Lipid Nanoparticles Consisting of Sterol-Conjugated Ionizable Lipids Enable Prolonged and Safe mRNA Delivery

mRNA offers a promising therapeutic approach for gene therapy, cancer treatment, and vaccine development. Lipid nanoparticles (LNPs) have emerged as a primary delivery system for mRNA. Ionizable lipids are key components of LNPs. Given the current limitations of LNPs regarding efficacy, safety, and stability, we undertook this research. We synthesized 11 asymmetric sterol-conjugated ionizable lipids. These lipids and their resulting LNP formulations were screened. Five of these ionizable lipids were selected, and a 40-50% molar ratio was determined to be optimal for the LNP formulation. Luciferase mRNA-loaded LNPs formulated with sterol-conjugated ionizable lipids demonstrated luminescence comparable to that of commercial LNPs composed of ALC-0315 and prolonged protein expression in mice. Furthermore, accelerated stability studies demonstrated that LNPs exhibited good stability. Additionally, LNPs loaded with varicella-zoster virus (VZV) gE mRNA successfully induced both humoral- and T-cell-mediated immune responses. Finally, <i>in vivo</i> safety studies revealed that LNPs based on these ionizable lipids exhibited improved safety profiles compared with commercially available LNPs. In conclusion, these sterol-conjugated ionizable lipid nanoparticles enable prolonged and safe mRNA delivery, representing a significant advance in mRNA delivery technology.