Targeting Atf4 for enhanced neuroprotection: Role of quercetin-loaded EVs in ischemic stroke

This study investigates the neuroprotective potential of extracellular vesicles (EVs) delivering quercetin-3-<i>O</i>-β-d-glucuronic acid (QG-EVs) in cerebral ischemia-reperfusion injury (CIRI). Targeted brain delivery of QG-EVs was confirmed, with neuron cells identified as pivotal in modulating CIRI through single-cell RNA sequencing (scRNA-seq). Activating transcription factor 4 (<i>Atf4</i>) was highlighted as a critical regulatory factor, and <i>in vitro</i> studies revealed that silencing <i>Atf4</i> diminished the neuroprotective effects of QG-EVs, increasing oxidative stress levels and neuronal apoptosis. In a CIRI mouse model, the knockdown of <i>Atf4</i> attenuated the protective outcomes provided by QG-EVs, further affirming the role of <i>Atf4</i> in mediating neuroprotection. Behavioral assessments and protein analysis showed that QG-EVs significantly reduced neuronal damage and pro-apoptotic markers, while improving neurological function via <i>Atf4</i> upregulation. The outcomes hint at the potential of QG-EVs as a beneficial therapeutic modality to mitigate neuronal damage in CIRI by enhancing <i>Atf4</i> expression, highlighting its potential for improving ischemic stroke outcomes.