Inhibition of Experimental Corneal Neovascularization by Sunitinib Administration

Cornea engraftment is the most common organ transplantation practiced around the world. The cornea is totally devoid of blood or lymphatic vessels, except in a peripheral zone called the limbus. This property, named “corneal angiogenic privilege”, is conserved among all mammals to maintain cornea transparency and optimal visual acuity. In pathological conditions such as trauma, infections or hypoxia, blood and lymphatic vessels can grow into the avascular cornea, reducing visual acuity. In case of keratoplasty, it also considerably increases the risk of cornea graft rejection and is so considered as a high-risk keratoplasty. Treatments improving cornea survival after transplantation need to be developed, notably aiming at blocking corneal neovascularization. Here, we evaluated the efficacy of Sunitinib, a broad-spectrum tyrosine kinase receptor inhibitor, to reduce experimental corneal neovascularization.
Cornea vascularization was induced by thermal cauterization applied in the center of C57Bl6 mice cornea, daily feeded with 40mg/kg Sunitinib or vehicule. Corneas were immunolabeled as whole mounts for CD31 and Lyve-1 to evidence blood and lymphatic vessels, 7, 11 and 17 days after cauterization. Whole mount pictures were analyzed by computer-assisted quantification, and relative vascular area, end-point density, node density, length density and maximal length of the vessels were determined to finely characterize blood and lymphatic vascular networks.
We observed an inhibition of angiogenesis after 17 days in Sunitinib treated mice, where blood vessel relative surface, end-point density, branching density and length density were 1.8-fold decreased. Maximum length of blood vessels was also significantly reduced in the Sunitinib treated group at days 11 and 17. Lymphangiogenesis was strongly inhibited from day 6 to day 17 after cauterization where all parameters, except maximum length of lymphatic vessels, were significantly decreased. In case of transient Sunitinib administration (feeding during the 7 first days), we did not observe any reduction in the extent of blood or lymphatic networks developing 21 days after lesion induction. In vitro experimentations using the aortic and lymphatic ring assays showed a strong angiogenesis inhibition induced by Sunitinib while lymphangiogenesis was not inhibited.
Our results show that the use of Sunitinib can strongly affect corneal neovascularisation and could enter in early treatment of such eye lesions to avoid vision loss and risk of cornea graft rejection. However, a punctual use of such tyrosine kinase inhibitor is not sufficient to stem neovascular reaction. In vitro experimentations show strong angiogenesis inhibition but normal lymphangiogenesis, suggesting indirect inhibitory effect of Sunitinib on corneal lymphangiogenesis.