Targeted mRNA Nanoparticles Ameliorate Blood-Brain Barrier Disruption Postischemic Stroke by Modulating Microglia Polarization.

The ischemic stroke is a major global health concern, with high mortality and disability rates. Unfortunately, there is a dearth of effective clinical interventions for managing poststroke neuroinflammation and blood-brain barrier (BBB) disruption that are crucial for the brain injury evolving and neurological deficits. By leveraging the pathological progression of an ischemic stroke, we developed an M2 microglia-targeting lipid nanoparticle (termed MLNP) approach that can selectively deliver mRNA encoding phenotype-switching interleukin-10 (m) to the ischemic brain, creating a beneficial feedback loop that drives microglial polarization toward the protective M2 phenotypes and augments the homing of m-loaded MLNPs (m@MLNPs) to ischemic regions. In a transient middle cerebral artery occlusion (MCAO) mouse model of an ischemic stroke, our findings demonstrate that intravenously injected m@MLNPs induce IL-10 production and enhance the M2 polarization of microglia. The resulting positive loop reinforces the resolution of neuroinflammation, restores the impaired BBB, and prevents neuronal apoptosis after stroke. Using a permanent distal MCAO mouse model of an ischemic stroke, the neuroprotective effects of m@MLNPs have been further validated by the attenuation of the sensorimotor and cognitive neurological deficits. Furthermore, the developed mRNA-based targeted therapy has great potential to extend the therapeutic time window at least up to 72 h poststroke. This study depicts a simple and versatile LNP platform for selective delivery of mRNA therapeutics to cerebral lesions, showcasing a promising approach for addressing an ischemic stroke and associated brain conditions.