| Auto vein graft has been the most commonly used as a bypass conduit for patients who undergo coronary and other peripheral arterial revascularization but by 10 years after the bypass graft operation, 40% to 60% of the grafts may occlude. The occlusion of the graft principally results from intimal hyperplasia, which is considered to result from migration and proliferation of intimal SMCs o-riginating from the media. Because smooth muscle cell replication plays a central role in the pathogenesis, a method to selectively eliminate dividing cells is to express a herpesvirus thymidine kinase gene, which phosphorylates the nucleo-side analogue ganciclovir into a toxic form that selectively leads to proliferating cell death. This method has been studied to therapy tumor or restenosis of arter-y. The purpose of this study was to investigate the effects of suicide gene therapy on vein SMCs proliferation and whether the intimal hyperplasia of cultured sa-phenous veins could be inhibited by local expression of a TK gene followed by ganciclovir administration.MethodThis study was firstly to investigate the efficiency, cellular targets, time curve of expression of mark gene after adenovirus - mediated transfer of gene into human saphenous veins ex vivo and rat vein grafts in vivo. The veins were obtained from patients and soaked in buffer liquid containing AdCMV. LacZ for different time. For improving the transgene efficiency longitudinal stretch and super physiological pressure were used. At the time points segments of vein were col-lected. Auto vein graft model was developed in Wister rats. Adenovirus vector carried LacZ gene dwelled in cervical veins for 30min. Blood fluid was restored in control group by relaxing the camps and vein grafts were transplanted into carotid system in experimental group. On the 3rd, 14th, 21st day after organ culture , samples were collected. Permeability of vessel walls was observed by scanning electron microscope. Histochemistry examination was performed. The samples carried out stains of HE, various immunohistochemistry or X - gal stain. The cells in the vein were qualified and indexes of gene transfer efficiency were compared among groups. VG and PCNA stains were carried out to study the increase of IH and medial SMC proliferation by a computer - assisted analysis. After 2 days of adenovirus - mediated gene transfer of thymidine kinase in cultured human saphenous veins or vein graft of rats, the existent of TK gene in the tissue of veins was studied using PCR and in situ hybridization . Add GCV to culture media or infused GCV to rats and observe changes in intimal hyperplasia of veins at day 14. The control group was transferred with Lacz gene and studied by histo-chemical stain to observe the efficacy of gene transferResultsAdenovirus vector could transfer the mark gene ( LacZ gene) into cultured veins and transplanting veins efficiently. Endothelium and SMCs could be the target cell of Adenovirus vector. Transgene efficacy had a positive relation with incubation time. SMCs were difficult to be transfected. In the experiment the longitudinal stretch and high press infusion were used to promote the transgene efficacy without denution of endothelium. After vein grafts transferred by Adenovirus carried LacZ, the galactosidase activity was studied at 3,14 and 21 days. Adenovirus vector could transfer LacZ into SMCs efficiently at day 3. Vein grafts expressed 1C AM - 1, VCAM - 1 obviously vs. normal veins into which gene was transferred. There was an inflammation reaction which led to endothelium lose. The activity of galactosidase in vein grafts reduced to 70% of normal transgene veins. At day 14 xenon gene expression was reduced especially in transplantingveins. At postopration day 21, galactosidase activities were undetective in all veins. The lose of endothelium may be the cause of reduction of transgene expression. The xenon gene expression retained for a relatively long time in SMCs. Intimal thickening is obviously in normal cultured human saphenous veins and t...
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