title: The effect of lipid molecular packing stress on cationic liposome-induced rabbit erythrocyte fusion.
abstract: The effect of curvature stress on the efficiency of cationic liposome-induced fusion between rabbit erythrocytes was studied. Multilamellar cationic liposomes containing 1,2-dioleoyl-3-trimethylammoniumpropane (DOTAP) and different PEs (1,2-dilnoleoyl-sn-glycero-3-phosphoethanolamine (dilin-PE), 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE), and lysophosphatidylethanolamine, egg (lyso-PE)) were used to induce cell-cell fusion. It was found that high cell-cell fusion yield (FY) of about 50% could be achieved in sucrose solution by using cationic liposomes containing 50% DOTAP. Cell-cell fusion was assayed by shape criterion and was verified by fluorescence microscopy, using a membrane dye mixing method. The curvature stress, as a result of mixing unsaturated PEs in cationic liposomes, had a significant effect on cell-cell FY which increased with the degree of acyl chain unsaturation, in the order dilin-PE > DOPE > POPE > lyso-PE. Replacement of dilin-PE, DOPE, or POPE by lyso-PE gradually in cationic liposomes lowered the cell-cell FY from 50% to 1%. Furthermore, cationic liposome induced cell lysis, and fusion between cationic liposomes and cells, as assayed by the N-(lissamine rhodamine B sulfonyl)-1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine, triethylammonium salt and N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)-1,2- dihexadecanoyl-sn-glycero-3-phosphoethanolamine, triethylammonium salt (Rh-PE/NBD-PE) energy transfer method, followed the same order as that for cell-cell fusion. Fusion between the negatively charged PS liposomes and cationic liposomes also followed the same order. The electric double layer screening by electrolytes in NaCl-containing solution and phosphate buffered saline (PBS) was found to reduce the cell-cell FY and cell lysis. These findings suggest that liposome-induced cell-cell fusion was achieved by cationic liposomes serving as fusion-bridges among cells.
authors.affiliation: Membrane Biophysics Laboratory, Roswell Park Cancer Institute, Buffalo, NY 14263, USA.
authors.forename: L H
authors.initials: LH
authors.lastname: Li
authors.forename: S W
authors.initials: SW
authors.lastname: Hui
mesh_terms: D000818:Animals; D002412:Cations; D002459:Cell Fusion / Q000187:drug effects* / Q000502:physiology*; D004912:Erythrocytes / Q000737:chemistry* / Q000187:drug effects*; D005229:Fatty Acids, Monounsaturated / Q000737:chemistry; D066298:In Vitro Techniques; D008055:Lipids / Q000737:chemistry*; D008081:Liposomes / Q000737:chemistry* / Q000494:pharmacology*; D008246:Lysophospholipids / Q000737:chemistry; D008561:Membrane Fusion; D010714:Phosphatidylethanolamines / Q000737:chemistry; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D011817:Rabbits; D055672:Static Electricity
chemical_list: D002412:Cations; D005229:Fatty Acids, Monounsaturated; D008055:Lipids; D008081:Liposomes; D008246:Lysophospholipids; D010714:Phosphatidylethanolamines; D000644:Quaternary Ammonium Compounds; C008301:lysophosphatidylethanolamine; C057561:1-palmitoyl-2-oleoylphosphatidylethanolamine; C020888:1,2-dielaidoylphosphatidylethanolamine; C070046:1,2-dioleoyloxy-3-(trimethylammonium)propane