Suppression of choroidal neovascularization by vasohibin-1, a vascular endothelium-derived angiogenic inhibitor

PURPOSE. To determine the expression of vasohibin-1 during the development of experimentally induced choroidal neovascularization (CNV) and to investigate the effect of vasohibin-1 on the generation of CNV. METHODS. CNV lesions were induced in the eyes of wild-type (WT) and vasohibin-1 knockout (KO) mice by laser photocoagulation. The expression of vasohibin-1, vascular endothelial growth factor (VEGF), VEGF receptor-1 (VEGFR1), VEGFR2, and pigment epithelial-derived factor (PEDF) was determined by semiquantitative reverse transcription-polymerase chain reaction. The expression of vasohibin-1 was also examined by immunohistochemistry with anti-CD68, anti-alpha smooth muscle actin (αSMA), anti-cytokeratin, and anti-CD31. Vasohibin-1 was injected into the vitreous and the activity and size of the CNV were determined by fluorescein angiography and in choroidal flat mounts. RESULTS. Vasohibin-1 was detected not only in CD31-positive endothelial cells but also in CD68-positive macrophages and αSMA-positive retinal pigment epithelial cells. Strong vasohibin-1 expression was observed at day 28, when the CNV lesions had regressed by histologic examination. The vasohibin-1 level was significantly decreased at day 14 and increased at day 28 after laser application. Significantly less VEGFR2 expression was observed on day 4 after vasohibin-1. The expression of PEDF was not significantly changed by vasohibin-1 injection. Vasohibin-1 injection significantly suppressed the CNV, with no adverse side effects. The CNV lesions in the vasohibin-1-KO mice were significantly larger than those in the WT mice. CONCLUSIONS. The endogenous expression of vasohibin-1 is associated with the natural course of the development of CNV. Intravitreal injections of vasohibin-1 may be a method for inhibiting CNV.