title: [Response of bone marrow mesenchymal stem cells to mechanical stretch and gene expression of transforming growth factor-beta and insulin-like growth factor-II under mechanical strain].
abstract: OBJECTIVE
  To study the response of rat bone marrow mesenchymal stem cells (MSCs) to a single period of mechanical strain and expression patterns of transforming growth factor-beta (TGF-beta) and insulin-like growth factor-II (IGF-II) after mechanical stretch.
  
  
  METHODS
  Bone marrow MSCs were isolated from SD rats and cultured in vitro. A four-point bending apparatus were used to perform a single period of mechanical strain (2000 microepsilon, 40 min) on MSCs. Cellular proliferation and alkaline phosphatase (ALP) activity of MSCs were examined and gene expression patterns of TGF-beta and IGF-II were detected by SYBR green quantitative real-time RT-PCR.
  
  
  RESULTS
  Cell proliferation, ALP activity and expression of TGF-beta and IGF-II were all significantly up-regulated in stretched MSCs when compared with their controls. The mRNA levels of TGF-beta and IGF-II got top increase immediately after mechanical loading and increased about 51.44 and 8.92 folds, respectively, when compared with control cells. Expression of TGF-beta and IGF-II decreased with time and returned to control level at 12 h after mechanical stimulus, despite of a small increase at 6 h.
  
  
  CONCLUSIONS
  The mechanical stretch can promote MSCs proliferation, up-regulate its ALP activity and induce a time-dependent expression increase of TGF-beta and IGF-II which in turn result in osteogenic differentiation of MSCs. Mechanical stimulus is a key stimulator for osteogenic differentiation of MSCs and vital for bone formation in distraction osteogenesis.
authors.affiliation: Dept. of Stomatology, Medical College of Dalian University, Dalian 116622, China.
authors.forename: Li-chi
authors.initials: LC
authors.lastname: Han
authors.forename: Meng-chun
authors.initials: MC
authors.lastname: Qi
authors.forename: Hong
authors.initials: H
authors.lastname: Sun
authors.forename: Jing
authors.initials: J
authors.lastname: Hu
authors.forename: Shu-juan
authors.initials: SJ
authors.lastname: Zou
authors.forename: Ji-hua
authors.initials: JH
authors.lastname: Li
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells; D002454:Cell Differentiation; D049109:Cell Proliferation; D007335:Insulin-Like Growth Factor II; D059630:Mesenchymal Stem Cells; D010012:Osteogenesis; D019857:Osteogenesis, Distraction; D012333:RNA, Messenger; D051381:Rats; D017207:Rats, Sprague-Dawley; D013002:Somatomedins; D016212:Transforming Growth Factor beta
chemical_list: D012333:RNA, Messenger; D013002:Somatomedins; D016212:Transforming Growth Factor beta; D007335:Insulin-Like Growth Factor II