Using RNAi to knock down the expression of particular receptors and signaling molecules is an intriguing pathway for neural engineering. For example, reducing the expression of neuropilin-2, a molecule that acts as a axon guiding cue, may improve axon outgrowth following injury.
In order to study one method, Ehlert et al injected short hairpin RNAs encoded by a lentiviral vector into the dorsal root ganglia at L4 and L5 of the spinal cord in rats. They used two types of short hairpin RNAs, one of which (A) was able to reduce the expression of Npn-2 as compared to controls. They measured Npn-2 mRNA via hapten-labeled RNA probes and GFP immunofluorescence:
The authors do encounter lots of the typical in vivo problems, especially cytotoxicity, probably due to saturation of the cell’s micro RNA synthesizing molecules. Still, these RNAi experiments are always interesting.
Elhert EM, et al. 2010 Cellular toxicity following application of adeno-associated viral vector-mediated RNA interference in the nervous system. BMC Neuro doi:10.1186/1471-2202-11-20