VEGF siRNA抑制鼠视网膜新生血管的实验研究

背景血管内皮生长因子（VEGF）在视网膜新生血管的发生过程中发挥重要作用，抑制VEGF是目前视网膜新生血管治疗和预防研究的热点。VEGF小片段干扰RNA（VEGFsiRNA）在抗肿瘤新生血管的研究中已经取得了显著疗效，但对于视网膜新生血管的干预作用报道较少。目的研究VEGF siRNA对鼠视网膜新生血管的抑制作用。方法48只新生C57BL／6J幼鼠采用随机数字表法随机分为正常对照组、模型对照组、空载体组和VEGF siRNA质粒转染组，每组12只幼鼠。7日龄C57BL／6J幼鼠36只及其母鼠置于密闭的氧舱5d建立缺氧性新生血管模型，其中12只幼鼠不进行质粒转染作为模型对照组，其余24只鼠玻璃体腔内注射脂质体（LF2000）包裹的空载体质粒或VEGF siRNA表达质粒。待小鼠19日龄时获取小鼠眼球并分离视网膜，用苏木精一伊红染色法计数各组小鼠视网膜新生血管内皮细胞核的数目，用实时荧光定量聚合酶链反应（tea-time PCR）法检测视网膜中VEGF mRNA的表达，并应用免疫荧光技术检测小鼠视网膜中VEGF蛋白的表达。结果正常对照组、模型对照组、空载体组和VEGFsiRNA质粒转染组19日龄小鼠视网膜突破内界膜的内皮细胞细胞核数目分别为（0．19±0．09）个、（24．89±2．03）个、（23．65±2．15）个和（8．83±1．12）个，表明VEGFsiRNA质粒转染组小鼠的新生血管内皮细胞数明显低于模型对照组和空载体组，差异均有统计学意义（q=5．67、q=4．97，P〈0．01）。Real-time PCR检测表明，正常对照组小鼠视网膜中仅见弱的VEGF mRNA表达，而模型对照组与空载体组VEGF mRNA表达量为正常对照组的52．3倍和36．7倍，VEGF siRNA质粒转染组小鼠视网膜VEGF mRNA的表达量为正常对照组的3．5倍，明显低于模型对照组与空载体组。VEGF siRNA对VEGF mRNA的抑制率为43．39％。免疫荧光染色显示，正常对照组小鼠VEGF蛋白呈弱阳性表达，模型对照组和空载体组VEGF小鼠视网膜中VEGF蛋白表达呈强阳性，VEGF siRNA质粒转染组VEGF蛋白表达明显减弱。结论玻璃体腔注射VEGF siRNA表达质粒可有效抑制C57BL／6J小鼠氧诱导视网膜病变模型新生血管的形成。

Inhibitory effect of vascular endothelial growth factor siRNA on retinal neovascularization in mouse

Background To suppress vascular endothelial growth factor (VEGF) is a researching hot topic for the treatment and prevention of retinal neovascularization.Some detectable efficacy of VEGF small interference RNA (VEGF siRNA) in anti-tumor neovascularization has been well-known.But relevant study on VEGF siRNA on retinal neovascularization is seldom.Objective Present study was to investigate the inhibiting effect of VEGF siRNA on retinal neovascularization.Methods The 48 clean C57BL/6J mice aged 7-day-old were randomly divided into normoxia group,hypoxia control group,vector group and VEGF siRNA group and 12 mice for each.Hypoxia models were established by raising the pups with mother mice in the airtight oxygen-cabin for 5 days.The lipofectamineTM 2000 (LF2000)-mediated vector plasmids or VEGF siRNA recombinant plasmids were then injected intravitreally in 12 12-day-old pup mice respectively.The animals were sacrificed in 1 week after intravitreal injection,and the numbers of vascular endothelial cell nuclei extending beyond the internal limiting membrane (ILM) were counted by hematoxylin-eosin stain.The expressions of VEGF protein and mRNA in retina were assayed by immunoinfluorescence technique and RT-PCR.Results The numbers of vascular endothelial cell nuclei extending beyond the ILM were 0.19±0.09,24.89±2.03,23.65±2.15 and 8.83±1.12 in normoxia group,model control group,vector group and VEGF siRNA group separately,showing significant decrease in VEGF siRNA group compared with model control group or vector group (q=5.67,q=4.97,P＜0.01).RT-PCR revealed that VEGF mRNA was faintly expressed in mouse retina in normoxia group.However,in model control group and vector group,the level of VEGF mRNA was 52.3 times and 36.7 times more than that of normoxia group respectively and only 3.5 times in VEGF siRNA group,presenting a inhibitory rate of 43.39% of VEGF siRNA on VEGF.Immunofluorescence showed that the expression of VEGF was weaker in normoxia group and strong positive response in model control group and vector group,but the expression intensity of VEGF protein was significantly weaker in VEGF siRNA group.Conclusion VEGF siRNA recombinant plasmids can efficiently inhibit retinal neovascularization in oxygen-induced retinopathy mouse model through intravitreal injection.