Enhanced cationic liposome-mediated transfection using the DNA-binding peptide mu (mu) from the adenovirus core

Promising advances in nonviral gene transfer have been made as a result of the production of cationic liposomes formulated with synthetic cationic lip ids (cytofectins) that are able to transfect cells. However few cationic li posome systems have been examined for their ability to transfect CNS cells. Building upon our earlier use of cationic liposomes formulated from 3 beta -[N-(N',N'-dimethylaminoethane)carbamoyl] cholesterol (DC-Chol) and dioleoy l-L-alpha -phosphatidyl-ethanolamine (DOPE), we describe studies using two cationic viral peptides, mu (mu) and Vp1, as potential enhancers for cation ic liposome-mediated transfection. Mu is derived from the condensed core of the adenovirus and was selected to be a powerful nucleic acid charge neutr alising and condensing agent Vp1 derives from the polyomavirus and harbours a classical nuclear localisation signal (NLS). Vp1 proved disappointing bu t lipopolyplex mixtures formulated from pCMV beta plasmid, mu peptide and D C-Chol/DOPE cationic liposomes were able to transfect an undifferentiated n euronal ND7 cell line with beta -galactosidase reporter gene five-fold more effectively than lipoplex mixtures prepared from pCMV beta plasmid and DC- Chol/DOPE cationic liposomes. Mu was found to give an identical enhancement to cationic liposome-mediated transfection of ND7 cells as poly-L-lysine ( pLL) or protamine sulfate (PA). The enhancing effects of mu were found to b e even greater (six- to 10-fold) when differentiated ND7 cells were transfe cted with mu-containing lipopolyplex mixtures. Differentiated ND7 cells rep resent a simple ex vivo-like post-mitotic CNS cell system. Successful trans fection of these cells bodes well for transfection of primary neurons and C NS cells in vivo. These findings have implications for experimental and the rapeutic uses of cationic liposome-mediated delivery of nucleic acids to CN S cells.