Human cone photoreceptor transplantation stimulates remodeling and restores function in AIPL1 model of end-stage Leber congenital amaurosis

Photoreceptor degeneration is a leading cause of untreatable sight loss. Previously, we showed that human pluripotent stem cell-derived cone photoreceptors (hCones) can rescue retinal function in the Rd1 mouse model of rod-cone dystrophy. However, retinal degenerations display markedly different severities and concomitant remodeling of the remaining retina; for photoreceptor replacement therapy to be broadly effective, it must work for a variety of disease phenotypes. Here, we sought to rescue the Aipl1^-/- model of Leber congenital amaurosis, a particularly fast, severe condition. After transplantation of hCones, host cone bipolar cells underwent extensive remodeling and formed nascent synaptic-like connections. Electrophysiological recordings showed robust rescue of light-evoked activity across visually relevant photopic intensities, and treated mice exhibited visually evoked optokinetic head-tracking behavior. Thus, human cone photoreceptor replacement therapy is feasible even in very severe cases of retinal dystrophy, offering promise as a disease-agnostic therapy in Leber congenital amaurosis (LCA) and in other advanced retinal degenerations.