Gene Therapy of Dominant CRX-Leber Congenital Amaurosis using Patient Stem Cell-Derived Retinal Organoids.

Anand Swaroop,Ananya Samanta,Kamil Kruczek,Laura Campello,Colin J. Chu,Linn Gieser,Mugdha Samant,Brian P. Brooks,Zepeng Qu,Benjamin R. Fadl,Suja Hiriyanna,Zachary Batz,James Gentry,Zhijian Wu

doi:10.1016/j.stemcr.2020.12.018

Abstract

SummaryMutations in the photoreceptor transcription factor gene cone-rod homeobox (CRX) 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-I138fs48 mutation, we established an in vitro model of CRX-LCA in retinal organoids that showed defective photoreceptor maturation by histology and gene profiling, with diminished expression of visual opsins. Adeno-associated virus (AAV)-mediated CRX gene augmentation therapy partially restored photoreceptor phenotype and expression of phototransduction-related genes as determined by single-cell RNA-sequencing. Retinal organoids derived from iPSCs of a second dominant CRX-LCA patient carrying K88N mutation revealed the loss of opsin expression as a common phenotype, which was alleviated by AAV-mediated augmentation of CRX. Our studies provide a proof-of-concept for developing gene therapy of dominant CRX-LCA and other CRX retinopathies.

Highlights

Leber congenital amaurosis (LCA) constitutes a group of rare early-onset retinal dystrophies with severe clinical manifestations, resulting in vision loss during infancy (den Hollander et al, 2008)
Mouse models have been valuable for elucidating disease etiology (Veleri et al, 2015) and for preclinical therapy development, leading to the first U.S Food and Drug Administration-approved adeno-associated virus (AAV)based gene therapy of recessive LCA caused by RPE65 mutations (Apte, 2018)
We previously described clinical presentations of two pediatric patients carrying c.G264T (p.K88N)- or c.413delT (p.I138fs48) dominant cone-rod homeobox (CRX) mutations manifested as LCA, with a complete loss of light-evoked responses in electroretinogram recordings (Nichols et al, 2010)

Summary

Introduction

Leber congenital amaurosis (LCA) constitutes a group of rare early-onset retinal dystrophies with severe clinical manifestations, resulting in vision loss during infancy (den Hollander et al, 2008). LCA is genetically heterogeneous with mutations identified in at least 25 genes; a vast majority of these are crucial for photoreceptor development and/or function (Kumaran et al, 2017). Most patients with LCA exhibit autosomal recessive inheritance. Mouse models have been valuable for elucidating disease etiology (Veleri et al, 2015) and for preclinical therapy development, leading to the first U.S Food and Drug Administration-approved adeno-associated virus (AAV)based gene therapy of recessive LCA caused by RPE65 mutations (Apte, 2018). It is widely recognized that available animal models do not fully capture complexities of human disease, slowing further clinical translation. No treatment currently exists for other, especially dominant, forms of LCA

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Discussion

Conclusion