Effects of pulsed electromagnetic fields on human chondrocytes: An in vitro study

H-3-thymidine incorporation was studied in cultured human nasal and articul ar chondrocytes exposed to low-energy, low-frequency pulsed electromagnetic fields (PEMFs) (75 Hz, 2.3 mT). The reverse transcriptase polymerase chain reaction (RT-PCR) analysis shows that human secondary chandrocytes derived from both nasal and articular cartilage express collagen type TI mRNA, whi ch is a specific marker of the chondrocyte phenotype. In a preliminary seri es of experiments, cells were exposed to PEMF for different time periods ra nging from 6 to 30 hours (timecourse), in medium supplemented with 10% or 0 .5% fetal calf serum (FCS) and in serum-free medium. The ratios between the H-3-thymidine incorporation in PEMFs and control cultures Show an increase of the cell proliferation in cultures exposed to PEMFs when serum is prese nt in the culture medium, whereas no effect was observed in serum-free cond itions. The increase in DNA synthesis, induced by PEMFs, was then evaluated only at the times of maximum induction and the results were analyzed by th e three-factor analysis of variance (ANOVA). The data presented in this study show that even if H-3-thymidine incorporat ion is higher in nasal than in articular chondrocytes, PEMF induce an incre ase in the proliferation of both cell types. Moreover, the concentration of FCS in the culture medium greatly influences the proliferative response of human chondrocytes to the PEMF exposure. Though normal human osteoblast ce lls increase their proliferation when exposed to PEMFs if only 10% FCS is p resent in the medium, human chondrocytes are able to increase their cell pr oliferation when exposed to PEMFs in the presence of both 0.5% and 10% of F CS in the medium. The results obtained may help to explain the basic mechan isms of PEMF stimulation of fracture healing.