Stepwise neutrophil-to-neuron targeting nanotherapy for mitochondrial protection and blood-brain barrier preservation in ischemic stroke.

Ischemic stroke is a leading cause of mortality and long-term disability worldwide, yet the clinical efficacy of reperfusion therapies remains severely constrained by a narrow therapeutic time window and secondary ischemia-reperfusion injury. Preserving the viability of the ischemic penumbra through early, multi-target neuroprotection represents a promising strategy to extend this window; however, effective approaches that simultaneously address neuronal mitochondrial dysfunction and blood-brain barrier (BBB) disruption are lacking. Here, we report a dual-modal, stepwise-targeting lipid nanoparticle (DM-LNP) platform that integrates mitochondrial protection with matrix metalloproteinase-12 (MMP-12) silencing to achieve coordinated neurovascular protection in ischemic stroke. DM-LNP is engineered with a sialic acid-based neutrophil-targeting outer layer and a reactive oxygen species (ROS)-responsive thioketal linker that enables ligand switching to expose a neuron-targeting Tet1 peptide within the ischemic microenvironment. This design allows sequential neutrophil-mediated BBB traversal (Modal I) and precise neuronal targeting (Modal II). Functionally, DM-LNP delivers MMP-12 siRNA to suppress downstream MMP activation and preserve BBB integrity, while a spermidine-derived gene carrier promotes Pink1-Parkin-mediated mitophagy, restores mitochondrial homeostasis, reduces oxidative stress, inhibits neuronal apoptosis, and drives microglial polarization toward an anti-inflammatory phenotype. In transient and prolonged middle cerebral artery occlusion models, DM-LNP significantly improves cerebral blood flow recovery, reduces infarct volume, alleviates neurological deficits, and extends the effective reperfusion window up to 8 h post-ischemia. Together, this work establishes a multifunctional, ROS-responsive nanotherapeutic strategy that stabilizes the neuron-microglia-BBB axis and offers a viable approach for extending reperfusion benefits in ischemic stroke.