title: Evidence of DNA transfer across a model membrane by a neutral amphiphilic block copolymer.
abstract: BACKGROUND
  Neutral amphiphilic triblock copolymers have been shown to be efficient for gene transfection in vivo, especially by direct injection into the muscle. To contribute to a better understanding of the underlying mechanisms, in the present study, we investigated the properties of a poly(ethylene oxide-b-4-vinylpyridine) diblock copolymer as vector for nucleic acid transfer, with the particular aim of shedding some light on a possible mechanism explaining the internalization of DNA by the transfected cells.
  
  
  METHODS
  Complexation of plasmid DNA with the PEO-b-P4VP diblock copolymer was investigated by ethidium bromide exclusion and gel electrophoresis assays. Interaction of the copolymer with a lipid model membrane was evaluated by electrophysiological assays and quantification of plasmid DNA was performed by quantitative polymerase chain reaction. In vivo luciferase transfection assays were finally performed.
  
  
  RESULTS
  The diblock copolymer was found to poorly interact with DNA up to a mass ratio (copolymer/DNA) as high as 150. At a concentration of 36 µg/ml, it induced the formation of mainly transient (but sometimes permanent) pores and the formation of those pores allowed the translocation of plasmid DNA across the model membrane. However, only low transgene expression was obtained; the luciferase levels observed with the diblock being of the same order of magnitude as those observed with the corresponding PEO and P4VP homopolymers.
  
  
  CONCLUSIONS
  These results strongly suggest that gene transfection by neutral block copolymers may involve the formation of cellular pores; in addition, they also highlight that in vivo gene transfection requires the use of adequately soluble block copolymers.
authors.affiliation: LAMBE, UEVE-CNRS-CEA, UMR 8587, Equipe Matériaux Polymères aux Interfaces, Université d'Evry, Evry, France.
authors.forename: Cécile
authors.initials: C
authors.lastname: Huin
authors.forename: Tony
authors.initials: T
authors.lastname: Le Gall
authors.forename: Benoît
authors.initials: B
authors.lastname: Barteau
authors.forename: Bruno
authors.initials: B
authors.lastname: Pitard
authors.forename: Tristan
authors.initials: T
authors.lastname: Montier
authors.forename: Pierre
authors.initials: P
authors.lastname: Lehn
authors.forename: Hervé
authors.initials: H
authors.lastname: Cheradame
authors.forename: Philippe
authors.initials: P
authors.lastname: Guégan
mesh_terms: D000818:Animals; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D005260:Female; D008051:Lipid Bilayers / Q000737:chemistry / Q000378:metabolism*; D051379:Mice; D015394:Molecular Structure; D011092:Polyethylene Glycols / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry*; D014162:Transfection
chemical_list: D008051:Lipid Bilayers; D011108:Polymers; D011725:Pyridines; D011092:Polyethylene Glycols; D004247:DNA; C029351:4-vinylpyridine