ObjectiveAutologous vein graft is the routine operation for ischemic diseases in cardiac and vascular surgery. However , the long - term patent rate of grafted vein currently is low. The unfavorable treating effect is mainly due to restenosis and occlusion on account of intimal hyperplasia. The pivot pathologic mechanisms of intimal hyperplasia are the migration into intima and proliferation of medial smooth muscle cell( SMC). And proliferation of SMC must enter cell cycle. Cell cycle has two "check points" ;one is Gl/S phrase also called "start point" ,the other is G2/M phrase. We observed the expression of CDK2,CDK4 gene which are most important in Gl/S phrase on intimal hyperplasia in autologous grafted vein of rat and consequently study the signifance of them to intimal hyperplasia.Materials and MethodsRat autologous vein graft model was established and 50 rats were divided into five groups at random; the grafted veins were respectively harvested at the 1st,2nd,3rd,7th,14th day after operation and the normal veins as blank control of the other side were harvested at the same time. We observed the changing of intimal hyperplasia by some morphologic methods (Haematoxylin - Eosin staining and Verhoeff - Van Gieson staining) , the intimal thickness were measured by computer graph analysis system;the expression of CDK2,4 protein by immuno-histochemical staining and calculated the positive cells of CDK2,4. At last we observed the expression of CDK2 ,4 mRNA by RT - PCR and analysis the resultby computer.Results(l)The average intimal thickness of grafted vein;3 days after grafted,the intimal thickness were observed significantly, and 1 week after grafted the intimal hyperplasia of autologous grafted vein nearly reached the high point. (2)Immuno-histochemical staining of CDK2 , CDK4: There are a small quantity of positive cell in normal vein. While the positive cell in grafted vein began to increase in second day after operation and reached the peak one week after grafting. Corn-paired with the positve cells within 2 days, the difference is significant. The tendency of expression of CDK2,CDK4 protein was similar. (3)Expression of CDK2N CDK4 mRNA detected by RT - PCR:the expression of CDK2.CDK4 mRNA was more than the control (3 - actin from the second day after grafting, and peak expression of CDK2,CDK4 was from 7th day to 14th day after operation. And the difference is significance compared the expression of 7th day and 14th day with 3th days before.Conclusions(1)The intimal hyperplasia of autologous grafted vein nearly reach peak one week after operation, and the tendency of intima hyperplasia still continued. (2) The expression of CDK2,CDK4 protein and mRNA increased from early phrase after vein grafting,and reached the high point from 7 day to 14' day after operation. (3) CDK2,CDK4 gene were probably important to intimal hyperplasia of autologous grafted vein and both of them maybe the hopeful target gene to limit the develop of restenosis of autologous grafted vein. |