The effects of a pulsed magnetic field on carotid restenosis and the expression of matrix metalloproteinase-2 in vascular smooth muscle cells

Abstract

Objective To investigate the effects of pulsed magnetic fields of different intensity on carotid restenosis (CRS), post carotid endarterectomy (CEA) and the expression of matrix metalloproteinase-2 (MMP-2)in vascular smooth muscle cells (VSMC). Methods An animal model of carotid altherosclerosis was established in 50 New Zealand rabbits by using air-drying lesions combined with high fat feed. After two months, the rabbits were treated with bilateral CEA, and then divided randomly into 3 groups. Two of the groups were treated with ei-ther 0.6 or 1.0 T pulsed magnetic fields, while the third group served as an untreated blank control. Changes in the pathology of the tunica intima were observed 1, 2 and 3 months after the CEA using morphologic analysis, and the expression of MMP-2 in the VSMC was determined using immunohistochemistry. Results The histological a-nalysis showed that the total luminal area, plaque area, the maximum plaque thickness and the proportion of siena-sis in the treated groups were all significandy lower, on average, than in the control group. At all three time points the average improvements in the 1.0 T group were significantly greater than in the 0.6 T group. The average ex-pression of MMP-2 in the treated groups was significantly lower than in the control group, especially in the 1.0 T group. Conclusions Pulsed magnetic field therapy positively influences CRS and the expression of MMP-2 in VSMC. Reduced MMP-2 expression might be one of the mechanisms through which pulsed magnetic fields prevent or lessen carotid restenosis post CEA. Key words: Carotid restenosis; Pulsed magnetic fields; Vascular smooth muscle cells; Matrix metal-loproteinase-2