title: On the mechanism whereby cationic lipids promote intracellular delivery of polynucleic acids.
abstract: The mechanism whereby cationic lipids destabilize cell membranes to facilitate the intracellular delivery of macromolecules such as plasmid DNA or antisense oligonucleotides is not well understood. Here, we show that cationic lipids can destabilize lipid bilayers by promoting the formation of nonbilayer lipid structures. In particular, we show that mixtures of cationic lipids and anionic phospholipids preferentially adopt the inverted hexagonal (H(II)) phase. Further, the presence of 'helper' lipids such as dioleoylphosphatidylethanolamine or cholesterol, lipids that enhance cationic lipid-mediated transfection of cells also facilitate the formation of the H(II)phase. It is suggested that the ability of cationic lipids to promote nonbilayer structures in combination with anionic phospholipids leads to disruption of the endosomal membrane following uptake of nucleic acid-cationic lipid complexes into cells, thus facilitating cytoplasmic release of the plasmid or oligonucleotide.
authors.affiliation: Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada.
authors.forename: I M
authors.initials: IM
authors.lastname: Hafez
authors.forename: N
authors.initials: N
authors.lastname: Maurer
authors.forename: P R
authors.initials: PR
authors.lastname: Cullis
mesh_terms: D002412:Cations; D002462:Cell Membrane / Q000378:metabolism*; D002784:Cholesterol / Q000378:metabolism; D015316:Genetic Therapy / Q000379:methods*; D020404:Glycerophospholipids / Q000378:metabolism; D006801:Humans; D008051:Lipid Bilayers; D008081:Liposomes / Q000032:analysis / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D010714:Phosphatidylethanolamines; D014162:Transfection / Q000379:methods*
chemical_list: C410262:1,2-dioleoyl-glycero-3-phosphatidyl ethanolamine; D002412:Cations; D020404:Glycerophospholipids; D008051:Lipid Bilayers; D008081:Liposomes; D010714:Phosphatidylethanolamines; D002784:Cholesterol