Large gradient high magnetic fi eld aff ects FLG29.1 cells diff erentiation to form osteoclast-like cells

Purpose : We aimed to investigate the eff ects of diff erent apparent gravities ( μ g, 1 g and 2 g) produced by large gradient high magnetic fi eld (LGHMF) on human preosteoclast FLG29.1 cells. Materials and methods : FLG29.1 cells were cultured in Roswell Park Memorial Institute (RPMI)-1640 medium. Cells were exposed to LGHMF for 72 h. On culture day 1, 2, 3, cell proliferation was detected by 3-(4,5)-dimethylthiahi-azo (-z-y1)-3,5-di-phenytetrazoliumromide (MTT) method. On day 3, cell apoptosis and necrosis were assayed by Hoechst and propidium iodide (PI) staining. After cells were exposed to LGHMF for 72 h with the induction of 12-o-tetradecanoylphorbol 13-acetate (TPA), Tartrate-Resistant Acid Phosphatase (TRAP) positive cells and nitric oxide (NO) release were detected by TRAP staining and Griess method, respectively. Intracellular TRAP activity was measured using nitrophenylphosphate (pNPP) as the substrate. Results: MTT detection revealed that compared to control, FLG 29.1 cell proliferation in the μ g and 2 g groups were promoted. However, there is no obvious diff erence between the 1 g and control groups. Hoechst-PI staining showed that LGHMF promoted cell apoptosis and necrosis, especially in the 2 g group. Exposure to LGHMF inhibited the NO concentration of supernatant. Both the TRAP activity and the number of TRAP positive cells were higher in cells of m g group than those in 2 g group. In the 1 g group, they were decreased signifi cantly compared to control. Conclusions : These fi ndings indicate that LGHMF could directly aff ect human preosteoclast FLG29.1 cells survival and diff erentiation. High magnetic fl ux inhibited osteoclasts formation and diff erentiation while reduced apparent gravity enhanced osteoclastogenesis.