Systemic Delivery of siRNA: Challenging but Promising

Small interfering RNA (siRNA) is a small, double-stranded RNA molecule that can suppress expression of specific genes. It will be a promising therapeutic agent for the treatment of viral and genetic diseases, such as HIV infection and cancer. However, it is extremely challenging to systemically deliver siRNA to the intended sites of action due to a variety of extracellular and intracellular barriers. Over the past decade, many novel patents have been developed to improve delivery efficiency and therapeutic efficacy of siRNA. The features of the carriers and technologies for systemic delivery of siRNA in these patents are summarized, and their clinical applications are discussed in this review.