title: The intracellular pharmacodynamics of siRNA is responsible for the low gene silencing activity of siRNA-loaded nanoparticles in dendritic cells.
abstract: The delivery of small interfering RNA (siRNA) to dendritic cells (DCs) is a challenging issue for siRNA-loaded lipid nanoparticles. The cause of this difficulty is unknown. The findings reported herein indicate that the rate-limiting step in gene silencing using siRNA-loaded lipid nanoparticles in DCs, as evidenced by a quantitative analysis of each process in siRNA delivery between mouse bone marrow derived DC (BMDC) and other cell lines, was not associated with the actual delivery of siRNA. A gene silencing of only 50% was observed in BMDC, even when a high dose was used. Contrary to our expectation, the interval between cellular uptake and the delivery of siRNA to the cytosol was not responsible for the low gene silencing. Meanwhile, a drastic difference was found in the relationship between the efficiency of gene silencing and the amount of intracellular intact siRNA. This fact indicates that the processes after cytosolic delivery of siRNA, namely the intracellular pharmacodynamics (PD) of siRNA, appear to be the rate-limiting step in gene silencing in BMDC. The findings reported here demonstrate the importance of the intracellular PD of siRNA delivered to cytosol in the development of siRNA delivery systems for gene silencing in DCs.
authors.affiliation: Faculty of Pharmaceutical Sciences, Hokkaido University, Kita 12 Nishi 6, Kita-ku, Sapporo 060-0812, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakamura
authors.affiliation: Faculty of Pharmaceutical Sciences, Hokkaido University, Kita 12 Nishi 6, Kita-ku, Sapporo 060-0812, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Fujiwara
authors.affiliation: Faculty of Pharmaceutical Sciences, Hokkaido University, Kita 12 Nishi 6, Kita-ku, Sapporo 060-0812, Japan.
authors.forename: Shota
authors.initials: S
authors.lastname: Warashina
authors.affiliation: Faculty of Pharmaceutical Sciences, Hokkaido University, Kita 12 Nishi 6, Kita-ku, Sapporo 060-0812, Japan. Electronic address: harasima@pharm.hokudai.ac.jp.
authors.forename: Hideyoshi
authors.initials: H
authors.lastname: Harashima
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000187:drug effects* / Q000378:metabolism*; D005260:Female; D020868:Gene Silencing / Q000187:drug effects*; D008055:Lipids / Q000493:pharmacokinetics; D051379:Mice; D053758:Nanoparticles / Q000008:administration & dosage*; D034741:RNA, Small Interfering / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000494:pharmacology*
chemical_list: D008055:Lipids; C086724:Lipofectamine; D034741:RNA, Small Interfering
keywords: Dendritic cells; Gene silencing; Intracellular pharmacodynamics; Lipid nanoparticles; siRNA