Effects of low-frequency pulsed electromagnetic fields on human osteoblast-like cells in vitro

We have studied the effects of low-frequency, low-energy pulsed electromagnetic fields (PEMFs) on human osteoblast-like cells in vitro, in order to investigate the biochemical mechanism(s) by which electrical stimulation can effect changes in skeletal metabolism. Bony nature of the cells was assayed by immunolabeling with antiosteonectin antibody. Multidish plates were placed between a pair of Helmoltz coils powered by a pulse generator (1.3 ms, 75 Hz) in a tissue culture incubator for 24 h. H-3-thymidine was added to the culture medium to evaluate cell proliferation. The acid-precipitable 3H-thymidine incorporation significantly increases in PEMF-exposed cells as compared to the control. PEMF exposure induces a two- to fivefold increase of DNA synthesis. Osteoblasts cultured for 24 h in a serum-free medium show a very low proliferation rate, and the exposure to PEMF does not stimulate DNA synthesis.