Next-generation materials for RNA–lipid nanoparticles: lyophilization and targeted transfection

Abstract

RNA, including mRNA, siRNA and miRNA, is part of a new class of patient treatments that prevent and treat several diseases. As an alternative to DNA therapy using plasmid DNA, RNA functions in the cellular cytosol, avoiding the potential risks of insertion into patient genomes. RNA drugs, including mRNA vaccines, need carrier materials for delivery into the patient's body. Several delivery carriers of mRNA, such as cationic polymers, lipoplexes, lipid–polymer nanoparticles and lipid nanoparticles (LNPs), have been investigated. For clinical applications, one of the most commonly selected types of RNA delivery carrier is LNPs, which are typically formed with (a) ionizable lipids, which bind to RNA; (b) cholesterol for stabilization; (c) phospholipids to form the LNPs; and (d) polyethylene glycol-conjugated lipids to prevent aggregation and provide stealth characteristics. Most RNA-LNP research has been devoted to achieving highly efficient RNA expression in vitro and in vivo. It is also necessary to study the extended storage of RNA-LNPs under mild conditions. One of the most efficient methods to store RNA-LNPs for a long time is to prepare freeze-dried (lyophilized) RNA-LNPs. Future research should include investigating LNP materials for the development of freeze-dried RNA-LNPs using optimal lipid components and compositions with optimal cryoprotectants. Furthermore, the development of sophisticated RNA-LNP materials for targeted transfection into specific tissues, organs or cells will be a future direction in the development RNA therapeutics. We will discuss the prospects for the development of next-generation RNA-LNP materials.