Predictive High-Throughput Platform for Dual Screening of mRNA Lipid Nanoparticle Blood-Brain Barrier Transfection and Crossing.

Lipid nanoparticle (LNP)-mediated nucleic acid therapies, including mRNA protein replacement and gene editing therapies, hold great potential in treating neurological disorders including neurodegeneration, brain cancer, and stroke. However, delivering LNPs across the blood-brain barrier (BBB) after systemic administration remains underexplored. In this work, we engineered a high-throughput screening transwell platform for the BBB (HTS-BBB), specifically optimized for screening mRNA LNPs. Unlike most transwell assays, which only assess transport across an endothelial monolayer, HTS-BBB simultaneously measures LNP transport and mRNA transfection of the endothelial cells themselves. We then use HTS-BBB to screen a library of 14 LNPs made with structurally diverse ionizable lipids and demonstrate it is predictive of in vivo performance by validating lead candidates for mRNA delivery to the mouse brain after intravenous injection. Going forward, this platform could be used to screen large libraries of brain-targeted LNPs for a range of protein replacement and gene editing applications.