Objective: To study the effects of fusion gene encoding the hVEGF(165) and fused hirudin on restenosis of injured carotid artery.
Methods: A fusion gene encoding hVEGF(165) and fused hirudin (hVEGF(165)-FH) was constructed and clone into the eukaryotic expression vector pcDNA3.0, thus constructing the plasmid VEGF(165)-FH/pcDNA3.0. Its activities to stimulate endothelial cell proliferation and to inhibit thrombosis were identified. Sixteen New Zealand rabbits underwent ligation of external carotid artery and a balloon was inserted into the common carotid artery for 30 minutes so as to construct model of restenosis of injured carotid artery. Then the rabbits were randomly divided into 4 equal groups. In the one-week and 3-week control groups, 400 microg of DNA of the plasmid pcDNA3.0 were transfused into the arterial lumen at the injured part immediately after the angioplasty, and 400 microg of DNA of the plasmid VEGF(165)-FH/pcDNA3.0 were transfused in the 1-week and 3-week experimental groups. One week and 3 weeks after the treatment peripheral blood samples were collected to detect the activated partial thromboplastin time (APTT), thrombin time (TT), and platelet aggregation rate, and then the rabbits underwent angiography to observe the situation of restenosis. Then the rabbits were killed to take out the injured part of artery to undergo pathological examination and Western blotting.
Results: The values of APTT, TT, and platelet aggregation rate were not significantly different among the 4 groups. Angiography conducted 1 and 3 weeks later showed that restenosis was significantly mild in the 2 experimental groups in comparison with the 2 control groups, and severe restenosis was seen in the 3-week control group. Western blotting showed that expression of specific fused protein could be found in the 1-week and 3-week experimental group, the amount of the latter group being less than that of the former group; however, no expression of specific fused protein was found in the 2 control groups. Pathological examination showed that the narrowing of lumen 1-week and 3-week experimental groups were 11.50% and 19.75%, both significantly milder than those of the 1-week and 3-week control groups (33.25% and 52.25% respectively, both f P < 0.05). VB staining showed that the (intima/media (I/M) ratio of the 1-week and 3-week experimental groups were 0.12 and 0.35 respectively, both significantly lower than those of the 2 control groups (0.50 and 1.07 respectively, both P < 0.05).
Conclusion: Accelerating re-endothelialization and inhibiting thrombosis, the fused gene hVEGF(165)-FH effectively prevents restenosis after angioplasty, On the basis of endothelial repair, construction of fused genes with double even multiple targets may be a novel and potential therapeutic approach for restenosis after percutaneous coronary intervention.