局部释放肝素的生物降解性支架的初步实验研究

Initial experimental study on a novel polymeric local heparin delivery stent

目的探讨携带肝素的生物降解性支架预防再狭窄的作用。方法应用已内酯和混旋丙交酯共聚物制成支架，并携带肝素，植入７只小型猪的颈动脉，观察不同时间的造影及病理改变。结果６只植入成功。植入成功者，１只因颈动脉破裂、支架内血栓形成死亡。３只动物分别于１个月（ｎ＝２）和２个月（ｎ＝１）处死，造影均未发现狭窄，光镜下仅见轻度内膜增生，扫描电镜观察支架表面已完全内皮化。２个月处死的另外２只动物造影显示狭窄，光镜下可见明显的平滑肌细胞增生。所有动物未见明显的异物反应。结论这种生物降解性支架，同时作为局部释放肝素的装置，可成功地植入颈动脉。

Objective To approach a new method for prevention of restenosis following balloon angioplasty. Methods A novel balloon expandable biodegradable stent made from copolymer of caprolactone (CL) and D, Llactide (LA) was developed, in which heparin was reserved inside. The initial experimental study was undergone in 7 mini swine carotid artery models. Angiographic and pathological changes were observed. Results stents were successfully deployed in 6 of the animals. One animal died of rupture of carotid artery and subacute thrombosis in the stent. In 3 animals no stenosis was found by angiography at 1 month (n=2) and 2 months (n=1) after the procedure, only mild neointimal proliferation was seen by light microscope (LM) and endotheliazation was observed by scanning electromicroscope (SEM). In 2 animals stenosis was detected by angiography and significant smooth muscle cell proliferation in neointima was observed by LM at 2 months. No significant reaction of foreign body was observed within 2 months. Conclusion This novel polymeric stent which also acts as a local heparin delivery device can be successfully deployed into carotid artery. It may be worthy for this device to be further improved and to be studied on its value in prevention of balloon angioplasty restenosis.