title: Osteogenic induction protects rat bone marrow-derived mesenchymal stem cells against hypoxia-induced apoptosis in vitro.
abstract: BACKGROUND
  Bone marrow-derived mesenchymal stem cells (BMSCs) undergo hypoxia-induced apoptosis when cells are transplanted from a normoxic to a hypoxic microenvironment in vivo. The effect of the osteogenic microenvironment on BMSCs under hypoxic conditions has not yet been revealed.
  
  
  METHODS
  In the current study, we investigated the effects on BMSCs of hypoxia and osteogenic induction (OI) individually and in combination. We isolated BMSCs from rat bone marrow and confirmed them by recognition of surface antigens using cytometry. After passaging the BMSCs to the third generation, we treated them with the following conditions: 1% oxygen and OI, normoxia and OI, and 1% oxygen without OI; normoxia without OI was the control condition. On days 3, 7, 14, and 21, we detected the expression levels of hypoxia inducible factor-1α and alkaline phosphate via Western blotting. Cellular apoptosis was detected by Hoechst staining and terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine, 5'-triphosphate nick end labeling; caspase activity was also detected.
  
  
  RESULTS
  The expression of hypoxia inducible factor-1α was induced and up-regulated when BMSCs were grown under 1% oxygen. The incidence of terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine, 5'-triphosphatenick end labeling-positive cells in the hypoxia plus OI group was much lower than that in the hypoxia group without OI. Caspase activity increased on days 3, 7, 14, and 21. The absolute value of caspase was statistically higher in the BMSC hypoxia group than in the other three groups, whose values were similar to each other.
  
  
  CONCLUSIONS
  Osteogenic induction could protect BMSCs against hypoxia-induced apoptosis. Bone marrow-derived mesenchymal stem cells may be appropriate candidate cells for cytotherapy for skeletal diseases.
authors: Department of Orthopedic Surgery, Shanghai Sixth People's Hospital, Shanghai Jiao Tong University, Shanghai, China.
authors: You-Shui
authors: YS
authors: Gao
authors: Hao
authors: H
authors: Ding
authors: Xue-Tao
authors: XT
authors: Xie
authors: Chang-Qing
authors: CQ
authors: Zhang
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D001854:Bone Marrow Cells / Q000473:pathology*; D020169:Caspases / Q000502:physiology; D002478:Cells, Cultured; D000860:Hypoxia / Q000503:physiopathology*; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000502:physiology; D066298:In Vitro Techniques; D059630:Mesenchymal Stem Cells / Q000473:pathology* / Q000502:physiology; D023421:Models, Animal; D010012:Osteogenesis / Q000502:physiology*; D051381:Rats; D013997:Time Factors; D015854:Up-Regulation / Q000502:physiology
chemical_list: C497444:Hif1a protein, rat; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D020169:Caspases
keywords: Apoptosis; Bone marrow–derived mesenchy-mal stem cells; Hypoxia; Osteogenic induction