title: Enhanced gene expression in lung by a stabilized lipoplex using sodium chloride for complex formation.
abstract: BACKGROUND
  In this study, we investigated the in vivo gene transfection efficacy of a 'surface charge regulated' (SCR) lipoplex, dispersed in the presence of an essential amount of NaCl during lipoplex formation.
  
  
  METHODS
  SCR lipoplexes were prepared and their physicochemical properties were analyzed. After intravenous (i.v.) administration, transfection efficacy, distribution characteristics, and liver toxicity were evaluated in mice.
  
  
  RESULTS
  At NaCl concentrations of 10 mM, the particle sizes of the SCR lipoplexes were about 120 nm and were compatible with a conventional lipoplex. However, fluorescent resonance energy transfer analysis revealed that cationic liposomes in the SCR lipoplexes increased fusion. After i.v. administration, the transfection activity in the lung of the SCR lipoplex (10 mM NaCl solution in the lipoplex) was approximately 10-fold higher than that of the conventional lipoplex. Pharmacokinetic studies demonstrated a higher distribution in lung by the SCR lipoplex. When the gene expression levels of the SCR lipoplex and conventional lipoplex were compared, the SCR lipoplex at a dose of 30 microg was compatible with that of the conventional lipoplex at a dose of 50 microg. A significantly higher serum alanine aminotransferase (ALT) activity and TNFalpha concentration was observed by the conventional lipoplex (pDNA dose; 50 microg), but this was not the case for the SCR lipoplex (pDNA dose; 30 microg).
  
  
  CONCLUSIONS
  We demonstrated that the SCR lipoplex could enhance the transfection efficacy in the lung without increasing the liver toxicity. Hence, the information will be valuable for the future use, design, and development of lipoplexes for in vivo applications.
authors.affiliation: Department of Drug Delivery Research, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Kawakami
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Ito
authors.forename: Shintaro
authors.initials: S
authors.lastname: Fumoto
authors.forename: Fumiyoshi
authors.initials: F
authors.lastname: Yamashita
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Hashida
mesh_terms: D000410:Alanine Transaminase / Q000097:blood; D000704:Analysis of Variance; D000818:Animals; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D031541:Fluorescence Resonance Energy Transfer; D015870:Gene Expression; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors / Q000008:administration & dosage* / Q000493:pharmacokinetics; D008081:Liposomes; D008156:Luciferases / Q000235:genetics; D008168:Lung / Q000378:metabolism*; D051379:Mice; D012965:Sodium Chloride / Q000378:metabolism*; D014162:Transfection / Q000379:methods*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D018076:DNA, Complementary; D008081:Liposomes; D014409:Tumor Necrosis Factor-alpha; D012965:Sodium Chloride; D008156:Luciferases; D000410:Alanine Transaminase