siRASA1 in vascular endothelial cells alleviates subretinal fibrosis through inhibiting macrophage-myofibroblast transdifferentiation via SHH signaling pathway.

Subretinal fibrosis (SRF) is a vision-threatening complication of neovascular age-related macular degeneration (nAMD) driven by angiogenesis, inflammation, and collagen deposition，which is refractory to current anti-VEGF treatments. This study investigates the role of RASA1 in promoting SRF through Sonic Hedgehog (SHH) signaling. We found that VEGF stimulation upregulates RASA1 in human umbilical vein endothelial cells (HUVECs), potentiating the secretion of SHH. Secreted SHH then activates the SHH-SMO/PTCH1-GLI1 axis in macrophages, driving their transdifferentiation into myofibroblasts and promoting fibrogenesis. Furthermore, a positive feedback loop was identified: macrophage-derived EFNB2 activated EphB4-RASA1 in HUVECs, exacerbating fibrosis. To therapeutically disrupt this circuit, we engineered a multifunctional nanoparticle system, MGPDA@Eylea/siRASA1, for the co-delivery of siRASA1 and the anti-VEGF drug Eylea. This nanotherapeutic demonstrated excellent biocompatibility and effectively attenuated the fibrotic cascade by suppressing RASA1 expression, inhibiting SHH signaling, and mitigating macrophage-to-myofibroblast transition (MMT), thereby delaying SRF progression. Our work unveils a previously unrecognized intercellular circuit driving fibrosis and presents a promising nanomedicine-based strategy for managing fibrotic complications in nAMD.