Suppression of retinal neovascularization by small-interference RNA targeting erythropoietin.

OBJECTIVE: To observe the effect of inhibition of retinal neovascularization by small-interference RNA (siRNA) targeting erythropoietin (EPO).

METHOD: Three siRNAs against EPO were designed and synthesized. Then they were transfected to NIH/3T3 cells by liposomes. RT-PCR and Western blot were used to evaluate the efficacy of siRNA in attenuating EPO expression in NIH/3T3 cells. One-week-old C57BL/6J mice were exposed to 75 +/- 2% oxygen for 5 days, then they were returned to room air to induce retinal neovascularization. The siRNA type shown as most powerful in reducing EPO expression in vitro was intravitreally injected in the treatment group. Retinal neovascularization was evaluated by angiography with injection of fluorescein-dextran and quantification of neovascular proliferative retinopathy after 5 days in room air. Moreover, RT-PCR and immunoblot analysis were used to determine whether local administration of siRNA could affect the expression of EPO in murine retinas.

RESULTS: Among the 3 designed siRNAs (named siEPO1-3), siEPO2 is the most efficient in inhibiting EPO expression. In this murine model of oxygen-induced retinopathy, retinal neovascularization in the eyes with siEPO2 injection was significantly reduced compared with that of the contralateral control eyes. Similarly, histological analysis indicates that the number of neovascular nuclei protruding into the vitreous cavity was decreased compared to the control eyes. Furthermore, the expression of EPO in the retinas injected with siEPO2 was dramatically decreased.

CONCLUSION: siRNA against EPO could inhibit experimental retinal neovascularization by reducing EPO expression in the retinas of mice. It may provide a powerful and novel therapeutic tool for ischemia-induced retinal diseases.