Thickening of the arterial intima and smooth muscle cell (SMC) proliferation remain major problems after vascular surgery and other types of vascular manipulations. We studied the effect of endothelial cell (EC)-specific vascular endothelial growth factor (VEGF) gene transfer on the thickening of the intima using a silicone collar inserted around carotid arteries that acted both as the agent that caused intimal SMC growth and as a reservoir for the transfected gene. The model preserved EC integrity and permitted direct extravascular gene transfer without any intravascular manipulation. Compared to beta-galactosidase (lacZ)-transfected control arteries, plasmid/liposome-mediated VEGF gene transfer significantly reduced intimal thickening 1 week after the gene transfer. Administration to the experimental animals of the nitric oxide (NO) synthase inhibitor L-NAME abolished the difference in intimal thickening between VEGF and lacZ-transfected arteries. Furthermore, VEGF caused NO release from cultured human umbilical vein EC. It is concluded that extravascular VEGF gene transfer attenuates intimal growth and could be useful for the prevention of intimal thickening during vascular surgery. Our results further suggest that VEGF may reduce SMC proliferation via a mechanism that involves VEGF-induced NO production from the endothelium.
Arterial gene transfer offers a promising new approach for the treatment of vascular disorders. However, no data are available about the gene transfer efficiency in human arteries in vivo. The aim of this study was to evaluate the safety and feasibility of catheter-mediated adenoviral gene transfer in human peripheral arteries. Ten patients (8 females, 2 males, mean age 80 +/- 8 years) suffering from chronic critical leg ischemia with a prior decision for amputation were recruited in the study. Gene transfer was performed in eight patients in conjunction with a conventional percutaneous transluminal angioplasty, using a perfusion coil balloon catheter. Two patients served as controls. Increasing concentrations of replication-deficient adenoviruses (titers from 1 x 10(8) to 4 x 10(10) PFU) containing a nuclear-targeted beta-galactosidase marker gene were administered into the arteries over 10 min via the catheter. Amputations were performed 20 to 51 hr after the procedures and gene transfer efficiency was evaluated in the transduced arteries using X-Gal staining for beta-galactosidase activity. Beta-galactosidase gene transfer was well tolerated and no adverse tissue responses or systemic complications were observed in any of the patients. Gene transfer was successful in six of the eight patients. Gene transfer efficiency varied between 0.04 and 5.0% of all arterial cells. Transgene expression was detected in smooth muscle cells, endothelial cells, and macrophages and in tunica adventitia. However, transgene activity was not evenly distributed in the arterial wall and no transgene activity was found beneath advanced atherosclerotic lesions. The safety and feasibility of in vivo gene transfer by adenoviral vectors to human peripheral arteries were established. Although improvements are still required in gene transfer efficiency, these findings suggest that adenoviruses can be used to deliver therapeutically active genes into human arteries.
We studied the efficiency of plasmid/liposome complexes, Moloney murine leukemia virus-derived (MMLV) retroviruses, pseudotyped vesicular stomatitis virus protein-G (VSV-G)-containing retroviruses, and adenoviruses in delivering genes into the rabbit carotid artery using a silastic collar applied to the adventitia. This method was used for gene transfer because (a) it provides a gene delivery reservoir; (b) no intraluminal manipulations are performed; (c) installation of the collar induces arterial smooth muscle cell (SMC) proliferation and enhances retroviral gene transfer efficiency where target cell proliferation is required. The transfer of the beta-galactosidase (lacZ) marker gene to the adventitia and media occurred with all gene transfer systems. Adenoviruses also transferred the beta-galactosidase gene to some endothelial cells. After 5 days, adenoviral vectors produced the highest gene transfer efficiency with up to 10%+/-6% of cells showing beta-galactosidase activity. Pseudotyped VSV-G retroviruses were also effective in achieving gene transfer in 0.05%+/-0.03% of cells in the adventitia and media. Plasmid/liposome complexes and MMLV retroviruses infected 0.05%+/-0.03% and <0.01%+/-0.01% of cells, respectively. It is concluded that replication-deficient adenoviruses, VSV-G pseudotyped retroviruses, and plasmid/liposome complexes can be used for gene transfer to the arterial wall using the collar method. Because the endothelium remains anatomically present throughout the experiments, the model may be useful for the gene transfer studies involving diffusible or secreted gene products that primarily act on the endothelium. Effects on medial SMC and even endothelium can be achieved from the adventitial side, suggesting an alternative route for the delivery of therapeutically useful genes into the arterial wall.
Lentiviral vectors encoding rabbit low-density lipoprotein receptor (LDLR) or green fluorescent protein (GFP) under the control of a liver-specific promoter (LSP) were used for intraportal gene transfer into the liver of hypercholesterolemic LDLR-deficient Watanabe Heritable Hyperlipidemic rabbits. In vitro cell culture analysis demonstrated functionality of the LSP-LDLR vector in mediating increased degradation of LDL in transduced liver cells. Twenty-five rabbits were each injected with 1 x 10(9) infectious virus particles into the portal vein. Liver biopsy samples were collected 4 weeks after the gene transfer and the rabbits were followed up for 2 years. Histological and RT-PCR analyses showed the expression of GFP and LDLR transgenes in the biopsy samples. Clinical chemistry and histological analyses revealed normal liver function and morphology during the 2-year follow-up with no safety issues. LSP-LDLR-treated rabbits demonstrated an average of 14 +/- 7% decrease in serum cholesterol levels during the first 4 weeks, 44 +/- 8% decrease at 1 year, and 34 +/- 10% decrease at the 2-year time point compared to the control rabbits. This study demonstrates the safety and potential benefits of the third-generation liver-specific lentiviral vectors in the treatment of familial hypercholesterolemia using direct intraportal liver gene therapy without the need for liver resection.
In this study we report an improved method for in vivo gene A 50% decrease was also observed in plasma triglycertransfer to liver. Repeated injections of Moloney murine ides. Liver function tests indicated a transient increase in leukemia virus-derived retroviruses containing LDL recepplasma alkaline phosphatase level up to 12 weeks after tor cDNA were given to the portal vein in combination with the gene transfer. In situ PCR and RT-PCR analyses india 10% partial liver resection and stimulation of hepatocyte cated that the transgene was present in periportal areas proliferation by plasmid/liposome-mediated thymidine kinand was transcribed to mRNA 1 week after the gene transase gene transfer and ganciclovir treatment. The method fer. Because of the relatively simple and controllable techwas used for the treatment of LDL receptor deficiency in nique we suggest that repeated retrovirus injections via a Watanabe heritable hyperlipidemic rabbits. We demonportal vein catheter together with the limited partial liver strate an increase in hepatocyte proliferation index by thyresection and plasmid/liposome-mediated thymidine kinmidine kinase and ganciclovir treatment from 0.9 to 1.35% ase gene transfer-ganciclovir treatment may be used and a maximum of 35% decrease in total plasma cholesto improve the results of retrovirus-mediated liver gene terol level 2-3 months after the gene transfer. A 20% therapy. decline was still present after a 52-week follow-up period.
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