'Tripod-like' lung-targeting (LuT) lipids for highly efficient and selective LNPs for gene delivery and editing.

Developing lung-targeting delivery systems is essential for treating pulmonary conditions such as genetic respiratory diseases, infections, fibrosis and cancer. We synthesized and evaluated 444 lung-targeting lipids (LuT lipids) that form lipid nanoparticles (LNPs) to efficiently deliver messenger RNA and CRISPR-Cas9 genome editors to lungs with minimal side effects. Empirical analyses revealed structure-activity relationships, with top-performing LuT lipids possessing a unique 'tripod-like' structure consisting of a quaternary amine head, three long alkyl chains as legs and a short chain as a handle. LuT lipids improved endosomal escape, cargo release and endogenous targeting via adsorption of plasma proteins. Lead 1A7B13 LNPs showed a 25.5-fold improvement in mRNA delivery and a 9.2-fold increase in CRISPR-Cas9 gene-editing efficiency compared to benchmark DOTAP SORT LNPs, achieving over 90% selectivity to the lungs. 1A7B13 LNPs effectively delivered IL-10 mRNA in a therapeutic model of acute lung injury. This study reveals the relationship between lipid structure and lung-targeting activity, enriching the toolkit for lung-specific carriers.