Promotion of vessel regression by local VEGF-A blockade improves the survival rate of corneal transplants

To primarily evaluate the efficacy of different topical vascular endothelial growth factor (VEGF) blocking treatments, namely Aflibercept and Bevacizumab, in promoting regression of pathologic corneal neovascularization (NV) and secondarily to investigate their effects on graft survival in a high-risk mouse corneal transplantation model. In addition, the immune modulatory effects were assessed. After 14 days of suture-induced, inflammatory corneal NV, sutures were removed. Anti-VEGF eye drops or vehicle controls were applied topically 3 times daily for one week. After 21 days, the regression of blood vessels (BVs) and lymphatic vessels (LVs) was assessed via immunofluorescence staining. In addition, corneal grafting was performed in another set of mice. Therefore, allogeneic donor corneas from C57BL/6N mice were used and graft survival was monitored weekly for 8 weeks. Finally, hem-and lymphangiogenesis as well as the phenotype of antigen-presenting cells (APCs) in draining lymph nodes (dLNs) and corneas were analyzed by immunohistochemistry and FACS, respectively. Both, Aflibercept and Bevacizumab eye drops supported the regression of both blood and lymphatic vessels. Aflibercept-treated corneas demonstrated decreased APC activation in the dLNs after treatment at day 21. In the high-risk transplantation model, both therapeutics could improve graft survival rates (Aflibercept: 60 %, P = 0.0091; Bevacizumab: 50 %, P = 0.0547) compared to control (10 %). Eight weeks post-transplantation, both treatment arms displayed decreased APC recruitment and an increased expression of Foxp3 on CD4⁺CD25⁺ T cells. Our study demonstrates that different topically applied anti-VEGF eye drops effectively reduce pre-existing corneal neovascularization and thereby improve subsequent high-risk corneal transplantation. This translational approach could become a promising strategy to improve the clinical outcome of high risk keratoplasty in patients.