Intimal Hyperplasia in an Atherosclerotic Model : Prevention with Low Dose Radiation

经皮腔内血管成形术（PTA）治疗动脉粥样硬化闭塞病变的有效性已被广泛接受。尽管其初始成功率很高，但再狭窄仍然是一个主要问题。PTA术后再狭窄主要由内膜增生引起。增生性平滑肌细胞在内膜增生过程中起重要作用。由于增殖性细胞通常对放射敏感，放射治疗可能对这个问题有用。本实验旨在探讨辐照对内膜增生的预防作用。选取动脉粥样硬化兔20只，饲喂含胆固醇饲料，分为4组，分别给予2、5、10、20 Gy的辐照。双股动脉内膜在单侧进行。对侧股动脉作为对照。1个月后行血管造影及组织学检查。2 Gy和5 Gy照射组与对照部位的内膜增生厚度无显著差异。然而，在10 gy照射组中，照射部位的内膜增生明显受到抑制。在20 gy照射组中观察到内侧变薄，但没有内膜增生，这可能导致血管造影显示的管腔扩张。放射治疗可以预防内膜增生。可能需要进一步研究辐照的最佳剂量和时间。

The usefulness of percutaneous transluminal angioplasty (PTA) for treatment of the atherosclectic occlusive lesions has been widely accepted. In spite of its high initial success rate, the restenosis remains a major problem. Restenosis after successful PTA are mainly caused by intimal hyperplasia. Proliferative smooth muscle cells play an important role in the process of intimal hyperplasia. Since proliferative cells are generally radiosensitive, radiation therapy may be useful in this issue.This experimental study was designed to investigate the effect of irradiation for prevention of intimal hyperplasia. Twenty atherosclerotic rabbits, fed with cholesterol-containing diet, were divided into four groups which were irradiated 2,5,10, and 20 Gy, respectively. The intima of both femoral arteries was performed on the unilateral side. The contralateral femoral artery served as a control. Angiograms as well as histologic specimens were obtained one month later.There were no significant differences in thickness of intimal hyperplasia beween irradiated and control sites in groups irradiated with 2 and 5 Gy. However, in a 10 Gy-irradiated group, intimal hyperplasia of the irradiated site was significantly suppressed. Medial thinning without intimal hyperplasia, which probably caused dilatation of the lumen on angiography, was observed in a 20 Gy-irradiated group. Radiation therapy may prevent intimal hyperplasia. Further investigation on the optimal dose and timing of irradiation may be needed.