USH2A-Mutated Human Retinal Organoids Model Rod-Cone Dystrophy.

PURPOSE: USH2A mutations are the leading cause of autosomal recessive retinitis pigmentosa (RP), a progressive blinding disease marked by photoreceptor degeneration. Animal models fail to recapitulate the features of USH2A RP seen in humans, and its earliest pathogenic events remain unknown. Here, we established a human model of USH2A RP using retinal organoids derived from patient induced pluripotent stem cells and CRISPR-Cas9-engineered isogenic-USH2A-/- induced pluripotent stem cells.

METHODS

We assessed organoids for cellular, molecular, and morphological defects using serial live imaging and whole organoid and fixed section analyses.

RESULTS

Both patient-derived and isogenic-USH2A-/- organoids showed preferential rod photoreceptor loss followed by widespread degeneration, consistent with the clinical phenotype. Additionally, isogenic-USH2A-/- organoids showed early defects in proliferation and structure.

CONCLUSIONS

Our findings suggest that molecular changes precede overt photoreceptor loss in USH2A RP, and pathogenesis may begin before clinical symptoms emerge. By defining early and late disease features, we provide new insight on the developmental origins of USH2A RP to guide therapeutic strategies.