title: The use of low-molecular-weight PEIs as gene carriers in the monkey fibroblastoma and rabbit smooth muscle cell cultures.
abstract: BACKGROUND
  Polyethylenimines (PEIs) and cationic polymers have been used successfully in gene delivery. In earlier reports, only large PEIs (MW>10 000) have shown significant transfection efficiency. In the present study, the roles of small PEIs (MW 700 and 2000) were studied as additional compounds to see if they can improve gene delivery with cationic liposomes.
  
  
  METHODS
  The TKBPVlacZ expression plasmid was transfected in the CV1-P (monkey fibroblastoma) and SMC (rabbit smooth muscle) cell lines using various combinations of PEIs (MW 700, 2000, and 25 000) and Dosper liposomes. The transfection efficiency was determined with the fluorometric ONPG (o-nitrophenol-beta-D-galactopyranoside) assay and histochemical X-gal staining. The toxicity of the transfection reagents was estimated by the MTT [3-(4,5-dimethylthiazolyl-2)-2,5-diphenyl tetrazolium bromide] assay.
  
  
  RESULTS
  Transfection of TKBPVlacZ plasmid by the small PEIs (MW 700 and 2000) combined with Dosper liposomes was associated with high expression of the lacZ reporter gene in the CV1-P and SMC cell lines. The transfection efficiencies of the low-molecular-weight PEI/liposome combinations were several fold higher than those of PEIs or liposomes alone. PEI/liposome combinations had no toxicity on the cell lines tested.
  
  
  CONCLUSIONS
  The low-molecular-weight PEIs could be used successfully for gene delivery when combined with the cationic liposomes, resulting in a synergistic increase of the transfection efficiency in both cell lines studied.
authors.affiliation: Department of Pharmacology and Toxicology, University of Kuopio, Kuopio, Finland.
authors.forename: Pasi
authors.initials: P
authors.lastname: Lampela
authors.forename: Johanna
authors.initials: J
authors.lastname: Räisänen
authors.forename: Pekka T
authors.initials: PT
authors.lastname: Männistö
authors.forename: Seppo
authors.initials: S
authors.lastname: Ylä-Herttuala
authors.forename: Atso
authors.initials: A
authors.lastname: Raasmaja
mesh_terms: D000818:Animals; D002412:Cations; D002478:Cells, Cultured; D004396:Coloring Agents / Q000494:pharmacology; D004247:DNA / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005347:Fibroblasts / Q000473:pathology; D018014:Gene Transfer Techniques; D005822:Genetic Vectors; D000882:Haplorhini; D008081:Liposomes / Q000378:metabolism; D009130:Muscle, Smooth / Q000166:cytology*; D009369:Neoplasms / Q000628:therapy*; D011817:Rabbits; D013778:Tetrazolium Salts / Q000494:pharmacology; D013844:Thiazoles / Q000494:pharmacology; D014162:Transfection
chemical_list: D002412:Cations; D004396:Coloring Agents; D008081:Liposomes; D013778:Tetrazolium Salts; D013844:Thiazoles; D004247:DNA; C022616:thiazolyl blue