The effect of subconjunctival suramin on corneal neovascularization in rabbits

Abstract

Purpose: To evaluate the effect of subconjunctival injection of suramin on corneal neovascularization in rabbits.

Methods: Corneal neovascularization was induced by silk suturing of the corneal stroma in 40 eyes of 40 male New Zealand white rabbits. Five days after suture placement, all rabbits were randomly divided into 4 groups of 10 rabbits and were treated subconjunctivally with balanced salt solution 0.1 mL (group 1), suramin 0.1 mL (10 mg/mL and 100 mg/mL, groups 2 and 3, respectively), and bevacizumab 2.5 mg/0.1 mL (group 4). Digital photographs of eyes were obtained and analyzed on days 7, 14, and 28 after subconjunctival injections. In addition, vascular endothelial growth factor (VEGF) enzyme-linked immunosorbent assay (ELISA) and immunohistochemical analyses were used to estimate the level of VEGF and the expression of VEGF and basic FGF in neovascularized cornea, respectively.

Results: The neovascularized area in control was increased significantly for 14 days after subconjunctival injection, but slightly decreased on day 28. On days 7 and 14, group 4 exhibited greater antiangiogenic effect than group 3, but group 3 exhibited greater antiangiogenic effect than group 4 on day 28. VEGF ELISA analysis showed the mean concentration of VEGF in group 4 was significantly lower than with other treatments for the first 14 days, but the mean concentration of VEGF in group 4 was similar to that with group 3 on day 28. Immunohistochemical analysis showed that the expressions of both VEGF and basic fibroblast growth factor (FGF) were reduced in group 3 and that bevacizumab reduced VEGF expression relative to basic FGF on day 28.

Conclusion: Subconjunctival suramin 100 mg/mL exhibited less antiangiogenic effect than bevacizumab 2.5 mg during the early period of treatment, but it had a longer effect than that of bevacizumab later. Therefore, the combination of subconjunctival bevacizumab and suramin may provide a more potent effect in early treatment as well as a longer antiangiogenic effect in neovascularized cornea.