title: Investigation of polyethylenimine-grafted-triamcinolone acetonide as nucleus-targeting gene delivery systems.
abstract: BACKGROUND
  Nuclear membrane is one of the main barriers in polymer mediated intracellular gene delivery. To improve the transgenic activity and safety of nonviral vector, triamcinolone acetonide (TA) as a nuclear localization signal was conjugated with different molecular weight polyethylenimine (PEI).
  
  
  METHODS
  Different molecular weight PEI [600, 1800, 25,000 (25k)] was conjugated with TA to synthesize PEI-TA by two-step reaction. Their physicochemical characteristics, in vitro cytotoxicity and transfection efficiency were evaluated. To investigate the difference of transfection efficiency of various molecular weight PEI-TA, their transfection mechanism was further investigated by confocal microscopy and competition assay. Transgenic expression in vivo was evaluated by injection into hepatic portal vein of mice.
  
  
  RESULTS
  All PEI-TA could form nanosize polyplexes with DNA and their physicochemical properties resemble each other. Their cytotoxicities were negligible compared to PEI 25k. The order of transfection efficiency was PEI 1800-TA > PEI 600-TA > PEI 25k-TA. A transfection mechanism study displayed that TA could inhibit considerably the transgenic activity of PEI 1800-TA and PEI 600-TA, but that of PEI 25k-TA was not inhibited. It was suggested that PEI 1800-TA and PEI 600-TA might translocate into the nucleus. Confocal microscopy investigation verified this suggestion. The data strongly suggested that the transfection efficiency of PEI 1800-TA in vivo was much higher than that of PEI 25k, which was consistent with the results obtained in vitro.
  
  
  CONCLUSIONS
  Low molecular weight PEI-TA could translocate into the nucleus efficiently. PEI 1800-TA presented higher transgenic activity and it has a great potential for gene therapy as a nonviral carrier.
authors.affiliation: Institute of Pharmaceutics, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, PR China.
authors.forename: Kun
authors.initials: K
authors.lastname: Ma
authors.forename: Minxin
authors.initials: M
authors.lastname: Hu
authors.forename: Meng
authors.initials: M
authors.lastname: Xie
authors.forename: Haijun
authors.initials: H
authors.lastname: Shen
authors.forename: Liyan
authors.initials: L
authors.lastname: Qiu
authors.forename: Weimin
authors.initials: W
authors.lastname: Fan
authors.forename: Hongying
authors.initials: H
authors.lastname: Sun
authors.forename: Shuqing
authors.initials: S
authors.lastname: Chen
authors.forename: Yi
authors.initials: Y
authors.lastname: Jin
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism*; D018014:Gene Transfer Techniques; D015316:Genetic Therapy; D005822:Genetic Vectors; D051379:Mice; D008813:Mice, Inbred ICR; D046529:Microscopy, Electron, Transmission; D011094:Polyethyleneimine / Q000032:analysis / Q000737:chemistry* / Q000633:toxicity; D014162:Transfection; D014222:Triamcinolone Acetonide / Q000032:analysis / Q000737:chemistry* / Q000633:toxicity
chemical_list: D011094:Polyethyleneimine; D014222:Triamcinolone Acetonide