Abstract:

BACKGROUND: The effect of magnetic field on osteoblast biology remains poorly understood.
OBJECTIVE: To evaluate the effect of the static magnetic field (SMF) with different intensities and exposure time on the proliferation, apoptosis and function of osteoblasts.
METHODS: Passage 3-5 Sprague-Dawley rat osteoblasts cultured in vitro were exposed to 0, 5, 22, 86, 135 mT SMF for 8, 12 and 24 hours. Cell proliferation and apoptosis changes and osteocalcin and carboxyterminal propeptide of typeⅠprocollagen (PICP) in the cell supernatant were determined.
RESULTS AND CONCLUSION: After exposure to 5, 22, 86, 135 mT SMF for 8, 12 hours, cell proliferation index was significantly higher compared with the control group (P < 0.05), and after exposure to SMF for 24 hours, the cell proliferation index was significantly higher only in the 5 mT SMF group than in the control group (P < 0.05). There was no significant difference in percentage of apoptotic cells after 0, 5, 22, 86, 135 mT SMF exposure at 8, 12 and 24 hours. After exposure to SMF for 8 hours, osteocalcin level in the 22, 86 and 135 mT SMF groups was significantly higher than that in the control group (P < 0.05). After exposure to SMF for 24 hours, osteocalcin level in the 135 mT group was significantly lower than that in the control group  (P < 0.05). After exposure to SMF for 8, 12 hours, PICP level was significantly higher in the 22, 86 mT SMF groups than in the control group (P < 0.05). After exposure to SMF for 24 hours, PICP level was significantly lower in the 135 mT SMF group than in the control group (P < 0.05). These findings suggest that short-time low-intensity magnetic field promotes the proliferation of osteoblasts and the secretion of osseous substance, while high-intensity magnetic field or long-time magnetic field exposure inhibits the proliferation of osteoblasts and the secretion of osseous substance.