Gene Silencing in the Brain with siRNA to Promote Long-Term Post-Stroke Recovery.

RNA interference is a promising strategy to degrade target RNAs of interest after stroke using small interfering RNA (siRNA). An optimized targeting such as combining a siRNA with a nontoxic transfection reagent that facilitates the effective delivery of siRNAs to the brain and subsequent cellular uptake after stroke is needed. Furthermore, an appropriate route of administration such as intravenous (tail vein or retro-orbital sinus) or cerebroventricular injection has to be used. Using siRNAs tagged with fluorescent probes shows the cellular uptake of siRNA. Efficacy and window of opportunity for a siRNA needs to be determined by testing multiple doses and time frame that alters the long-term functional outcomes. Real-time PCR/western blots can be used to determine the siRNA efficiency by evaluating the knockdown of the RNA/protein of interest. In siRNA studies, it is also essential to identify a proper dose (efficacious, but not toxic) by histopathologic testing to identify any toxicity in the peripheral organs and CNS. This chapter describes the strategies to deliver siRNAs to treat stroke and to facilitate post-stroke long-term recovery.