title: Actively-targeted polyion complex micelles stabilized by cholesterol and disulfide cross-linking for systemic delivery of siRNA to solid tumors.
abstract: For small interfering RNA (siRNA)-based cancer therapies, we report an actively-targeted and stabilized polyion complex micelle designed to improve tumor accumulation and cancer cell uptake of siRNA following systemic administration. Improvement in micelle stability was achieved using two stabilization mechanisms; covalent disulfide cross-linking and non-covalent hydrophobic interactions. The polymer component was designed to provide disulfide cross-linking and cancer cell-targeting cyclic RGD peptide ligands, while cholesterol-modified siRNA (Chol-siRNA) provided additional hydrophobic stabilization to the micelle structure. Dynamic light scattering confirmed formation of nano-sized disulfide cross-linked micelles (<50 nm in diameter) with a narrow size distribution. Improved stability of Chol-siRNA-loaded micelles (Chol-siRNA micelles) was demonstrated by resistance to both the dilution in serum-containing medium and counter polyion exchange with dextran sulfate, compared to control micelles prepared with Chol-free siRNA (Chol-free micelles). Improved stability resulted in prolonged blood circulation time of Chol-siRNA micelles compared to Chol-free micelles. Furthermore, introduction of cRGD ligands onto Chol-siRNA micelles significantly facilitated accumulation of siRNA in a subcutaneous cervical cancer model following systemic administration. Ultimately, systemically administered cRGD/Chol-siRNA micelles exhibited significant gene silencing activity in the tumor, presumably due to their active targeting ability combined with the enhanced stability through both hydrophobic interactions of cholesterol and disulfide cross-linking.
authors.affiliation: Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Oe
authors.affiliation: Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: R James
authors.initials: RJ
authors.lastname: Christie
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: Mitsuru
authors.initials: M
authors.lastname: Naito
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: Stewart A
authors.initials: SA
authors.lastname: Low
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: Shigeto
authors.initials: S
authors.lastname: Fukushima
authors.affiliation: Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Kazuko
authors.initials: K
authors.lastname: Toh
authors.affiliation: Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Miura
authors.affiliation: Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Yu
authors.initials: Y
authors.lastname: Matsumoto
authors.affiliation: Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan; Polymer Chemistry Division, Chemical Resources Laboratory, Tokyo Institute of Technology, R1-11, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan.
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Nishiyama
authors.affiliation: Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. Electronic address: miyata@bmw.t.u-tokyo.ac.jp.
authors.forename: Kanjiro
authors.initials: K
authors.lastname: Miyata
authors.affiliation: Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan; Department of Materials Engineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan; Department of Bioengineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan; Center for NanoBio Integration, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan. Electronic address: kataoka@bmw.t.u-tokyo.ac.jp.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Kataoka
mesh_terms: D000578:Amidines / Q000138:chemical synthesis / Q000737:chemistry; D000818:Animals; D002784:Cholesterol / Q000737:chemistry*; D003432:Cross-Linking Reagents / Q000737:chemistry*; D004220:Disulfides / Q000737:chemistry*; D004705:Endocytosis; D005260:Female; D018014:Gene Transfer Techniques; D006367:HeLa Cells; D006801:Humans; D007477:Ions; D008027:Light; D008819:Mice, Nude; D008823:Micelles; D009369:Neoplasms / Q000378:metabolism* / Q000473:pathology; D009842:Oligopeptides / Q000138:chemical synthesis / Q000737:chemistry; D010456:Peptides, Cyclic / Q000138:chemical synthesis / Q000737:chemistry; D011092:Polyethylene Glycols / Q000138:chemical synthesis / Q000737:chemistry; D011107:Polylysine / Q000138:chemical synthesis / Q000737:chemistry; D066244:Proton Magnetic Resonance Spectroscopy; D034741:RNA, Small Interfering / Q000378:metabolism*; D012542:Scattering, Radiation
chemical_list: D000578:Amidines; D003432:Cross-Linking Reagents; D004220:Disulfides; D007477:Ions; D008823:Micelles; D009842:Oligopeptides; D010456:Peptides, Cyclic; D034741:RNA, Small Interfering; D011107:Polylysine; D011092:Polyethylene Glycols; C047981:arginyl-glycyl-aspartic acid; D002784:Cholesterol
keywords: Active targeting; Cholesterol modified siRNA; Cyclic RGD peptide; Polyion complex micelle; siRNA delivery