AAV-mediated regeneration of neurons in injury-induced and inherited retinal degeneration

Loss of retinal neurons is a leading cause of irreversible vision impairment, yet adult mammalian retinas lack the ability to regenerate these cells. In this study, we developed an adeno-associated virus (AAV)-based strategy to reprogram endogenous Muller glia into retinal neurons. Using stringent genetic lineage tracing, immunohistochemistry, electrophysiology and single-cell multiomic profiling, we show that AAV delivery of a stabilized, phospho-insensitive Neurogenin2 variant (Neurog2-9SA) efficiently converts Muller glia into multiple types of retinal neurons, including bipolar, starburst amacrine, and a small population of photoreceptor-like cells, in both injury-induced and inherited retinal degeneration models. The generated neurons exhibit electrical properties of retinal neurons, light-evoked responses and integrate into existing retinal circuitry. Single-cell multiomics analysis reveal that Neurog2-9SA induces reprogramming by remodeling chromatin accessibility, activating neurogenic transcriptional networks, and represses glial identity programs. Inhibiting Notch signaling markedly enhances reprogramming efficiency. Together, these findings establish Neurog2-9SA as a potent and clinically relevant factor for AAV-mediated reprogramming and provide a foundation for approaches to regenerate neuronal cells and restore function in retinal diseases.