Background — Ischemia and oxidative stress are the leading mechanisms for tissue injury. An ideal strategy for preventive/protective therapy would be to develop an approach that could confer long-term transgene expression and, consequently, tissue protection from repeated ischemia/reperfusion injury with a single administration of a therapeutic gene. In the present study, we used recombinant adeno-associated virus (rAAV) as a vector for direct delivery of the cytoprotective gene heme oxygenase-1 (HO-1) into the rat myocardium, with the purpose of evaluating this strategy as a therapeutic approach for long-term protection from ischemia-induced myocardial injury. Methods and Results — Human HO-1 gene (hHO-1) was delivered to normal rat hearts by intramyocardial injection. AAV-mediated transfer of the hHO-1 gene 8 weeks before acute coronary artery ligation and release led to a dramatic reduction (>75%) in left ventricular myocardial infarction. The reduction in infarct size was accompanied by decreases in myocardial lipid peroxidation and in proapoptotic Bax and proinflammatory interleukin-1β protein abundance, concomitant with an increase in antiapoptotic Bcl-2 protein level. This suggested that the transgene exerts its cardioprotective effects in part by reducing oxidative stress and associated inflammation and apoptotic cell death. Conclusions — This study documents the beneficial therapeutic effect of rAAV-mediated transfer, before myocardial injury, of a cytoprotective gene that confers long-term myocardial protection from ischemia/reperfusion injury. Our data suggest that this novel “pre-event” gene transfer approach may provide sustained tissue protection from future repeated episodes of injury and may be beneficial as preventive therapy for patients with or at risk of developing coronary ischemic events.

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.

Both retro- and adenovirus-mediated gene therapy have been suggested as a novel approach to the treatment of malignant brain tumors. However, little information is available about the gene transfer efficiency in human malignant glioma in vivo. We compared the feasibility and safety of retrovirus- and adenovirus-mediated beta-galactosidase gene transfer in human malignant glioma. Beta-galactosidase gene was transferred to 10 patients with malignant glioma via a catheter inserted into the tumor. The catheter was left in place until the tumor resection. To maximize gene transfer efficiency, gene transfer vectors (BAG retroviruses, titer, 6 x 10(5) CFU; and adenoviruses, titer from 3 x 10(8) to 3 x 10(10) PFU) were injected into the tumor via the catheter once a day for three consecutive days, followed by tumor resection 1-2 days later. Tumor was resected in such a way that the catheter was still in place inside the tumor, which permitted accurate histological analysis of the transduced tumors. X-Gal staining for beta-galactosidase activity was used to study gene transfer efficiency and distribution of the marker gene. Beta-galactosidase gene transfer was well tolerated with both vectors. Except for two patients with clear increases in serum adenovirus antibody titers, no adverse tissue responses or systemic complications were noticed in any of the patients. Gene transfer was successful in all patients. Gene transfer efficiency varied between <0.01 and 4% with retroviruses and between <0.01 and 11% with adenoviruses. However, the transgene activity was not evenly distributed in the tumors. Both glioma cells and endothelium in the tumor blood vessels were transduced with retro- and adenovirus vectors. In conclusion, the safety and feasibility of in vivo gene transfer to human malignant glioma was established with retro- and adenovirus vectors. Adenoviruses were more efficient than retroviruses in achieving in vivo gene transfer. Transduction of endothelial cells may have important consequences for the proposed treatment strategies and selection of treatment genes. The results justify clinical gene therapy trials for malignant glioma.

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.