[Human osteoblasts response to different magnitudes of mechanical stimulation in vitro].
OBJECTIVE
To investigate the effect of different magnitudes of tensile strain on human osteoblasts differentiation.


METHODS
According to the strain amplification mechanism at cellular level and a data calculated by finite element analysis, the cellular level strain of 0.8%, 1.6%, 2.4% and 3.2% was respectively applied to human osteoblasts for 48 h at a frequency of 1 Hz. Alkaline phosphatase activity and the expression of osteoblast-related genes were detected by Semi-Quantitative RT-PCR and densitometric analysis.


RESULTS
Alkaline phosphatase activity significantly increased at 0.8% and 1.6%. The level of osteocalcin mRNA increased at 2.4% and 3.2%. Cbfa1/Runx2 gene expression only increased at 3.2%. Comparing to static control, mRNA level of type I collagen increased at every magnitude. The mRNA level decreased at 0.8% and increased at 3.2% when compared to the group with 1.6% elongation.


CONCLUSIONS
Higher magnitudes of strain enhance expression of osteocalcin, type I collagen gene and Cbfa1/Runx2 in human osteoblasts, but lost the ability to increase ALP activity which is remained by lower magnitudes of strain. Type I collagen gene expression increases in a strain magnitude dependent manner.
Zhu
Jun-feng
JF
Department of Orthopaedics, the Sixth Affiliated People's Hospital of Shanghai Jiaotong University, Shanghai 200233, China.
Zhang
Xian-long
XL
Wang
Cheng-tao
CT
Zhang
Xiao-ling
XL
Peng
Xiao-chun
XC
Bai
Xue-ling
XL
D000469:Alkaline Phosphatase / Q000378:metabolism; D002460:Cell Line; D049109:Cell Proliferation; D024042:Collagen Type I / Q000378:metabolism; D050659:Core Binding Factor Alpha 1 Subunit / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D010006:Osteoblasts / Q000166:cytology* / Q000378:metabolism; D015675:Osteocalcin / Q000378:metabolism; D013314:Stress, Mechanical
D024042:Collagen Type I; D050659:Core Binding Factor Alpha 1 Subunit; C493709:RUNX2 protein, human; D015675:Osteocalcin; D000469:Alkaline Phosphatase