Effects Of Subconjunctival Injected AMD3100,a Specific Antagonist Of CXCR4, On Alkali-Induced Corneal Neovascularization In Mice

Purpose: To investigate the effects of subconjunctival and intraperitoneal injected AMD3100 on alkali-induced corneal neovascularization and its mechanism.Methods: Alkali-induced corneal neovascularization animal model were constructed of in C57/BL mice. SDF-1 and CXCR4 expression in the corneal tissue were detect by immunohistochemistry, RT-PCR and Western Blot at different time points after alkali burn; AMD3100 was administrated by subconjunctival and intraperitoneal injection. And the mice were randomly divided into 4 groups: subconjunctival injection group, subconjunctival injection control group, intraperitoneal injection group and intraperitoneal injection control group; The number of inflammatory cells, microvessel density, VEGFR2, CD34, SDF-1 and CXCR4 expression in corneal tissue of each group were detected at different time points after alkali burn; Flow cytometry was used to detect the number of EPC in the peripheral blood of subconjunctival and intraperitoneal injection group at different time points after the injection of AMD3100.Results: Normal mouse corneal tissues only contain traces of SDF-1, CXCR4 mRNA and protein. Three days after alkali burn, the expression start to increase, and reached the peak at the 7th day, 14 days began to decrease but still higher than normal levels; Corneal inflammation index, microvessel density, VEGFR2 and CD34 level in subconjunctival injection group were all lower than the control group and the intraperitoneal injection group, and the difference of the SDF-1 and CXCR4 expression level among the four groups had no statistically significant. The numbers of EPCs in peripheral blood of intraperitoneal injection group were significantly increased at different time points. And the number of EPCs in peripheral blood at different time points after injection was not increased when compared with the number before injection.Conclusions: The expressions of SDF-1/CXCR4 are increased after alkali burn in corneal tissue of mice, which may indicated that SDF-1/CXCR4 plays an important role in the formation of corneal neovascular formation in alkali-induced corneal neovascularization. Intraperitoneal injection of AMD3100 could significantly increase the number of EPCs in peripheral blood, while subconjunctival injection was just the opposite. Subconjunctival injection of AMD3100 could reduce alkali-induced corneal neovascularization probably through competitive antagonist the binding of SDF-1 to CXCR4 and blocking its biological function, as well as reducing the EPCs gathered to the injury tissue.