Abstract:

BACKGROUND: Systemic administration of rapamycin has been demonstrated to inhibit graft neovascularization following corneal transplantation. However, the effect of rapamycin eye drops remains unknown.
OBJECTIVE: To explore the role of vascular endothelial growth factor (VEGF) and inflammatory factor during the inhibition of rapamycin eye drops on corneal neovascularization.
METHODS: Corneal neovascularization in the left eye was induced by suture method, and the 12 SD rats were randomly assigned to normal saline and rapamycin groups. Drugs were delivered, 1 drop each, 4 times daily since 1 day after operation. Rat corneas were checked by slit lamp microscope daily. The length of corneal neovascularization was measured at days 3, 7, and 14 to calculate the area of corneal neovascularization. The expression of VEGF and interleukin-2 receptor α (IL-2Rα) was detected by immunohistochemical techniques at 14 days.
RESULTS AND CONCLUSION: Corneal neovascularization area of normal saline group was significantly greater than rapamycin group at each time point (P=0), indicating that rapamycin eye drop inhibited corneal neovascularization following suture. Compared with normal saline group, the expression of VEGF and IL-2Rα was significantly decreased in corneal epithelia, stroma, corneal neovascular endothelium and epithelium at the suture site, as well as inflammatory cells of rapamycin group. Moreover, the inflammatory cell infiltrate was reduced in the pathological sections of rapamycin group. Results show that rapamycin eye drops inhibit corneal neovascularization, possibly by reducing the expression of VEGF and IL-2Rα.