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

Background: This study aimed to investigate the effect of the vibration of osteoblasts on the cell cycle, cell differentiation, and aging. Materials and Methods: 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. Results: Cell proliferation increased significantly at 30 and 300 Hz rather than 0 Hz. Several cells were in the late G(2)/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. Conclusions: The results suggest that providing optimal vibration to osteoblasts promotes cell cycle progression and differentiation and induces cell aging.