Dendrimers as Vectors for Small Interfering RNA Transfection in the Nervous System

A broad description for gene therapy might include both the replacement of absent or defective genes using plasmid DNA and the selective interference with signaling pathways involved in the genesis of various diseases by knocking down mRNA expression using RNA interference (RNAi) technology. The use of RNAi has a great potential for drug development, but since this molecule is cell‐impermeant, first it must overcome the different barriers that preclude its arrival to the target cells. To achieve this goal, the genetic material must be transported by a carrier, generally a nanoparticle. In this chapter, we have discussed the barriers that a nanoparticle must cross to deliver its cargo to the central nervous system and how dendrimers can overcome most of these barriers. In addition, several examples of successful delivery to neuronal cells both in vivo and in vitro are presented. The use of molecular modeling to predict the interaction of dendrimers with genetic material which facilitates the design of chemical synthesis strategies is also presented.