title: In vivo activity of nuclease-resistant siRNAs.
abstract: Chemical modifications have been incorporated into short interfering RNAs (siRNAs) without reducing their ability to inhibit gene expression in mammalian cells grown in vitro. In this study, we begin to assess the potential utility of 2'-modified siRNAs in mammals. We demonstrate that siRNA modified with 2'-fluoro (2'-F) pyrimidines are functional in cell culture and have a greatly increased stability and a prolonged half-life in human plasma as compared to 2'-OH containing siRNAs. Moreover, we show that the 2'-F containing siRNAs are functional in mice and can inhibit the expression of a target gene in vivo. However, even though the modified siRNAs have greatly increased resistance to nuclease degradation in plasma, this increase in stability did not translate into enhanced or prolonged inhibitory activity of target gene reduction in mice following tail vein injection. Thus, this study shows that 2'-F modified siRNAs are functional in vivo, but that they are not necessarily more potent than unmodified siRNAs in animals.
authors.affiliation: Department of Surgery, Center for Genetic and Cellular Therapies, Duke University Medical Center, Durham, NC 27710, USA.
authors.forename: Juliana M
authors.initials: JM
authors.lastname: Layzer
authors.forename: Anton P
authors.initials: AP
authors.lastname: McCaffrey
authors.forename: Alice K
authors.initials: AK
authors.lastname: Tanner
authors.forename: Zan
authors.initials: Z
authors.lastname: Huang
authors.forename: Mark A
authors.initials: MA
authors.lastname: Kay
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Sullenger
mesh_terms: D000818:Animals; D004720:Endonucleases / Q000378:metabolism*; D008163:Luminescent Measurements; D051379:Mice; D034741:RNA, Small Interfering / Q000378:metabolism*; D014162:Transfection
chemical_list: D034741:RNA, Small Interfering; D004720:Endonucleases