title: Novel shielded transferrin-polyethylene glycol-polyethylenimine/DNA complexes for systemic tumor-targeted gene transfer.
abstract: Tumor-targeting DNA complexes which can readily be generated by the mixing of stable components and freeze-thawed would be very advantageous for their subsequent application as medical products. Complexes were generated by the mixing of plasmid DNA, linear polyethylenimine (PEI22, 22 kDa) as the main DNA condensing agent, PEG-PEI (poly(ethylene glycol)-conjugated PEI) for surface shielding, and Tf-PEG-PEI (transferrin-PEG-PEI) to provide a ligand for receptor-mediated cell uptake. Within the shielding conjugates, PEG chains of varying size (5, 20, or 40 kDa) were conjugated with either linear PEI22 (22 kDa) or branched PEI25 (25 kDa). The three polymer components were mixed together at various ratios with DNA; particle size, surface charge, in vitro transfection activity, and systemic gene delivery to tumors was investigated. In general, increasing the proportion of shielding conjugate in the complex reduced surface charge, particle size, and in vitro transfection efficiency in transferrin receptor-rich K562 cells. The particle size or surface charge of the complexes containing the PEG-PEI conjugate did not significantly change after freeze-thawing, while complexes without the shielding conjugate aggregated. Complexes containing PEG-PEI conjugate efficiently transfected K562 cells after freeze-thawing. Furthermore the systemic application of freeze-thawed complexes exhibited in vivo tumor targeted expression. For complexes containing the luciferase reporter gene the highest expression was found in tumor tissue of mice. An optimum formulation for in vivo application, PEI22/Tf-PEG-PEI/PEI22-PEG5, containing plasmid DNA encoding for the tumor necrosis factor (TNF-alpha), inhibited tumor growth in three different murine tumor models. These new DNA complexes offer simplicity and convenience, with tumor targeting activity in vivo after freeze-thawing.
authors.affiliation: Pharmaceutical Biology-Biotechnology, Department for Pharmacy, Ludwig-Maximilians-Universitaet, Butenandtstrasse 5-13, D-81377 Muenchen, Germany.
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Kursa
authors.forename: Greg F
authors.initials: GF
authors.lastname: Walker
authors.forename: Vanessa
authors.initials: V
authors.lastname: Roessler
authors.forename: Manfred
authors.initials: M
authors.lastname: Ogris
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Roedl
authors.forename: Ralf
authors.initials: R
authors.lastname: Kircheis
authors.forename: Ernst
authors.initials: E
authors.lastname: Wagner
mesh_terms: D000818:Animals; D004247:DNA / Q000008:administration & dosage* / Q000627:therapeutic use; D004337:Drug Carriers / Q000737:chemistry*; D005260:Female; D015316:Genetic Therapy; D006801:Humans; D020014:K562 Cells; D051379:Mice; D008815:Mice, Inbred Strains; D008970:Molecular Weight; D009374:Neoplasms, Experimental / Q000628:therapy*; D011092:Polyethylene Glycols / Q000737:chemistry; D011094:Polyethyleneimine / Q000737:chemistry; D014162:Transfection; D014168:Transferrin / Q000737:chemistry; D016896:Treatment Outcome; D014409:Tumor Necrosis Factor-alpha / Q000008:administration & dosage / Q000235:genetics / Q000627:therapeutic use
chemical_list: D004337:Drug Carriers; D014168:Transferrin; D014409:Tumor Necrosis Factor-alpha; D011092:Polyethylene Glycols; D011094:Polyethyleneimine; D004247:DNA