title: Use of poly(ethylene glycol)-lipid conjugates to regulate the surface attributes and transfection activity of lipid-DNA particles.
abstract: We evaluated the use of poly(ethylene glycol) (PEG)-modified lipids to control the surface properties of a lipid-based gene transfer system. The lipid-DNA particles (LDPs) used form spontaneously when plasmid DNA is added to mixed detergent lipid micelles consisting of the non-ionic detergent n-octyl-D-glucopyranoside, the cationic lipid dioleyldimethylammonium chloride (DODAC), the zwitterionic lipid 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE), and selected PEG-modified phosphatidylethanolamines. The inclusion of DODAC is required to form the hydrophobic lipid-DNA complex. DOPE is included to facilitate dissociation of DNA from the cationic lipid and the PEG-modified lipids are added in an effort to stabilize the surface attributes of the resulting lipid-DNA particles. We used PEG-lipids that varied in acyl chain composition because of recent results demonstrating acyl chain dependent transfer of PEG-lipids from lipid vesicles, providing the potential to allow a transformation of the surface properties due to loss of surface grafted PEG. The addition of PEG-modified lipids does not interfere in LDP formation and its presence favors formation of smaller particles (75 nm in contrast to 130 nm in the absence of the PEG-modified lipid). PEG-lipid incorporation causes a concentration dependent reduction in LDP-mediated transfection of B16/BL6 melanoma cells, a result that can be partially attributed to a reduction in particle binding to cells. However, significant LDP binding to B16/BL6 cells was still observed under conditions where LDP transfection activity was reduced by more than 85%. The potential for PEG to interfere with LDP processing following cell binding is discussed.
authors.affiliation: Department of Advanced Therapeutics, British Columbia Cancer Agency, 601 West 10th Ave., Vancouver, B.C., V5Z 1L3, Canada.
authors.forename: P
authors.initials: P
authors.lastname: Harvie
authors.forename: F M
authors.initials: FM
authors.lastname: Wong
authors.forename: M B
authors.initials: MB
authors.lastname: Bally
mesh_terms: D000818:Animals; D004247:DNA / Q000008:administration & dosage* / Q000737:chemistry; D015316:Genetic Therapy / Q000379:methods; D005822:Genetic Vectors; D008055:Lipids / Q000008:administration & dosage / Q000737:chemistry*; D008546:Melanoma, Experimental; D051379:Mice; D010316:Particle Size; D011092:Polyethylene Glycols / Q000737:chemistry*; D013499:Surface Properties; D014162:Transfection / Q000379:methods*; D014407:Tumor Cells, Cultured
chemical_list: D008055:Lipids; D011092:Polyethylene Glycols; D004247:DNA