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Subcutaneous Delivery of Hepatocyte Targeted sub-50 nm Nanoencapsulated siRNA Mediates Gene Silencing
Poster Title: Subcutaneous Delivery of Hepatocyte Targeted sub-50 nm Nanoencapsulated siRNA Mediates Gene Silencing
Submitted on 26 Oct 2017
Author(s): BT Kren, D Tolbot, V Korman, GM Unger
Affiliations: University of Minnesota, GeneSegues Therapeutics
This poster was presented at 2011 ASGCT National Meeting, Seattle, Washington
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Poster Information
Abstract: Modulating gene expression via RNA interference (RNAi) by siRNAs has reinvigorated nonviral delivery of nucleic acids (NA). Treatment of chronic disease by RNAi requires achieving and maintaining silencing of a specific target gene transcript, requiring a patient-friendly delivery method for the repeat administration of siRNAs. Subcutaneous (sq) delivery is a desirable method for this goal, yet 2 major barriers have hindered this approach, the sequestration of the NAs at the injection site and in endosomes with subsequent degradation in the target cells. The novel nonviral sub-50 nm (s50) crystallized capsule delivery system developed by GeneSegues can use any appropriate targeting protein, peptide or carbohydrate for the capsule shell. This specifies the receptor-mediated uptake of the capsule by the specific cell-type in vivo via the ligand used. The capsule’s 10-25 nm size, crystallized-structure and neutral-charge mediate efficient in vivo penetration of tissues, and cellular uptake via the non-endosomal lipid rafts pathway, delivering the NA cargo intact to the nucleus and cytoplasm of the target cell. We previously showed asialoorasomucoid (ASOR) s50 capsules mediate hepatocyte specific delivery of plasmids in vivo following intravenous (iv) delivery (JCI, 2009). In this study we show that sq delivery of s50 ASOR encapsulated unmodified siRNAs targeting coagulation factor VII (FVII) at a dose of 1 mg/kg resulted in significant loss of FVII mRNA transcript with the nadir observed 2 days post-injection reflecting a 52% ± 4% decrease in FVII mRNA. By day 4, transcript levels returned to 90% of control levels. An ASOR s50 encapsulated 20 mer single stranded (ss) RNAi chimeric DNA/RNA (5’-14 phosphodiester DNA residues followed by 6 2’-O-methyl RNA bases) having the same sequence as the siRNA guide-strand resulted in a 49% ± 5% decrease in FVII mRNA 2 days post-injection at 0.5 mg/kg sq. The RNAi treated FVII transcript levels increased by day 4 to 70% of untreated values. At day 3 after 0.5 mg/kg sq dosing, a 15% and 30% reduction in the FVII mRNA levels were observed with the siRNA and RNAi, respectively. Thus at equal dosing, the RNAi targeting FVII mediated a larger and more persistent decrease in the FVII transcript. This is consistent with our in vitro data indicating the ss RNAi molecule engages both the RNase H and Ago2-RISC mediated silencing pathways when delivered using the novel s50 nm capsule. Targeting ApoB using an modified siRNA or the same ss chimeric RNA guide-strand structure in ASOR s50 capsules sq gave similar results, yet decreased transcript levels persisted for a longer period. In conclusion this data indicates that sq administration of siRNAs in s50 nm ASOR capsules mediates efficient silencing of hepatocyte expressed transcripts for a duration of ≥ 4 days. Moreover, the novel ss chimeric RNA/DNA guide-strand chemistry was shown to be equally efficacious in silencing different target genes as their respective siRNAs. This suggests that sq administration s50 ASOR encapsulated NAs targeting hepatocyte-expressed genes every 3 days may potentially achieve the persistent gene-silencing necessary for treatment of chronic disease in a clinically relevant Summary: This poster presentation summarizes in vivo work demonstrating the utility of a novel protein-liganded nanoparticle delivery system for repeat dosing in nucleic acid, specifically, RNAi delivery.Report abuse »
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