title: PEG-detachable polyplex micelles based on disulfide-linked block catiomers as bioresponsive nonviral gene vectors.
abstract: PEG-based polyplex micelles, which can detach the surrounding PEG chains responsive to the intracellular reducing environment, were developed as nonviral gene vectors. A novel block catiomer, PEG-SS-P[Asp(DET)], was designed as follows: (i) insertion of biocleavable disulfide linkage between PEG and polycation segment to trigger PEG detachment and (ii) a cationic segment based on poly(aspartamide) with a flanking N-(2-aminoethyl)-2-aminoethyl group, P[Asp(DET)], in which the Asp(DET) unit acts as a buffering moiety inducing endosomal escape with minimal cytotoxicity. The polyplex micelles from PEG-SS-P[Asp(DET)] and plasmid DNA (pDNA) stably dispersed in an aqueous medium with a narrowly distributed size range of approximately 80 nm due to the formation of hydrophilic PEG palisades while undergoing aggregation by the addition of 10 mM dithiothreitol (DTT) at the stoichiometric charge ratio, indicating the PEG detachment from the micelles through the disulfide cleavage. The PEG-SS-P[Asp(DET)] micelles showed both a 1-3 orders of magnitude higher gene transfection efficiency and a more rapid onset of gene expression than PEG-P[Asp(DET)] micelles without disulfide linkages, due to much more effective endosomal escape based on the PEG detachment in endosome. These findings suggest that the PEG-SS-P[Asp(DET)] micelle may have promising potential as a nonviral gene vector exerting high transfection with regulated timing and minimal cytotoxicity.
authors.affiliation: Department of Materials Engineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Seiji
authors.initials: S
authors.lastname: Takae
authors.forename: Kanjiro
authors.initials: K
authors.lastname: Miyata
authors.forename: Makoto
authors.initials: M
authors.lastname: Oba
authors.forename: Takehiko
authors.initials: T
authors.lastname: Ishii
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Nishiyama
authors.forename: Keiji
authors.initials: K
authors.lastname: Itaka
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Yamasaki
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Koyama
authors.forename: Kazunori
authors.initials: K
authors.lastname: Kataoka
mesh_terms: D002412:Cations; D004247:DNA / Q000008:administration & dosage / Q000737:chemistry* / Q000235:genetics; D004220:Disulfides / Q000737:chemistry*; D005822:Genetic Vectors / Q000737:chemistry* / Q000493:pharmacokinetics; D006367:HeLa Cells; D006801:Humans; D008823:Micelles; D010455:Peptides / Q000737:chemistry*; D010957:Plasmids / Q000008:administration & dosage / Q000737:chemistry / Q000235:genetics; D011092:Polyethylene Glycols / Q000737:chemistry*; D014162:Transfection / Q000379:methods*
chemical_list: D002412:Cations; D004220:Disulfides; D008823:Micelles; D010455:Peptides; C033141:poly-beta-benzyl-aspartate; D011092:Polyethylene Glycols; D004247:DNA