Nucleic acid delivery using dendrimer composed of amino acids

Dendrimer composed of L-lysines as a branch unit, dendritic poly(L-lysine), formed neutral complex with plasmid DNA, and showed high transfection efficiency without cytotoxity in vitro. Compared with linear type poly(L-lysine), uptake of the complex was lower, however, amount of transferred DNA to cytosol was larger. As compaction level of the DNA was lower, it is reasonably supposed that the high transfection efficiency of dendritic poly(L-lysine) was due to easy release of free DNA from the complex and easy access of transcription factors to the DNA. After intravenously injection, intact DNA was observed in the blood, liver and lung even at 3 hours. Furthermore, we succeeded to deliver siRNA using dendritic poly(L-lysine) to the liver, and inhibitory effect of target gene expression could be detected. Dendritic poly(L-lysine) is expected to be used as a siRNA carrier that works in vivo.