Treatment For Restenosis Of Vein Grafts Using The System Including A Replication-defective Recombinant Adenovirus Vector Containing CMV Promotor And Escherichia Coli Cytosine Deaminase Gene

Coronary artery bypass graft is one of the most important method to treat coronary diseases. Autologous vein continues to be the most commonly used conduit. But the long-term patency remains very low, about 50% after grafts have been implanted for 10 years. Intimal hyperplasia due to the immigration and proliferation of smooth muscle cells is considered as one of the main causes of restenosis. The development of gene therapy make it possible to treat restenosis using virus directed enzyme prodrug therapy. It is know that the product of Escherichia coli cytosine deaminase gene can phosphorylate the non-toxic prodrug-5-fluro-cytosine to form a nucleoside analog-5-flurourail which is one of the most potent cytotoxic drug and can inhibit the proliferation of the proliferation of the smooth muscle cells. Moreover, through a mechanism termed as bystander effect, the proliferation of the adjacent cells which are not transfected by CD gene can also be inhibited by 5-FC. hi this experiment, the rein grafts are transfected with a replication-defective adenoviral vector containing CD gene driven by CMV promoter, and 5-FC are concomitant administrated in order to evaluate the effect of CD/5FC suicide system on the intimal hyperplasia of the bypass graft.Aim: To evaluate the therapy effect of CD/5-FC suicide gene system on therestenosis after the operation of coronary artery vascular by-pass graft.Method: The supernatant containing AdCMVCD is injected to the rabbit external jugular vein after upstream and occlusion downstream. After 30 min, this vein segment was implanted to the carotid of common side using the cuff technique. The untreated vein graft and AdCMVlacz transfected vein graft were used as control. Four-weeks later the vein grafts were isolated and the transfection efficiency were evaluated by RT-PCR and the quantification of the activity of 3 -Lac. Morphological changes of the SMC were observed under light microscope and transmission electron microscope. The diameter, area of vessel cavities, intima and media, were assayed quantitatively and the relative cavity lose rates were calculated. The inhibition effects on the intima and media were accessed using statistics methods.Result:1. Gene transfection with adenoviral vector is very effective and reliable.2. Comparing with the control group, the area of intima and media of the AdCMVCD group is significant small and the relative cavity lose rates decreased. (AdCMVCD group 3.68+0.42%; control group 9.68 + 0.4%, P<0.01).3. The relative cavities lose rate, area of intima and media of the AdCMVLacz group is higher than the control group.Conclusion: Our experiment shows that AdcMVCD suicide gene therapy system is so effective that is can be used to treat the restenosis of the coronary artery bypass graft.