负载VEGF聚合物修饰铂金微弹簧圈栓塞动脉瘤模型的研究

Affection of embolism on rat aneurysm model with new platinum coils modified by VEGF

目的 探讨负载血管内皮生长因子（VEGF）的聚合物修饰铂金微弹簧圈对动脉瘤的栓塞效果. 方法 健康雌性SD大鼠54只采用随机数字表法分为普通铂金微弹簧罔组、聚合物涂层修饰组和负载VEGF组,每组各18只.分别将各组弹簧圈片断植入大鼠右侧颈总动脉,在弹簧圈远端将颈总动脉结扎后恢复血流,则颈总动脉残端形成囊状动脉瘤,弹簧圈片断位于动脉瘤囊内.于术后15d、30 d和90 d每组取6只大鼠,将包含有弹簧圈的一段动脉切下,同时切取普通铂金微弹簧圈组大鼠左侧一段颈总动脉作为空白对照组.HE染色观察标本内皮细胞的增殖和纤维化程度；免疫组织化学染色检测血管性假血友病因子（vwf）的表达；Western blotting检测动脉瘤局部VEGF的释放情况. 结果 术后10d、30 d、90 d时负载VEGF组动脉瘤组织纤维化分级明显高于普通铂金微弹簧圈组,术后30d时负载VEGF组纤维化分级高于聚合物涂层修饰组,差异均有统计学意义（P＜0.05）；免疫组织化学染色检测显示负载VEGF组铂金微弹簧圈在栓塞动脉瘤模型后很快形成血栓并机化,动脉瘤腔内完全被纤维化的组织填塞,并且纤维化的组织中有呈vwf阳性表达的新生小血管形成,另外3组均未观察到vwf呈阳性表达的新生血管；Western blotting结果显示负载VEGF组在术后15d、30 d时动脉瘤壁组织中VEGF因子水平明显高于其他组,而90 d时VEGF因子水平明显低于其他组. 结论 负载VEGF的聚合物修饰铂金微弹簧圈可在动脉瘤腔内缓慢释放VEGF,刺激动脉瘤内细胞增生,促进血栓机化,形成致密的纤维化组织,达到更快、更完全地闭塞动脉瘤的效果.

Objective To explore the embolization effect of new platinum coils coated with [4COOH-P （DLLA-co-TMC）] biodegradable polymer and released vascular endothelial growth factor （VEGF） into intracranial aneurysms on rat intracranial aneurysms. Methods A total of 54 adult healthy female SD rats were randomly divided into Group Ⅰ with general platinum coils, Group Ⅱ with polymer-coated platinum coils and Group Ⅲ with platinum coils modified with VEGF （n=18）.The right common carotid arteries （CCA） of rats in each group were exposed; and the 8 mm lengths of platinum coil segments were inserted into the ligated right CCA of rats. The distal right CCA was performed ligation and restored the blood flow; 6 rats each time at 15,30 and 90 d after the surgery were chosen;and the distal right CCA was used as aneurysm models,and the left CCA without the coil placement or surgical disruption in Group I with general platinum coil was chosen as normal control.The proliferation and fibrosis of endothelial cells were observed by HE staining; von Willebrand Factor （vWF） expression was detected by immunohistochemical staining; and VEGF expression was examined by Western blotting. Results Cellular proliferation and fibrosis in Group Ⅲ with platinum coils modified with VEGF enjoyed significantly higher grade than those in Group Ⅰ with general platinum coils 10,60 and 90d after the surgery （P〈0.05）; Cellular proliferation and fibrosis in Group Ⅲ with platinum coils modified with VEGF enjoyed significantly higher grades than those in Group Ⅱ with polymer-coated platinum coils 30 d after the surgery （P〈0.05）.Pathological observations showed that the massive intimal hyperplasia and substantial clot completely occluded the aneurysm lumen in Group Ⅲ with platinum coils modified with VEGF; New small blood vessels having vwf-positive expression were noted in the fiberized tissues;the thrombosis in Group Ⅰ with general platinum coils and Group Ⅱ with polymer-coat platinum coils were not fully organized and showed loose hyperplasia structure with a large number of internal spaces.Western blotting indicated that the VEGF level in Group Ⅲ with platinum coils modified with VEGF were significantly higher than that in other groups 15 and 30 d after the operation,however,the VEGF level in Group Ⅲ with platinum coils modified with VEGF 90 d after the surgery was decreased because the lumen completed fibration and degradation of 4COOH-P （DLLA-co-TMC）. Conclusion The VEGF-eontaining biodegradable polymer,by slowly releasing VEGF to modify the surface of platinum coils, could enhance the cellular proliferation, thrombosis and formation of dense fibrous tissue in aneurysm lumen; as compared with general platinum coils,these new platinum coils could occlude the rat aneurysm faster and more completely.