Mechanical stretch promotes proliferation of rat bone marrow mesenchymal stem cells

Tissues and cells in the body are continuously exposed to a complex mechanical environment. Mechanical stimulations are critical to morphological, developmental and functional states of living cells, and the fashion of the mechanical stimulation applied to the cells is supposed to be extremely important for the induced cell response and function. In this study, we investigated whether mechanical stretch regulates and promotes proliferation of rat bone marrow mesenchymal stem cells (rMSCs) in vitro. rMSCs from rat bone marrow were isolated, purified and subjected to a cyclic equiaxial stretch treatment, and then MTT assay was adopted and expression of c-fos gene was measured by RT-PCR to access cell proliferation. The results demonstrated that OD values of rMSCs increased in a time-dependent and magnitude-dependent manner after exposure to 1 Hz stretch within 15-60 min and 2-8% strain. Expression of c-fos gene in rMSCs subjected to stretch treatment (1 Hz, 8% strain and 60 min) is significantly higher than that of unstimulated control cells. These results suggest that mechanical stretch plays an important role in regulating the cell growth and proliferation, and an appropriate mechanical stretch treatment could promote proliferating capacity of rMSCs.