title: Comparative gene transfer between cationic and thiourea lipoplexes.
abstract: BACKGROUND
  We have previously developed lipopolythiourea lipids as neutral DNA condensing agents for systemic gene delivery. Optimization of the lipopolythiourea structure led to efficient transfecting agents. To further evaluate these lipids, we investigated the internalization process of the thiourea lipoplexes and their intracellular mechanism of transfection versus that of cationic lipoplexes.
  
  
  METHODS
  The MTT test was used for cytotoxicity assessment. Transfection efficiency was determined by luciferase read-out. Permeation to propidium iodide and enhanced green fluorescent protein was evaluated by flow cytometry. Kinetics of internalization and DNA release were monitored by confocal microscopy with labelled DNA. Endocytosis inhibitors were used to study the mechanisms of lipoplex internalization.
  
  
  RESULTS
  Although thiourea/DNA complexes exhibit an almost similar level of transfection compared to that of cationic complexes, the thiourea lipoplexes were shown to be six-fold less internalized. Complexes were able to permeabilize the cytoplasmic membrane to 30 kDa molecules. Finally, DNA was shown to be released in less than 10 min in the cellular cytoplasm versus 30 min for cationic lipoplexes.
  
  
  CONCLUSIONS
  Despite a weaker internalization compared to cationic lipids, the thiourea lipoplexes were able to transfect cells at a similar level as a result of its greater ability to destabilize the cytoplasmic membrane and release DNA.
authors: Inserm, U640, CNRS, UMR8151, Unité de Pharmacologie Chimique et Génétique, Université Paris Descartes, Faculté de Pharmacie, Paris, France.
authors: Marie
authors: M
authors: Breton
authors: Jeanne
authors: J
authors: Leblond
authors: Johanne
authors: J
authors: Seguin
authors: Patrick
authors: P
authors: Midoux
authors: Daniel
authors: D
authors: Scherman
authors: Jean
authors: J
authors: Herscovici
authors: Chantal
authors: C
authors: Pichon
authors: Nathalie
authors: N
authors: Mignet
mesh_terms: D000818:Animals; D001692:Biological Transport; D002412:Cations; D002460:Cell Line; D004705:Endocytosis; D005453:Fluorescence; D018014:Gene Transfer Techniques; D006801:Humans; D042541:Intracellular Space / Q000378:metabolism; D007700:Kinetics; D008055:Lipids / Q000737:chemistry*; D051379:Mice; D018613:Microscopy, Confocal; D010539:Permeability; D010957:Plasmids / Q000235:genetics; D013696:Temperature; D013890:Thiourea / Q000737:chemistry*; D014162:Transfection
chemical_list: D002412:Cations; D008055:Lipids; D013890:Thiourea