Technical Note: Focused ultrasound-mediated blood-brain barrier opening for delivery of LNP-packaged modRNA therapy in a mouse model of Niemann-Pick Disease Type C

Abstract

Efficient delivery of molecular therapies to the central nervous system (CNS) remains a major barrier to treating neurogenetic disorders such as Niemann-Pick type C (NPC) disease. Focused ultrasound-mediated blood-brain barrier opening (FUS-BBBO) has emerged as a non-invasive strategy to enhance delivery of systemically administered therapeutics. In this study, we evaluated whether FUS-BBBO could enable delivery of lipid nanoparticle (LNP)-packaged modified mRNA (modRNA) to the cerebellum in an NPC mouse model. A pilot study in wild-type mice demonstrated successful FUS-mediated BBB opening, delivery of LNP-packaged GFP mRNA, and subsequent protein expression in the cerebellum. We then performed a controlled study in NPC mice comparing delivery of LNP-GFP and LNP-NPC modRNA using intravenous administration with and without FUS-BBBO. BBB opening was confirmed by contrast-enhanced MRI in FUS-treated animals. Quantitative PCR revealed the presence of GFP mRNA in the cerebellum following FUS-BBBO, whereas NPC mRNA was minimal or undetectable across groups. However, no GFP or NPC1 protein expression was detected in the cerebellum by western blot in any experimental group. Consistent with this, no therapeutic effect on Purkinje cell survival was observed. These results demonstrate that while FUS-BBBO reliably induces BBB opening and can facilitate limited delivery of LNP-packaged mRNA to the brain, this did not translate into detectable protein expression or therapeutic benefit in the NPC model under the conditions tested. This discrepancy between successful delivery in wild-type mice and lack of efficacy in diseased animals points to potential important biological and/or formulation-dependent barriers that must be addressed to enable effective CNS delivery of LNP-based mRNA therapies.