osteogenic media, and treated with various concentrations (1, 5, and 10 μM) of the 20(S) analogue of hydroxycholesterol. Evaluation of cellular osteogenic activity was performed. The role of the hedgehog signaling pathway in hydroxycholesterol-mediated osteogenesis was evaluated by hedgehog inhibition assays.
  
  
  RESULTS
  Alkaline phosphatase activity, bone-related gene expression, and mineralization were all significantly increased in cultures of human adipose-derived stem cells treated with 5 μM of 20(S)-hydroxycholesterol relative to controls. In addition, induction of hydroxycholesterol-mediated osteogenesis was mitigated by the addition of the hedgehog pathway inhibitor to cell cultures, implicating the hedgehog signaling pathway in the osteogenic mechanism on human adipose-derived stem cells by hydroxycholesterol.
  
  
  CONCLUSIONS
  These in vitro studies demonstrate that hydroxycholesterol exerts an osteoinductive influence on human adipose-derived stem cells and that these effects are mediated at least in part through the hedgehog signaling pathway.
authors.affiliation: Los Angeles, Calif. From the Division of Plastic and Reconstructive Surgery, Department of Surgery, David Geffen School of Medicine at UCLA.
authors.forename: Anisa
authors.initials: A
authors.lastname: Yalom
authors.forename: Akishige
authors.initials: A
authors.lastname: Hokugo
authors.forename: Sarah
authors.initials: S
authors.lastname: Sorice
authors.forename: Andrew
authors.initials: A
authors.lastname: Li
authors.forename: Luis A
authors.initials: LA
authors.lastname: Segovia Aguilar
authors.forename: Patricia
authors.initials: P
authors.lastname: Zuk
authors.forename: Reza
authors.initials: R
authors.lastname: Jarrahy
mesh_terms: D017667:Adipocytes / Q000166:cytology*; D000469:Alkaline Phosphatase / Q000378:metabolism; D054338:Cell Transdifferentiation / Q000502:physiology*; D003470:Culture Media; D053823:Hedgehog Proteins / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D006888:Hydroxycholesterols / Q000494:pharmacology*; D066298:In Vitro Techniques; D010012:Osteogenesis / Q000502:physiology*; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods; D012680:Sensitivity and Specificity; D015398:Signal Transduction; D013234:Stem Cells / Q000166:cytology* / Q000187:drug effects; D023822:Tissue Engineering; D014704:Veratrum Alkaloids / Q000494:pharmacology
chemical_list: D003470:Culture Media; D053823:Hedgehog Proteins; D006888:Hydroxycholesterols; D014704:Veratrum Alkaloids; D000469:Alkaline Phosphatase; C000541:cyclopamine