Nanocarrier Based Small Interfering RNA siRNA System for Targeting Ocular Neovascularization

Abstract

The study investigated a promising approach to combat diabetic retinopathy (DR), a vision-threatening complication of diabetes caused by overexpression of vascular endothelial growth factor (VEGF). The research focused on using small interfering RNAs (siRNAs) to target and downregulate the Human antigen R (HuR) protein, which is key in stabilizing VEGF-A mRNA. To achieve this, the study initially designed three siRNAs to inhibit HuR mRNA. These siRNAs were successfully transfected into human retinal pigment epithelial cells (ARPE-19) using Lipofectamine 2000. The researchers found that this led to a significant reduction in HuR mRNA levels, resulting in decreased levels of both HuR and VEGF-A proteins. Additionally, the study delved into advanced delivery methods. Lipopolyplexes (LPPs) were formulated using a combination of a cationic polymer (polyethyleneimine or PEI) and lipid nanoparticles (liposomes). This approach addressed the limitations of traditional gene delivery methods, offering improved stability, reduced toxicity, and enhanced siRNA protection against degradation. Modified chitosan (CsAr) complexes were also explored to improve cellular uptake of siRNA. These complexes were encapsulated in anionic liposomes, producing lipidated LCAr particles with enhanced characteristics and lower toxicity. The efficacy of these delivery systems was demonstrated both in vitro (using human ARPE-19 cells) and in vivo (using diabetic rats). The results showed a significant reduction in HuR and VEGF levels, indicating the potential therapeutic value of intravitreal treatment with HuR-siRNA delivered via LPPs. In summary, this study highlights the promising use of siRNA technology to target HuR and, consequently, VEGF, in the context of DR. It also emphasizes the importance of advanced delivery methods, such as LPPs and LCAr complexes, for enhancing the stability and effectiveness of siRNA-based therapies.