Yonsei Med J.  2010 Nov;51(6):954-959. 10.3349/ymj.2010.51.6.954.

Pulsed Electromagnetic Field Stimulates Cellular Proliferation in Human Intervertebral Disc Cells

• Lee HM
• Kwon UH
• Kim H
• Kim HJ
• Kim B
• Park JO
• Moon ES
• Moon SH

• KMID: 1779646
• DOI: http://doi.org/10.3349/ymj.2010.51.6.954

Abstract

PURPOSE
The purpose of this study is to investigate the mechanism of cellular proliferation of electromagnetic field (EMF) on human intervertebral disc (IVD) cells.
MATERIALS AND METHODS
Human IVD cells were cultured three-dimensionally in alginate beads. EMF was exposed to IVD cells with 650Omega, 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, [3H]-thymidine, and [35S]-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 NG-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).
CONCLUSION
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.

Keyword

Electromagnetic fields; intervertebral disc; nitric oxide; prostaglandin E2

MeSH Terms

Adult
Aspirin/pharmacology
Cell Proliferation/*radiation effects
Collagen/metabolism
Dinoprostone/metabolism
*Electromagnetic Fields
Enzyme Inhibitors/pharmacology
Female
Humans
Intervertebral Disk/*pathology/radiation effects
Male
Middle Aged
Nitric Oxide/metabolism
Tetrazolium Salts/pharmacology
Thiazoles/pharmacology
omega-N-Methylarginine/pharmacology

Figure

• 

  Fig. 1 Percent control of DNA synthesis measured by 3H-thymidine incorporation (CPM). Control: the cultures without EMF exposure; EMF: the cultures with EMF exposure for 72 hours. EMF+NMMA: the cultures with EMF (72 hours) and Monomethyl-L-arginine. EMF+ASA: the cultures with EMF (72 hours) and acetylsalicylic acid. *p < 0.05. CPM, counts per minute; EMF, electromagnetic field; NMMA, NG-Monomethyl-L-arginine; ASA, acetylsalicylic acid.

• 

  Fig. 2 Percent control of proteoglycan synthesis measured by 35S-Sulfate incorporation (CPM). Control: the cultures without EMF exposure; EMF: the cultures with EMF exposure for 72 hours. EMF+NMMA: the cultures with EMF (72 hours) and Monomethyl-L-arginine. EMF+ASA: the cultures with EMF (72 hours) and acetylsalicylic acid. *p < 0.05, CPM, counts per minute; EMF, electromagnetic field; NMMA, NG-Monomethyl-L-arginine; ASA, acetylsalicylic acid; NS, not-significant.

• 

  Fig. 3 Effect of EMF (72 hours) on mRNA expression of aggrecan and collagen type I and II. There was no statistically significant difference in mRNA expression of aggrecan and collagen type I and II compared to the control. EMF, electromagnetic field.

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