title: Intracellular delivery of membrane-impermeable hydrophilic molecules to a hepatoblastoma cell line by asialoglycoprotein-labeled liposomes.
abstract: OBJECTIVE
  Mammalian hepatic receptors are specific for the terminal D-galactose of desialylated glycoproteins. This study used asialofetuin-labeled liposomes (AF-liposomes) to target hepatoma cells using this receptor mechanism, and investigated their efficiency in intracellular delivery of membrane-impermeable hydrophilic molecules to a hepatoblastoma cell line (HepG2).
  
  
  METHODS
  Inulin was used as a model molecule. Blank liposomes consisting of phosphatidylcholine:phosphatidic acid:cholesterol in 6:1:6 molar ratio were prepared. Palmitoyl-asialofetuin was anchored onto the blank liposomes using a detergent dialysis method. 3H-inulin was entrapped in the AF-liposomes by dehydration (freeze-drying) and rehydration followed by freeze-thaw sonication. Plain liposomes (N-liposomes) were prepared by the same process but without AF. HepG2 cells were incubated for 3 hours with free 3H-inulin, N-liposomal 3H-inulin, AF-liposomal 3H-inulin, or free AF. The cellular uptake of 3H-inulin and the cell viability were then determined. Uptake of AF-liposomes in a non-hepatoma cell line, NIH3T3, was also studied for comparison.
  
  
  RESULTS
  Cellular uptake of free inulin was negligible while uptake of liposomal inulin, either in N-liposomes or in AF-liposomes, was significant (p < 0.01). The uptake of AF-liposomal inulin was significantly higher than that of N-liposomal inulin in HepG2 cells but not in NIH3T3 cells. Free AF and blank AF-liposomes inhibited the HepG2 cell uptake of AF-liposomal inulin.
  
  
  CONCLUSIONS
  These results indicate that AF-liposomes enhanced intracellular delivery of a membrane-impermeable hydrophilic drug into hepatoma cells by a receptor mechanism. AF-liposomes are a potential drug carrier for intracellular delivery of membrane-impermeable hydrophilic drugs to HepG2 cells.
authors.affiliation: School of Pharmacy, College of Medicine, National Taiwan University, 1 Jen-Ai Road, Section 1, Taipei, Taiwan.
authors.forename: H Y
authors.initials: HY
authors.lastname: Yu
authors.forename: J H
authors.initials: JH
authors.lastname: Lin
mesh_terms: D016475:3T3 Cells / Q000378:metabolism; D000818:Animals; D001212:Asialoglycoproteins; D002463:Cell Membrane Permeability; D004337:Drug Carriers; D006801:Humans; D007444:Inulin / Q000008:administration & dosage* / Q000493:pharmacokinetics; D008081:Liposomes; D008114:Liver Neoplasms, Experimental / Q000378:metabolism*; D051379:Mice; D014407:Tumor Cells, Cultured
chemical_list: D001212:Asialoglycoproteins; D004337:Drug Carriers; D008081:Liposomes; D007444:Inulin