Intracellular delivery of proteins with a new lipid-mediated delivery system

There are many very effective methods to introduce transcriptionally active DNA into viable cells but approaches to deliver functional proteins are li mited. We have developed a lipid-mediated delivery system that can deliver functional proteins or other bioactive molecules into living cells. This de livery system is composed of a new trifluoroacetylated lipopolyamine (TFA-D ODAPL) and dioleoyl phosphatidylethanolamine (DOPE). This cationic formulat ion successfully delivered antibodies, dextran sulfates, phycobiliproteins, albumin, and enzymes (beta -galactosidase and proteases) into the cytoplas m of numerous adherent and suspension cells. Two systems were used to demon strate that the proteins were delivered in a functionally active form. Firs t, intracellular beta -galactosidase activity was clearly demonstrated with in X-gal-stained cells after TFA-DODAPL:DOPE-mediated delivery of the enzym e. Second, the delivery system mediated delivery of several caspases (caspa se 3, caspase 8, and granzyme B) into cultured cell lines and primary cells triggering apoptosis. Mechanistic studies showed that up to 100% of the pr otein mixed with the lipid formulation was captured into a lipid-protein co mplex, and up to 50% of the input protein associated with cells. This lipid -mediated transport system makes protein delivery into cultured cells as co nvenient, effective, and reliable as DNA transfection.