Adenine base editor correction of pathogenic variations associated with inherited retinal dystrophy in patient iPSC and retinal organoids

Inherited retinal dystrophies (IRDs) are a group of incurable, genetically heterogeneous diseases that cause progressive degeneration of the retina, leading to the loss of vision. Genome editing technologies offer a powerful prospect for mutation correction and single-dose cures for these diseases. Here, we investigated the potential of adenine base editing (ABE) to correct a panel of causative genetic variations in patient-derived induced pluripotent stem cells (iPSCs) and identified parameters that can efficiently correct a pathogenic variation in the <i>AIPL1</i> gene (c.665G>A, p.Trp222∗), which is associated with autosomal recessive Leber congenital amaurosis type 4. To investigate correction of the variant in a patient-relevant model, retinal organoids (ROs) were derived from corrected isogenic and patient-derived iPSCs. Adenine base editor components were delivered to ROs via lipofection as chemically modified RNA or via a split intein system following dual-AAV transduction. The data show AIPL1 rescue in photoreceptor cells with both delivery systems and restoration of the AIPL1 target protein, cyclic guanosine monophosphate phosphodiesterase 6-a critical component of the visual transduction system-in treated rod photoreceptors. These proof-of-principle experiments highlight the utility of ROs for investigating the potential of ABE technology as a means to treat IRDs.