Pulsed electromagnetic field stimulates cellular proliferation in human intervertebral disc cells.
OBJECTIVE
The purpose of this study is to investigate the mechanism of cellular proliferation of electromagnetic field (EMF) on human intervertebral disc (IVD) cells.


METHODS
Human IVD cells were cultured three-dimensionally in alginate beads. EMF was exposed to IVD cells with 650 Ω, 1.8 millitesla magnetic flux density, 60 Hz sinusoidal wave. Cultures were divided into a control and EMF group. Cytotoxicity, DNA synthesis and proteoglycan synthesis were measured by MTT assay, [(3)H]-thymidine, and [(35)S]-sulfate incorporation. To detect phenotypical expression, reverse transcription-polymerase chain reactions (RT-PCR) were performed for aggrecan, collagen type I, and type II mRNA expression. To assess action mechanism of EMF, IVD cells were exposed to EMF with N(G)-Monomethyl-L-arginine (NMMA) and acetylsalicylic acid (ASA).


RESULTS
There was no cytotoxicity in IVD cells with the EMF group in MTT assay. Cellular proliferation was observed in the EMF group (p < 0.05). There was no difference in newly synthesized proteoglycan normalized by DNA synthesis between the EMF group and the control. Cultures with EMF showed no significant change in the expression of aggrecan, type I, and type II collagen mRNA compared to the control group. Cultures with NMMA (blocker of nitric oxide) or ASA (blocker of prostaglandin E2) exposed to EMF demonstrated decreased DNA synthesis compared to control cultures without NMMA or ASA (p < 0.05).


CONCLUSIONS
EMF stimulated DNA synthesis in human IVD cells while no significant effect on proteoglycan synthesis and chondrogenic phenotype expressions. DNA synthesis was partially mediated by nitric oxide and prostaglandin E2. EMF can be utilized to stimulate proliferation of IVD cells, which may provide efficient cell amplification in cell therapy to degenerative disc disease.
Lee
Hwan-Mo
HM
Department of Orthopaedic Surgery, Yonsei University College of Medicine, Seoul, Korea.
Kwon
Un-Hye
UH
Kim
Hyang
H
Kim
Ho-Joong
HJ
Kim
Boram
B
Park
Jin-Oh
JO
Moon
Eun-Soo
ES
Moon
Seong-Hwan
SH
D000328:Adult; D001241:Aspirin / Q000494:pharmacology; D049109:Cell Proliferation / Q000528:radiation effects*; D003094:Collagen / Q000378:metabolism; D015232:Dinoprostone / Q000378:metabolism; D004574:Electromagnetic Fields; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006801:Humans; D007403:Intervertebral Disc / Q000473:pathology* / Q000528:radiation effects; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000378:metabolism; D013778:Tetrazolium Salts / Q000494:pharmacology; D013844:Thiazoles / Q000494:pharmacology; D019323:omega-N-Methylarginine / Q000494:pharmacology
D004791:Enzyme Inhibitors; D013778:Tetrazolium Salts; D013844:Thiazoles; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D003094:Collagen; C022616:thiazolyl blue; D015232:Dinoprostone; D001241:Aspirin