Patient-Derived Induced Pluripotent Stem Cells for Modeling Splicing Factor Retinitis Pigmentosa in Retinal Pigmented Epithelial Cells and Retinal Organoids
Retinitis pigmentosa is the leading cause of inherited blindness, affecting 1 in 3,000 individuals throughout the world. Advancements in genetic screening have helped the field identify the vast range of genetic mutations that can result in the retinal dystrophy observed in retinitis pigmentosa patients, but the underlying pathogenic mechanisms of these mutations are not well understood. Two major questions remain in understanding the pathology of this disease. First, the degree to which certain cell types are affected remains undetermined, namely the photoreceptors and their supportive retinal pigment epithelial cells. Second, the molecular mechanisms by which these diseases take place are not fully elucidated. In addition to being costly, animal models have limitations in recapitulating the pathology of these ocular diseases, especially with regards to patient-specific retinitis pigmentosa mutations. Induced pluripotent stem cells hold significant potential to elucidate the mechanisms of disease. This work characterizes the pathology of autosomal dominant retinitis pigmentosa and autosomal recessive retinitis pigmentosa using in vitro disease models with human cells. A point mutation in PRPF8, a ubiquitously expressed splicing factor, causes autosomal dominant retinitis pigmentosa. This dissertation presents a novel cellular model of splicing factor retinitis pigmentosa using patient-derived, gene-corrected induced pluripotent stem cells. By differentiating both diseased and corrected cells into retinal pigmented epithelial cells and retinal organoids, genetic and functional analyses were performed to identify the differences between diseased and healthy retinal cells. Previously identified defects in murine retinal pigmented epithelial cell function were not identified in human retinal pigmented epithelial cells. By using unbiased RNA sequencing analysis, differences have been identified in the retinal pigmented epithelial cells at the level of long noncoding RNA and cell cycle regulation. Taken together, these finding highlight the importance of using human cells for disease modeling of the retina and the role of long noncoding RNA and cell cycle regulation in the pathology of splicing factor retinitis pigmentosa.