硅膜-镁合金可降解支架置入兔食管可行性及组织反应——体外和体内初步研究

Insertion of biodegradable silicon-covered magnesium alloy stent in esophagus: a preliminary in vitro and in vivo study of feasibility and tissue reaction in experimental rabbits

目的体外研究硅膜-镁合金可降解支架的机械特性和降解行为,体内研究其置入兔食管的可行性及组织反应。方法体外测试硅膜-镁合金可降解支架的机械压缩恢复性能和降解行为。30只健康荷兰兔随机分为硅膜-镁合金支架组(n=15,透视导引下将支架置入兔食管下1/3段)和对照组(n=15,未作任何干预),支架置入后1、2、4周两组兔分别接受食管造影,同时于各时间点分别处死5只兔,取材作组织学检查。结果体外测试显示硅膜-镁合金可降解支架表现出良好的柔韧性和弹性,在p H4.0、p H7.4磷酸缓冲液中降解均慢于镁合金裸支架;体内测试显示支架置入后所有实验兔耐受性良好,食管直径在置入前为(9.2±0.8)mm,置入后1、2、4周分别为(9.7±0.7)mm、(9.6±0.8)mm、(9.6±0.5)mm(P>0.05)。支架组6只兔发生支架移位(1周时1只,2周时1只,4周时4只)。支架组食管上皮、平滑肌层变薄等食管壁重建与对照组比较,差异有统计学意义(P<0.05);支架置入后食管壁损伤及胶原沉积等组织反应与对照组比较,差异无统计学意义(P>0.05)。结论硅膜-镁合金可降解支架置入兔食管技术上可行,可提供至少2周支撑力,支架移位率可接受,未发生严重食管壁损伤及胶原沉积。

Objective To study the mechanical properties and degradation behavior of biodegradable silicon-covered magnesium alloy stent in vitro, to investigate the technical feasibility of its implantation into rabbit esophagus and to observe the tissue reaction in vivo. Methods The mechanical compression recovery properties and the degradation behavior of biodegradable silicon-covered magnesium alloy stent were tested in vitro. A total of 30 healthy Holland rabbits were randomly divided into silicon-covered magnesium alloy stent group （n=15） and control group （n=15）. For rabbits in the silicon-covered magnesium alloy stent group fluoroscopy-guided insertion of the stent into the lower third segment of esophagus was conducted, while for rabbits in the control group no intervention was adopted. One, 2 and 4 weeks after the implantation of the stent, esophagography was performed for all rabbits of both groups, and each time every 5 rabbits from both groups were sacrificed, the specimens were collected and sent for histological examinations. Results In vitro test indicated that biodegradable silicon-covered magnesium alloy stent had good flexibility and elasticity, and in phosphate-buffered saline with pH 4.0 or pH 7.4 it degraded more slowly than bare magnesium alloy stent. In vivo test showed that the stent implantation could be well tolerated by all experimental rabbits. Before stent insertion the esophageal diameter was（9.2±0.8） mm, and at one, 2 and 4 weeks after stent insertion the esophageal diameters were （9.7±0.7） mm, （9.6±0.8） mm and （9.6±0.5） mm respectively （P〉0.05）. In the silicon-covered magnesium alloy stent group, stent displacement occurred in 6 rabbits in one week （n=1）, 2 weeks （n=1） and 4 weeks （n=4）. After stent implantation, the tissue reactions such as esophageal wall injury, collagen deposition, etc. were not obviously different from those in the control group （P〉0.05）. Conclusion It is technically feasible to insert silicon-covered magnesium alloy stent into the rabbit＇s esophagus, the stent can provide sufficient support for at least 2 weeks, the stent displacement rate is low and acceptable, and no severe esophageal wall injury and collagen deposition are observed（J Intervent Radiol, 2017, 26： 816-822）