Objective: To observe the degradation process of biodegradable magnesium alloy stent (BMAS) in vivo in order to evaluate its degradation time and biological safety. Methods: Twenty-four male New Zealand white rabbits were divided into two groups: group A (n=12) and group B (n=12). The BMAS (a total of 12) was implanted in the infrarenal aorta of each rabbit in group A, while group B was the control group, without treatment. Color Doppler ultrasound was used at the 1, 2, 3, 4 months postoperatively to observe the degradation process of stents in group A. The arterial blood samples and main organs of two groups were also collected for biochemical examination and biosafety. Degradation assessment included transmission X-ray tomography (XRT), scanning electron microscope (SEM) and energy dispersion spectrum (EDS). Results: The XRT showed that the morphology of the stent was basically intact at 1 month after implantation, then scaffold composites were gradually degraded and absorbed. Degradation was basically completed at 4 months after operation. The early degradation products were Mg(2+) , then gradually replaced by Ca(2+) , P and other inorganic composition. There was no obvious adverse reactions in group A during the 4 months follow-up period. There was no statistical difference between the two groups in blood biochemical and pathological results (all P>0.05). Conclusion: BMAS can be degraded within 4 months in the abdominal aorta of rabbit, and the main degradation products are Ca(2+) and P, with good biosafety.
目的： 观察生物可降解镁合金支架在兔体内的降解过程，评估其降解时间及生物安全性。 方法： 纳入24只雄性新西兰大白兔，分为A、B两组，每组各12只，A组每只于肾下腹主动脉植入1枚可降解镁合金支架，共计12枚，B组为对照组，不做处理。于术后1、2、3、4个月分别行彩色多普勒超声观察A组支架降解情况并获取支架段血管标本，同时收集A、B两组动物动脉血液标本、主要器官组织，经X线三维成像、扫描电镜能谱分析、病理切片及血生化分析评价镁合金支架降解过程及其生物安全性。 结果： X线三维成像显示支架植入后1个月形态基本完整，随后支架丝降解，衬度降低，支架形态、连续性丢失；4个月时支架丝吸收衬度明显降低，镁合金基本完成降解，被机体吸收，转化成低密度成分。经能谱分析镁支架早期降解为镁离子，随后逐渐被钙、磷等无机成分所取代。A组动物于观察期间未见明显不良反应，血生化检测血钙[(3.08±0.54) mmol/L比(2.70±0.81) mmol/L，P＝0.19]、血镁[(1.02±0.16)mmol/L比(1.03±0.17)mmol/L，P＝0.88]、血磷[(1.52±0.30)mmol/L比(1.55±0.33)mmol/L，P＝0.87]、血肌酐[(3.49±0.34)μmol/L比(3.43±0.50)μmol/L，P＝0.73]等指标与B组正常兔比较差异均无统计学意义。主要脏器病理切片HE染色，形态结构正常，无病理学改变。 结论： 可降解镁支架在兔腹主动脉内4个月完成基本降解，降解产物主要为钙、磷等成分，具有良好的生物安全性。.
Keywords: Biocompatible materials; Biosafety; Blood vessels; Degradation in vivo; Stents.