INHIBITION OF BONE FORMATION BY HIGH INTENSITY PULSED ELECTROMAGNETIC FIELD IN MC3T3-E1 CELLS

To investigate the effects of pulsed electromagnetic field (PEMF) with high electric field intensity on bone formation in murine osteoblast-like MC3T3-E1 cells, proliferation, alkaline phosphotase (ALP) activity, mineralized nodule formation, Collagen Type I (COL-I) and core-binding factor (Cbf)a1 mRNA expression, and bone morphogenetic protein (BMP)2/4 and mothers against decapentaplegic (Smad)1/5/8 protein expression were examined in cultured MC3T3-E1 cells after exposure to PEMF at the field intensities of 0kV/m, 50kV/m or 400kV/m for 400 consecutive pulses daily for 7 consecutive days. After 50 kV/m of PEMF exposure, none of the above parameters of MC3T3-E1 cells changed significantly when compared to the control groups. However, the proliferation, ALP activity and mineralized nodule formation of MC3T3-E1 cells in 400 kV/m PEMF exposure groups decreased significantly although COL-I and Cbfa1 mRNA expression and BMP2/4 and Smad1/5/8 protein expression did not change. The PEMF we used at high electric field intensity suppressed proliferation, differentiation and mineralization of MC3T3-E1 cells in culture and appeared to be harmful for bone formation.