Nanotechnology-Based Delivery Systems and Retinal Pigment Epithelium: Advances, Targeting Approaches, and Translational Challenges.

The retinal pigment epithelium (RPE) is essential for maintaining retinal integrity, and its dysfunction underlies several progressive ocular diseases, including age-related macular degeneration, choroidal neovascularization (CNV), inherited retinal disorders (IRDs), and proliferative vitreoretinopathy (PVR). Although current therapies have improved disease management, they mainly target secondary pathological mechanisms and do not directly preserve or restore RPE function. Moreover, the delivery of therapeutic molecules or genes to the RPE remains a major challenge due to the presence of multiple ocular barriers and the need for sustained, localized action. Nanomedicine offers innovative solutions to these limitations by enabling precise, controlled, and cell-specific delivery of drugs and genetic materials. Engineered nanocarriers can be optimized to traverse ocular barriers, enhance bioavailability, and modulate the retinal microenvironment. This review summarizes recent advances in nanoscale delivery systems for RPE-targeted therapies, focusing on design principles, targeting strategies, and therapeutic applications, and discusses the translational challenges that must be addressed to bring nanotechnology-based treatments closer to clinical application.