The Experimental Study Of Recombinant Human Endostatin Inhibiting On Corneal Neovascularization Of Rats

OBJECTIVE: To investigate the inhibitory proliferation effect of recombinant human endostatin (rh-ES) on corneal neovascularization after alkali burn in rat, and to explore its possible mechanism.METHOD:Clean-health adult male SD rats were randomly divided into recombinant human endostatin treatment group and the normal saline control group ,chose the right eye as experimental eye,the lefe as nomal conrol.Experimental rats corneal neovascularization model induced by corneal alkali burn was established, modeling after 30 min, respectively injection under a microscope subconjunctival with recombinant human endostatin (PBS with the preparation of 0.2 g / L of endostatin suspension) and 12.5 ul normal saline in the two groups, followed by the next day, continuous administration 5th, experimental period is 21 days. In 1th,5th,7th,10th,14th,21th days after injury, using slit lamp camera photographed CNV record growth of the state and area of CNV, analysis of the experimental group corneal by histologic observation and computer image; immunohistochemical method for each experimental group MVD, as well as VEGF and MMP-2 expression was semi-quantitative detection in corneal tissue of the cornea.RESULTS:1 Neovascularization growth area. The experimental group neovascularization germinated vascular buds in after modeling 24h, area of angiogenesis growing reached the peak in 10th day, each group area of angiogenesis, after that growth slowly, gradual changed sparse and degraded; each time point recombinant human endostatin treatment groups'neovascularization areas were less than the normal saline control groups'(P<0.01).2 Corneal histopathological changes. Under optical microscopes, corneal alkali burned have different levels of inflammatory cell infiltration and fibroblast proliferation, the experimental groups'inflammatory cells basically the same; a large number of angiogenesis in the normal saline control group, its lumen was coarse, at the same time , scarcely in recombinant human endostatin treatment group.3 Micro vessel density (MVD). The experimental groups microvessel density increased, irregular shape, the uneven distribution of neovascular basement membrane incompletely, endostatin group microvascular density was significantly reduced at different time points over the normal saline group(P<0.01).4 The expression of VEGF protein in normal SD rat cornea is a very low level. Corneal every layers, as well as endothelial cell of neovascularization , the expression of VEGF was significantly increased after injury in both experimental groups. Each time point the expression of VEGF in corneal tissue recombinant human endostatin treatment group are significantly lower than the normal saline concol group(P<0.05).Both groups VEGF expression was positively correlated with the number of MVD( r₁=0.768,P₁< 0.05; r₂=0.768,P₂< 0.05).5 MMP-2 are mainly expressed in the epithelial cell layer in normal SD rat cornea.After injury the expression of MMP-2 in the corneal epithelial cells, infiltration of inflammatory cells, stromal cells and corneal neovascularization endothelial cells was significantly increased after injury in both experimental groups. Each time point recombinant human endostatin treatment groups'expression of MMP-2 in the vascular endothelial of cells corneal tissue was significantly lower than normal saline conrol groups'.Both experimental group were higher than normal control group(P<0.05).The expressions of MMP-2 in inflammatory cells have no significant difference in both experimental groups(P>0.05).CONCLUSIONS: Recombinant human endostatin may positively inhibit the growth of corneal neovascularization of the rat.It's inhibitory proliferation effect may be related with reducing the expression of VEGF and MMP - 2 in corneal tissue.