90Sr血管内照射防治内膜损伤后再狭窄

目的研究常规治疗剂量和高剂量99Sr照射对血管壁平滑肌的生物学效应.方法18只新西兰兔分为3组,行髂动脉内膜剥脱术后,12只用90Sr后装技术行血管内照射,距放射源中心轴线2 mm深度血管壁吸收剂量分别为16和50Gy,6只未行血管内照射治疗作为对照组.28 d后处死动物进行组织病理学分析.结果50Gy组血管中层组织为类内皮样细胞所覆盖,其血栓发生率(3/6只)高于对照组(0/6只)和16Gy组(1/6只).16Gy组狭窄指数、增殖指数、增殖细胞核抗原阳性率和凋亡细胞阳性率与对照组比较差异有显著性.50Gy组狭窄指数、增殖指数与对照组和16Gy组比较,差异均有显著性.结论16Gy组血管内膜增生受到明显抑制,剂量增加到50Gy时,内膜增生现象完全受到抑制,除血栓发生率较高外,未见其他如假性动脉瘤等血管严重并发症.

Endovascular brachytherapy for the prevention of neointimal hyperplasia with 90 Sr seeds afterloading system in a rabbit restenosis model

Objective To evaluate the dose effect of intravascular radiation on the smooth muscle cells (SMCs) of arterial wall with an encapsulated 90Sr seeds afterloading system. Methods 18 rabbits were divided into three groups. In 12 rabbits, after endothelial denudation of one of the iliac artery randomly with 2.5 mm-balloon catheter, intravascular irradiation was performed with 90Sr seeds through afterloading using different dosages (16, 50 Gy at 2 mm from central axis of the radiation source). The control group was other 6 rabbits without intravascular irradiation. Then, 28 d after intervention, all of the rabbits were sacrificed and the vessels were excised with morphologic examinations. Results The thrombotic rate in 50 Gy group (3/6) was higher than that of control (0/6) and 16 Gy (1/6) groups. Additionally, in 50 Gy group, the media layer of vessel was covered by endothelium-like cells. Whereas in 16 Gy group, the indexes of stenosis and proliferation, the rate of SMCs proliferating cell nuclear antigen and apoptosis differed significantly from control. The indexes of stenosis, proliferation in 50 Gy group compared with the control and 16 Gy groups also showed significantly different. Conclusion The result demonstrated that neointimal proliferation was markedly depressed after 16 Gy irradiation, and was completely inhibited after 50 Gy irradiation. Aside from the high thrombotic rates, severe complications such as fibrosis, aneurysm formation and necrosis were not revealed.