title: Tumor-targeted gene therapy: strategies for the preparation of ligand-polyethylene glycol-polyethylenimine/DNA complexes.
abstract: Surface-shielded DNA delivery systems have been synthesized with virus-like characteristics that target gene expression into distant tumor tissues. Polyethylenimine (PEI)/DNA complexes ('polyplexes') conjugated with the cell-binding ligand transferrin (Tf) or epidermal growth factor (EGF) were used to achieve receptor-mediated endocytosis. The surface charge of the complexes was masked by covalently linking PEI to polyethylene glycol (PEG). Three alternatives for generating these surface-shielded formulations were utilized, attaching ligand and PEG molecules to PEI either before or after DNA complex formation. The stabilized formulations could be ultra-concentrated, stored frozen, and applied systemically after thawing. Intravenous injection of Tf-PEG-coated polyplexes resulted in gene transfer to subcutaneous Neuro2a neuroblastoma tumors of syngeneic A/J mice; EGF-PEG-coated polyplexes were intravenously applied for targeting human hepatocellular carcinoma xenografts in SCID mice. In these models, luciferase marker gene expression levels in tumor tissues were 10- to 100-fold higher than in other organ tissues. Repeated systemic application of Tf-PEG-PEI/DNA complexes encoding tumor necrosis factor alpha (TNF-alpha) into tumor-bearing mice induced tumor necrosis and inhibition of tumor growth in three murine tumor models of different tissue origin (Neuro2a, M-3 or B16 melanoma).
authors.affiliation: Pharmaceutical Biology-Biotechnology, Department of Pharmacy, Ludwig-Maximilians-Universitaet, Butenandtstr. 5-13, D-81377, Muenchen, Germany.
authors.forename: Manfred
authors.initials: M
authors.lastname: Ogris
authors.forename: Greg
authors.initials: G
authors.lastname: Walker
authors.forename: Thomas
authors.initials: T
authors.lastname: Blessing
authors.forename: Ralf
authors.initials: R
authors.lastname: Kircheis
authors.forename: Markus
authors.initials: M
authors.lastname: Wolschek
authors.forename: Ernst
authors.initials: E
authors.lastname: Wagner
mesh_terms: D000818:Animals; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004247:DNA / Q000008:administration & dosage* / Q000737:chemistry; D004815:Epidermal Growth Factor / Q000737:chemistry; D005079:Excipients; D005260:Female; D005615:Freezing; D018390:Gene Targeting; D015316:Genetic Therapy / Q000379:methods*; D006801:Humans; D007202:Indicators and Reagents; D008024:Ligands; D051379:Mice; D008805:Mice, Inbred A; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D009368:Neoplasm Transplantation; D010316:Particle Size; D011092:Polyethylene Glycols / Q000737:chemistry*; D011094:Polyethyleneimine / Q000737:chemistry*; D014162:Transfection; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics; D014462:Ultrafiltration
chemical_list: D005079:Excipients; D007202:Indicators and Reagents; D008024:Ligands; D014409:Tumor Necrosis Factor-alpha; D011092:Polyethylene Glycols; D004815:Epidermal Growth Factor; D011094:Polyethyleneimine; D004247:DNA