A transfection reagent composition comprising: 30-60 MOL. % of a cationic lipid, or a pharmaceutical acceptable salt thereof; 10-60 MOL % of a structural lipid; 10-20 MOL % of a triglyceride; and 0.1 to about 10 MOL. % of a stabilizing agent, is provided. The transfection agent is effective in transfecting cells, particularly neurons, with siRNA, mRNA and plasmid nucleic acid, Sand maintaining viability of the cells as well as activity of the delivered nucleic acid.