Characterisation of a mouse cerebral microvascular endothelial cell line (bEnd.3) after oxygen glucose deprivation and reoxygenation

Oxidized Carbon Nanoparticles Enhance Cellular Energetics With Application to Injured Brain

Pro-energetic effects of functionalized, oxidized carbon nanozymes (OCNs) are reported. OCNs, derived from harsh acid oxidation of single-wall carbon nanotubes or activated charcoal are previously shown to possess multiple nanozymatic activities including mimicking superoxide dismutase and catalyzing the oxidation of reduced nicotinamide adenine dinucleotide (NADH) to NAD+. These actions are predicted to generate a glycolytic shift and enhance mitochondrial energetics under impaired conditions. Impaired mitochondrial energy metabolism is increasingly recognized as an important facet of traumatic brain injury (TBI) pathophysiology and decreases the efficiency of electron transport chain (ETC)-coupled adenosine triphosphate (ATP) and NAD+ regeneration. In vitro, OCNs promote a pro-aerobic shift in energy metabolism that persists through ETC inhibition and enhances glycolytic flux, glycolytic ATP production, and cellular generation of lactate, a crucial auxiliary substrate for energy metabolism. To address specific mechanisms of iron injury from hemorrhage, OCNs with the iron chelator, deferoxamine (DEF), covalently-linked were synthesized. DEF-linked OCNs induce a glycolytic shift in-vitro and in-vivo in tissue sections from a rat model of TBI complicated by hemorrhagic contusion. OCNs further reduced hemorrhage volumes 3 days following TBI. These results suggest OCNs are promising as pleiotropic mediators of cell and tissue resilience to injury.

The Basic Requirement of Tight Junction Proteins in Blood-Brain Barrier Function and Their Role in Pathologies

This review addresses the role of tight junction proteins at the blood-brain barrier (BBB). Their expression is described, and their role in physiological and pathological processes at the BBB is discussed. Based on this, new approaches are depicted for paracellular drug delivery and diagnostics in the treatment of cerebral diseases. Recent data provide convincing evidence that, in addition to its impairment in the course of diseases, the BBB could be involved in the aetiology of CNS disorders. Further progress will be expected based on new insights in tight junction protein structure and in their involvement in signalling pathways.

Inhibition of Heat Shock Protein 90 Attenuates the Damage of Blood-Brain Barrier Integrity in Traumatic Brain Injury Mouse Model

Heat shock protein 90 (HSP90) is widely found in brain tissue. HSP90 inhibition has been proven to have neuroprotective effects on ischemic strokes. In order to study the role of HSP90 in traumatic brain injury (TBI), we carried out the present study. A novel inhibitor of the HSP90 protein, 17-dimethylaminoethylamino-17-demethoxygeldanamycin (17-DA), has been investigated for its function on the blood-brain barrier (BBB) damage after traumatic brain injury (TBI) in mouse models. These C57BL/6 mice were used as a TBI model and received 17-DA (0.1 mg/kg/d, intraperitoneally) until the experiment ended. To find out whether 17-DA may protect against TBI in vitro, bEnd.3 cells belonging to mouse brain microvascular endothelium were used. The HSP90 protein expressions were raised after TBI at the pericontusional area, especially at 3 d. Our study suggested that 17-DA-treated mice improved the recovery ability of neurological deficits and decreased brain edema, Evans blue extravasation, and the loss of tight junction proteins (TJPs) post-TBI. 17-DA significantly promoted cell proliferation and alleviated apoptosis by inhibiting the generation of intracellular reactive oxygen species (ROS) to downregulate cleaved caspase-3, matrix metallopeptidase- (MMP-) 2, MMP-9, and P-P65 in bEnd.3 cells after the injury. As a result, we assumed that the HSP90 protein was activated post-TBI, and inhibition of HSP90 protein reduced the disruption of BBB and improved the neurobehavioral scores in a mouse model of TBI through the action of 17-DA, which inhibited ROS generation and regulated MMP-2, MMP-9, NF-κB, and caspase-associated pathways. Thus, blocking HSP90 protein may be a potential therapeutic strategy for TBI.

Carnosine Protects against Cerebral Ischemic Injury by Inhibiting Matrix-Metalloproteinases

Stroke is one of the leading causes of death and disability worldwide. However, treatment options for ischemic stroke remain limited. Matrix-metalloproteinases (MMPs) contribute to brain damage during ischemic strokes by disrupting the blood-brain barrier (BBB) and causing brain edemas. Carnosine, an endogenous dipeptide, was found by us and others to be protective against ischemic brain injury. In this study, we investigated whether carnosine influences MMP activity. Brain MMP levels and activity were measured by gelatin zymography after permanent occlusion of the middle cerebral artery (pMCAO) in rats and in vitro enzyme assays. Carnosine significantly reduced infarct volume and edema. Gelatin zymography and in vitro enzyme assays showed that carnosine inhibited brain MMPs. We showed that carnosine inhibited both MMP-2 and MMP-9 activity by chelating zinc. Carnosine also reduced the ischemia-mediated degradation of the tight junction proteins that comprise the BBB. In summary, our findings show that carnosine inhibits MMP activity by chelating zinc, an essential MMP co-factor, resulting in the reduction of edema and brain injury. We believe that our findings shed new light on the neuroprotective mechanism of carnosine against ischemic brain damage.

A novel rat model of chronic subdural hematoma: Induction of inflammation and angiogenesis in the subdural space mimicking human-like features of progressively expanding hematoma

Pathophysiological mechanisms of chronic subdural hematoma (CSDH) involve localized inflammation, angiogenesis, and dysregulated coagulation and fibrinolysis. The scarcity of reproducible and clinically relevant animal models of CSDH hinders further understanding the underlying pathophysiology and improving new treatment strategies. Here, we developed a novel rat model of CSDH using extracellular matrices (Matrigel) and brain microvascular endothelial cell line (bEnd.3 cells). One hundred-microliter of Matrigel-bEnd.3 cell (10⁶ cells per milliliter) mixtures were injected into the virtual subdural space of elderly male Sprague-Dawley rats. This approach for the first time led to a spontaneous and expanding subdural hematoma, encapsulated by internal and external neomembranes, formed as early as 3 d, reached its peak at 7 d, and lasted for more than 14 d, mimicking the progressive hemorrhage observed in patients with CSDH. The external neomembrane and hematoma fluid involved numerous inflammatory cells, fibroblasts, and highly fragile neovessels. Furthermore, a localized pathophysiological process was validated as evidenced by the increased expressions of inflammatory and angiogenic mediators in external neomembrane and hematoma fluid rather than in peripheral blood. Notably, the specific expression profiles of these mediators were closely associated with the dynamic changes in hematoma volume and neurological outcome. In summary, the CSDH model described here replicated the characteristics of human CSDH, and might serve as an ideal translational platform for preclinical studies. Meanwhile, the crucial roles of angiogenesis and inflammation in CSDH formation were reaffirmed.

miR-98 reduces endothelial dysfunction by protecting blood-brain barrier (BBB) and improves neurological outcomes in mouse ischemia/reperfusion stroke model

Most neurological diseases, including stroke, lead to some degree of blood-brain barrier (BBB) dysfunction. A significant portion of BBB injury is caused by inflammation, due to pro-inflammatory factors produced in the brain, and by leukocyte engagement of the brain endothelium. Recently, microRNAs (miRNAs) have appeared as major regulators of inflammation-induced changes to gene expression in the microvascular endothelial cells (BMVEC) that comprise the BBB. However, miRNAs' role during cerebral ischemia/reperfusion is still underexplored. Endothelial levels of miR-98 were significantly altered following ischemia/reperfusion insults, both in vivo and in vitro, transient middle cerebral artery occlusion (tMCAO), and oxygen-glucose deprivation (OGD), respectively. Overexpression of miR-98 reduced the mouse's infarct size after tMCAO. Further, miR-98 lessened infiltration of proinflammatory Ly6C^HI leukocytes into the brain following stroke and diminished the prevalence of M1 (activated) microglia within the impacted area. miR-98 attenuated BBB permeability, as demonstrated by changes to fluorescently-labeled dextran penetration in vivo and improved transendothelial electrical resistance (TEER) in vitro. Treatment with miR-98 improved significantly the locomotor impairment. Our study provides identification and functional assessment of miRNAs in brain endothelium and lays the groundwork for improving therapeutic approaches for patients suffering from ischemic attacks.

XQ-1H regulates Wnt/GSK3β/β-catenin pathway and ameliorates the integrity of blood brain barrier in mice with acute ischemic stroke

10-O-(N, N-dimethylaminoethyl) ginkgolide B methanesulfonate (XQ-1H), a novel analog of ginkgolide B, has been preliminarily recognized to show bioactivities against ischemia-induced injury. However, the underlying mechanism still remains to be fully elucidated. The aim of this study was to investigate the effect of XQ-1H against cerebral ischemia/reperfusion injury (CIRI) from the perspective of blood brain barrier (BBB) protection, and explore whether the underlying mechanism is associated with Wnt/GSK3β/β-catenin signaling pathway activation. The therapeutic effects of XQ-1H were evaluated in mice subjected to middle cerebral artery occlusion/reperfusion (MCAO/R) and in immortalized mouse cerebral endothelial cells (bEnd.3) challenged by oxygen and glucose deprivation/reoxygenation (OGD/R). Results showed that treatment with XQ-1H improved neurological behavior, reduced brain infarction volume, diminished edema, and attenuated the disruption of BBB in vivo. In vitro, XQ-1H increased cell viability and maintained the barrier function of bEnd.3 monolayer after OGD/R. Moreover, the protection of XQ-1H was accompanied with activation of Wnt/GSK3β/β-catenin pathway and upregulation of tight junction proteins. Notably, the protection of XQ-1H was abolished by Wnt/GSK3β/β-catenin inhibitor XAV939 or β-catenin siRNA, indicating XQ-1H exerted protection in a Wnt/GSK3β/β-catenin dependent profile. In summary, XQ-1H attenuated brain injury and maintained BBB integrity after CIRI, and the possible underlying mechanism may be related to the activation of Wnt/GSK3β/β-catenin pathway and upregulation of tight junction proteins.

Lychee seed polyphenol protects the blood-brain barrier through inhibiting Aβ(25-35)-induced NLRP3 inflammasome activation via the AMPK/mTOR/ULK1-mediated autophagy in bEnd.3 cells and APP/PS1 mice

Blood-brain barrier (BBB) dysfunction has been implicated in Alzheimer's disease (AD) and is closely linked to the release of proinflammatory cytokines in brain capillary endothelial cells. We have previously reported that lychee seed polyphenols (LSP) exerted anti-neuroinflammatory effect. In this study, we aimed to explore the protective effect of LSP on BBB integrity. The monolayer permeability of bEnd.3 cells, and the mRNA level and protein expression of tight junction proteins (TJs), including Claudin 5, Occludin, and ZO-1, were examined. In addition, the inhibition of Aβ(25-35)-induced NLRP3 inflammasome activation, and the autophagy induced by LSP were investigated by detecting the expression of NLRP3, caspase-1, ASC, LC3, AMPK, mTOR, and ULK1. Furthermore, the cognitive function and the expression of TJs, NLRP3, caspase-1, IL-1β, and p62 were determined in APP/PS1 mice. The results showed that LSP significantly decreased the monolayer permeability and inhibited the NLRP3 inflammasome in Aβ(25-35)-induced bEnd3 cells. In addition, LSP induced autophagy via the AMPK/mTOR/ULK1 pathway in bEnd.3 cells, and improved the spatial learning and memory function, increased the TJs expression, and inhibited the expression of NLRP3, caspase-1, IL-1β, and p62 in APP/PS1 mice. Therefore, LSP protects BBB integrity in AD through inhibiting Aβ(25-35)-induced NLRP3 inflammasome activation via the AMPK/mTOR/ULK1-mediated autophagy.

let-7g counteracts endothelial dysfunction and ameliorating neurological functions in mouse ischemia/reperfusion stroke model

Stroke is a debilitating disease, accounting for almost 20% of all hospital visits, and 8% of all fatalities in the United States in 2017. Following an ischemic attack, inflammatory processes originating from endothelial cells within the brain microvasculature can induce many toxic effects into the impacted area, from both sides of the blood brain barrier (BBB). In addition to increased BBB permeability, impacted brain microvascular endothelial cells can recruit macrophages and other immune cells from the periphery and can also trigger the activation of microglia and astrocytes within the brain. We have identified a key microRNA, let-7g, which levels were drastically diminished as consequence of transient middle cerebral artery occlusion (tMCAO) in vivo and oxygen-glucose deprivation (OGD) in vitro ischemia/reperfusion conditions, respectively. We have observed that let-7g* liposome-based delivery is capable of attenuating inflammation after stroke, reducing BBB permeability, limiting brain infiltration by CD3+CD4+ T-cells and Ly6G+ neutrophils, lessening microglia activation and neuronal death. These effects consequently improved clinical outcomes, shown by mitigating post-stroke gait asymmetry and extremity motor function. Due to the role of the endothelium in propagating the effects of stroke and other inflammation, treatments which can reduce endothelial inflammation and limit ischemic damage and improving recovery after a stroke are required. Our findings demonstrate a critical link between the CNS inflammation and the immune system reaction and lay important groundwork for future stroke pharmacotherapies.

Co-Culturing of Endothelial and Cancer Cells in a Nanofibrous Scaffold-Based Two-Layer System

Angiogenesis is critical for local tumor growth. This study aimed to develop a three-dimensional two-layer co-culture system to investigate effects of cancer cells on the growth of endothelial cells (ECs). Poly(ε-caprolactone) (PCL) nanofibrous membranes were generated via electrospinning of PCL in chloroform (C-PCL-M) and chloroform and dimethylformamide (C/DMF-PCL-M). We assembled a two-layer co-culture system using C-PCL-M and C/DMF-PCL-M for EC growth in the upper layer with co-cultured cancer cells in the lower layer. In the absence of vascular endothelial growth factor (VEGF), growth of bEND.3 ECs decreased on C/DMF-PCL-M but not on C-PCL-M with time. Growth of bEND.3 cells on C/DMF-PCL-M was enhanced through co-culturing of CT26 cancer cells and enhanced growth of bEND.3 cells was abrogated with anti-VEGF antibodies and sorafenib. However, EA.hy926 ECs displayed steady growth and proliferation on C/DMF-PCL-M, and their growth was not further increased through co-culturing of cancer cells. Moreover, chemical hypoxia in CT26 cancer cells upon treatment with CoCl₂ enhanced the growth of co-cultured bEND.3 cells in the two-layer system. Thus, EC growth on the nanofibrous scaffold is dependent on the types of ECs and composition of nanofibers and this co-culture system can be used to analyze EC growth induced by cancer cells.

The Traditional Chinese Medicine Compound, GRS, Alleviates Blood-Brain Barrier Dysfunction

Introduction

Traditional Chinese medicine (TCM) provides unique advantages for treatment of ischemic stroke, an aging-related vascular disease. Shengmai powder (GRS) is composed of three active components, specifically, ginsenoside Rb1, ruscogenin and schisandrin A, at a ratio of 6:0.75:6. The main objective of this study was to evaluate the effects of GRS on blood–brain barrier (BBB) dysfunction under conditions of middle cerebral artery occlusion/reperfusion (MCAO/R).

Methods

C57BL/6J mice subjected to MCAO/R were used as a model to assess the protective effects of varying doses of GRS (6.4, 12.8, and 19.2 mg/kg) on BBB dysfunction.

Results

GRS reduced cerebral infarct volume and degree of brain tissue damage, improved behavioral scores, decreased water content and BBB permeability, and restored cerebral blood flow. Moreover, GRS promoted expression of zona occludens-1 (ZO-1) and claudin-5 while inhibiting matrix metalloproteinase 2/9 (MMP-2/9) expression and myosin light chain (MLC) phosphorylation. In vitro, GRS (1, 10, and 100 ng/mL) enhanced the viability of bEnd.3 cells subjected to oxygen glucose deprivation/reoxygenation (OGD/R) and decreased sodium fluorescein permeability.

Conclusion

Consistent with in vivo findings, ZO-1 and claudin-5 were significantly upregulated by GRS in bEnd.3 cells under OGD/R and MMP-2/9 levels and MLC phosphorylation reduced through the Rho-associated coil-forming protein kinase (ROCK)/cofilin signaling pathway. Based on the collective findings, we propose that the TCM compound, GRS, plays a protective role against I/R-induced BBB dysfunction.

Rabies virus glycoprotein-amplified hierarchical targeted hybrids capable of magneto-electric penetration delivery to orthotopic brain tumor

Compact nanohybrids can potentially unite various therapeutic features and reduce side effects for precise cancer therapy. However, the poor accumulation and limited tumor penetration of drugs at the tumor impede the manifestation of nanomedicine. We developed a rabies virus glycoprotein (RVG)-amplified hierarchical targeted hybrid that acts as a stealthy and magnetolytic carrier that transports dual tumor-penetrating agents incorporating two drugs (boron-doped graphene quantum dots (B-GQDs)/doxorubicin and pH-responsive dendrimers (pH-Den)/palbociclib). The developed RVG-decorated hybrids (RVG-hybrids) enhance the accumulation of drugs at tumor by partially bypassing the BBB via spinal cord transportation and pH-induced aggregation of hierarchical targeting. The penetrated delivery of dual pH-Den and B-GQD drugs to deep tumors is actuated by magnetoelectric effect, which are able to generate electrons to achieve electrostatic repulsion and disassemble the hybrids into components of a few nanometers in size. The synergy of magnetoelectric drug penetration and chemotherapy was achieved by delivery of the B-GQDs and pH-Den to orthotopic tumors, which prolonged the host survival time. This RVG-amplified dual hierarchical delivery integrated with controlled and penetrated release from this hybrid improve the distribution of the therapeutic agents at the brain tumor for synergistic therapy, exhibiting potential for clinic use.

Evaluation of long-term rt-PA effects on bEnd.3 endothelial cells under ischemic conditions; changes in ZO-1 expression and glycosylation of the bradykinin B2 receptor

Recombinant tissue plasminogen activator (rt-PA) has proven effective in the treatment of acute ischemic stroke, despite the increased risk of hemorrhagic transformation (HT), its major associated complication. Although it is known that HT is related to blood brain barrier (BBB) disruption, the underlying mechanisms are not well established. We assessed time-dependent effects of rt-PA on the bEnd.3 murine brain endothelial cell line subjected either to normoxia or to 2.5 h of oxygen and glucose deprivation (OGD), evaluating a longer period than has previously been done, beyond 6 h post-reoxygenation. Parameters of cell viability, metabolic activity, ionic and transcellular permeability, as well as levels of claudin-5, zonula occludens-1 (ZO-1) and bradykinin B2 receptor (B2R) protein expression were analyzed at 24, 48 and 72 h post-reoxygenation with or without the administration of rt-PA. rt-PA treatment increased both the ionic and transcellular permeability until 72 h and did not modify cell viability or metabolic activity or the expression of claudin-5, ZO-1 and B2R under normoxia at any analyzed time. Under OGD conditions, rt-PA exacerbated OGD effects on metabolic activity from 48 to 72 h, increased transcellular permeability from 24 to 72 h, significantly decreased ZO-1 protein levels at the plasma membrane and increased B2R glycosylation at 72 h post-reoxygenation. Our findings suggest that a long-term analysis is necessary to elucidate time-dependent molecular mechanisms associated to BBB breakdown due to rt-PA administration under ischemia. Thus, protective BBB therapies after ischemic stroke and rt-PA treatment should be explored at least until 72 h after OGD and rt-PA administration.

Cigarette smoke extract exacerbates hyperpermeability of cerebral endothelial cells after oxygen glucose deprivation and reoxygenation

Cigarette smoking is a risk factor for stroke and is linked to stroke severity. Previous studies have shown that cigarette smoke extract (CSE) triggers endothelial dysfunction in vitro by initiating oxidative stress and/or an inflammatory response. In addition, cerebral endothelial dysfunction (particularly at the level of the blood-brain barrier [BBB]) contributes to stroke pathogenesis. Therefore, we hypothesized that cigarette smoking may influence stroke, at least in part, by exacerbating ischaemia-induced BBB disruption. To test this, we examined the effect of CSE on the permeability of cerebral endothelial cells exposed to oxygen glucose deprivation and reoxygenation (OGD + RO). We found that the loss of BBB integrity following ischaemic/reperfusion-like conditions was significantly worsened by CSE. Despite this being associated with increased mRNA expression of Nox catalytic subunits, reactive oxygen species (ROS) levels were however markedly lower. Furthermore, this occurred in association with elevated expression of antioxidant enzymes (SOD1, SOD2, and Gpx-1), suggesting an antioxidant defence response. Lastly, we found that CSE significantly upregulated mRNA expression of cytokines (IL-6 and TGF-β). Collectively, these results show that acute exposure to CSE worsens BBB disruption caused by OGD + RO, however, this is not linked to elevated ROS levels but may involve inflammatory mechanisms.

The impact of endothelial cell death in the brain and its role after stroke: A systematic review

The supply of oxygen and nutrients to the brain is vital for its function and requires a complex vascular network that, when disturbed, results in profound neurological dysfunction. As part of the pathology in stroke, endothelial cells die. As endothelial cell death affects the surrounding cellular environment and is a potential target for the treatment and prevention of neurological disorders, we have systematically reviewed important aspects of endothelial cell death with a particular focus on stroke. After screening 2876 publications published between January 1, 2010 and August 7, 2019, we identified 154 records to be included. We found that endothelial cell death occurs rapidly as well as later after the onset of stroke conditions. Among the different cell death mechanisms, apoptosis was the most widely investigated (92 records), followed by autophagy (20 records), while other, more recently defined mechanisms received less attention, such as lysosome-dependent cell death (2 records) and necroptosis (2 records). We also discuss the differential vulnerability of brain cells to injury after stroke and the role of endothelial cell death in the no-reflow phenomenon with a special focus on the microvasculature. Further investigation of the different cell death mechanisms using novel tools and biomarkers will greatly enhance our understanding of endothelial cell death. For this task, at least two markers/criteria are desirable to determine cell death subroutines according to the recommendations of the Nomenclature Committee on Cell Death.

Combining Human Umbilical Cord Blood Cells With Erythropoietin Enhances Angiogenesis/Neurogenesis and Behavioral Recovery After Stroke

Disruption of blood flow in the brain induces stroke, the leading cause of death and disability worldwide. However, so far the therapeutic options are limited. Thus, the therapeutic efficacy of cell-based approaches has been investigated to develop a potential strategy to overcome stroke-induced disability. Human umbilical cord blood cells (hUCBCs) and erythropoietin (EPO) both have angiogenic and neurogenic properties in the injured brain, and their combined administration may exert synergistic effects during neurological recovery following stroke. We investigated the therapeutic potential of hUCBC and EPO combination treatment by comparing its efficacy to those of hUCBC and EPO alone. Adult male Sprague-Dawley rats underwent transient middle cerebral artery occlusion (MCAO). Experimental groups were as follows: saline (injected once with saline 7 d after MCAO); hUCBC (1.2 × 10⁷ total nucleated cells, injected once via the tail vein 7 d after MCAO); EPO (500 IU/kg, injected intraperitoneally for five consecutive days from 7 d after MCAO); and combination of hUCBC and EPO (hUCBC+EPO). Behavioral measures (Modified Neurological Severity Score [mNSS] and cylinder test) were recorded to assess neurological outcomes. Four weeks after MCAO, brains were harvested to analyze the status of neurogenesis and angiogenesis. In vitro assays were also conducted using neural stem and endothelial cells in the oxygen-glucose deprivation condition. Performance on the mNSS and cylinder test showed the most improvement in the hUCBC+EPO group, while hUCBC- and EPO-alone treatments showed superior outcomes relative to the saline group. Neurogenesis and angiogenesis in the cortical region was the most enhanced in the hUCBC+EPO group, while the findings in the hUCBC and EPO treatment alone groups were better than those in the saline group. Astrogliosis in the brain tissue was reduced by hUCBC and EPO treatment. The reduction was largest in the hUCBC+EPO group. These results were consistent with in vitro assessments that showed the strongest neurogenic and angiogenic effect with hUCBC+EPO treatment. This study demonstrates that combination therapy is more effective than single therapy with either hUCBC or EPO for neurological recovery from subacute stroke. The common pathway underlying hUCBC and EPO treatment requires further study.

Oxygen Management at the Microscale: A Functional Biochip Material with Long-Lasting and Tunable Oxygen Scavenging Properties for Cell Culture Applications

Oxygen plays a pivotal role in cellular homeostasis, and its partial pressure determines cellular function and fate. Consequently, the ability to control oxygen tension is a critical parameter for recreating physiologically relevant in vitro culture conditions for mammalian cells and microorganisms. Despite its importance, most microdevices and organ-on-a-chip systems to date overlook oxygen gradient parameters because controlling oxygen often requires bulky and expensive external instrumental setups. To overcome this limitation, we have adapted an off-stoichiometric thiol-ene-epoxy polymer to efficiently remove dissolved oxygen to below 1 hPa and also integrated this modified polymer into a functional biochip material. The relevance of using an oxygen scavenging material in microfluidics is that it makes it feasible to readily control oxygen depletion rates inside the biochip by simply changing the surface-to-volume aspect ratio of the microfluidic channel network as well as by changing the temperature and curing times during the fabrication process.

Epidermal growth factor treatment has protective effects on the integrity of the blood-brain barrier against cerebral ischemia injury in bEnd3 cells

Tight junctions (TJs) serve an important role in maintaining the integrity of the blood-brain barrier (BBB), while neurological disorders, including ischemic stroke, induce TJ disruption and increase BBB permeability; results include edema formation and hemorrhage transformation. Cerebral endothelium protection presents a promising approach in ischemic stroke therapy. In the current study, protective effects of the epidermal growth factor (EGF) on ischemia-induced disruption of BBB integrity were examined using an oxygen-glucose deprivation (OGD) model in bEnd3 cells. Expression levels of claudin-5 and TJ protein-1 (ZO-1) were determined by reverse transcription-quantitative polymerase chain reaction and western blot analysis. Cell viability was evaluated by cell counting kit-8 assay and the endothelial permeability of Lucifer yellow (LY) was assessed using Transwell assays. The results revealed that post-ischemia administration of EGF (250 ng/ml) significantly attenuated the decrease in mRNA (P<0.05) and protein (P<0.01) expression levels of claudin-5 and ZO-1, and the increase in endothelial permeability of LY (P<0.05) induced by 4 h OGD exposure followed by 24 h reoxygenation. In addition, EGF did not significant affect cell viability. The current study suggested a potential of EGF to improve BBB integrity against ischemic injury by upregulating the expression of TJ proteins and reducing endothelial permeability.

MALAT1 lncRNA Induces Autophagy and Protects Brain Microvascular Endothelial Cells Against Oxygen-Glucose Deprivation by Binding to miR-200c-3p and Upregulating SIRT1 Expression

There is growing evidence that long noncoding RNAs (lncRNAs) play important roles in various biological processes. Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is one of the most highly upregulated lncRNAs in cerebral ischemia. However, the molecular mechanism of MALAT1 during cerebral ischemia is still unclear. This experiment is intended to investigate the role of MALAT1 in cerebral ischemia and its relationship with autophagy. Oxygen-glucose deprivation (OGD) in brain microvascular endothelial cells (BMECs) was used to mimic ischemic-like conditions in vitro. Real-time PCR, MTT, LDH assay and western blot were used to evaluate the levels of MALAT1, miR-200c-3p, SIRT1, cell survival and proteins. We found that the expression of MALAT1 and LC3BII were upregulated and p62 was downregulated by OGD. Inhibition of MALAT1 attenuated the autophagy activation and promoted cell death. We further revealed that MALAT1 downregulated the expression of miR-200c-3p by directly binding to miR-200c-3p. Furthermore, miR-200c-3p inhibited the autophagy and survival in BMECs by binding to 3'UTR of SIRT1, whereas MALAT1 overturned the inhibitory effect of miR-200c-3p. In conclusion, our study illuminated a novel Malat1-miR-200c-3p-SIRT1 pathway in the regulation of autophagy, in which, MALAT1 activates autophagy and promotes cell survival by binding to miR-200c-3p and upregulating SIRT1 expression.

Sphingosine-1-Phosphate Receptor 1 Activation Enhances Leptomeningeal Collateral Development and Improves Outcome after Stroke in Mice

BACKGROUND

Development of collateral circulation after acute ischemic stroke is triggered by shear stress that occurs in pre-existing arterioles. Recently, sphingosine-1-phosphate receptor 1 (S1P1) on endothelial cells was reported to sense shear stress and transduce its signaling pathways.

METHODS

BALB/c mice (n = 118) were subjected to permanent middle cerebral artery occlusion (pMCAO) or sham operation. We investigated the effect of an S1P1-selective agonist SEW2871 on leptomeningeal collateral arteries and neurological outcome after pMCAO.

RESULTS

Immunohistochemistry showed that without treatment, the expression of S1P1 on endothelial cells of leptomeningeal arteries and capillaries increased early after pMCAO, peaking at 6 hours, whereas a significant increase in the expression of S1P1 in neurons was seen from 24 hours later. After intraperitoneal administration of SEW2871 for 7 days after pMCAO, the number of leptomeningeal collateral arteries was significantly increased, cerebral blood flow improved, infarct volume was decreased, and neurological outcome improved compared with the controls. Significantly increased phosphorylation of endothelial nitric oxide synthase (eNOS) as early as 6 hours after pMCAO and higher expression of tight junction proteins at postoperative day 3 were observed with SEW2871 treatment as assessed by Western blot. Daily administration of SEW2871 also increased capillary density in peri-infarct regions and promoted monocyte/macrophage mobilization to the surface of ischemic cortex at 7 days after pMCAO.

CONCLUSIONS

An S1P1-selective agonist enhanced leptomeningeal collateral circulation via eNOS phosphorylation and promoted postischemic angiogenesis with reinforced blood-brain barrier integrity in a mouse model of acute ischemic stroke, leading to smaller infarct volume and better neurological outcome.

Early oxygen therapy does not protect the brain from vasogenic edema following acute ischemic stroke in adult male rats

Brain edema aggravates primary brain injury and increases its mortality rate after ischemic stroke. It is believed that normobaric oxygen therapy (NBO) may produce neuroprotective effects against ischemic stroke; however, reports have been controversial, and its effects on vasogenic brain edema as a major complication of brain ischemia have not been clarified. The present study investigates the effects of NBO on cerebral edema and blood – brain barrier integrity using rat model of ischemic stroke. Transient focal cerebral ischemia was induced in adult male Sprague-Dawley rats by left middle cerebral artery occlusion (MCAO) for 90 min followed by 24 h reperfusion. Early NBO supplementation was started 15 min after MCAO and continued for 90 min. The results of the present study show that early oxygen therapy following acute ischemic stroke does not reduce vasogenic brain edema, nor does it protect against oxidative stress-induced BBB destruction. Additionally, cerebral edema formation occurs in conjunction with an increased mortality rate, serious brain injury, and impairment of brain antioxidant power. These findings suggest that further experimental studies should be carried out to clarify the beneficial effects and potential side effects of early oxygen therapy in acute ischemic stroke before its clinical use.