Cationic amino acid based lipids as effective nonviral gene delivery vectors for primary cultured neurons

The delivery of specific genes into neurons offers a potent approach for treatment of diseases as well as for the study of neuronal cell biology. Here we investigated the capabilities of cationic amino acid based lipid assemblies to act as nonviral gene delivery vectors in primary cultured neurons. An arginine-based lipid, Arg-C₃-Glu2C₁₄, and a lysine-based lipid, Lys-C₃-Glu2C₁₄, with two different types of counterion, chloride ion (Cl^-) and trifluoroacetic acid (TFA ^-), were shown to successfully mediate transfection of primary cultured neurons with plasmid DNA encoding green fluorescent protein. Among four types of lipids, we optimized their conditions such as the lipid-to-DNA ratio and the amount of pDNA and conducted a cytotoxicity assay at the same time. Overall, Arg-C₃-Glu2C₁₄ with TFA^- induced a rate of transfection in primary cultured neurons higher than that of Lys-C ₃-Glu2C₁₄ using an optimal weight ratio of lipid-to-plasmid DNA of 1. Moreover, it was suggested that Arg-C ₃-Glu2C₁₄ with TFA^- showed the optimized value higher than that of Lipofectamine2000 in experimental conditions. Thus, Arg-C₃-Glu2C₁₄ with TFA^- is a promising candidate as a reliable transfection reagent for primary cultured neurons with a relatively low cytotoxicity.