IN VIVO CUTANEOUS GENE THERAPY

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The long-term objective of this research is to develop cutaneous gene therapy for inherited dermatological disorders. Currently, the most favored approach is ex vivo gene transfer followed by transplantation of the gene-modified cells back to the donor. This procedure is costly, time consuming and will require full thickness excision at the graft site. In addition, this surgery will result in scarring and contracture and ultimately limit the area that can be treated. A preferred alternative would be in vivo gene transfer whereby new genetic material is introduced directly into the epidermis. As a postdoctoral research associate I succeeded in developing a mouse model for in vivo transduction of skin using retroviral vectors. Following dermabrasion, the re-epithelializing surface was transduced directly with high titer retroviruses. In immunodeficient mice and transgenic mice tolerant to the transgene product (beta-gal), long term expression was noted (40 weeks). However, in normal mice, expression was lost by three weeks post-transduction. Preliminary studies showed a correlation between presence of transgene-specific immunological responses and duration of transgene expression. Additional evidence obtained with cells in culture suggested that retrovirus-directed transgene expression could be modulated by cytokines such as interferons. This proposal sets forth a plan to determine whether immune-mediated loss of transgene expression results from inhibition of expression or cytolysis of transduced cells; to characterize the responsible immune responses; and finally use this knowledge to design vectors to circumvent the immune responses to the transgene. Strategies proposed include the vectors that in addition to the transgene, express an anti-sense RNA complementary to beta2-microglobulin to inhibit MHC class I expression or encode immunosuppressive cytokines gene (e.g. IL-10). Development of a vector that circumvents the immune responses to the transgene would overcome a major obstacle to clinical application of gene therapy.