Vertical Vibration of Mouse Osteoblasts Promotes Cellular Differentiation and Cell Cycle Progression and Induces Aging In Vitro

This study aimed to investigate the effect of the vibration of osteoblasts on the cell cycle, cell differentiation, and aging. Primary maxilla osteoblasts harvested from eight-week-old mice were subjected to vibration at 3, 30, and 300 Hz once daily for 30 min; control group, 0 Hz. A cell proliferation assay and Cell-Clock Cell Cycle Assay were performed 24 h after vibration. Osteoblast differentiation assay, aging marker genes, SA-β-Gal activity, and telomere length (qPCR) were assayed two weeks post- vibration once every two days. Cell proliferation increased significantly at 30 and 300 Hz rather than 0 Hz. Several cells were in the late G /M stage of the cell cycle at 30 Hz. The osteoblast differentiation assay was significantly higher at 30 Hz than at 0 Hz. Runx2 mRNA was downregulated at 30 Hz compared to that at 0 Hz, while osteopontin, osteocalcin, and sclerostin mRNA were upregulated. p53/p21, p16, and c-fos were activated at 30 Hz. SA-β-Gal activity increased significantly at 30 or 300 Hz. Telomere length was significantly lower at 30 or 300 Hz. The results suggest that providing optimal vibration to osteoblasts promotes cell cycle progression and differentiation and induces cell aging.