Strategies and Approaches for siRNA Delivery

The present review discusses about RNA interference (RNAi) and its significance in gene therapy. The review mainly focuses on small interference RNA (siRNA) as a mediator of RNAi, its therapeutic benefits and various formulation strategies employed to overcome siRNA delivery hurdles. RNAi is a regulatory process which occurs endogenously within the cell wherein short double-stranded RNA (siRNA) effects sequence-specific posttranscriptional gene silencing. Even though siRNA assists researchers with its powerful therapeutic benefits, there are significant hurdles in developing efficient delivery systems for its systemic administration. These are extracellular and intracellular barriers for siRNA delivery. The present review addresses about pros and cons of gene therapy and superior advantages provided by siRNA over plasmid DNA in gene therapy. It also discloses about the discovery, mechanism of action, significance and applications of siRNA based gene therapies, challenges in its delivery and strategies for overcoming delivery hurdles. Furthermore, emphasis is provided on viral and non – viral vector based siRNA delivery and the significance of lipid based siRNA delivery, the lipoplexes over polymer based siRNA delivery - the polyplexes, followed by recent advances in siRNA based technologies directed against variety of diseases. Keywords: Endosomal escape, gene therapy, lipoplexes, polyplexes, siRNA, vectors