经外膜缓释雷帕霉素抑制兔同种异体移植血管内膜增生的研究

目的：探讨雷帕霉素抑制血管移植后再狭窄的作用机制.方法：健康雄性新西兰大耳白兔36只,随机选取其中18只切取腹主动脉,经20%甲醛浸泡48 h去除抗原活性.另18只动物随机分为3组,腹主动脉移植去抗原同种异体腹主动脉后给予不同处理.A组：血管移植后不予处理;B组：在移植血管外膜及吻合口周围涂抹20% pluronic F-127多聚凝胶0.5 ml;C组：在相同部位涂抹含0.5 mg雷帕霉素的20% pluronic F-127多聚凝胶0.5 ml.术后4周获取移植血管,HE染色观察移植血管内膜增生情况,计算机图像分析系统测量移植血管内膜厚度,免疫组化SP法检测移植血管α-actin、PCNA和p27kip1的表达.结果：术后4周,A、B组较C组内膜增生明显（P＜0.05）.增生的血管内膜均可见类似于血管平滑肌的α-actin阳性表达.各组移植血管增生的内膜均可见不同程度的PCNA、p27kip1阳性表达.C组α-actin和PCNA的表达较A、B组明显降低（P＜0.05）,而p27kip1的表达较A、B组明显增多（P＜0.05）.结论：对20% pluronic F-127多聚凝胶携带雷帕霉素涂抹移植血管外膜可有效抑制移植血管平滑肌细胞增殖.雷帕霉素抑制移植血管再狭窄的机制与其上调移植血管组织中p27kip1的表达而使细胞增殖周期受抑有关.

Study of slow-releasing rapamycin on adventitia in inhibiting intima hyperplasia of vascular grafts in rabbits

Objective：To investigate the mechanism of rapamycin on inhibition of restenosis of vascular grafts on infrarenal abdominal aorta in rabbit. Methods：Thirty-six healthy male New Zealand rabbits were used in the stud- y. Abdominal aortae were removed from 18 rabbits,and their antigenicity was eliminated by immersing in 20% formalin for 24 hours. Another group of 18 rabbits received transplantation of antigencity removed allogenic aorta. They were divided into three groups： group A received no treatment after transplantation. Rabbits in group B, 0. 5 ml 20% pluronic F-127 gel was locally applied to the adventitia of the grafts and around the anastomoses. In group C, 0.5ml 20% pluronic F-127 gel containing 0.5 mg rapamycin was locally applied to the adventitia of the grafts and anastomosis. The grafts were harvested 4 weeks after anastomosis. Hyplasia of the intima was observed under the microscope. The thickness of intima of the grafts was measured by electronic imaging system to estimate the degree of intima hyperplasia. The expression of α-actin, proliferating cell nuclear antigen （PCNA） and p27kipl of grafts were assessed by immunohistochemistvy. Results： Four weeks after the operation, the intima of the grafts in group A and B was thickened obviously （P〈0.05） compared with group C. The expression of α-actin was positive in the hyperplastic intima, similar to that found in the smooth muscle cells of blood vessels. PCNA and p27kip1 were positively expressed in the thickened intima of the grafts of all the groups in difference extent. Compared to the group A and B, the expression of α-actin and PCNA in group C were remarkably inhibited （P〈0.05）, while the expression of p27klpl was remarkably enhanced （P〈0.05）. Conclusions.. Smearing of rapamycin and pluronic F-127 gel on graft adventitia of vascular grafts can effectively inhibit hyperplasia of vascular smooth muscle cells, the mechanism of which may be related to the increase in p27kip1 expression, which induces inhibition of cell generation cycle.