Poly(ethylene glycol)-poly-l-glutamate complexed with polyethyleneimine-polyglycine for highly efficient gene delivery in vitro and in vivo.

To improve gene transfection efficiency in vitro and in vivo, we first grafted polyglycine (PGly) onto branched polyethyleneimine (PEI) (molecular weight MW 25 kDa) to obtain a novel gene vector PGly-PEI (PPG), before complexing it with poly(ethylene glycol)-poly-l-glutamate (PEG-PLG) for adjusting the charge density of PEI. We named the resulting nano-polyplex PG/PPG. The PPGs demonstrated improved gene transfection efficiency after grafting with polyglycine, and the efficiency could be further increased with the introduction of PEG-PLG. The PG/PPG exhibited not only excellent DNA and siRNA transfection capacity in various cell lines including HeLa, CHO, HepG2, MCF7 and Huh7, but also reduced cytotoxicity compared with PEI. Besides, PG/PPG induced a higher degree of cell apoptosis when mixed genes of pKH3-rev-casp-3 plasmid and siBcl2 were used rather than either of them. Furthermore, PG/PPG was highly resistant to serum, which led to enhanced in vivo red fluorescent protein (RFP) expression in HeLa tumors. These results suggested that PG/PPG is a promising gene carrier for highly efficient gene delivery.