title: Stimulatory effect of polyethylene glycol (PEG) on gene expression in mouse liver following hydrodynamics-based transfection.
abstract: BACKGROUND
  Rapid intravenous injection of a large volume of plasmid DNA (pDNA), i.e. a transfection procedure based on hydrodynamics, is known to be an efficient and liver-specific method of in vivo gene delivery. However, the gene expression is transient.
  
  
  METHODS
  We investigated the effect of addition of polyethylene glycol (PEG) to a solution of naked pDNA (luciferase) on the expression of the gene in mouse liver following transfection by the hydrodynamics-based technique. In addition, the mechanism leading to the enhancement of the gene expression was studied.
  
  
  RESULTS
  The addition of 1% (w/v) PEG2000 to the pDNA solution enhanced the resulting gene expression in the liver. Increasing the PEG2000 concentration to more than 1 and up to 10% (w/v) rather diminished the gene expression level. By contrast, increasing the molecular weight of PEG to over 2000 up to 10 000 did not affect the level of gene expression. Histopathological and serum-chemistry examinations indicated that hydrostatic or osmotic pressure increased tissue and hepatocellular damage in a PEG-concentration-dependent manner, and resulted in a decrease in gene expression. Quantitative evaluation showed that the enhanced gene expression resulted from stabilization of the pDNA introduced into the hepatocytes and an enhancement of the transport of intact pDNA to the nucleus.
  
  
  CONCLUSIONS
  For most gene therapy applications and gene function studies, sustained expression of the introduced gene(s) is necessary. This simple method to achieve enhanced gene expression in liver may have a great potential for a wide variety of laboratory studies in molecular and cellular biology as well as possibly for future clinical applications in humans.
authors.affiliation: Department of Pharmacokinetics and Biopharmaceutics, Faculty of Pharmaceutical Sciences, The University of Tokushima, 1-78-1 Sho-machi, Tokushima 770-8505, Japan.
authors.forename: Tatsuhiro
authors.initials: T
authors.lastname: Ishida
authors.forename: Wenhao
authors.initials: W
authors.lastname: Li
authors.forename: Zhihui
authors.initials: Z
authors.lastname: Liu
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kiwada
mesh_terms: D000818:Animals; D002462:Cell Membrane; D004247:DNA; D004337:Drug Carriers / Q000494:pharmacology*; D020869:Gene Expression Profiling; D018014:Gene Transfer Techniques; D015316:Genetic Therapy / Q000379:methods; D022781:Hepatocytes; D007275:Injections, Intravenous; D008099:Liver; D008156:Luciferases / Q000096:biosynthesis; D008297:Male; D051379:Mice; D009995:Osmosis; D010539:Permeability; D010957:Plasmids / Q000235:genetics; D011092:Polyethylene Glycols / Q000494:pharmacology*; D014162:Transfection / Q000379:methods*
chemical_list: D004337:Drug Carriers; D011092:Polyethylene Glycols; D004247:DNA; D008156:Luciferases