Arginine-rich cell-penetrating peptides deliver gene into living human cells

Transgenesis is a process that introduces exogenous nucleic acids into the genome of an organism to produce desired traits or evaluate function. Improvements of transgenic technologies are always important pursuit in the last decades. Recently, cell-penetrating peptides (CPPs) were studied as shuttles that can internalize into cells directly and serve as carriers to deliver different cargoes into cells. In the present study, we evaluate whether arginine-rich CPPs can be used for gene delivery into human cells in a noncovalent fashion. We demonstrate that three arginine-rich CPPs (SR9, HR9, and PR9) are able to transport plasmid DNA into human A549 cells. For the functional gene assay, the CPP-delivered plasmid DNA containing the enhanced green fluorescent protein (EGFP) coding sequence could be actively expressed in cells. The treatment of calcium chloride did not facilitate the CPP-mediated transfection efficiency, but enhance the gene expression intensity. Mechanistic studies further revealed that HR9/DNA complexes mediate the direct membrane translocation pathway for gene delivery. Our results suggest that arginine-rich CPPs, especially HR9, appear to be a high efficient and promising tool for gene transfer.