Small molecule ligands for enhanced intracellular delivery of lipid nanoparticle formulations of siRNA

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.From the Clinical EditorIn 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.

Graphical AbstractThis study has identified cardiac glycosides as potential targeting ligands for enhanced delivery of lipid nanoparticles (LNP) formulations of siRNA. Cardiac glycosides bind to their cell surface receptor Na+/K+ ATPase and stimulate internalization of the receptor. A PEG-lipid containing strophanthidin (STR, a cardiac glycoside) at the distal end of PEG was constructed and incorporated into the LNP siRNA systems. We observed more cellular uptake of STR-targeted LNP siRNA systems than non-targeted systems. This enhanced LNP siRNA uptake in turn led to improved marker gene silencing in vitro.Figure optionsDownload high-quality image (302 K)Download as PowerPoint slide