The delivery of cytokines into the subretinal space may play an important role in the treatment of retinal degenerative diseases such as age related macular degeneration and certain forms of retinitis pigmentosa. These diseases, which constitute the leading cause of adult onset blindness spring from a variety of genetic sources, and have few available treatment options. Transplantation of retinal cells, as well as delivery of genes to restore lost function are currently being investigated both in the laboratory and clinical setting as possible treatments. This proposal combines elements of both procedures with the goal of long-term drug delivery into the subretinal space. Preliminary research has shown that single dose injection of cytokines into the eye show short-term prevention of photoreceptor degeneration in rat disease models. In order to achieve long-term delivery and prevention we propose the use of genetically modified cells which can overexpress the desired cytokines upon external pharmacological signaling. The method of action of these primarily neurotrophic cytokines could be simultaneously in the photoreceptor and the retinal pigmented epithelium (RPE). We propose that these biomolecules cause upregulation in photoreceptor metabolism, maintaining viable pre-dystrophic levels of gene expression. In the RPE upregulation prevents dedifferentiation into a wound-healing phenotype allowing maintenance of the immunoisolating blood-retina barrier. We intend to use the genetically altered transplant model to investigate these two hypotheses, following photoreceptor rescue and cellular metabolism. The long term goal of this project is to provide tissue engineering therapy which can be applicable to retinal dystrophies with differing etiology.
