Qi et al. Bone-related Genes Expression in MSCs after Mechanical Strain doi: 10.4248/IJOS.09021 Expression of Bone-related Genes in Bone Marrow MSCs after Cyclic Mechanical Strain: Implications for Distraction Osteogenesis

Aim Understanding the response of mesenchymal stem cells (MSCs) to mechanical strain and their consequent gene expression patterns will broaden our knowledge of the mechanobiology of distraction osteogenesis. Methodology In this study, a single period of cyclic mechanical stretch (0.5 Hz, 2,000 με) was performed on rat bone marrow MSCs. Cellular proliferation and alkaline phosphatase (ALP) activity was examined. The mRNA expression of six bone-related genes (Ets-1, bFGF, IGF-, TGF-β, Cbfa1 and ALP) was detected using real-time quantitative RT-PCR. Results The results showed that mechanical strain can promote MSCs proliferation, increase ALP activity, and up-regulate the expression of these genes. A significant increase in Ets-1 expression was detected immediately after mechanical stimulation, but Cbfa1 expression became elevated later. The temporal expression pattern of ALP coincided perfectly with Cbfa1. Conclusion The results of this study suggest that mecha-nical strain may act as a stimulator to induce differentiation of MSCs into osteoblasts, and that these bone-related genes may play different roles in the response of MSCs to mechanical stimulation. Keywords distraction osteogenesis, mechanical strain, mesenchymal stem cell (MSC), osteogenic factor, gene expressio