Lipid 51 is a top-performing thioglycerol-based biodegradable ionizable lipid disclosed in PCT patent WO2026/147683 (Eli Lilly, filed Dec 16, 2025). Built with cleavable thioester linkages, it balances neutral surface charge at physiological pH and protonatable amines in acidic endosomes for efficient mRNA encapsulation and endosomal escape. Formulated into LNPs with DSPC, cholesterol and DMG-PEG2K, it exhibits favorable particle size, low PDI and high RNA loading efficiency. In intracerebroventricular (ICV) mouse tests targeting central nervous system (CNS), it delivers Cre mRNA to brain neurons far more potently than Lipid 1/2/3, with the highest tissue fluorescent signal among all tested candidates. It shows low cellular toxicity in vitro and robust CNS tropism, making it an optimal carrier for brain-targeted mRNA and CRISPR gene editing therapeutics.
