Efficient in vivo siRNA delivery by stabilized d-peptide-based lipid nanoparticles

Abstract

RNA interference (RNAi) has shown great potential for clinical treatment of a variety of diseases. As an effective post-transcriptional regulation, RNAi induces degradation of specific target mRNA, leading to a decreased level of disease related gene product, which could be resistant to conventional small molecule therapeutics. Because of the relatively small size of short interfering RNA (siRNA) as well as it's robustness in the design of efficient 20–22 nucleotide sequences targeting any known gene, delivery of siRNA in vitro and in vivo has achieved tremendous success by the design and fabrication of various carrier materials including peptides, lipids, and polymers. While siRNA delivery efficiency of these materials proved to be appreciable, their tissue specificity, biocompatibility and cytotoxicity still need much improvement. We report a novel siRNA delivery material designed by optimization of our previously reported peptidomimetic based lipoplex. The novel lipoplex, which bears a D-amino acid based dipeptide head group, possesses an ideal balance of increased stability in a tissue environment, and enhanced efficiency of tissue specific delivery as well as minimized cytotoxicity. The novel lipoplex carrying siRNA efficiently targeted mouse liver, initiated RNAi and knocked down the apoB dose dependently, which is confirmed by both RT-qPCR and Western blotting. Moreover, the novel lipoplex does not induce any apparent cytotoxicity, as confirmed by the measurement of liver enzyme levels in serum.