Beneficial effects of the Src inhibitor, dasatinib, on breakdown of the blood-retinal barrier.

Src kinase signaling is important in the regulation of microvascular barrier function and endothelial hyperpermeability. This study was designed to evaluate the protective effect of dasatinib, a potent Src inhibitor used clinically for the treatment of cancer, against the breakdown of the blood-retinal barrier (BRB) and the retinal vascular leakage caused by vascular endothelial growth factor (VEGF) and diabetes. We examined the effects of dasatinib on VEGF-induced endothelial hyperpermeability and the loss of vascular endothelial (VE)-cadherin, an endothelial junctional protein. Dasatinib inhibited VEGF-induced phosphorylation of Src in human retinal microvascular endothelial cells (HRMECs). In vitro and in vivo vascular permeability assays showed that dasatinib blocked the VEGF-enhanced hyperpermeability of HRMECs and decreased VEGF-mediated retinal vascular leakage in mice. Immunofluorescent staining of VE-cadherin showed that dasatinib abolished the junctional disappearance of VE-cadherin in VEGF-treated HRMECs and murine retinal vasculature. In addition, we examined the protective effect of dasatinib against diabetes-induced retinal vascular leakage in streptozotocin-induced diabetic rats. An intravitreal injection of dasatinib substantially inhibited the development of hyperpermeable retinal vasculature. Our results indicate that dasatinib is a promising agent for the prevention and treatment of diabetes-induced retinal vascular leakage.