title: Hypoxia induces osteogenesis in rabbit adipose-derived stem cells overexpressing bone morphogenic protein-2.
abstract: OBJECTIVE
  Hypoxic culture potentiates mesenchymal stem cells (MSCs) to survive and secrete various growth factors. Genetically modified stem cells overexpressing bone morphogenic protein-2 (BMP-2) demonstrate strong osteogenic ability. Hence, we investigated the coeffect of hypoxic culture conditions and BMP-2 overexpression on the osteogenic ability of rabbit adipose-derived stem cells (rASCs) in vitro.
  
  
  METHODS
  Rabbit adipose-derived stem cells with or without adenoviral-BMP-2 transduction were cultured in hypoxic (1%) and normoxic (21%) conditions. Cell viability, attachment, and proliferation were compared. Real-time PCR amplification of osteogenic and angiogenic genes including alkaline phosphatase (ALP), osteocalcin (OCN), HIF-1α, and vascular endothelial growth factor (VEGF) was performed. Moreover, ALP activity, immunofluorescent staining of OCN, and mineralization assay by alizarin red S quantification and von Kossa staining were conducted.
  
  
  RESULTS
  Cells under hypoxic conditions attached better within 12 h and proliferated faster. While BMP-2 overexpression and hypoxic condition separately elevated the transcription of key osteogenic and angiogenic genes, a cooperative effect was observed to enhance the upregulation of osteogenic as well as angiogenic genes. Identical changes were observed in ALP activity, immunofluorescent staining of OCN, and mineralization assay.
  
  
  CONCLUSIONS
  Hypoxic culture can enhance the osteogenic ability of BMP-2 gene-modified rASCs, which provides a strategy to improve the osteogenesis of rASCs for in vivo bone regeneration.
authors.affiliation: Department of Prosthodontics, Ninth People's Hospital, Shanghai Jiao Tong University, School of Medicine, Shanghai, China; Oral Bioengineering and Regenerative Medicine Lab, Shanghai Research Institute of Stomatology, Ninth People's Hospital, Shanghai Key Laboratory of Stomatology, Shanghai Jiao Tong University, School of Medicine, Shanghai, China.
authors.forename: L
authors.initials: L
authors.lastname: Xu
authors.forename: X
authors.initials: X
authors.lastname: Sun
authors.forename: K
authors.initials: K
authors.lastname: Cao
authors.forename: Y
authors.initials: Y
authors.lastname: Wu
authors.forename: D
authors.initials: D
authors.lastname: Zou
authors.forename: Y
authors.initials: Y
authors.lastname: Liu
authors.forename: X
authors.initials: X
authors.lastname: Zhang
authors.forename: X
authors.initials: X
authors.lastname: Zhang
authors.forename: G
authors.initials: G
authors.lastname: Wang
authors.forename: Q
authors.initials: Q
authors.lastname: Huang
authors.forename: X
authors.initials: X
authors.lastname: Jiang
mesh_terms: D000818:Animals; D055396:Bone Morphogenetic Protein 2 / Q000032:analysis* / Q000235:genetics; D015687:Cell Hypoxia / Q000502:physiology*; D002478:Cells, Cultured; D059630:Mesenchymal Stem Cells / Q000502:physiology*; D010012:Osteogenesis / Q000502:physiology*; D011817:Rabbits; D060888:Real-Time Polymerase Chain Reaction; D014161:Transduction, Genetic
chemical_list: D055396:Bone Morphogenetic Protein 2
keywords: BMP-2; adipocyte; hypoxia preconditioning; osteogenesis; stem cells