Beta irradiation inhibits neointimal formation in vein grafts

Objective The study was to evaluate the effect of beta irradiation on intimal proliferation response in vein grafts. Methods An autogenous vein graft model was established in 40 rats by transplanting internal branch of jugular vein to carotid artery by end\|to\|end anastomosis.The vein was irradiated by 32 P before anastomosis.Four dose schedules were studied:(1) control graft(nonirradiated);(2) irradiated with 8 Gy;(3) 18 Gy;and (4) 36 Gy.The grafted veins were harvested at 2 weeks after the operation.IH (intimal hyperplasia) and SMC (smooth muscle cell) proliferation were histologically and immunohistochemically observed and analyzed by a computer digitalizing system. Results In 18 Gy and 36 Gy \|irradiated grafts compared with the control,there was a significant decrease in the average intimal thickness ( P 0 05).There was no significant difference between the two irradiation groups ( P 0 05).Immunohistochemical analysis of PCNA indicated decrease of positive cells in both 18 Gy and 36 Gy groups compared with 8 Gy and the control group ( P 0 01).There was no significant difference between 18 Gy and 36 Gy ( P 0 05) groups,and there was also no significant difference between 8 Gy and the control group ( P 0 05). Conclusion These preliminary results demonstrate that proper dose of beta irradiation in vein graft inhibits smooth muscle cells proliferation and neointimal hyperplasia in rat.\;