Inhibition of Exo70, an Exocyst Complex Component, Enhances mRNA Delivery Efficiency of Lipid Nanoparticle

Background/Objectives: Lipid nanoparticles (LNPs) are actively being studied as therapeutics and vaccines for various diseases. While LNPs can deliver nucleic acids, their efficiency is limited by the multi-step pathways involved in intracellular trafficking. Crucially, endosomal recycling-driven exocytosis acts as a major problem, rerouting LNPs away from the cytosol and thereby preventing efficient nucleic acid release. Upon entering the cell, LNPs are frequently expelled via endosomal recycling before delivering nucleic acids to cytosol. Previous studies reported that inhibition or deletion of Exo70, a component of the exocyst complex, leads to the accumulation of endosomes because of preventing endosomal recycling. In this study, we investigate the impact of Exo70 inhibition by endosidin-2 (ES-2), an Exo70 inhibitor, on LNP delivery efficiency. Methods: SM-102, cholesterol, DMG-PEG, and DSPC were dissolved in ethanol, while mRNA was dissolved in an aqueous phase to formulate LNPs. Co-treatment of ES-2 with LNPs was performed to evaluate its effect on mRNA delivery, and the resulting delivery efficiency was assessed both in vitro and in vivo. Results: Co-treatment of ES-2 with LNPs significantly enhanced mRNA delivery efficiency, resulting in up to a 4.06-fold increase in vitro and a 3.63-fold increase in vivo. Conclusions: Our findings demonstrate that suppression of Exo70 significantly enhances the mRNA delivery efficiency of LNPs, and this strategy could be applied for the development of mRNA therapeutics.