镁合金支架在兔腹主动脉中的降解

Degradation of a magnesium alloy stent in the rabbit abdominal aorta

背景:国外研究发现镁合金支架是安全有效的,国内对于镁合金支架降解性能的研究不多。目的:探讨可降解AZ31镁合金支架在兔腹主动脉中的降解情况及降解过程对血管的影响。方法:在28只新西兰大白兔腹主动脉植入可降解AZ31镁合金支架,在植入的30,60,90,120 d进行X射线检查及支架植入段血管组织学观察。结果与结论:(1)X射线检查:植入后30 d,支架完全扩张,结构完整;植入后60 d,支架变形,部分支架断裂,失去支撑作用;植入后90 d,只有少量支架支杆残留,大部分支架已降解;植入后120 d,血管中无支架支杆残留,支架已完全降解;(2)组织学观察结果:植入后60 d的剩余支架支杆数小于植入后30 d(P<0.05),植入后90 d的剩余支架支杆数小于植入后30,60 d(P<0.05),植入后120 d的剩余支架支杆数小于植入后30,60,90 d(P<0.05);剩余支杆数和天数呈负相关,支架完全降解天数为植入后124.8 d。植入90 d的血管内膜面积大于植入后30,60,120 d(P<0.05),血管管腔面积小于小于植入后30,60,120 d(P<0.05);后3个时间点的血管内膜面积与血管管腔面积比较差异无显著性意义;(3)结果表明,可降解AZ31镁合金支架在大白兔腹主动脉内完全降解时间为124.8 d,在支架植入90 d时血管内膜增生和管腔狭窄最明显,90 d后血管内膜增生和管腔狭窄逐渐减轻。

BACKGROUND： Foreign studies have found that the magnesium alloy stent is safe and effective, but there are few studies on the degradation performance of magnesium alloy stents in China. OBJECTIVE： To investigate the degradation of degradable AZ31 magnesium alloy stent in the rabbit abdominal aorta and the effect of degradation process on vascularization. METHODS： Twenty-eight rabbits were enrolled, and the degradable AZ31 magnesium alloy stent was implanted into the rabbit abdominal aorta. Postoperative abdominal aortic X-ray examination and histological observation were done at 30, 60, 90, 120 days after implantation. RESULTS AND CONCLUSION：（1） X-ray examination： 30 days after implantation, the stent expanded completely with structural integrity; 60 days after implantation, the stent deformation, partial stent fracture, and lose of support were found; 90 days after implantation, only a small amount of support rod residues were found, and the majority of the stent was degraded; and 120 days after implantation, there was no support rod residual, and the stent was degraded completely.（2） Histological observation： 60 days after implantation, the number of residual support rods was less than that 30 days after implantation（P〈0.05）, the number value at 90 days after implantation was lower than that at 30 and 60 days after implantation（P〈0.05）, and the number value at 120 days after implantation was lower than that at 30, 60, 90 days after implantation（P〈0.05）, indicating that the number of residual support rods was negatively correlated with post-implantation days. The time for complete stent degradation was 124.8 days. The intimal area at 90 days after implantation was higher than that at 30, 60, 120 days after implantation（P〈0.05）, while the lumen area was smaller than that at 30, 60, 120 days after implantation（P〈0.05）. There was no significant difference in the intimal area and lumen area at latter three time points after implantation. To conclude, the degradation of the degradable AZ31 magnesium alloy stent in the rabbit abdominal aorta can be completed within 124.8 days, and at 90 days after the stent is implanted, vascular intimal hyperplasia and lumen stenosis are most serious, and then gradually reduced.