Improved Differentiation of Human Retinal Organoids Producing Mature Photoreceptors with Budding Calyceal Process-like Structure and Usher Protein Expression

Human retinal organoids derived from pluripotent stem cells represent a robust in vitro model for investigating retinal development and disease mechanisms of retinal disorders. However, achieving structural maturation that faithfully recapitulates the intricate architecture of photoreceptors within a feasible and cost-efficient culture timeframe remains a significant challenge. Here, we present an optimized differentiation protocol that enables the generation of retinal organoids exhibiting advanced photoreceptor maturation within 140 days. Photoreceptors in the retinal organoids displayed compartmentalized architecture, including distinct inner and outer segments and connecting cilia. Notably, we observed the emergence of budding calyceal process-like structures—a feature not previously emphasized in photoreceptors derived from pluripotent stem cells. These results suggest that our protocol may promote advanced photoreceptor maturation within a relatively shortened culture period. Thus, this method could serve as a useful model for investigating retinal development and related pathologies, building upon previous protocols.