Inject Small Interfering RNA (siRNA) Targeting VEGF Effectively Inhibits Retinal Neovascularization In A Mouse Model

Backgroud Retinal vasoproliferative disease is the most common cause of severe visual loss in people in developed countries . recently, there are more patiens of diabetic retinopathy,age related macular degeneration, ischaemic central retinal vein occulation, retinopathy of prematurity in our country . Ischemia promotes new blood vessel proliferation in an attempt to restore blood flow. Aberrant neovascularization resulting in newly formed blood vessels intrud into the vitreous of the eye (referred to as preretinal neovascularization). These new vessels destroy the normal retinal architecture and may hemorrhage, easily causing bleeding into the eye, which ultimately impairs vision. The only approved treatment consists in destroying parts of the peripheral retina by laser or cryocoagulation in order to diminish hypoxic tissue and thus reduce reactive neovascularization. Insight intothe molecular mechanisms of neovascular eye disorders can provide new targets for novel nondestructive therapeutic agents. Vascular endothelial growth factor (VEGF) is upregulated by hypoxia . Increased intravitreal and intraretinal levels of VEGF are associated with retinal neovascularization in patients with ischemic retinopathy . RNA interference (RNAi) is a process conserved throughout many eukaryotic organisms, in which the presence of double stranded RNA (dsRNA) in a cell results in the destruction of mRNAs whose sequences share homology to the dsRNA. This phenomenon is now being exploited as a powerful tool for reverse genetics, and shows great promise for therapeutic applications. Recently it was demonstrated that subretinal delivery of siRNA directed against murine VEGF significantly inhibited CNV after laser photoco-agulation. At recent, we inject VEGFSiRNA in vitrous in the oxygen-induced mouse model for oxygen induced retinopathy. The purpose of this study was to demonstrate the feasibility of vitrous injection VEGFSiRNA to restrain retinal neovascularization.Objective To investigate the effect of vitrous injection VEGFSiRNA on experimental retinal neovascularization. Observe: 1. The effect of vitrous injection VEGFSiRNA on suppress retinal neovascularization. 2. The change of VEGF and VEGFmRNA in retina 3. The change of eye after vitrous injection VEGFSiRNA.Methods From postnatal day seven (P7) on, 24 C57BL/6J mice were kept in a 75% oxygen environment for five days. The others 8 mice were maintained in normal air condition. On postnatal day 12 (P12) ,16 mice received an intravitreal injection of high or low does of VEGFSiRNA;8 mice received an intravitreal injection of no-silenceSiRNA as the nagetive control. The animals were sacrificed by injection of 1% sodiumpentobarbital on P17. The retina Vascular proliferations were quantified by counting blood vessel endothelial cell of retina pathological section. Retina VEGF is also measured by imraunohistochetnistry. The expression of VEGFmRNA was measured by rever transcription-polymerase chain reaction.Results1 The effect of vitrous injection VEGFSiRNA on retinal neovascula-rizationRetina pathological section HE Staining result: intravitreal injection of of VEGFSiRNA has less vascular endothelial cell than control. (P<0.01) it means there are less neovascular.2 The change of VEGF and VEGFmRNA after vitrous injection VEGFSiRNA Compare to control, mice with vitrous injection VEGFSiRNA retinal VEGFmRNA A value is lower, and immunohistochemistry has less VEGF staining.(P<0. 01)3 The effect of vitrous injection VEGFSiRNA on eye.Compare to control, eye' s weight of mice with vitrous injection VEGFSiRNA is no different. (P>0. 05)Cornea and lens is still transparence. Pathology section is not abnormal.Conclusion1> vitrous injection VEGFSiRNA can inhibits retinal neovascularization. 2, vitrous injection VEGFSiRNA can decrease retinal VEGFmRNA. 3^, vitrous injection VEGFSiRNA do not affect mouse eye growth, development and cause other complication.