Polymeric micelles for siRNA delivery

Post-transcriptional gene silencing mechanism using small interfering RNA (siRNA) as a potential therapeutic modality has generated great interest in recent years. However, significant hurdles such as off-target effects, possible immunogenicity, in vivo instability and effective delivery to the cellular and intracellular site of action following systemic administration should be overcome before synthetic siRNA can be used as an effective therapeutic agent. Development of several siRNA delivery systems as well as chemical modification of the siRNA structure has been pursued to combat problems associated with therapeutic use of siRNA. Among different structures, polymeric micelles have attracted tremendous attention in recent years as promising carriers for targeted siRNA delivery. The aim of this manuscript is to review different polymeric micelles of siRNA developed to date and provide an overview on the extent of in vitro/in vivo success in siRNA delivery, targeted gene silencing or therapeutic activity by these siRNA delivery systems.