title: [Osteoblastic differentiation and gene expression profile change in rat bone marrow mesenchymal stem cells after a single period of mechanical strain].
abstract: OBJECTIVE
  To evaluate the osteoblastic differentiation and compare the difference in the gene expression of rat bone marrow mesenchymal stem cells (MSCs) affected by a single period of mechanical strain.
  
  
  METHODS
  Bone marrow MSCs were harvested from the femurs and tibiae of SD rats and cultured in vitro. A four-point bending apparatus were used to perform a single 40-minute period of 2,000 microepsilon mechanical strain on these MSCs. The proliferation of the MSCs was tested by MTT on scheduled date, and the osteoblastic differentiation of the MSCs was measured by testing the expression of osteocalcin and alkaline phosphate (ALP) activity of these cells. In addition, we have investigated the possible mechanisms underlying the action of the single 40-minute period of 2,000 microepsilon mechanical strain on these MSCs, after profile blotted and handled by bioinformation, the gene expressions of these two periods of MSCs were examined.
  
  
  RESULTS
  The MSCs have grown well in vitro. Our experiment showed that mechanical environment did not weaken the proliferation of the MSCs. However, the ALP activity and the expression of osteocalcin were significantly up-regulated by the 2,000 microepsilon mechanical strain. Using the 27 K Rat Genome Array, 416 different expressions were found. The rate of different genes was 2.8%, of which the expressions of 247 genes increased (61 genes remarkably increased) and 169 genes decreased (74 genes remarkably decreased) in these two periods of MSCs.
  
  
  CONCLUSIONS
  Mechanical strain induced the osteoblastic differentiation of the MSCs, which may be attributed to the different gene levels.
authors.affiliation: State Key Laboratory of Oral Diseases, Sichuan University, Chengdu 610041, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Gao
authors.forename: Ji-Hua
authors.initials: JH
authors.lastname: Li
authors.forename: Li-Chi
authors.initials: LC
authors.lastname: Han
authors.forename: Yong-Qing
authors.initials: YQ
authors.lastname: Ma
authors.forename: Jing
authors.initials: J
authors.lastname: Hu
authors.forename: Dan
authors.initials: D
authors.lastname: Qu
authors.forename: Yu-Chun
authors.initials: YC
authors.lastname: Xu
mesh_terms: D000469:Alkaline Phosphatase; D000818:Animals; D001854:Bone Marrow Cells; D002454:Cell Differentiation; D049109:Cell Proliferation; D002478:Cells, Cultured; D059630:Mesenchymal Stem Cells; D010006:Osteoblasts; D015675:Osteocalcin; D051381:Rats; D017207:Rats, Sprague-Dawley; D059467:Transcriptome
chemical_list: D015675:Osteocalcin; D000469:Alkaline Phosphatase