title: Uronic acids functionalized polyethyleneimine (PEI)-polyethyleneglycol (PEG)-graft-copolymers as novel synthetic gene carriers.
abstract: In this study, we investigated galacturonic (GalAc)- and mannuronic (ManAc) acids as novel targeting ligands for receptor-mediated gene delivery. GalAc and ManAc were coupled to either polyethyleneimine (PEI) or PEI-polyethyleneglycol (PEG). Furthermore, lactobionic acid (LacAc), which comprises a GalAc-related carbohydrate ring, was coupled to each of the polymers through its open-chain gluconic acid moiety. The molar mass distributions of the polymers were characterized by analytical ultracentrifugation and size exclusion chromatography. PEI-conjugate-pDNA complexes were transfected into HepG2-, HeLa-, and 16HBE14o(-)-cells. Gene expression mediated by GalAc- and LacAc-functionalized PEI-conjugates was lower than for PEI. In contrast, gene expression mediated by ManAc-functionalized PEI-conjugates was up to three orders of magnitude higher than for the other tested PEI-conjugates, in particular for negatively charged gene vectors at low N/P ratios, independent of the cell line. Pre-incubation of cells with an excess of ManAc before transfection significantly inhibited transfection rates only for ManAc-functionalized PEI-conjugates. Coupling of methyl-alpha-d-mannuronic acid to PEI resulted in significantly lower transfection rates than for ManAc-PEI based complexes. Together with fluorescence microscopy images of fluorescein-labelled ManAc-functionalized dextrans and FACS analyses of cells, these results demonstrate that receptor-mediated endocytosis of ManAc-PEI-conjugate-pDNA complexes via ManAc-specific receptors was involved in gene transfer. In conclusion, ManAc-modification of PEI-polymers represents a novel strategy for receptor-mediated gene delivery which could be promising for in vivo application.
authors.affiliation: Ludwig-Maximilians-University, Pediatrics, Munich Germany.
authors.forename: Sabine I
authors.initials: SI
authors.lastname: Weiss
authors.forename: Nathalie
authors.initials: N
authors.lastname: Sieverling
authors.forename: Maren
authors.initials: M
authors.lastname: Niclasen
authors.forename: Christof
authors.initials: C
authors.lastname: Maucksch
authors.forename: Andreas F
authors.initials: AF
authors.lastname: Thünemann
authors.forename: Helmuth
authors.initials: H
authors.lastname: Möhwald
authors.forename: Dietrich
authors.initials: D
authors.lastname: Reinhardt
authors.forename: Joseph
authors.initials: J
authors.lastname: Rosenecker
authors.forename: Carsten
authors.initials: C
authors.lastname: Rudolph
mesh_terms: D000818:Animals; D002460:Cell Line; D003911:Dextrans / Q000737:chemistry / Q000378:metabolism; D018014:Gene Transfer Techniques; D006603:Hexuronic Acids / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D015394:Molecular Structure; D010316:Particle Size; D011092:Polyethylene Glycols / Q000737:chemistry* / Q000378:metabolism; D011094:Polyethyleneimine / Q000737:chemistry* / Q000378:metabolism; D011108:Polymers / Q000737:chemistry* / Q000378:metabolism; D014162:Transfection
chemical_list: D003911:Dextrans; D006603:Hexuronic Acids; D011108:Polymers; D011092:Polyethylene Glycols; C007819:galacturonic acid; D011094:Polyethyleneimine; C008324:mannuronic acid