Exosome-mediated delivery of an anti-angiogenic peptide inhibits pathological retinal angiogenesis

Background: Pathological angiogenesis is the hallmark of many vision-threatening diseases. Anti-VEGF is a primary treatment with substantial beneficial effects. However, such agents require frequent intravitreal injections. Our previous work established a method for effectively modifying exosomes (EXOs) for loading therapeutic peptides. Here, we used this system to load the anti-angiogenic peptide KV11, aiming to establish an EXO-based therapy strategy to suppress neovascularization in the retina. Methods: Using an anchoring peptide, CP05, we linked KV11 to endothelial cell (EC) derived EXOs, yielding EXO(KV11). We tested the delivery efficiency of EXO(KV11) via two commonly used ocular injection methods: retro-orbital injection and intravitreal injection. Deploying an oxygen-induced retinopathy (OIR) model and a VEGF injection model, we tested the effects of EXO(KV11) on neovascular formation, EC proliferation, and vascular permeability. In vitro experiments were used to test the mechanism and to analyze the effects of EXO(KV11) on EC proliferation, migration, and sprouting. Results: By using the EXO loading system, KV11 was more efficiently delivered to the blood vessels of the mouse retina via retro-orbital injection. In both OIR model and VEGF injection model, EXO(KV11) was more effective than KV11 alone in inhibiting neovascularization and vessel leakage. The therapeutic effect of retro-orbital injection of EXO(KV11) was comparable to the intravitreal injection of VEGF-trap. Mechanistically, KV11 alone inhibited VEGF-downstream signaling, while EXO(KV11) showed a stronger effect. Conclusions: We used EXOs as a carrier for intraocular delivery of KV11. We showed that KV11 itself has an anti-angiogenic effect through retro-orbital injection, but that this effect was greatly enhanced when delivered with EXOs. Thus, this system has the potential to treat proliferative retinopathy via retro-orbital injection which is a less invasive manner compared with intravitreal injection.