Effects of a Static Magnetic Field on Mineralization of MC3T3-E1 Cells

Abstract

Static magnetic field (SMF) has been utilized for the retention of removable partial dentures. This study indicated that an SMF influences not only the mechanical attachment but also promotes osteoblast-like cells calicification. Although these effects of an SMF remain to be biologically understood, increased in vitro bone-like formation suggests its future applicability. Abstract Purpose: The stage at which bone formation was influenced by a static magnetic field (SMF) remains to be elucidated. The purpose of this study was to investigate the initial and long-term effects of moderate-intensity SMF on mouse osteoblastic cells (MC3T3-E1). Methods: MC3T3-E1 osteoblastic cell cultures were exposed to SMF (250 mT, Nd-Fe-B disc magnet). The long-term effect of this exposure was evaluated by measuring mineralized nodule formation. Osteoblastic cell proliferation was assessed using a colorimetric proliferation assay (WST-8); differentiation was evaluated by measuring alkaline phosphatase (ALP) activity ; and noncollagenous gene expression was evaluated using real-time PCR to determine the initial and early responses. Results: After a month of continuous SMF exposure, mineralized nodule formation increased significantly. The initial proliferative activity decreased and was not related to apoptotic changes. ALP activity and the gene expression levels of secreted phosphoprotein 1 (SPP1), integrin binding sialoprotein, and bone gla protein were not influenced by the SMF exposure. Conclusion: Moderate-intensity (250 mT) SMF exposure increased mineralized nodule formation in mouse osteoblastic MC3T3-E1 cells. However, gene expression related to decreased cell proliferation and unaltered cell differentiation and bone matrix did not correlate with the long-term effects observed following SMF exposure. The mechanism by which SMF exposure influences osteoblast mineralization remains unknown.