Carrier Matrix for SiRNA-mediated Gene Knock Down to Promote Neuronal Regeneration

Axons in the adult vertebrate central nervous system (CNS) exhibit almost no regeneration after injury, partly because of the presence of neurite outgrowth inhibitors in the CNS. The aim of this study is to enhance functional recovery and axon regrowth using siRNA in order to transiently inhibit the intracellular signalling pathway of central components into which various repulsive inputs converge. An effort concerning this objective is to find an appropriate carrier matrix for binding, stabilization, and promoting cellular uptake of siRNA. Chitosan is a biocompatible and biodegradable material which enables a strong electrostatic binding of oligonucleotides. In this study we present the effective binding of siRNA to chitosan under formation of nanoparticles. Analysis of different kinds of chitosan-siRNA nanoparticles using gel-retardation assays demonstrated high stability of those complexes abrogated only after addition of competing agents. Finally, cell transfection experiments with fluorescentiy labelled siRNA showed efficient uptake of chitosan-siRNA nanoparticles into different cell types which play an important role in the nervous system. Our results therefore highlight the potential application of chitosan in siRNA-mediated gene knock down to promote neuronal regeneration after spinal cord injury.