title: Small molecule ligands for enhanced intracellular delivery of lipid nanoparticle formulations of siRNA.
abstract: Gene silencing activity of lipid nanoparticle (LNP) formulations of siRNA requires LNP surface factors promoting cellular uptake. This study aimed to identify small molecules that enhance cellular uptake of LNP siRNA systems, then use them as LNP-associated ligands to improve gene silencing potency. Screening the Canadian Chemical Biology Network molecules for effects on LNP uptake into HeLa cells found that cardiac glycosides like ouabain and strophanthidin caused the highest uptake. Cardiac glycosides stimulate endocytosis on binding to plasma membrane Na(+)/K(+) ATPase found in all mammalian cells, offering the potential to stimulate LNP uptake into various cell types. A PEG-lipid containing strophanthidin at the end of PEG (STR-PEG-lipid) was synthesized and incorporated into LNP. Compared to non-liganded systems, STR-PEG-lipid enhanced LNP uptake in various cell types. Furthermore, this enhanced uptake improved marker gene silencing in vitro. Addition of STR-PEG-lipid to LNP siRNA may have general utility for enhancing gene silencing potency.
  
  
  BACKGROUND
  In this study, the authors identified small molecules that enhance cellular uptake of lipid nanoparticle siRNA systems, then used them as LNP-associated ligands to improve gene silencing potency.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada. tam7@mail.ubc.ca
authors.forename: Yuen Yi C
authors.initials: YY
authors.lastname: Tam
authors.forename: Sam
authors.initials: S
authors.lastname: Chen
authors.forename: Josh
authors.initials: J
authors.lastname: Zaifman
authors.forename: Ying K
authors.initials: YK
authors.lastname: Tam
authors.forename: Paulo J C
authors.initials: PJ
authors.lastname: Lin
authors.forename: Steven
authors.initials: S
authors.lastname: Ansell
authors.forename: Michel
authors.initials: M
authors.lastname: Roberge
authors.forename: Marco A
authors.initials: MA
authors.lastname: Ciufolini
authors.forename: Pieter R
authors.initials: PR
authors.lastname: Cullis
mesh_terms: D000818:Animals; D004705:Endocytosis / Q000235:genetics; D020868:Gene Silencing / Q000187:drug effects; D018014:Gene Transfer Techniques; D006367:HeLa Cells; D006801:Humans; D008024:Ligands; D008055:Lipids / Q000008:administration & dosage* / Q000737:chemistry; D053758:Nanoparticles / Q000008:administration & dosage* / Q000737:chemistry; D034741:RNA, Small Interfering / Q000737:chemistry / Q000235:genetics*; D000254:Sodium-Potassium-Exchanging ATPase / Q000235:genetics / Q000378:metabolism; D013327:Strophanthidin / Q000008:administration & dosage* / Q000737:chemistry
chemical_list: D008024:Ligands; D008055:Lipids; D034741:RNA, Small Interfering; D013327:Strophanthidin; D000254:Sodium-Potassium-Exchanging ATPase