Using patient iPSC-derived retinal organoids to identify mechanism underlying inherited blindness caused by mutations in the NPHP5 gene

Abstract

Purpose : Leber congenital amaurosis (LCA) is a congenital retinal dystrophy that is caused by mutations >25 genes. The mechanism of photoreceptor dysfunction in LCA caused by mutations in the cilia-associated gene NPHP5 remained unclear.

Methods : Using iPSCs derived from patients with NPHP5 mutations and respective familial controls, we generated 3D cultured organoids with photoreceptors as well as retinal pigmented epithelium (RPE) in monolayer cultures.

Results : Patient and control iPSCs exhibited similar differentiation with consistent staining of retinal lineage specific markers. However, morphology of cultured organoids revealed outer segment like structures that come out later in the patients than controls. RNA-Seq results suggested that regulation of rhodopsin mediated signaling pathway, visual perception and photoreceptor maintenance were significantly affected by the mutation. Furthermore, cilia defects were observed in patient fibroblast and RPE manifesting as longer and branched cilia.

Conclusions : These results suggest that the human NPHP5 mutation induced cilia defects in photoreceptors and RPE, leading to retinal degeneration by affecting the formation of outer segments. Our studies provide a mechanistic understanding of NPHP5-LCA using patient-derived cells and should help in designing therapeutic interventions.

This is a 2020 ARVO Annual Meeting abstract.