Inhibitory Effects Of Suramin On Corneal Neovascularization After Corneal Alkali Burn

Objective: Corneal neovascularization(CNV) frequently cause cornea lossing diaphaneity , evoking severe visual disorder,so it become one of the important growing blind oculopathies. Corneal chemical burn, particularly alkali burn, easily induce corneal neovascularization,but the therapeutics extremely troublesome.So recent years mankind pay more close attention to the research of depressant effects on corneal neovascularization. Suramin is one of hydrosoluble chemical synthesis drug,it can conjugate recipient of growth factor, thus refrain the connection of growth factor and target cell.It make use of curing parasite,malignant tumor, Metabolic disease and so on.The applications on ophthalmology are much developed. For approaching the inhibitory effects of suramin on corneal neovascularization .This experiment was that suramin utend new vessels model of rabbit after corneal alkali burn. Observe the state of new vessels, VEGF and IGF-â… in cautery cornea.All these were expected to provide experimentel and theoretical accordance of suramin's clinical applications in the future.Methods: Forty-eight Newzerland white rabbits were divided randomly into three groups :the blank group,the control group and the suramin group. The control group and the suramin group rabbits were induced to alkali burn models. The suramin group rabbits were given eyedrop application of suramin in dosis of 8g/L. The control group rabbits were given eyedrop application of Chloramphenicol.The eyes were examined on distinct days after surgery by slit lamp microscope and calculated the areae of CNV.4 rabbits were killed on 1,4,7 and 14 day randomly in each groups and the cornea was extirpated.Half of every cornea was used to make tissue secions and stained with HE for light microscope study.The computer image analysis system was used to analysis the expression of VEGF and IGF-â… in cornea after immunohistochemistry stain.The rest of cornea was made samples for transmission electron microscope for observing the ultrastructure changes of the corneal epithelium.SPSS 12.0 was used to analyse data of this study.Results:1 Through slit lamp microscope:Both control group and suramin group animals, cornea alkali burn zone were dropsical and nepheloid. Control group:On the 1st day after alkali burn, conjunctival congestion was conspicuous,the blood vessel of limbus corneae was engorged, inflammatory reaction was conspicuous, excretion was more; On the 3th day, there was vascular bud of new vessels on limbus corneae, to the corneal center quickly;On the 7th day, the length of new vessels already reached alkali burn zone, cornea was still to remain dropsical and nepheloid; On the 14th day,the caliber of new vessel diminished,the area of creep didn't extinct. Suramin group: On the 1st day after alkali burn, conjunctival congestion was medium, the blood vessel of limbus corneae was engorged slightly, inflammatory reaction was levis; On the 3th day, there was vascular bud of new vessels on partial limbus corneae, growing leniter; On the 7th day, the length of new vessels reached the edge of alkali burn zone; On the 14th day,the color of new vessels turned light,the area contracted.Blank group:There were no change.2 The area of corneal new vessels:There were no new vessels among three groups on the 1st day after alkali burn;On the 4th,7th,14th day,there were no change in blank group,but corneal new vessels were discovered in both control group and suramin group. Compared with the control group,the areae of CNV of the suramin group were decreased significantly (p<0.01).3 The immunohistochemistry analysis of VEGF and IGF-â… :The express of VEGF and IGF-â… had no change in blank group. The contents of VEGF and IGF-I in the control group and the suramin group were advanced significantly compared with the blank group on the 1st,4th,7th day after alkali burn (p<0.01),but the expressions of VEGF and IGF-I in the suramin group was lower significantly than the control group(p<0.01) . There were no distinguished difference among the three group on the 14th day (P>0.05). Meanwhile confirmed that VEGF and IGF-I assumed linear correlation.4 The change of histopathology4.1 Light microscope:The corneal epithelium was integrated in blank group, cell ranked concinnously, inflammatory cell infiltration was few discovered among endothelial cell. Control group:On the 1st day after alkali burn, the corneal epithelium wasn't integrated, cell ranked indiscriminately,most inflammatory cell infiltration was discovered among endothelial cell. On the 4th day, inflammatory cell was increased, a great quantity new vessel emerged. On the 7th day, corneal epithelium was integrated, magnanimous inflammatory cell still to remain infiltrated, it is thus clear that generous new vessels in substantia propria layer, riper. On the 14th day, inflammatory cell decreased, magnanimous ripe new vessels were in substantia propria layer, caliber diminished. Suramin group: On the 1st day after alkali burn, corneal epithelium wasn't integrated, inflammatory cell infiltration was discovered among endothelial cell. On the 4th day, cell ranked concinnously, it is thus evident that inflammatory cell among epithelium and hypothallus, new vessels showed up on limbus corneae. On the 7th day, corneal epithelium was integrated, manipulus of inflammatory cell infiltrated, it is thus clear that new vessels in substantia propria layer, riper. On the 14th day, inflammatory cell decreased, ripe new vessels were in substantia propria layer, caliber diminished. 4.2 Electron microscope: Blank group: corneal epithelium nomadic microvillus were more, intercellular space was normal, the conjunctions of bridge corpuscle and hemidesmosome were more, mitochondria in cytoplasm were normal. Control group: corneal epithelium nomadic microvillus depleted obviously, intercellular space widened obviously, the conjunctions of bridge corpuscle and hemidesmosome decreased obviously, subtotal cristae and membrane of mitochondria in cytoplasm coalesced or vanished, rough endoplasmic reticulum stretched strikingly, degranulations were conspicuous. Suramin group: corneal epithelium nomadic microvillus depleted slightly, intercellular space widened, the conjunctions of bridge corpuscle and hemidesmosome decreased slightly, few cristae and membrane of mitochondria in cytoplasm coalesced or vanished, degranulations were seen.Conclusion:1 VEGF and IGF-I facilitate neovascularization after alkali burn and they were linear correlation.2 Suramin could refrain corneal neovascularization after alkali burn.3 Suramin could promote the epithelial renovation after corneal hazard.