Effects of Extremely Low-Frequency-Pulsed Electromagnetic Field on Different-Derived Osteoblast-Like Cells

Abstract

The aim of this study is to investigate the effects of extremely low-frequency pulsed electromagnetic field (PEMF) on osteoblast-like cells. PEMF with a magnetic flux density of 1.55 mT at 48 Hz was employed to stimulate the MC3T3-E1 cell and the primary osteoblast cell derived from 2-day-old Sprague Dawley (SD) rat calvaria for different time. MTS method was applied to analyze cell proliferation and flow cytometry to detect cell cycle. The intracellular alkaline phosphatase (ALP) activity was measured by colorimetry. Our results demonstrated that PEMF of 1.55 mT at 48 Hz did not affect cell number of MC3T3-E1 cell, whereas the cell percentage of S and G₂M phase decreased significantly. Although the cell number of the primary osteoblast cell did not alter by MTS assay after being exposed to PEMF for 24 h continuously, the cell percentage of S and G₂M phase increased significantly. When culture time extended to 48 h, the cell number increased greatly and the cell percentage of S and G₂M phase decreased significantly despite of the exposure type. After the primary osteoblast cell was exposed to PEMF for 24 h continuously, the ALP activity decreased significantly, whereas it increased significantly when being exposed to PEMF for 48 h continuously. From the results we concluded that PEMF of 1.55 mT at 48 Hz did not affect proliferation and differentiation of MC3T3-E1 cell, but it promoted proliferation, inhibited differentiation at proliferation stage, and promoted differentiation at differentiation stage of primary osteoblast cells.

Keywords:

• Pulsed electromagnetic field
• Osteoblast
• Cell proliferation
• Cell differentiation

Notes

¹24N, the cultures grew normally for 24 h continuously; 24E, the cultures were exposed to PEMF for 24 h continuously; 48N, the cultures grew normally for 48 h continuously; 48NE, the cultures were normally cultured for 24 h following another 24 h culture in PEMF; 48EN, the cultures were exposed to PEMF for 24 h following further 24 h normal culture; 48E, the cultures were exposed to PEMF for 48 h continuously.