title: Hypoxia Suppresses Spontaneous Mineralization and Osteogenic Differentiation of Mesenchymal Stem Cells via IGFBP3 Up-Regulation.
abstract: Hypoxia has diverse stimulatory effects on human adipose-derived stem cells (ASCs). In the present study, we investigated whether hypoxic culture conditions (2% O₂) suppress spontaneous mineralization and osteogenic differentiation of ASCs. We also investigated signaling pathways and molecular mechanisms involved in this process. We found that hypoxia suppressed spontaneous mineralization and osteogenic differentiation of ASCs, and up-regulated mRNA and protein expression of Insulin-like growth factor binding proteins (IGFBPs) in ASCs. Although treatment with recombinant IGFBPs did not affect osteogenic differentiation of ASCs, siRNA-mediated inhibition of IGFBP3 attenuated hypoxia-suppressed osteogenic differentiation of ASCs. In contrast, overexpression of IGFBP3 via lentiviral vectors inhibited ASC osteogenic differentiation. These results indicate that hypoxia suppresses spontaneous mineralization and osteogenic differentiation of ASCs via intracellular IGFBP3 up-regulation. We determined that reactive oxygen species (ROS) generation followed by activation of the MAPK and PI3K/Akt pathways play pivotal roles in IGFBP3 expression under hypoxia. For example, ROS scavengers and inhibitors for MAPK and PI3K/Akt pathways attenuated the hypoxia-induced IGFBP3 expression. Inhibition of Elk1 and NF-κB through siRNA transfection also led to down-regulation of IGFBP3 mRNA expression. We next addressed the proliferative potential of ASCs with overexpressed IGFBP3, but IGFBP3 overexpression reduced the proliferation of ASCs. In addition, hypoxia reduced the osteogenic differentiation of bone marrow-derived clonal mesenchymal stem cells. Collectively, our results indicate that hypoxia suppresses the osteogenic differentiation of mesenchymal stem cells via IGFBP3 up-regulation.
authors: College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon 21983, Korea. wisdom-ks@hanmail.net.|Stemore Co., Ltd., Incheon 21983, Korea. wisdom-ks@hanmail.net.
authors: Ji Hye
authors: JH
authors: Kim
authors: College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon 21983, Korea. sei_mee@naver.com.|Department of Integrated OMICS for Biomedical Sciences, Yonsei University, Seoul 03722, Korea. sei_mee@naver.com.
authors: Sei Mee
authors: SM
authors: Yoon
authors: Inha University School of Medicine, Translational Research Center and Inha Research, Institute for Medical Sciences, Incheon 21983, Korea. sunuksong@inha.ac.kr.
authors: Sun U
authors: SU
authors: Song
authors: College of Pharmacy, Ajou University, Suwon 16499, Korea. sgpark@ajou.ac.kr.
authors: Sang Gyu
authors: SG
authors: Park
authors: Department of Dermatology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul 03722, Korea. susini@naver.com.
authors: Won-Serk
authors: WS
authors: Kim
authors: Department of Biochemistry, Stony Brook University, Stony Brook, NY 11790, USA. allpleache@naver.com.
authors: In Guk
authors: IG
authors: Park
authors: College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon 21983, Korea. jinulee@yonsei.ac.kr.
authors: Jinu
authors: J
authors: Lee
authors: College of Pharmacy, Yonsei Institute of Pharmaceutical Sciences, Yonsei University, Incheon 21983, Korea. brian99@empal.com.|Stemore Co., Ltd., Incheon 21983, Korea. brian99@empal.com.
authors: Jong-Hyuk
authors: JH
authors: Sung
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology*; D015687:Cell Hypoxia / Q000235:genetics / Q000502:physiology*; D049109:Cell Proliferation / Q000235:genetics / Q000502:physiology; D002478:Cells, Cultured; D006801:Humans; D047468:Immunoprecipitation; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000235:genetics / Q000378:metabolism*; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000378:metabolism*; D051379:Mice; D010012:Osteogenesis / Q000235:genetics / Q000502:physiology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D018972:Insulin-Like Growth Factor Binding Protein 3; D017382:Reactive Oxygen Species
keywords: IGFBP3; adipose-derived stem cells; hypoxia; osteogenic differentiation; reactive oxygen species