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Aging is one of the key mechanisms of vascular dysfunction and contributes to the initiation and progression of ischemic stroke (IS). Our previous study demonstrated that ACE2 priming enhanced the protective effects of exosomes derived from endothelial progenitor cells (EPC-EXs) on hypoxia-induced injury in aging endothelial cells (ECs). Here, we aimed to investigate whether ACE2-enriched EPC-EXs (ACE2-EPC-EXs) could attenuate brain ischemic injury by inhibiting cerebral EC damage through their carried miR-17-5p and the underlying molecular mechanisms. The enriched miRs in ACE2-EPC-EXs were screened using the miR sequencing method. EPC-EXs, ACE2-EPC-EXs, and ACE2-EPC-EXs with miR-17-5p deficiency (ACE2-EPC-EXs antagomiR-17-5p ) were administered to transient middle cerebral artery occlusion (tMCAO)-operated aged mice or coincubated with hypoxia/reoxygenation (H/R)-treated aging ECs. The results showed that (1) the level of brain EPC-EXs and their carried ACE2 were significantly decreased in aged mice compared to in young mice, and (2) after tMCAO, aged mice displayed increases in brain cell senescence, infarct volume, and neurological deficit score (NDS) and a decrease in cerebral blood flow (CBF). (3) Compared with EPC-EXs, ACE2-EPC-EXs were enriched with miR-17-5p and more effective in increasing ACE2 and miR-17-5p expression in cerebral microvessels, accompanied by obvious increases in cerebral microvascular density (cMVD) and cerebral blood flow (CBF) and decreases in brain cell senescence, infarct volume, neurological deficit score (NDS), cerebral EC ROS production, and apoptosis in tMCAO-operated aged mice. Moreover, silencing of miR-17-5p partially abolished the beneficial effects of ACE2-EPC-EXs. (4) In H/R-treated aging ECs, ACE2-EPC-EXs were more effective than EPC-EXs in decreasing cell senescence, ROS production, and apoptosis and increasing cell viability and tube formation. In a mechanistic study, ACE2-EPC-EXs more effectively inhibited PTEN protein expression and increased the phosphorylation of PI3K and Akt, which were partially abolished by miR-17-5p knockdown. Altogether, our data suggest that ACE-EPC-EXs have better protective effects on ameliorating aged IS mouse brain neurovascular injury by inhibiting cell senescence, EC oxidative stress, apoptosis, and dysfunction by activating the miR-17-5p/PTEN/PI3K/Akt signaling pathway., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Introduction: Multicellular crosstalk within the brain tissue has been suggested to play a critical role in maintaining cerebral vascular homeostasis. Exosomes (EXs) mediated cell-cell communication, but its role in cerebral ischemic injury is largely unknown. Rab27a is one of the major genes controlling EX release. Here, we explored the role of Rab27a in regulating brain EXs secretion, and the effects of Rab27a-mediated EXs on ischemia evoked cerebral vascular disruption and brain injury., Methods: Cerebral ischemia was induced in Rab27a knockout (Rab27a -/- ) and wide type (WT) mice by transient middle cerebral artery occlusion (tMCAO). Differential gene expression analysis was performed in ischemic brain tissue by using mRNA sequencing. EXs isolated from brain tissue of Rab27a -/- and WT mice (EX WT or EX Rab27a-/- ) were pre-administrated into tMCAO operated Rab27a -/- mice or oxygen and glucose deprivation (OGD) treated primary brain vascular endothelial cells (ECs)., Results: We demonstrated that Rab27a expression in the peri-infarct area of brain was significantly elevated, which was associated with local elevation in EXs secretion. Rab27a deficiency dramatically decreased the level of EXs in brain tissue of normal and tMCAO-treated mice, and Rab27a -/- mice displayed an increase in infarct volume and NDS, and a decrease in cMVD and CBF following tMCAO. Pre-infusion of EX WT increased the brain EXs levels in the tMCAO operated Rab27a -/- mice, accompanied with an increase in cMVD and CBF, and a decrease in infarct volume, NDS, ROS production, and apoptosis. The effects of EX Rab27a-/- infusion were much diminished although in a dose-dependent manner. In OGD-treated ECs, EX Rab27a-/- showed less effectivity than EX WT in decreasing ROS overproduction and apoptosis, paralleling with down-regulated expression of NOX2 and cleaved caspase-3., Conclusion: Our study demonstrates that Rab27a controls brain EXs secretion and functions, contributing to cerebral vascular protection from ischemic insult by preventing oxidative stress and apoptosis via down-regulating NOX2 and cleaved caspase-3 expression., (© 2022 The Authors. CNS Neuroscience & Therapeutics published by John Wiley & Sons Ltd.)

Background/aims: Vascular dementia (VD) results in cognition and memory deficit. Exosomes and their carried microRNAs (miRs) contribute to the neuroprotective effects of mesenchymal stromal cells, and miR-132-3p plays a key role in neuron plasticity. Here, we investigated the role and underlying mechanism of MSC EX and their miR-132-3p cargo in rescuing cognition and memory deficit in VD mice., Methods: Bilateral carotid artery occlusion was used to generate a VD mouse model. MiR-132-3p and MSC EX levels in the hippocampus and cortex were measured. At 24-h post-VD induction, mice were administered with MSC EX infected with control lentivirus (EX Con ), pre-miR-132-3p-expressing lentivirus (EX miR-132-3p ), or miR-132-3p antago lentivirus (EX antagomiR-132-3p ) intravenously. Behavioral and cognitive tests were performed, and the mice were killed in 21 days after VD. The effects of MSC EX on neuron number, synaptic plasticity, dendritic spine density, and Aβ and p-Tau levels in the hippocampus and cortex were determined. The effects of MSC EX on oxygen-glucose deprivation (OGD)-injured neurons with respect to apoptosis, and neurite elongation and branching were determined. Finally, the expression levels of Ras, phosphorylation of Akt, GSK-3β, and Tau were also measured., Results: Compared with normal mice, VD mice exhibited significantly decreased miR-132-3p and MSC EX levels in the cortex and hippocampus. Compared with EX Con treatment, the infusion of EX miR-132-3p was more effective at improving cognitive function and increasing miR-132-3p level, neuron number, synaptic plasticity, and dendritic spine density, while decreasing Aβ and p-Tau levels in the cortex and hippocampus of VD mice. Conversely, EX antagomiR-132-3p treatment significantly decreased miR-132-3p expression in cortex and hippocampus, as well as attenuated EX miR-132-3p treatment-induced functional improvement. In vitro, EX miR-132-3p treatment inhibited RASA1 protein expression, but increased Ras and the phosphorylation of Akt and GSK-3β, and decreased p-Tau levels in primary neurons by delivering miR-132-3p, which resulted in reduced apoptosis, and increased neurite elongation and branching in OGD-injured neurons., Conclusions: Our studies suggest that miR-132-3p cluster-enriched MSC EX promotes the recovery of cognitive function by improving neuronal and synaptic dysfunction through activation of the Ras/Akt/GSK-3β pathway induced by downregulation of RASA1., (© 2022. The Author(s).)