title: Smart polyion complex micelles for targeted intracellular delivery of PEGylated antisense oligonucleotides containing acid-labile linkages.
abstract: A novel pH-sensitive and targetable antisense ODN delivery system based on multimolecular assembly into polyion complex (PIC) micelles of poly(L-lysine) (PLL) and a lactosylated poly(ethylene glycol)-antisense ODN conjugate (Lac-PEG-ODN) containing an acid-labile linkage (beta-propionate) between the PEG and ODN segments has been developed. The PIC micelles thus prepared had clustered lactose moieties on their peripheries and achieved a significant antisense effect against luciferase gene expression in HuH-7 cells (hepatoma cells), far more efficiently than that produced by the nonmicelle systems (ODN and Lac-PEG-ODN) alone, as well as by the lactose-free PIC micelle. In line with this pronounced antisense effect, the lactosylated PIC micelles showed better uptake than the lactose-free PIC micelles into HuH-7 cells; this suggested the involvement of an asialoglycoprotein (ASGP) receptor-mediated endocytosis process. Furthermore, a significant decrease in the antisense effect (27 % inhibition) was observed for a lactosylated PIC micelle without an acid-labile linkage (thiomaleimide linkage); this suggested the release of the active (free) antisense ODN molecules into the cellular interior in response to the pH decrease in the endosomal compartment is a key process in the antisense effect. Use of branched poly(ethylenimine) (B-PEI) instead of the PLL for PIC micellization led to a substantial decrease in the antisense effect, probably due to the buffer effect of the B-PEI in the endosome compartment, preventing the cleavage of the acid-labile linkage in the conjugate. The approach reported here is expected to be useful for the construction of smart intracellular delivery systems for antisense ODNs with therapeutic value.
authors.affiliation: Department of Materials Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
authors.forename: Motoi
authors.initials: M
authors.lastname: Oishi
authors.forename: Fumi
authors.initials: F
authors.lastname: Nagatsugi
authors.forename: Shigeki
authors.initials: S
authors.lastname: Sasaki
authors.forename: Yukio
authors.initials: Y
authors.lastname: Nagasaki
authors.forename: Kazunori
authors.initials: K
authors.lastname: Kataoka
mesh_terms: D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D004337:Drug Carriers / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D004705:Endocytosis; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D007785:Lactose / Q000737:chemistry; D049409:Luciferases, Firefly / Q000235:genetics; D009682:Magnetic Resonance Spectroscopy; D008823:Micelles; D008856:Microscopy, Fluorescence; D020319:Oligodeoxyribonucleotides, Antisense / Q000737:chemistry / Q000494:pharmacology*; D011092:Polyethylene Glycols / Q000737:chemistry*; D011094:Polyethyleneimine / Q000737:chemistry; D011107:Polylysine / Q000737:chemistry
chemical_list: D004337:Drug Carriers; D008823:Micelles; D020319:Oligodeoxyribonucleotides, Antisense; D011107:Polylysine; D011092:Polyethylene Glycols; D011094:Polyethyleneimine; D049409:Luciferases, Firefly; D007785:Lactose