Receptor-mediated gene delivery to HepG2 cells by ternary assemblies containing cationic liposomes and cationized asialoorosomucoid.

Unilamellar cationic liposomes have been prepared from an equimolar mixture of 3beta[N',N'-dimethylaminopropane)-carbomoyl] cholesterol (Chol-T), a higher homologue of 3beta[N',N'-dimethylaminoethane)-carbomoyl] cholesterol (DC-Chol), and dioleoylphosphatidyl-ethanolamine. The DNA binding capabilities of Chol-T and Chol-T/DOPE liposomes have been demonstrated in lipid impregnated paper-DNA binding assays and gel retardation experiments, respectively. These liposomes have been combined with pRSVL plasmid DNA and N-ethyl-N'-(3-trimethylpropylammonium) carbodiimide iodide modified asialoorosomucoid (Me+ CDI urea-AOM) to generate ternary electrostatic assemblies intended for selective entry into cells displaying the galactose-specific lectin. This effect has been evaluated in the human hepatocellular carcinoma cell line HepG2 in which high levels of luciferase activity were achieved (up to 1.84 x 10(7) relative light units/mg protein) after transfection with complexes containing liposomes (1-3 microg), Me+CDI urea-AOM (2 microg), and DNA (0.5 microg) in 0.5 mL culture medium. Transfections conducted in the presence of free asialoorosomucoid afforded much lower luciferase activity (up to 1.5 x 10(5) relative light units/mg protein) confirming that DNA uptake was predominantly via asialoorosomucoid receptor-mediated endocytosis. We concluded therefore that modular complexes used in our study display the carbohydrate moiety of the glycoprotein component prominently, thus permitting interaction of terminal galactose units with their cognate receptors on the cell membrane.