脉冲磁场对颈动脉内膜切除术后再狭窄及血管平滑肌细胞基质金属蛋白酶表达的影响

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

目的观察不同强度脉冲磁场对颈动脉粥样硬化家兔模型颈动脉内膜切除术（CEA）后再狭窄（CRS）及血管平滑肌细胞基质金属蛋白酶-2（MMP-2）表达的影响。方法家兔50只，使用干燥气体损伤结合高脂饲料喂养，制作家兔颈动脉粥样硬化模型。高脂饲料喂养2个月后行CEA手术。术后将实验动物分为对照组和2个治疗组（0．6T治疗组和1．0T治疗组）。2个治疗组分别采用磁感应强度为0．6T和1．0T的脉冲电磁场进行治疗。CEA术后1，2及3个月对病变血管进行组织形态学分析，并使用免疫组化方法观察血管平滑肌细胞MMP-2表达的变化。结果组织形态学分析示，CEA术后，0．6T治疗组和1．0T治疗组在总管腔面积、斑块面积、斑块厚度和狭窄程度方面均低于对照组（P〈0．05），且1．0T治疗组较0．6T治疗组降低程度更显著；术后2～3个月，0．6T治疗组和1．0T治疗组MMP-2的表达水平低于对照组（P〈0．01），1．0T治疗组表达水平低于0．6T治疗组（P〈0．05）。结论较强强度脉冲磁场能抑制CEA术后再狭窄颈动脉内膜MMP-2的表达，MMP-2表达的降低可能是脉冲磁场防治CEA术后CRS的机制之一。

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 ceils （ VSMC）. Methods An animal model of carotid ahherosclerosis 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 either 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 analysis showed that the total luminal area, plaque area, the maximum plaque thickness and the proportion of stenosis in the treated groups were all significantly 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 expression 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.