Lipopolyplexes comprising imidazole/imidazolium lipophosphoramidate, histidinylated polyethyleneimine and siRNA as efficient formulation for siRNA transfection.

Lipopolyplexes formulations resulting from association of nucleic acid, cationic liposomes and a cationic polymer are attracting formulations for siRNA delivery. Herein, imidazole- and imidazolium-based liposomes in association with histidinylated polymers are studied to produce siRNA lipopoplyplexes (LPRi) subsequently used for gene silencing. Several kinds of imidazole/histidine liposomes and cationic polymers are tested. The gene silencing effect is evaluated with synthetic siRNA directed against EGFP or luciferase mRNA, in HeLa cells stably expressing EGFP or B16F10 melanoma cells stably expressing luciferase, respectively. SiRNA formulations are compared with those prepared using some commercial transfection reagents. One formulation called His-lPEI LPRi100 comprising siRNA, histidinylated lPEI (His-lPEI) and liposomes 100 made with O,O-dioleyl-N-[3N-(N-methylimidazolium iodide)propylene] phosphoramidate and O,O-dioleyl-N-histamine phosphoramidate appears to give the best specific inhibition of gene expression at 10nM siRNA in a dose-dependent manner with low cytotoxicity. This formulation exhibits a size and a zeta potential of 60 nm and +84 mV, respectively. According to our previous works, histidinylated lipopolyplexes appears as a versatile formulation for DNA, mRNA and siRNA transfection.