Experimental Research Of The Effect Of All-trans-retinoic Acid To Inhibit Intimal Proliferation In Healing Vein Bypass Grafts

Object: To examine the effect of atRA on proliferation and apoptasis rates of smooth muscle cell in healing vein bypass grafts and in human saphenous vein organ culture.Methods:1.Autogenous vein graft model was established in 40 rats by transpjanting the internal branch of the jugular vein to the carotid artery by end-to-end anastomosis. Animals were divided into two group: atRA group and control group and received atRA(10mg/kg/d) or vehicle(corn oil) from 4 days preoperation to 10 days postoperation. Animals were killed and the grafted veins were harvested at 7^ 14 days respectively after the operation .the grafted veins were then processed for staining and measurements: average intimal thickness^ proliferating cell nuclear antigen ^ expression of bcl-2 were observed pathologically and immunohistochemically. they were analyzed by a computerized system. Apoptosis was measured by the TUNEL assay. 2. 30 segments( 1 cm) human saphenous vein were divided into 3 groups:HSV group A atRA group and control group.the human saphenous vein segments of atRA group and control group were maintained in organ culture for 14 days with either lOOuM atRA , or equivalent concentrations of pure ethanol(vehicle). All 30 segments human saphenous vein were harvested and then processed for staining and measurements intimal hyperplasia(IH) -> smooth muscle cell proliferation were observed pathologically and immunohistochemically. They were analyzed by a computerized system. The presence of apoptotic smooth muscle cell was demonstrated by TUNEL method.Results: 1.There was a significant decrease in the average intimal thickness -, proliferation and proliferation index of smooth muscle cell at 7, 14 days in the atRA group(p<0.05), intimal proliferation index has a significant decrease in the atRA group at 7 days(p<0.05) but no significant difference at 14 days(p>0.05); Apoptotic rates were significant higher in the atRA group at 7 days(p<0.05) but no significant difference at 14 days(p>0.05); There was no significant difference in expression ofbcl-2 between the groups (p>0.05) . 2.Cultured saphenous vein segments developed neointimal formation and marked smooth muscle cell proliferation. There was a significant decrease in the average intimal thickness in the atRA group. Immunohistochemical analysis of PCNA indicated decreased positive cells in the atRA group compared with the control group. Apoptosis of smooth muscle cell was highter in the atRA group than in the control group. There was no significant difference in expression of bcl-2 between atRA group and control group.Conclusion:!.These preliminary results demonstrated that atRA(10mg/kg/d) inhibits smooth muscle cell proliferation and induces smooth muscle cell apoptosis in rats; The apoptosis induced by atRA was through a pathway independent of the bcl-2 gene . 2.These preliminary results demonstrated that atRA(lOOum) inhibits smooth muscle cell proliferation and induces smooth muscle cell apoptosis in human saphenous vein organal culture.