title: Membrane perturbation and the mechanism of lipid-mediated transfer of DNA into cells.
abstract: Mixtures of cationic lipids and unsaturated phosphatidylethanolamine are used extensively for the intracellular delivery of plasmids and antisense oligodeoxynucleotides (ODN) in vitro. However, the mechanism by which cytoplasmic delivery of these large molecules is achieved remains unclear. The common hypothesis is that phosphatidylethanolamine promotes fusion of lipid/DNA particles with endosomal membranes, but this is inconsistent with several reports that have failed to correlate the fusogenic activity of a wide variety of lipid/DNA particles, measured by lipid mixing techniques, with their transfection activity. To address this issue further we have conducted a detailed analysis of the lipid mixing and DNA transfer activity of two, physically similar but functionally different, lipid/DNA particles composed of equimolar dioleyldimethylammonium chloride (DODAC) and dioleoylphosphatidylethanolamine (DOPE) or dioleoylphosphatidylcholine (DOPC). In combination with DODAC both phospholipids form almost identical lipid/DNA particles, they are endocytosed by cells to the same extent and each undergoes equivalent lipid mixing with cell membranes after uptake. Despite this, DNA transfer is 10- to 100-fold more extensive for lipid/DNA particles containing DOPE. We conclude that lipid mixing between lipid-based delivery systems and endosomal membranes must occur for DNA transfer to occur. However, the potency of different lipid/DNA particles correlates better with the ability of the exogenous lipid to disrupt membrane integrity.
authors.affiliation: Inex Pharmaceutials Corp, Burnaby, BC, Canada. bmui@inexpharm.com
authors.forename: B
authors.initials: B
authors.lastname: Mui
authors.forename: Q F
authors.initials: QF
authors.lastname: Ahkong
authors.forename: L
authors.initials: L
authors.lastname: Chow
authors.forename: M J
authors.initials: MJ
authors.lastname: Hope
mesh_terms: D000818:Animals; D001483:Base Sequence; D001693:Biological Transport, Active; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D006224:Cricetinae; D004247:DNA / Q000008:administration & dosage* / Q000235:genetics / Q000378:metabolism*; D016503:Drug Delivery Systems; D011992:Endosomes / Q000378:metabolism; D066246:ErbB Receptors / Q000235:genetics; D018014:Gene Transfer Techniques; D020404:Glycerophospholipids / Q000008:administration & dosage / Q000378:metabolism; D006801:Humans; D050356:Lipid Metabolism; D008055:Lipids / Q000008:administration & dosage*; D020319:Oligodeoxyribonucleotides, Antisense / Q000008:administration & dosage / Q000235:genetics / Q000378:metabolism; D010713:Phosphatidylcholines / Q000008:administration & dosage / Q000378:metabolism; D010714:Phosphatidylethanolamines; D000644:Quaternary Ammonium Compounds / Q000008:administration & dosage / Q000378:metabolism; D014162:Transfection
chemical_list: C410262:1,2-dioleoyl-glycero-3-phosphatidyl ethanolamine; D020404:Glycerophospholipids; D008055:Lipids; D020319:Oligodeoxyribonucleotides, Antisense; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D000644:Quaternary Ammonium Compounds; C015831:dimethyldioctadecylammonium; D004247:DNA; D066246:ErbB Receptors; C017251:1,2-oleoylphosphatidylcholine