Gene therapy of dominant CRX-Leber congenital amaurosis using patient retinal organoids I

Mutations in the cone-rod homeobox (CRX) transcription factor lead to distinct retinopathy phenotypes, including early-onset vision impairment in dominant Leber congenital amaurosis (LCA). Using induced pluripotent stem cells (iPSCs) from a patient with CRX-I138fs mutation, we established an in vitro model of CRX-LCA in retinal organoids that exhibit defective photoreceptor maturation by histology and gene profiling including diminished expression of visual opsins. Gene therapy by delivery of an additional correct CRX allele using an AAV vector partially restored photoreceptor phenotype and expression of phototransduction-related genes as revealed by single cell RNA-sequencing. Retinal organoids derived from iPSCs of a second dominant CRX-LCA patient carrying a K88N mutation revealed loss of opsin expression as a common phenotype, which could also be alleviated by AAV-mediated overexpression of CRX. Our studies provide the proof-of-concept for development of gene therapy for dominant CRX-LCA and other CRX-retinopathies. Profiling gene expression of retinal organoids with and without CRX mutations