Leber Congenital Amaurosis (LCA) is the most severe form of inherited retinal degenerative diseases and is characterized by early on-set nystagmus and blindness, generally occurring within the first year of life. 21% of LCA patients carry mutations in the CEP290 gene, implicating it as a major contributor to the disease. Moreover, CEP290-associated LCA is inherited in an autosomal recessive manner, making it a good candidate for gene-replacement therapy. The recent success of a phase I gene therapy trial for LCA also highlights this treatment as a feasible option for LCA patients. Although this disease may be treatable by gene-replacement therapy using viral vectors, the size of CEP290 precludes the current vector system (adeno-associated virus - AAV) from efficiently packaging the gene. An alternative to AAV for ocular gene transfer is lentivirus. The packaging limit is much greater than that of AAV, and thus will accommodate the large CEP290 gene. Moreover, lentiviral vectors can transduce multiple cell types in the eye, including photoreceptors and retinal pigment epithelium - cell types important in the disease progression of LCA. Pre-clinical animal models of LCA will be useful for studying the effectiveness of CEP290-replacement therapy. The CEP290rd16 mouse model carries a homozygous in-frame 897 bp deletion in the Cep290 gene. These mice display early progressive degeneration of the outer segment and reduction in thickness of the outer nuclear layer, which resembles the human disease. In addition to the CEP290rd16 mouse model, generation of tissue specific retinal cell types from patients with CEP290-associated LCA will make a good model for studying the effectiveness of CEP290-replacement therapy. New induced pluripotent stem cell (iPSC)-based technologies are providing researchers with the ability to model and study human disease and therapeutic correction. In this proposal we aim to generate iPSCs and subsequently photoreceptor precursor cells from a mouse model of retinal degeneration as well as patients with CEP290-associated LCA retinal degenerative disorder. These cells will be used both in and ex vivo for the study of therapeutic gene correction using lentiviral vectors and induced pluripotent stem cell technology.
Leber Congenital Amaurosis (LCA) is the most severe form of inherited retinal degenerative diseases for which there is currently no cure. We plan to harness the tremendous regenerative power of patient-specific stem cells and gene therapy to correct the genetic defect and restore retinal function.
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