Spotlighting the criticality of lipid quality control through a mechanistic investigation of mRNA activity loss in lipid nanoparticles.

Lipid nanoparticles (LNPs) have gained much attention after the recent launch of mRNA based Covid vaccines. For mRNA encapsulated within LNPs to be successfully translated into target proteins, the mRNA must maintain its integrity and also be free of any unintended chemical modifications. Any process or raw material related impurities-and their degradation products-pose risks of chemically modifying mRNA, thereby affecting the quality of the final product. Given its inherent chemical reactivity and close association with the LNP lipids, encapsulated mRNA is especially susceptible to modifications by reactive impurity species present in the lipids. In our recent efforts to understand mRNA-lipid interactions within LNPs, we observed that the degradants of labile lipid peroxide species in ionizable lipids react with nucleotides in mRNA, resulting in loss of mRNA's translation efficiency in vitro. Specifically, we identified peroxide species in unsaturated dialkene groups were converted to a variety of reactive aldehyde products in mRNA LNP formulations. These findings enhance the current understanding of the adduct formation between mRNA and aldehyde species, and emphasize the critical role of deep analytical characterization of ionizable lipid stability and purity to enhance LNP product quality and shelf-life.