Background: Accumulating evidence has indicated that Low-Magnitude High-Frequency Vibration (LMHFV) can promote fracture healing, and thus, holds promise as a treatment for osteoporosis. However, few studies have reported the effects of LMHFV, especially intermittent LMHFV (iLMHFV) on osteoblasts in vitro. In this study, we examined the effects of sostenuto and intermittent LMHFV (sLMHFV and iLMHFV, respectively) on MC3T3-E1 preosteoblast proliferation and production of osteogenic and osteoclastogenic proteins.
Methods: The cell proliferation was determined using MTT assay for up to 7 d. The expression levels of the osteogenic proteins Alkaline Phosphatase (ALP), Osteocalcin (OCN), and Collagen type I (COL I), and the osteoclastogenic protein nuclear factor-κB ligand (RANKL) and its inhibitor Osteoprotegerin (OPG) were determined by Real time PCR and/or Western blot analysis. The ALP activity was determined using a fluorometric assay. The secretion of osteoclastogenic cytokines RANKL and M-CSF was assessed by ELISA.
Results: Our results showed that neither sLMHFV nor iLMHFV affected MC3T3-E1 cell proliferation. However, both sLMHFV and iLMHFV increased the expression of the osteogenic proteins ALP, OCN, and COL I. SLMHFV and iLMHFV also inhibited the secretion of the osteoclastogenic cytokines RANKL and M-CSF and decreased the OPG/RANKL ratio. These osteogenic and anti-osteoclastogenic effects were most profound with short iLMHFV.
Conclusion: These finding could eventually contribute to the development of potential treatment regimen for osteoporosis using LMHFV.