Intravitreal Injection Of Beavcizumab Arrests Retinal Neovascularization In Rat Models

PURPOSE To evaluate the efficacy of intravitreal different dosage of Bevacizumab(Avastin) for the treatment of retinal neovascularization in animal models.METHODS Seven days after birth,54 Sprague-Dawley rats were divided into 6 groups,and 9 rats in each group.Among these groups,one in room air for all the time(Group 1);other groups of rats were exposed to 80%constant oxygen for 5 days and then back to room air for seven days.Intravitreal different dosage of Bevacizumab(Group 3:0μg/5μl,Group 4:5μg/μl, Group 5:25μg/μl,Group 6:125μg/μl)was injected as treatment into right eyes in four groups of rats when they were brought back to room air,and the remaining group of rats(Group 2) received nothing.After the period of 12 days,at which time one rat from each group was sacrificed and assessed for retinal neovascularization with injection of ink(right eyes),abnormal neovascularization was assessed using dissected,flat-mounted retinas by ink infusion.The remaining rats from each group were then killed and assessed for retinal neovascularization by Hematoxylin and Eosin Staining,retinal neovascularization was quantified by counting pre-retinal endothelial cells.RESULTS1.Retinal observation:Retinal examination revealed significant retinal neovascular,especially in vitreous cavity,leakage and enlarged non-perfusion regions in the perimeter of the retina in Group 2 and Group 3,while Group 1 showed normal.Significant reduction of retinal neovascular was observed in groups with treatment of intravitreal Bevacizumab.Group 4 and Group 5 appears no difference with the naked eye,and neovascular in vitreous cavity disappeared in Group 6.2.Neovascularization counting:The number of pre-retinal endothelial cells was(2.76±0.75) in Group 1.In Group 2 and Group 3,there are(31.44±0.90)and(31.40±1.26)cells,which showed no significant difference between them(t=0.078,P＞0.05),and significant difference in number of pre-retinal endothelial cells was found between Group1 and Group 2 (t=69.263,P＜0.01).The number of nucleolus of vascular endothelial cells on the surface of retina was(16.60±1.35)in Group 4,(15.19±0.68)in Group 5 and(9.55±0.95)in Group 6. Significant difference was found between Group 3 and the groups treating with Bevacizumab(P＜0.01).There are also showed significant difference between three groups treating with bevacizumab(P＜0.05 between Group 4 and Group 5,P＜0.01 between other groups).Conclusion Intravitreal injection of Bevacizumab can arrest retinal neovascularization in SD rat models,and the more Bevacizumab we give the fewer neovascularization we found.