Regulation of cyclic longitudinal mechanical stretch on proliferation of human bone marrow mesenchymal stem cells.

Mechanical stimulation is critical to both physiological and pathological states of living cells. Although a great deal of research has been done on biological and biochemical regulation of the behavior of bone marrow mesenchymal stem cells (MSCs), the influence of biomechanical factors on their behavior is still not fully documented. In this study, we investigated the modulation of mechanical stretch magnitude, frequency, and duration on the human marrow mesenchymal stem cells (hMSCs) proliferation by an in vitro model system using a mechanical stretch loading apparatus, and optimized the stretch regime for the proliferation of hMSCs. We applied 3-(4,5-dimethylthiazol-2-yl)- 2,5-diphenyl tetrasodium bromide (MTT) assay to estimate the overall proliferative effects of the stretch on hMSCs. We found that fibronectin coating increased adhesion to silicone chamber surface, however, it did not show significant effect on proliferation of hMSCs. A frequency of 1 Hz was more effective in stimulating hMSCs proliferation. At 1 Hz, 5% strain for 15, 30, 60 min, the significant increase of hMSCs proliferation was observed. Proliferation was enhanced at 1 Hz, 10% strain for 15, 30 min, while decreased for 60 min. At 1 Hz, 15% strain, 15 min stretch resulted in the decrease of proliferation, and 30 min and 60 min stretch showed an increased proliferation. Long time (12 and 24 h) strain application blocked the proliferation. These results indicate that mechanical stretch plays an important role in hMSCs growth and proliferation; an appropriate mechanical stretch regime could be a novel approach to promoting proliferation of hMSCs in vitro.