Gene therapy methods in cardiovascular diseases

Local gene transfer into the vascular wall offers a promising alternative to treat atherosclerosis-related diseases. Blood vessels are among the easiest targets for gene therapy because of percutaneous, catheter-based treatment methods. On the other hand, gene transfer to the artery wall can also be accomplished from adventitia either by ex vivo gene transfer and implantation of transfected cells or by direct in vivo gene transfer methods. In the future, as the pathological processes in arteries are better understood, several therapeutic genes could be combined and these "gene cocktails" are expected to produce enhanced therapeutic effects in vascular gene therapy. We have developed a new, efficient technique for performing ex vivo gene transfer to rabbit arterial wall using autologous SMC. The cells were harvested from rabbit ear artery, transfected in vitro with VSV-G pseudotyped lacZ retrovirus, and returned back to the adventitial surface of the carotid artery using a silicone collar or collagen sheet placed around the artery. The transduced SMCs implanted with a high efficiency and expressed beta-galactosidase marker gene at a very high level 7 days and 14 days after the operation. The level of lacZ expression decreased thereafter, but was still easily detectable for at least 6 months and was exclusively localized to the site of cell implantation inside the collar. Development of new vectors, such as baculovirus, for gene transfer will provide targeted, efficient, and safer methods for gene delivery. Plasmids and viruses coding for more than one protein, and bearing regulatory elements, would be useful for future gene therapy applications. Also, constructing second-generation viruses that contain fewer endogenous genes in their genome may reduce immunological reactions caused by the first-generation adenoviruses. In conditions where stable expression of therapeutic proteins is needed, it is necessary to develop better ex vivo and in vivo gene transfer strategies. Also, production of viruses that can efficiently transfect nondividing cells will be important for future applications of vascular gene therapy. However, current knowledge from vascular gene transfer experiments strongly suggests that vascular gene transfer is a promising new alternative for the treatment of cardiovascular diseases.