Anti-angiogenic effect of KR-31831 on corneal and choroidal neovascularization in rat models.

We attempt to determine the effect and mechanism of KR-31831 in rat models of corneal neovascularization and choroidal neovascularization (CNV). Corneal neovascularization was induced by silver nitrate cauterization. Balanced salt solution (for control), KR-31831 (0.1 mg/mL), and bevacizumab (10 mg/mL) were applied topically with or without subsequent subconjunctival injection (10 μL). The degree of corneal neovascularization was compared among treatments. The effects of intravitreal (0.1 and 0.3 mg/mL) and intraperitoneal (25 mg/kg) of KR-31831, and intravitreal injection of bevacizumab (2.5 mg/mL) were compared in a laser-induced CNV model. FITC-dextran was used to observe the choroid vessels and to evaluate vessel leakage by fluorescence intensity. In the silver nitrate cauterized rat, topical KR-31831 (P = 0.008) or bevacizumab (P = 0.008) reduced effectively the area of corneal neovascularization compared to control on day 14. This was reduced further by additional subconjunctival injection of KR-31831 (P = 0.024) and bevacizumab (P = 0.016). After KR-31831 application, vascular endothelial growth factor (VEGF) receptor 2 and matrix metalloproteinase (MMP)-2 expression was decreased in the cornea. In the CNV model, intravitreal (0.3 mg/mL) and intraperitoneal KR-31831 inhibited significantly the CNV area (P = 0.008 and P = 0.008, respectively) and fluorescence leakage (P = 0.008 and P = 0.032, respectively). This effect was more significant compared to intravitreal bevacizumab in terms of the CNV area (P = 0.032 and P = 0.008, respectively) and fluorescence leakage (P = 0.016 and P = 0.008, respectively). The anti-angiogenic effect of KR-31831 was comparable in the cornea and more effective in the choroid compared to that of bevacizumab, and it may exert its effect by VEGF signaling and MMP-2.