Aging Inhibits Emergency Angiogenesis and Exacerbates Neuronal Damage by Downregulating DARS2

Background: Early vascular regeneration is important for the speedy recovery of neurological function following ischemic stroke. M2-like microglia polarization decreases and vascular regeneration weakens with aging. The function of mitochondrial respiratory chain is dependent on M2-like polarization in microglia. DARS2 gene is a marker for mitochondrial respiratory chain function, but its specific molecular mechanism affecting acute angiogenesis of microglia during ischemic stroke in elderly individuals remains unclear. Methods: A murine model of middle cerebral artery occlusion (MCAO) was used to perform animal behavioral assessments, immunoblotting, tube formation and chick embryo chorioallantoic membrane assays. A D-galactose-induced cellular senescence model was established in BV2 cells. Results: Aging significantly exacerbates acute brain injury 24 hours post-cerebral ischemia-reperfusion, with increased expression of M1-like microglial markers and a concomitant decrease in M2-like microglial markers. Additionally, aging can inhibit DARS2 protein expression, adversely affect angiogenesis and reduce brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor A (VEGFA) expression. In vitro, oxygen-glucose deprivation/reoxygenation and re-glucose (OGD/R) demonstrated that DARS2 gene knockout in young microglia replicates the phenotypic characteristics observed in aged microglia. Conclusion: This study suggests that aging impedes M2-like microglial polarization by downregulating DARS2 expression in microglia, thereby impairing emergency angiogenesis during acute ischemic stroke and exacerbating neuronal damage. Keywords: ischemic stroke, angiogenesis, DARS2, microglia