Retinal Organoid-Derived Exosomes Reduce CNV Lesion and Restore RPE Integrity in Mouse Laser-Induced Choroidal Neovascularization (CNV) Model

To address the shortcomings of existing anti-VEGF monotherapy in neovascular age-related macular degeneration (nAMD), we investigated the therapeutic capabilities of exosomes obtained from human induced pluripotent stem cell (hiPSC)-derived retinal organoids in a mouse model of laser-induced choroidal neovascularization (CNV). To evaluate Retinal Organoid-derived exosome (RO-Exo) distribution after intravitreal (IVT) injection, calcein-labeled RO-Exo was observed using confocal microscopy. CNV was induced in C57BL/6 J mice by laser photocoagulation. RO-Exo was isolated from retinal organoids (differentiation days 55-65) and injected 5 days post-laser. Therapeutic efficacy was evaluated on day 12. Vascular leakage and CNV size were assessed by angiography and CD31 immunostaining. We also examined HIF-1α/VEGF-A expression (Western blotting), Retinal Pigment Epithelium (RPE) integrity markers (immunofluorescence staining for α-SMA, fibronectin, and ZO-1), and the activation of the Mitogen-Activated Protein Kinase (MAPK) pathway (phospho-ERK, -p38, -JNK) in CNV lesions. After IVT injection, RO-Exo migrated to the RPE layer, showing high retinotropic distribution. In the CNV model, RO-Exo significantly reduced vascular leakage and CNV size, with greater suppression of HIF-1α and VEGFA expression than aflibercept, the standard-of-care anti-VEGF drug. CD31-positive vasculature was decreased, accompanied by downregulation of fibronectin (a fibrotic marker) and restoration of RPE hexagonality and integrity. Furthermore, RO-Exo inhibited the activation of ERK, P38, and JNK in CNV lesions. Our study results demonstrate that RO-Exo exhibits multi-target therapeutic effects-including anti-angiogenic, anti-fibrotic, and neuroprotective actions-offering a promising alternative to conventional anti-VEGF therapy for nAMD.