title: Precise engineering of siRNA delivery vehicles to tumors using polyion complexes and gold nanoparticles.
abstract: For systemic delivery of siRNA to solid tumors, a size-regulated and reversibly stabilized nanoarchitecture was constructed by using a 20 kDa siRNA-loaded unimer polyion complex (uPIC) and 20 nm gold nanoparticle (AuNP). The uPIC was selectively prepared by charge-matched polyionic complexation of a poly(ethylene glycol)-b-poly(L-lysine) (PEG-PLL) copolymer bearing ∼40 positive charges (and thiol group at the ω-end) with a single siRNA bearing 40 negative charges. The thiol group at the ω-end of PEG-PLL further enabled successful conjugation of the uPICs onto the single AuNP through coordinate bonding, generating a nanoarchitecture (uPIC-AuNP) with a size of 38 nm and a narrow size distribution. In contrast, mixing thiolated PEG-PLLs and AuNPs produced a large aggregate in the absence of siRNA, suggesting the essential role of the preformed uPIC in the formation of nanoarchitecture. The smart uPIC-AuNPs were stable in serum-containing media and more resistant against heparin-induced counter polyanion exchange, compared to uPICs alone. On the other hand, the treatment of uPIC-AuNPs with an intracellular concentration of glutathione substantially compromised their stability and triggered the release of siRNA, demonstrating the reversible stability of these nanoarchitectures relative to thiol exchange and negatively charged AuNP surface. The uPIC-AuNPs efficiently delivered siRNA into cultured cancer cells, facilitating significant sequence-specific gene silencing without cytotoxicity. Systemically administered uPIC-AuNPs showed appreciably longer blood circulation time compared to controls, i.e., bare AuNPs and uPICs, indicating that the conjugation of uPICs onto AuNP was crucial for enhancing blood circulation time. Finally, the uPIC-AuNPs efficiently accumulated in a subcutaneously inoculated luciferase-expressing cervical cancer (HeLa-Luc) model and achieved significant luciferase gene silencing in the tumor tissue. These results demonstrate the strong potential of uPIC-AuNP nanoarchitectures for systemic siRNA delivery to solid tumors.
authors.affiliation: Department of Materials Engineering, Graduate School of Engineering, The University of Tokyo , Tokyo 113-8656, Japan.
authors.forename: Hyun Jin
authors.initials: HJ
authors.lastname: Kim
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Takemoto
authors.forename: Yu
authors.initials: Y
authors.lastname: Yi
authors.forename: Meng
authors.initials: M
authors.lastname: Zheng
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Maeda
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Chaya
authors.forename: Kotaro
authors.initials: K
authors.lastname: Hayashi
authors.forename: Peng
authors.initials: P
authors.lastname: Mi
authors.forename: Frederico
authors.initials: F
authors.lastname: Pittella
authors.forename: R James
authors.initials: RJ
authors.lastname: Christie
authors.forename: Kazuko
authors.initials: K
authors.lastname: Toh
authors.forename: Yu
authors.initials: Y
authors.lastname: Matsumoto
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Nishiyama
authors.forename: Kanjiro
authors.initials: K
authors.lastname: Miyata
authors.forename: Kazunori
authors.initials: K
authors.lastname: Kataoka
mesh_terms: D004337:Drug Carriers / Q000737:chemistry*; D020868:Gene Silencing; D006046:Gold / Q000737:chemistry*; D006367:HeLa Cells; D006801:Humans; D053768:Metal Nanoparticles / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D009369:Neoplasms / Q000235:genetics / Q000378:metabolism*; D011092:Polyethylene Glycols / Q000737:chemistry*; D011107:Polylysine / Q000737:chemistry*; D034741:RNA, Small Interfering / Q000008:administration & dosage* / Q000737:chemistry* / Q000235:genetics
chemical_list: D004337:Drug Carriers; D034741:RNA, Small Interfering; D011107:Polylysine; D011092:Polyethylene Glycols; D006046:Gold
keywords: cancer therapy; gold nanoparticle; siRNA delivery; unimer polyion complex