Targeting of glycosylated lipoplexes in HepG2 cells: Anomeric and C-4 epimeric preference of the asialoglycoprotein receptor.

This study was conducted to determine the capacity of the asialoglycoprotein receptor on the hepatocyte-derived cell line HepG2 to exhibit an anomeric preference with respect to the D-galacto moiety on cationic liposome membrane-anchored cholesteryl-α-D-galactopyranoside (Choαgal) and cholesteryl-β-Dgalactopyranoside (Cholβgal) in cationic liposome/pGL3 plasmid DNA complexes constructed for non-viral, hepatocyte-directed gene transfer. In addition, cholesteryl-α-D-glucopyranoside (Choαglu) and cholesteryl-β-D-glucopyranoside (Cholβglu) were separately formulated into cationic liposomes at the same mole ratio (11%) to examine the C-4 epimeric selectivity of the asialoglycoprotein lectin for the glucopyranosides displayed in derived lipoplexes. Lipoplex formation was examined by gel retardation, ethidium displacement assays, and transmission electron microscopy. Plasmid DNA was shown to be fully liposome associated and maximally compacted at a liposome:DNA ratio of 6:1 (weight ratio), corresponding to a +/- charge ratio of 1.3 with complexes falling in the 80–200 nm size range, whereas at a 5:1 w/wratio [1.1 (+/-) charge ratio] lipoplexes were somewhat smaller (50–100 nm) but promoted higher transgene activity in HepG2 cells than 6:1 (w/w) lipoplexes, in the following order: Cholβgal > Cholαgal > Cholβglu = Cholαglu. Transgene activity levels in HeLa cells which lack the asialoglycoprotein receptor were approximately 10% of those achieved in HepG2 cells. Moreover, transgene activity in HepG2 cells was reduced by approximately 90% in the presence of excess asialofetuin, a ligand for the asialoglycoprotein lectin. [ABSTRACT FROM AUTHOR]