可降解镁合金气管支架在兔气管狭窄模型中初步应用

The application of biodegradable magnesium alloy tracheal stent in treating tracheostenosis:preliminary study in rabbit tracheal stenosis model

目的探讨可降解镁合金气管支架制备及其在气管狭窄动物模型中应用的安全性及可行性。方法采用气管软骨环间横行切开气管,并用毛刷环形破坏气管黏膜方法制备兔气管狭窄模型30例。镁锌钇钕(Mg-Zn-Y-Nd)合金经热挤压和冷拉拔工艺制备出直径0.24 mm和0.28 mm两种丝材,通过单根丝一体化整体编织技术将两种合金丝编织成8 mm×20 mm气管裸支架各15枚,并检测其物理性能。透视下将两种支架分别植入气管狭窄模型兔气管内,并于术后3、7、15、30、60 d各处死两种支架3只兔,评价支架金属丝断裂、支架压缩、支架降解及气管黏膜肉芽组织增生情况。结果两种镁合金支架支撑力均略大于镍钛(Ni-Ti)合金支架,丝材直径0.28 mm支架支撑力大于直径0.24 mm支架;丝材直径0.24 mm、0.28 mm支架平均扩张率分别为76.46%、84.66%;镁合金支架完全自膨性能略低于Ni-Ti合金支架。术后3 d支架结构完整,无坍塌;术后7 d支架结构基本完整,有部分丝材断裂,未见组织增生;术后15 d支架基本坍塌,大部分丝材断裂,未见组织增生;术后30 d支架完全降解,气管内壁光滑,未见组织增生;术后60 d气管内壁光滑,未见组织增生。结论镁合金支架径向支撑力稍强于Ni-Ti合金支架,金属丝易断裂,但生物相容性良好,可降低肉芽组织增生。

Objective To discuss the preparation of biodegradable magnesium alloy tracheal stent and to evaluate its safety and the feasibility in treating tracheostenosis in rabbit tracheal stenosis model. Methods Transection of trachea through tracheal cartilage was performed in 30 experimental rabbits, which was followed by artificial annular damage to the tracheal mucosa with a nylon hairbrush, in this way the rabbit tracheal stenosis model was established. Through hot extrusion and cold drawing process of magnesiumzinc-yttrium-neodymium （mg-zn-y-nd） alloy, the two types of wire with a diameter of 0.24 mm and 0.28 mm were prepared respectively. Using braided monofilament integration technology, the wire was then knitted into 8 mm^20 mm bare tracheal stents, and every 15 bare tracheal stents made from 0.24 mm and 0.28 mm were thus manufactured, their physical properties were tested. Under fluoroscopy guidance, the two kinds of stents were separately implanted into the trachea of the rabbit models with tracheal stenosis. Every three rabbits from each group were sacrificed each time at 3 days, 7 days, 15 days, one month and 2 months after the operation. The fracture of stent wire, the compression of stent, the degradation of stent and the proliferation of granulation tissue in trachea were evaluated. Results The supporting force of both the two kinds of magnesium alloy stent was slightly larger than that of the nickel titanium （Ni-Ti） alloy stent. The supporting force of the stent made from 0.28 mm wire was greater than that of the stent made from 0.24 mm wire. The mean stent expansion rate of 0.24 mm and 0.28 mm diameter wire. stents were 76.46% and 84.66% respectively. The complete-self-expanding properties of magnesium alloy stent were slightly lower than that of Ni-Ti alloy stent. At 3 days after the procedure, the stent structure was intact and no stent collapse was observed. At 7 days after the procedure, the stent structure was basically complete, fracture of partial wire could be seen, and no tissue hyperplasia was observed. At 15 days after the procedure, the stent basically collapsed, most of the wire was fractured, and still no tissue hyperplasia was observed. At 30 days after the procedure, complete degradation of the stent was observed, the inner wall of the trachea was smooth, and no tissue hyperplasia was seen. At 60 days after the procedure, the inner wall of the trachea was smooth, and no tissue hyperplasia was found. Conclusion The radial supporting force of magnesium alloy stent is slightly stronger than that of the Ni- Ti alloy stent, its metal wire is easy to break, but it has excellent biocompatibility and can depress granulation tissue hyperplasia.