The Study On The Relation Between Proliferative Diabetic Retinopathy And Erythropoietin

Recently, a new study suggest that erythropoietin is an independent, potent, ischemia-induced angiogenic factor mediating proliferative diabetic retinopathy. It may be a potential therapeutic target in the treatment of proliferative diabetic retinopathy. VEGF has been certificated a primary mediator of intraocular angiogenesis and permeability in proliferative diabetic retinopathy. But it's insufficient to prevent retinal neovascularization only inhibit the effect of VEGF, maybe some other factors involve in the angiogenesis of retina. Erythropoietin has angiogenic activity in nonocular tissues, it's not clear that how it mediate intraocular angiogenesis. Doctor Aiello who is a professor of Medical college of Harvard University said, therapic efforts should take into account not only VEGF but also other factors that may play a substantial role in the processes that threaten sight. The purpose of our study is to investigate the concentration of erythropoietin (EPO) in the vitreous fluid of patients with proliferative diabetic retinopathy (PDR) and study expression of erythropoietin in anoxic retina of rat induced by cobalt chloride (CoCl₂). Part IDetection of the Levels of EPO in the Vitreous of Patients withProliferative Diabetic RetinapathyPurpose To investigate the concentration of erythropoietin (EPO) in the vitreousfluid of patients with proliferative diabetic retinopathy (PDR).Methods The concentration of EPO in the ocular fluid of 10 normal subjects, 15patients with proliferative diabetic retinopathy (PDR) and retinal neovascularization,12 patients with hemorrhagic retinal periphlebitis, were detected by using enzymelinked immunosorbent assay (ELISA).Results In normal group (n=10),the mean of EPO in the vitreous fluids was 33.5(19.9-63.8mU/ml)mU/ml. In PDR group(n=15), that of 880.7(157.0-1850.0mU/ml) mU/ml, in hemorrhagic retinal periphlebitis group(n=12) , that of 396.4(83.7-1080.0mU/ml) mU/ml. There was a significant difference among groups (P<0.0001). The concentration of EPO in vitreous fluid were significantly higher in the patients with PDR and hemorrhagic retinal periphlebitis than the normal groups.( Hemorrhagic retinal periphlebitis vs Normal , p=0.038;PDRvs Normal, P<0.0001). In normal group (n=10),the mean of EPO in the plasma was 21.3(16.3-25.5mU/ml) mU/ml. In PDR group(n=15), that of 20.7 (14.4-28.7mU/ml) mU/ml, in hemorrhagic retinal periphlebitis group(n=12) , that of 25.3(12.4-63.8mU/ml) mU/ml. There wasn't a significant difference among groups (P>0.05). Then we analysis the association of the concentration of EPO in vitreous fluid and plasma; no significant correlation was observed between the vitreous and plasma concentrations of erythropoietin.Conclusion The concentration of EPO in the vitreous of patients with PDR were elevated, there was no significant correlation between the vitreous and plasma concentrations of erythropoietin. Part IIThe Study on Expression of erythropoietin in Anoxic Retina of Ratinduced by Cobalt ChloridePurpose To study expression of erythropoietin in anoxic retina of rat induced bycobalt chloride (CoCl₂).Methods The animal model of anoxic retina of rat can be induced by cobaltchloride via intravitreal injection. Cobalt chloride were injected into the vitreous bodyof the left eyes of rats, PBS were injected into the vitreous body of the right eyes ofrats as an experimental control group. The rats treated with nothing were observed asnormal control group. We put the rats to death on the day 1W,2W,3W after theintravitreal injection. Then we examine the expression of EPO in the retina of rats byimmunohistochemistry.Results Compared with the normal control group, the expression of EPO elevated inthe rats treated with cobalt chloride (P<0.05) .There was a significant differenceamong the groups treated with cobalt chloride (P<0.01) ,the expression of EPOincreased according to the days after the intravitreal injection. It implied that therewas a strong association between the expression of EPO and hypoxia. Cells whichexpress EPO were discovered in GCL, INL and ONL.Conclusion The expression levels of EPO in retina of rat increased when hypoxiaoccurred, EPO are expressed in GCL, INL and ONL in rat retina.