Ionizable lipid chemistry in lipid nanoparticles determines delivery efficiency to hepatic stellate cells.

Lipid nanoparticles (LNPs) are clinically validated carriers for delivering drug agents for liver diseases. However, designing LNPs for delivery to hepatic stellate cells (HSCs) remains challenging. Here, using 12 ionizable lipids, including the approved MC3, SM-102, and ALC-0315, we demonstrate that ionizable lipid chemistry in LNPs determines the efficiency of delivery to HSCs. Using siRNAs targeting genes expressed exclusively in mouse HSCs (Reln) and hepatocytes (Ttr), we formulated an siRNA cocktail with LNPs. Systemic administration of 0.3 mg/kg body weight siRNA cocktails to mice caused varying Reln suppression (0-80 %) across the 12 lipids with consistent Ttr suppression (>90 %). Among the physicochemical properties of ionizable lipids, the delivery efficiency to HSCs could be influenced by the dipole moment of the ionizable lipids. The best-performing ALC-0315 LNP exhibited dose-dependent activity in HSCs (siRNA ED50 ∼ 0.03 mg/kg body weight) and durable silencing (up to 88 %) over two weeks, without toxicity, at 2 mg/kg. A comparative study in wild-type and ApoE-deficient mice revealed that ALC-0315 LNP delivery to HSCs was either independent of or slightly dependent on ApoE. In primary human activated HSCs, ALC-0315 LNPs induced robust cellular uptake and effective knockdown of heat shock protein 47, a therapeutic target for liver fibrosis, compared with MC3 LNPs. These findings will contribute to the development of advanced ionizable lipid-based LNPs for delivery to HSCs without targeting ligands.