Frequency-Regulated Repeated Micro-Vibration Promotes Osteoblast Differentiation Through BMP Signaling in MC3T3-E1 Cells

Physical stimulation, which is a key factor affecting the metabolism of osteoblasts and their precursor cells, plays an important role in bone remodeling; however, the role of micro-vibrations in osteoblast differentiation is unclear. In the present study, we determined the effects of frequency-regulated repeated micro-vibration (FRMV) on cell proliferation and established a method to induce osteoblast differentiation through FRMV using the mouse pre-osteoblast-like cell line MC3T3-E1, which is widely used in bone metabolism research. The results indicated that FRMV significantly influenced the proliferation of MC3T3-E1 cells in a normal growth medium. FRMV at 42.2 Hz significantly promoted proliferation, whereas FRMV at 92.1 Hz showed no effect on the proliferation rate. Moreover, FRMV at 42.2 Hz significantly increased alkaline phosphatase (ALP) enzyme activity and ALP gene expression in MC3T3-E1 cells. Treatment with LDN193189, a bone morphogenetic protein (BMP) signaling inhibitor, revealed that the FRMV-induced upregulation in ALP enzyme activity and ALP gene expression were significantly suppressed in MC3T3-E1 cells. The results suggest that the FRMV protocol developed in the present study induces osteoblast differentiation through the BMP signaling pathway. Thus, FRMV may contribute to the development of effective bone regeneration technologies.