[Effect of pulsed electromagnetic field on the changes of osteoclasts in ovariectomized rats bone marrow culture in vitro].

Objective: To investigate the effect of pulsed electromagnetic fields (PEMs) on inducing osteoclastic like cell (OLC) formation changes and apoptosis in ovariectomized (OVX) rats bone marrow culture in vitro.
Methods: Thirty healthy three-month-old female Wistar rats were either sham-operated (Sham) or ovariectomized (OVX) and randomly divided into three groups: group A (OVX + PEMs, 18 rats), group B (OVX, 6 rats) and group C (Sham, 6 rats); group A was again randomly divided into three groups: A1, A2, A3. The frequencies adopted were 1.5, 2, 75 Hz and 30 minutes for once a day. All rats were fed with normal diet for 3 months, then the bone marrow of all rats were cultured, 2 days later, group A cells (including group A1, A2, A3) were collected and exposed to different frequencies PEMs for 2 weeks (30 min/day). In order to observe the changes of osteoclasts and count their numbers, cells were taken for Wright Giemsa staining, tartrate-resistance acid phosphatase (TRAP) staining and Hoechst 33258 staining.
Results: TRAP staining results indicated the number of OLC in group C was the least, then was group A2, A3, A1, B. The number of OLC in group B was remarkably increased (P < 0.01; vs group C, A2). The number of OLC in group B was significantly increased (P < 0.05; vs group A1, A3). Hoechst 33258 staining results indicated the number of apoptosis of OLC in group C was more than other groups, which of group C, A2 was significantly increased (P < 0.05; vs group B).
Conclusion: PEMs had decreased the formation of OLC and increased the number of apoptosis of OLC in ovariectomized (OVX) rats bone marrow culture in vitro, the effects of 2 Hz was the best. PEMs would be a new way of osteoporosis therapy.