Endovascular irradiation prevents smooth muscle cell proliferation and neointimal hyperplasia in rabbits.

The present study examined the temporal responses and the efficacy of 192Ir-HDR endovascular irradiation for preventing smooth muscle cell proliferation of rabbit iliac arteries after PTA with a cutting balloon catheter. Endovascular irradiation with 12 Gy was randomly performed on the one side of iliac arterial segment with the unirradiated side serving as a control. Animals were euthanatized 1, 2, 3, 4, 8 and 12 week(s) after angioplasty. Histopathological and immunohistochemical studies were carried out. Histopathology showed repair of the dissection by cellular accumulation and a striking reduction in the amount of neointimal hyperplasia in the irradiated arteries as compared with control vessels. A peak of PCNA-positive ratio was in neointima of the control arterial segments at a week. 2-4 weeks after irradiation, the neointimal PCNA-positive ratio was still significantly increased in the control arterial segments compared with the irradiated arterial segments. After 8 weeks, PCNA-positive ratio was below 1% in both irradiated arterial segments and the control. Our results showed that the 192Ir-HDR afterloading irradiation with a dose of 12 Gy can be considered sufficient for inhibiting neointimal hyperplasia in angioplastized rabbit iliac arteries with cutting balloon catheter.