837. Colon-Directed Delivery of Viral Vectors Using Virus-Microbead Conjugates for Gene Therapy of Inflammatory Bowel Disease

Abstract

In the course of the last few years, we have developed a novel gene transfer technology that allows for safe and efficient delivery of recombinant viral vectors to target sites for gene therapy applications. In this technology, viral particles are attached stably to the surfaces of microbeads and then delivered to target sites in the form of virus-microbead conjugates. Such conjugates can infect cells at efficiencies equivalent to or even greater than free viral vectors. In particular, the transduction of target cells, which are poorly permissive to infection by free viral vectors, can be considerably enhanced, providing the attached viral vectors with broader tropism. This gene transfer technology is currently being used to develop a gene transfer strategy for inflammatory bowel disease (IBD). By using an adenoviral vector carrying the gene for a potent anti- inflammatory factor, interleukin-10 (IL-10), we are asking if the adenoviral vector could be delivered to inflamed lesions in the colon upon intra-colonical administration of virus-microbead conjugates by enema and if this could raise local IL-10 levels in the colon for the amelioration of colitis. We have demonstrated by using mouse colitis models that intra-colonical administration of adenoviral vectors carrying the mouse IL-10 gene in the form of virus-microbead conjugates provided enhanced amelioration of colitis over the same adenoviral vectors that were administered in free form. This greater effectiveness for the amelioration of colitis is derived, primarily, from enhanced transduction of colonic tissue and subsequent high- level production of IL-10 locally in the inflamed colon. We have also initiated a study to test if adeno-associated viral vectors (AAV) could be used in the form of virus-microbead conjugates for their focused delivery to inflamed lesions in the colon. Experiments using AAV carrying a marker gene suggest that the use of virus-microbead conjugates can enhance the transduction of colonic tissue by AAV in a mouse colitis model. We are now asking if intra-colonical administration of AAV carrying the mouse IL-10 gene in the form of virus-microbead conjugates could raise local IL-10 levels for the amelioration of colitis by efficient transduction of the inflamed colon. These results suggest the potential for this gene transfer technology to serve as an effective gene therapy strategy for IBD. A clear advantage of this technology over other virus-mediated gene transfer strategies for the therapy of IBD, including those involving systemic delivery of viral vectors, is that the delivery of viral vectors and subsequent production of IL-10 (or other therapeutic proteins) is focused at inflamed lesions. In addition, since all viral particles are anchored stably to microbeads, uncontrolled delivery of viral vectors to and subsequent transduction of other organs should be minimized. These characteristics should not only maximize the therapeutic effectiveness but also enhance the safety of the use of viral vectors.