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PubMed | Harvard University, Japan National Cardiovascular Center Research Institute, Neuroprotection Research Laboratory and RIKEN
Type: Journal Article | Journal: The Journal of neuroscience : the official journal of the Society for Neuroscience | Year: 2015

Oligodendrocyte precursor cells (OPCs) in the adult brain contribute to white matter homeostasis. After white matter damage, OPCs compensate for oligodendrocyte loss by differentiating into mature oligodendrocytes. However, the underlying mechanisms remain to be fully defined. Here, we test the hypothesis that, during endogenous recovery from white matter ischemic injury, astrocytes support the maturation of OPCs by secreting brain-derived neurotrophic factor (BDNF). For in vitro experiments, cultured primary OPCs and astrocytes were prepared from postnatal day 2 rat cortex. When OPCs were subjected to chemical hypoxic stress by exposing them to sublethal CoCl2 for 7 d, in vitro OPC differentiation into oligodendrocytes was significantly suppressed. Conditioned medium from astrocytes (astro-medium) restored the process of OPC maturation even under the stressed conditions. When astro-medium was filtered with TrkB-Fc to remove BDNF, the BDNF-deficient astro-medium no longer supported OPC maturation. For in vivo experiments, we analyzed a transgenic mouse line (GFAP(cre)/BDNF(wt/fl)) in which BDNF expression is downregulated specifically in GFAP(+) astrocytes. Both wild-type (GFAP(wt)/BDNF(wt/fl) mice) and transgenic mice were subjected to prolonged cerebral hypoperfusion by bilateral common carotid artery stenosis. As expected, compared with wild-type mice, the transgenic mice exhibited a lower number of newly generated oligodendrocytes and larger white matter damage. Together, these findings demonstrate that, during endogenous recovery from white matter damage, astrocytes may promote oligodendrogenesis by secreting BDNF.The repair of white matter after brain injury and neurodegeneration remains a tremendous hurdle for a wide spectrum of CNS disorders. One potentially important opportunity may reside in the response of residual oligodendrocyte precursor cells (OPCs). OPCs may serve as a back-up for generating mature oligodendrocytes in damaged white matter. However, the underlying mechanisms are still mostly unknown. Here, we use a combination of cell biology and an animal model to report a new pathway in which astrocyte-derived BDNF supports oligodendrogenesis and regeneration after white matter damage. These findings provide new mechanistic insight into white matter physiology and pathophysiology, which would be broadly and clinically applicable to CNS disease.


Lauer A.,Goethe University Frankfurt | Lauer A.,Neuroprotection Research Laboratory | Cianchetti F.A.,Cornell University | Van Cott E.M.,Harvard University | And 10 more authors.
Circulation | Year: 2011

Background-: The direct thrombin inhibitor dabigatran etexilate (DE) may constitute a future replacement of vitamin K antagonists for long-term anticoagulation. Whereas warfarin pretreatment is associated with greater hematoma expansion after intracerebral hemorrhage (ICH), it remains unclear what effect direct thrombin inhibitors would have. Using different experimental models of ICH, this study compared hematoma volume among DE-treated mice, warfarin-treated mice, and controls. Methods and Results-: CD-1 mice were fed with DE or warfarin. Sham-treated mice served as controls. At the time point of ICH induction, DE mice revealed an increased activated partial thromboplastin time compared with controls (mean±SD 46.1±5.0 versus 18.0±1.5 seconds; P=0.022), whereas warfarin pretreatment resulted in a prothrombin time prolongation (51.4±17.9 versus 10.4±0.3 seconds; P<0.001). Twenty-four hours after collagenase-induced ICH formation, hematoma volume was 3.8±2.9 μL in controls, 4.8±2.7 μL in DE mice, and 14.5±11.8 μL in warfarin mice (n=16; Welch ANOVA between-group differences P=0.007; posthoc analysis with the Dunnett method: DE versus controls, P=0.899; warfarin versus controls, P<0.001; DE versus warfarin, P=0.001). In addition, a model of laser-induced cerebral microhemorrhage was applied, and the distances that red blood cells and blood plasma were pushed into the brain were quantified. Warfarin mice showed enlarged red blood cell and blood plasma diameters compared to controls, but no difference was found between DE mice and controls. Conclusions-: In contrast with warfarin, pretreatment with DE did not increase hematoma volume in 2 different experimental models of ICH. In terms of safety, this observation may represent a potential advantage of anticoagulation with DE over warfarin. © 2011 American Heart Association, Inc.


Xing C.,Neuroprotection Research Laboratory | Levchenko T.,Northeastern University | Guo S.,Neuroprotection Research Laboratory | Stins M.,Johns Hopkins University | And 2 more authors.
Journal of Cerebral Blood Flow and Metabolism | Year: 2012

Minocycline has been proposed as a way to blunt neurovascular injury from matrix metalloproteinases (MMPs) during stroke. However, recent clinical trials suggest that high levels of minocycline may have deleterious side-effects. Here, we showed that very high minocycline concentrations damage endothelial cells via calpain/caspase pathways. To alleviate this potential cytotoxicity, we encapsulated minocycline in liposomes. Low concentrations of minocycline could not reduce tumor necrosis factor α (TNFα)-induced MMP-9 release from endothelial cells. But low concentrations of minocycline-loaded liposomes significantly reduced TNFα-induced MMP-9 release. This study provides proof-of-concept that liposomes may be used to deliver lower levels of minocycline for targeting MMPs in cerebral endothelium. © 2012 ISCBFM All rights reserved.


Cao J.,Neuroprotection Research Laboratory | Guo S.,Neuroprotection Research Laboratory | Arai K.,Neuroprotection Research Laboratory | Lo E.H.,Neuroprotection Research Laboratory | Ning M.,Neuroprotection Research Laboratory
Methods in Molecular Biology | Year: 2013

Successful innovative proteomic analysis is highly dependent on molecular biology techniques at the surveying and validation stage. This is because mass spectrometry (MS) analyses of complex samples are limited by their dynamic range for detection-so careful front-end sample preparation, fractionation, and enrichment are crucial tofind biologically relevant signals in an extremely complex extracellular environment. Here, we share a very useful and simple front-end surveying methodology-lectin blotting-for proteomic analysis of glycosylation patterns-the most abundant posttranslational modification in extracellular signaling. Lectin blotting is an effective biochemical technique based on lectin-glycan interactions. It is used to detect and characterize carbohydrate epitopes on protein or lipids. Depending on lectin patterns, specific lectins can be used as tags to enrich glycoproteins for further proteomic analysis. In this method, proteins or lipids are resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and transferred electrophoretically to adsorbent membranes such as nitrocellulose or polyvinylidene di fl uoride (PVDF) membranefirst. Transferred proteins or lipids are subsequently analyzed by probes including labeled lectins. In this chapter, we provide a detailed methodology of lectin blotting for glycol-proteomic analysis. This method is robust and can be used for complex cell lysates, conditioned media, or human samples to monitor glycosylation pattern following extracellular signal transduction. Here, we will use patient plasma samples post hypothermic therapy-an extremely complex medium-as a tool to describe in detail the technique of lectin blotting for proteomic analysis. © Springer Science+Business Media New York 2013.


Shindo A.,Neuroprotection Research Laboratory | Shindo A.,Mie University | Maki T.,Neuroprotection Research Laboratory | Mandeville E.T.,Neuroprotection Research Laboratory | And 13 more authors.
Stroke | Year: 2016

Background and Purpose-Pentraxin 3 (PTX3) is released on inflammatory responses in many organs. However, roles of PTX3 in brain are still mostly unknown. Here we asked whether and how PTX3 contributes to blood-brain barrier dysfunction during the acute phase of ischemic stroke. Methods-In vivo, spontaneously hypertensive rats were subjected to focal cerebral ischemia by transient middle cerebral artery occlusion. At day 3, brains were analyzed to evaluate the cellular origin of PTX3 expression. Correlations with blood-brain barrier breakdown were assessed by IgG staining. In vitro, rat primary astrocytes and rat brain endothelial RBE.4 cells were cultured to study the role of astrocyte-derived PTX3 on vascular endothelial growth factor-mediated endothelial permeability. Results-During the acute phase of stroke, reactive astrocytes in the peri-infarct area expressed PTX3. There was negative correlation between gradients of IgG leakage and PTX3-positive astrocytes. Cell culture experiments showed that astrocyte-conditioned media increased levels of tight junction proteins and reduced endothelial permeability under normal conditions. Removing PTX3 from astrocyte-conditioned media by immunoprecipitation increased endothelial permeability. PTX3 strongly bound vascular endothelial growth factor in vitro and was able to decrease vascular endothelial growth factor-induced endothelial permeability. Conclusions-Astrocytes in peri-infarct areas upregulate PTX3, which may support blood-brain barrier integrity by regulating vascular endothelial growth factor-related mechanisms. This response in astrocytes may comprise a compensatory mechanism for maintaining blood-brain barrier function after ischemic stroke. © 2016 American Heart Association, Inc.

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