Microvibration stimulates β-catenin expression and promotes osteogenic differentiation in osteoblasts

Previous studies have demonstrated that low-magnitude, high-frequency (LMHF) mechanical vibrations (LM<1g; HF<20-90Hz) can benefit bone formation. However, the underlying mechanism is unclear. In this study, MC3T3-E1 cells were exposed to LMHF vibrations of different magnitudes to assess the effect of vibrations on β-catenin expression, which regulates osteogenic differentiation. LMHF vibrations (0.14-0.49g)increased cell viability, alkaline phosphatase activity and calcification in a dose (magnitude)-dependent manner. The level of β-catenin expression increased 1.6-fold using 0.49g LMHF vibrations compared to the control. Similarly, the use of LMHF vibrations increased Runx2 protein expression with the greatest effect at 0.32g exposure. The levels of BMP2, Osterix and Cyclin D1 protein expression were also elevated and were expressed highest in cells exposed to 0.49g. mRNA expression levels of these proteins were similarly affected by exposure to LMHF vibrations. These results suggest that LMHF vibrations promote cell viability and osteogenic differentiation of osteoblasts by up-regulating related proteins and genes. The activation of β-catenin plays an important role in the effect of microvibration exposure in osteoblasts.