On the delivery of small interfering RNAs into mammalian cells.

RNA interference is becoming the technique of choice for analysing gene function and drug target validation. In this process, sequence-specific gene inhibition is initiated by small RNA duplexes, known as small interfering RNAs (siRNAs). The possibility that exogenously delivered siRNAs or endogenously expressed hairpin siRNAs can cause the destruction of specific target mRNA in vitro and in animal models has been demonstrated. However, the key challenges for the development of siRNAs as human therapeutics is largely dependent on the development of suitable delivery agents and improved siRNA specificity. This review highlights recent advances in siRNA delivery, as well as challenging problems related to immune stimulation.