SiRNA Targeting Mammalian Target Of Rapamycin (mTOR) Attenuates Experimental Proliferative Vitreoretinopathy

Purpose: To investigate the effect of mammalian target of rapamycin (mTOR) specific siRNA on proliferative vitreoretinopathy (PVR).Methods: Cultured human retinal pigment epithelial (hRPE) cell line D407 was treated with three mTOR specific small interfering RNAs. Cell proliferation, attachment, spreading and migration were performed. Real time reverse transcriptase polymerase chain reaction was performed to investigate the collagen mRNA expression. Enzyme-linked immunosorbent assays (ELISA) and immunocytochemical analyses were performed to investigate the extracellular and intracellular type I, III and IV collagen production. The impact of the mTOR specific siRNA on collagen production in vivo and on proliferative vitreoretinopathy (PVR) was tested using a rabbit model in which PVR was induced by the injection of hRPE cells.Results: Decreasing mTOR expression by about 82% using small interfering RNA resulted in significant decrease in cell spreading, migration,collagen mRNA expression, extracellular and intracellular type I, III and IV collagen production. Furthermore, knocking down of mTOR significantly reduced the production of collagen in vivo. Whereas retinal detachment occurred in 100% of the control group animals, co-injection of the mTOR specific siRNA substantially reduced the severity and incidence (50%) of retinal detachments.Conclusions: mTOR plays an important role in regulation the expression of collagen type I, III and IV collagen in hRPE cells in vitro and in vivo. Gene therapy with mTOR specific siRNA attenuates PVR in a rabbit model of the disease. This may be a new approach to preventing PVR in humans.