An insight into the use of cationic peptides for plasmid DNA delivery in cells.

In this work, we contribute an insight into the ability of cationic peptides for the delivery of plasmid DNA in cells. Although most peptides used for cellular transfection are cationic, not all of them possess this potential. Using plasmid DNA bearing reporter genes and cells of the breast cancer MDA-MB 435 line, we show at first that only peptides in an α-helical structure can give high levels whereas peptides with a β-strand structure cannot. Amphipathic peptides rich in lysine, namely L10K5 or L13K6, adopting both an α-helical structure are able to be used for this task. Subsequently, we show that protamine, equally rich in basic arginine, but not having an α-helical structure, cannot alone efficiently deliver DNA. However, it improved the transfection level by cationic liposomes, undoubtedly by a condensing effect. This enhancement in transfection by protamine was not observed using the peptide L13K6 and this peptide did not behave as protamine to enhance the transfection level of cationic liposomes.