Background This study aimed to explore the role of mesenchymal stromal cells (MSCs)-derived exosomes (MSCs-Exo) in the cerebral ischemia–reperfusion (I/R) injury. Methods Exosomes were isolated from MSCs of adult C57BL/6J mice by the gradient centrifugation method. The expression of miR-26a-5p and CDK6 in MSCs-Exo and mice brain tissues were evaluated by qRT-PCR and western blot. miR-26a-5p mimics and miR-NC were transfected into MSCs, and exosomes were isolated from the MSCs stably expressing miR-26a-5p. Then MSCs-Exo-miR-26a-5p mimics or MSCs-Exo-miR-NC was injected into mice through the tail vein, or added into medium to stimulate BV-2 cells. Cell viability was evaluated by CCK-8 assay. Cell apoptosis was detected by flow cytometry. The apoptosis in brain tissues was evaluated by TUNEL staining assay. Bioinformatics analysis and luciferase reporter assay were performed to determine the binding relationship between miR-26a-5p and CDK6. Results miR-26a-5p was downregulated and CDK6 was upregulated in MSCs-Exo of MCAO-mice and OGD-induced MSCs. MSCs-Exo-miR-26a-5p mimics significantly reduced cell apoptosis of OGD-injured BV-2 cells. MSCs-Exo-miR-26a-5p mimics significantly reduced the infarct volume of MCAO-induced mice. Luciferase reporter assay revealed that CDK-6 was a target of miR-26a-5p. In addition, MSCs-Exo-miR-26a-5p mimics significantly decreased the expression of CDK6 in both OGD-induced BV-2 cells and the brain tissues of MCAO-treated mice. Conclusion Our results indicated that MSCs‑Exo attenuated I/R injury in mice by inhibiting microglia apoptosis might via exosomal miR-26a-5p mediated suppression of CDK6. Our study shed light on the application of MSC-Exo as a potential therapeutic tool for cerebral I/R injury.

Background: Astragalin (AG), a flavonoid from many traditional herbs and medicinal plants, has been described to exhibit in vitro anti-inflammatory activity. The paper aimed to study the effects of astragalin on anti-inflammatory, anti-oxidative ability and apoptosis signaling pathway in brain tissue of rats with cerebral ischemia-reperfusion injury, and to explore its possible mechanism.Methods: The rat model of focal cerebral ischemia-reperfusion injury was established by suture method. It was randomly divided into 5 groups, sham operation group, ischemia-reperfusion (I/R) treatment group, and astragalin treatment I / R group (12.5, 25, 50 mg / kg). After 24 h of reperfusion, the neurological deficits of the rats were analyzed and HE staining was performed. The volume of cerebral infarction was calculated by triphenyltetrazolium chloride (TTC) staining, and the apoptosis of nerve cells was detected by TUNEL staining. In addition, the content of malondialdehyde (MDA), nitric oxide (NO), superoxide dismutase (SOD), glutathione (GSH) assay and glutathione peroxidase (GSH-Px) were measured in rat brain tissue. Western blot analysis was used to determine the expression of related proteins.Results: Compared with I/R group, the neurological deficit score and infarct volume of I/R rats were reduced in the astragalin treatment group. In the astragalin treatment group, MDA and NO levels in I/R rats were reduced, antioxidant enzymes and superoxide dismutase (SOD) activity were increased. In the astragalin treatment group, NF-κB (p65) and cyclooxygenase-2 (COX-2) expression levels were down-regulated, NF-E2-related factor 2 (Nrf2) nucleus and heme oxygenase-1 (HO-1) protein expression levels were up-regulated. In addition, the astragalin treatment can inhibit apoptosis, down-regulate Bax and cleaved caspase-3 expression, up-regulate Bcl-Xl expression. Conclusion:The antioxidant properties of astragalin may play an important role in improving cerebral ischemiareperfusion injury.

We sought to investigate the role of the adenosine A1 receptors (A1ARs) in white matter lesions under chronic cerebral hypoperfusion (CCH) and explore the potential repair mechanisms by activation of the receptors. A right unilateral common carotid artery occlusion (rUCCAO) method was used to construct a CCH model. 2-chloro-N6-cyclopentyladenosine (CCPA), a specific agonist of A1ARs, was used to explore the biological mechanisms of repair in white matter lesions under CCH. The expression of mammalian target of rapamycin (mTOR), phosphorylation of mTOR (P-mTOR), myelin basic protein (MBP, a marker of white matter myelination) were detected by Western-blot. Pro-inflammatory cytokine tumor necrosis factor-α (TNF-α) and anti-inflammatory cytokine interleukin-10 (IL-10) levels were determined by ELISA. Compared with the control groups on week 2, 4 and 6, in CCPA-treated groups, the ratio of P-mTOR/mTOR, expression of MBP and IL-10 increased markedly, while the expression of TNF-α reduced at week 6. In conclusion, A1ARs appears to reduce inflammation in white matter via the mTOR signaling pathway in the rUCCAO mice. Therefore, A1ARs may serve as a therapeutic target during the repair of white matter lesions under CCH.

Microglial activation-mediated inflammatory damage to oligodendrocytes is a key step in the etiology of ischemic white matter lesions. The adenosine A1 receptor (A1R) and adenosine A2a receptor (A2aR) have been reported to regulate the activation of microglia, however, the underlying mechanisms remain elusive. Thus, the present study used a microglia/oligodendrocyte co‑culture model exposed to low glucose/hypoxia, and treated with agonists/antagonists of A1R and A2aR to investigate the role of A1R and A2aR. Changes in A1R and A2aR expression and inflammatory cytokine secretion by the microglia, and oligodendrocyte damage, after exposure were examined. Low glucose/hypoxia induced a higher elevation of A1R than A2aR. In addition, activation of A1R inhibited A2aR protein expression and vice versa. The A1R antagonist DPCPX (100 nM) and A2aR agonist CGS 21680 (100 nM) inhibited microglial activation, reduced the production of inflammatory cytokines and attenuated oligodendrocyte damage, along with elevating the levels of phosphorylated nuclear factor (NF)‑κB and cyclic adenosine monophosphate response element binding protein (CREB). These data indicate that an A1R‑A2aR imbalance is able to modulate low glucose‑induced microglial activation and the cellular immune response through altering NF‑κB and CREB phosphorylation. This suggests that rebalancing A1R‑A2aR is a promising approach for treating white matter injury.