Intranasal Administration of Extracellular Vesicles Mitigates Apoptosis in a Mouse Model of Neonatal Hypoxic-Ischemic Brain Injury

Introduction: Neonatal hypoxic-ischemic brain injury (HIBI) results in significant morbidity and mortality despite current available therapies. Seeking a potential supplemental therapy for HIBI, we investigated the neuroprotective effects of extracellular vesicles derived from neural stem cells (NSC-EVs) and hypoxia-preconditioned brain cells (brain-EVs). Methods: HIBI was induced in postnatal day 9 mice by carotid ligation followed by hypoxia. Following injury, NSC-EVs, brain-EVs, or saline were administered intranasally. Brains were assessed for infarct size, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining, and caspase-3 expression. Additionally, brain-EV microRNA (miRNA) contents were analyzed by miRNA sequencing. Results: Both EV treated groups showed decreased infarct size (brain-EVs p = 0.004 and NSC-EVs p = 0.052), and although NSC-EV administration resulted in significantly fewer TUNEL+ cells (p = 0.0098), there was no change in caspase-3 expression after NSC-EV administration, suggesting a caspase-3-independent mechanism. Brain-EVs resulted in a nonsignificant decrease in TUNEL+ cells (p = 0.167) but significant decreases in caspase expression (cleaved p = 0.015 and intact p = 0.026). Brain-EVs consistently expressed several miRNAs, including two which have been shown to be downregulated after HIBI: miR-342-3p and miR-330-3p. Conclusion: Understanding the regenerative effects and contents of NSC-EVs and brain-EVs could allow for the development of targeted EV-based therapies that could reduce morbidity and mortality for neonates affected by HIBI.

Automated summary

The neuroprotective effects of extracellular vesicles derived from neural stem cells and hypoxia-preconditioned brain cells were investigated in neonatal hypoxic-ischemic brain injury (HIBI). Both types of vesicles showed decreased infarct size, and NSC-EVs resulted in significantly fewer TUNEL+ cells. Brain-EVs expressed specific miRNAs that have been shown to be downregulated after HIBI. Understanding the regenerative effects and contents of these vesicles could lead to targeted therapies for reducing morbidity and mortality in neonates affected by HIBI.