TY - JOUR A1 - Kraft, Peter A1 - De Meyer, Simon F. A1 - Kleinschnitz, Christoph T1 - Next-Generation Antithrombotics in Ischemic Stroke: Preclinical Perspective on ‘Bleeding-Free Antithrombosis’ JF - Journal of Cerebral Blood Flow and Metabolism N2 - The present antithrombotic drugs used to treat or prevent ischemic stroke have significant limitations: either they show only moderate efficacy (platelet inhibitors), or they significantly increase the risk for hemorrhages (thrombolytics, anticoagulants). Although most strokes are caused by thrombotic or embolic vessel occlusions, the pathophysiological role of platelets and coagulation is largely unclear. The introduction of novel transgenic mouse models and specific coagulation inhibitors facilitated a detailed analysis of molecular pathways mediating thrombus formation in models of acute ischemic stroke. Prevention of early platelet adhesion to the damaged vessel wall by blocking platelet surface receptors glycoprotein Ib alpha (GPIbα) or glycoprotein VI (GPVI) protects from stroke without provoking bleeding complications. In addition, downstream signaling of GPIbα and GPVI has a key role in platelet calcium homeostasis and activation. Finally, the intrinsic coagulation cascade, activated by coagulation factor XII (FXII), has only recently been identified as another important mediator of thrombosis in cerebrovascular disease, thereby disproving established concepts. This review summarizes the latest insights into the pathophysiology of thrombus formation in the ischemic brain. Potential clinical merits of novel platelet inhibitors and anticoagulants as powerful and safe tools to combat ischemic stroke are discussed. KW - von Willebrand factor KW - platelets KW - glycoprotein Ib KW - FXII KW - coagulation KW - Stim Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-126538 VL - 32 IS - 10 ER - TY - JOUR A1 - Boltze, Johannes A1 - Kleinschnitz, Christoph A1 - Reymann, Klaus G. A1 - Reiser, Georg A1 - Wagner, Daniel-Christoph A1 - Kranz, Alexander A1 - Michalski, Dominik T1 - Neurovascular pathophysiology in cerebral ischemia, dementia and the ageing brain – current trends in basic, translational and clinical research JF - Experimental & Translational Stroke Medicine N2 - The 7th International Symposium on Neuroprotection and Neurorepair was held from May 2nd to May 5th, 2012 in Potsdam, Germany. The symposium, which directly continues the successful Magdeburg meeting series, attracted over 330 colleagues from 29 countries to discuss recent findings and advances in the field. The focus of the 2012 symposium was widened from stroke and traumatic brain injury to neurodegenerative diseases, notably dementia, and more generally the ageing brain. Thereby, emphasis was given on neurovascular aspects of neurodegeneration and stroke including the blood–brain barrier, recent findings regarding the pathomechanism of Alzheimer’s disease, and brain imaging approaches. In addition, neurobiochemical aspects of neuroprotection, the role of astrogliosis, the clinical progress of cell-based approaches as well as translational hurdles and opportunities were discussed in-depth. This review summarizes some of the most stimulating discussions and reports from the meeting. KW - translational research KW - small vessel disease KW - Alzheimer’s disease KW - cerebral ischemia KW - neurorepair KW - neuroprotection KW - vascular dementia KW - mitochondria KW - astrogliosis KW - in vivo imaging Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-126679 VL - 4 IS - 14 ER - TY - JOUR A1 - Minnerup, Jens A1 - Sutherland, Brad A. A1 - Buchan, Alastair M. A1 - Kleinschnitz, Christoph T1 - Neuroprotection for Stroke: Current Status and Future Perspectives JF - International Journal of Molecular Science N2 - Neuroprotection aims to prevent salvageable neurons from dying. Despite showing efficacy in experimental stroke studies, the concept of neuroprotection has failed in clinical trials. Reasons for the translational difficulties include a lack of methodological agreement between preclinical and clinical studies and the heterogeneity of stroke in humans compared to homogeneous strokes in animal models. Even when the international recommendations for preclinical stroke research, the Stroke Academic Industry Roundtable (STAIR) criteria, were followed, we have still seen limited success in the clinic, examples being NXY-059 and haematopoietic growth factors which fulfilled nearly all the STAIR criteria. However, there are a number of neuroprotective treatments under investigation in clinical trials such as hypothermia and ebselen. Moreover, promising neuroprotective treatments based on a deeper understanding of the complex pathophysiology of ischemic stroke such as inhibitors of NADPH oxidases and PSD-95 are currently evaluated in preclinical studies. Further concepts to improve translation include the investigation of neuroprotectants in multicenter preclinical Phase III-type studies, improved animal models, and close alignment between clinical trial and preclinical methodologies. Future successful translation will require both new concepts for preclinical testing and innovative approaches based on mechanistic insights into the ischemic cascade. KW - free radical scavenger KW - ischemic cascade KW - acute ischemic stroke KW - trial KW - focal cerebral-ischemia KW - interleukin-1 receptor antagonist KW - colony-stimulating factor KW - tissue-plasminogen activator KW - traumatic brain injury KW - placebo-controlled KW - alias pilot trial KW - damage cool aid KW - neuroprotection KW - ischemic stroke KW - translation KW - STAIR Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-134730 VL - 13 IS - 9 ER - TY - JOUR A1 - Rolfes, Leoni A1 - Ruck, Tobias A1 - David, Christina A1 - Mencl, Stine A1 - Bock, Stefanie A1 - Schmidt, Mariella A1 - Strecker, Jan-Kolja A1 - Pfeuffer, Steffen A1 - Mecklenbeck, Andreas-Schulte A1 - Gross, Catharina A1 - Gliem, Michael A1 - Minnerup, Jens A1 - Schuhmann, Michael K. A1 - Kleinschnitz, Christoph A1 - Meuth, Sven G. T1 - Natural Killer Cells Are Present in Rag1\(^{−/−}\) Mice and Promote Tissue Damage During the Acute Phase of Ischemic Stroke JF - Translational Stroke Research N2 - Rag1\(^{−/−}\) mice, lacking functional B and T cells, have been extensively used as an adoptive transfer model to evaluate neuroinflammation in stroke research. However, it remains unknown whether natural killer (NK) cell development and functions are altered in Rag1\(^{−/−}\) mice as well. This connection has been rarely discussed in previous studies but might have important implications for data interpretation. In contrast, the NOD-Rag1\(^{null}\)IL2rg\(^{null}\) (NRG) mouse model is devoid of NK cells and might therefore eliminate this potential shortcoming. Here, we compare immune-cell frequencies as well as phenotype and effector functions of NK cells in Rag1\(^{−/−}\) and wildtype (WT) mice using flow cytometry and functional in vitro assays. Further, we investigate the effect of Rag1\(^{−/−}\) NK cells in the transient middle cerebral artery occlusion (tMCAO) model using antibody-mediated depletion of NK cells and adoptive transfer to NRG mice in vivo. NK cells in Rag1\(^{−/−}\) were comparable in number and function to those in WT mice. Rag1\(^{−/−}\) mice treated with an anti-NK1.1 antibody developed significantly smaller infarctions and improved behavioral scores. Correspondingly, NRG mice supplemented with NK cells were more susceptible to tMCAO, developing infarctions and neurological deficits similar to Rag1−/− controls. Our results indicate that NK cells from Rag1−/− mice are fully functional and should therefore be considered in the interpretation of immune-cell transfer models in experimental stroke. Fortunately, we identified the NRG mice, as a potentially better-suited transfer model to characterize individual cell subset-mediated neuroinflammation in stroke. KW - infarction KW - middle cerebral artery occlusion KW - animal model KW - inflammation KW - natural killer cells Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-308924 SN - 1868-4483 SN - 1868-601X VL - 13 IS - 1 ER - TY - JOUR A1 - Ehling, Petra A1 - Göb, Eva A1 - Bittner, Stefan A1 - Budde, Thomas A1 - Ludwig, Andreas A1 - Kleinschnitz, Christoph A1 - Meuth, Sven G. T1 - Ischemia-induced cell depolarization: does the hyperpolarization-activated cation channel HCN2 affect the outcome after stroke in mice? JF - Experimental & Translational Stroke Medicine N2 - Background Brain ischemia is known to include neuronal cell death and persisting neurological deficits. A lack of oxygen and glucose are considered to be key mediators of ischemic neurodegeneration while the exact mechanisms are yet unclear. In former studies the expression of two different two-pore domain potassium \((K_{2P})\) channels (TASK1, TREK1) were shown to ameliorate neuronal damage due to cerebral ischemia. In neurons, TASK channels carrying hyperpolarizing \(K^+\) leak currents, and the pacemaker channel HCN2, carrying depolarizing \(I_h\), stabilize the membrane potential by a mutual functional interaction. It is assumed that this ionic interplay between TASK and HCN2 channels enhances the resistance of neurons to insults accompanied by extracellular pH shifts. Methods In C57Bl/6 (wildtype, WT), \(hcn2^{+/+}\) and \(hcn2^{-/-}\) mice we used an in vivo model of cerebral ischemia (transient middle cerebral artery occlusion (tMCAO)) to depict a functional impact of HCN2 in stroke formation. Subsequent analyses comprise behavioural tests and hcn2 gene expression assays. Results After 60 min of tMCAO induction in WT mice, we collected tissue samples at 6, 12, and 24 h after reperfusion. In the infarcted neocortex, hcn2 expression analyses revealed a nominal peak of hcn2 expression 6 h after reperfusion with a tendency towards lower expression levels with longer reperfusion times. Hcn2 gene expression levels in infarcted basal ganglia did not change after 6 h and 12 h. Only at 24 h after reperfusion, hcn2 expression significantly decreases by ~55%. However, 30 min of tMCAO in hcn2-/- as well as hcn2+/+ littermates induced similar infarct volumes. Behavioural tests for global neurological function (Bederson score) and motor function/coordination (grip test) were performed at day 1 after surgery. Again, we found no differences between the groups. Conclusions Here, we hypothesized that the absence of HCN2, an important functional counter player of TASK channels, affects neuronal survival during stroke-induced tissue damage. However, together with a former study on TASK3 these results implicate that both TASK3 and HCN2 which were supposed to be neuroprotective due to their pH-dependency, do not influence ischemic neurodegeneration during stroke in the tMCAO model. KW - ischemia Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-131887 VL - 5 IS - 16 ER - TY - JOUR A1 - Ehling, Petra A1 - Göb, Eva A1 - Bittner, Stefan A1 - Budde, Thomas A1 - Ludwig, Andreas A1 - Kleinschnitz, Christoph A1 - Meuth, Sven G. T1 - Ischemia-induced cell depolarization: does the hyperpolarization-activated cation channel HCN2 affect the outcome after stroke in mice? JF - Experimental & Translational Stroke Medicine N2 - Background Brain ischemia is known to include neuronal cell death and persisting neurological deficits. A lack of oxygen and glucose are considered to be key mediators of ischemic neurodegeneration while the exact mechanisms are yet unclear. In former studies the expression of two different two-pore domain potassium \((K_{2P})\) channels (TASK1, TREK1) were shown to ameliorate neuronal damage due to cerebral ischemia. In neurons, TASK channels carrying hyperpolarizing \(K^+\) leak currents, and the pacemaker channel HCN2, carrying depolarizing Ih, stabilize the membrane potential by a mutual functional interaction. It is assumed that this ionic interplay between TASK and HCN2 channels enhances the resistance of neurons to insults accompanied by extracellular pH shifts. Methods In C57Bl/6 (wildtype, WT), \(hcn2^{+/+}\) and \(hcn2^{-/-}\) mice we used an in vivo model of cerebral ischemia (transient middle cerebral artery occlusion (tMCAO)) to depict a functional impact of HCN2 in stroke formation. Subsequent analyses comprise behavioural tests and hcn2 gene expression assays. Results After 60 min of tMCAO induction in WT mice, we collected tissue samples at 6, 12, and 24 h after reperfusion. In the infarcted neocortex, hcn2 expression analyses revealed a nominal peak of hcn2 expression 6 h after reperfusion with a tendency towards lower expression levels with longer reperfusion times. Hcn2 gene expression levels in infarcted basal ganglia did not change after 6 h and 12 h. Only at 24 h after reperfusion, hcn2 expression significantly decreases by ~55%. However, 30 min of tMCAO in hcn2-/- as well as hcn2+/+ littermates induced similar infarct volumes. Behavioural tests for global neurological function (Bederson score) and motor function/coordination (grip test) were performed at day 1 after surgery. Again, we found no differences between the groups. Conclusions Here, we hypothesized that the absence of HCN2, an important functional counter player of TASK channels, affects neuronal survival during stroke-induced tissue damage. However, together with a former study on TASK3 these results implicate that both TASK3 and HCN2 which were supposed to be neuroprotective due to their pH-dependency, do not influence ischemic neurodegeneration during stroke in the tMCAO model. KW - neurology Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-129240 VL - 5 IS - 16 ER - TY - JOUR A1 - Niklass, Solveig A1 - Stoyanov, Stoyan A1 - Garz, Cornelia A1 - Bueche, Celine Z. A1 - Mencl, Stine A1 - Reymann, Klaus A1 - Heinze, Hans-Jochen A1 - Carare, Roxana O. A1 - Kleinschnitz, Christoph A1 - Schreiber, Stefanie T1 - Intravital imaging in spontaneously hypertensive stroke-prone rats-a pilot study JF - Experimental & Translational Stroke Medicine N2 - Background There is growing evidence that endothelial failure and subsequent blood brain barrier (BBB) breakdown initiate cerebral small vessel disease (CSVD) pathology. In spontaneously hypertensive stroke-prone rats (SHRSP) endothelial damage is indicated by intraluminal accumulations of erythrocytes (erythrocyte thrombi) that are not observed with current magnetic resonance imaging techniques. Two-photon microscopy (2 PM) offers the potential for real-time direct detection of the small vasculature. Thus, within this pilot study we investigated the sensitivity of 2 PM to detect erythrocyte thrombi expressing initiating CSVD phenomena in vivo. Methods Eight SHRSP and 13 Wistar controls were used for in vivo imaging and subsequent histology with haematoxylin-eosin (HE). For 2 PM, cerebral blood vessels were labeled by fluorescent Dextran (70 kDa) applied intraorbitally. The correlation between vascular erythrocyte thrombi observed by 2 PM and HE-staining was assessed. Artificial surgical damage and parenchymal Dextran distribution were analyzed postmortem. Results Dextran was distributed within the small vessel walls and co-localized with IgG. Artificial surgical damage was comparable between SHRSP and Wistar controls and mainly affected the small vasculature. In fewer than 20% of animals there was correlation between erythrocyte thrombi as observed with 2 PM and histologically with HE. Conclusions Contrary to our initial expectations, there was little agreement between intravital 2 PM imaging and histology for the detection of erythrocyte thrombi. Two-photon microscopy is a valuable technique that complements but does not replace the value of conventional histology. KW - SHRSP KW - Intravital imaging KW - 2 PM KW - CSVD Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-121353 VL - 6 ER - TY - JOUR A1 - Fluri, Felix A1 - Heinen, Florian A1 - Kleinschnitz, Christoph T1 - Intravenous Thrombolysis in a Stroke Patient Receiving Rivaroxaban JF - Cerebrovascular Disease Extra N2 - No abstract available. KW - anticoagulants KW - intravenous thrombolysis KW - acute ischemic stroke Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-128816 VL - 2013 IS - 3 ER - TY - JOUR A1 - Kleinschnitz, Christoph A1 - Niemczyk, Gabriele A1 - Rehberg-Weber, Karin A1 - Wernsdörfer, Colin T1 - Interferon Beta-1a (AVONEX®) as a treatment option for untreated patients with multiple sclerosis (AXIOM): a prospective, observational study JF - International Journal of Molecular Sciences N2 - The efficacy and safety of first-line disease-modifying therapies (DMT) for relapsing-remitting multiple sclerosis (RRMS) has been demonstrated in pivotal, randomized trials, but these studies do not reflect the routine care setting where treatment gaps or switches are common. The Avonex as Treatment Option for Untreated MS Patients (AXIOM) trial assessed the efficacy of newly-initiated intramuscular interferon beta-1a (IM IFNb-1a) after a treatment-free interval, with particular consideration of the previous course of disease and therapy. The AXIOM trial was an open, 12-month, observational, non-interventional study with a retrospective and a prospective part conducted in Germany. RRMS patients with a treatment-free interval of at least three months were included and treated with IFNb-1a for up to 12 months. Relapse rate, disability progression, injection-related parameters and quality of life observed during the prospective part were compared with retrospectively-collected data. Two hundred and thirty five RRMS patients participated in AXIOM. The mean relapse rate decreased from 1.1 in the three months before baseline to 0.2 per quarter during the twelve-month observational period; the Multiple Sclerosis Functional Composite score improved during twelve months of IM IFNb-1a treatment, while the Expanded Disability Status Scale score did not change over the course of this study. Compared to previous DMTs (IM IFNb-1a, subcutaneous IFNb-1a (SC IFNb-1a), SC IFNb-1b, glatiramer acetate), the patients experienced less injection site reactions and flu-like symptoms, with a stated improved quality of life. IM IFNb-1a was effective and well accepted in RRMS patients with no or discontinued previous therapy. These results from the routine care setting may inform optimization of DMT treatment in RRMS, but need confirmation in further studies. KW - subcutaneous injection KW - therapy KW - trial KW - relapsing-remitting multiple sclerosis KW - injection site reactions; KW - efficacy KW - quality of life KW - disease-modifying therapy Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-148487 VL - 16 ER - TY - JOUR A1 - Weise, Gesa A1 - Basse-Lüsebrink, Thomas C. A1 - Kleinschnitz, Christoph A1 - Kampf, Thomas A1 - Jakob, Peter M. A1 - Stoll, Guido T1 - In Vivo Imaging of Stepwise Vessel Occlusion in Cerebral Photothrombosis of Mice by \(^{19}\)F MRI JF - PLoS One N2 - Background \(^{19}\)F magnetic resonance imaging (MRI) was recently introduced as a promising technique for in vivo cell tracking. In the present study we compared \(^{19}\)F MRI with iron-enhanced MRI in mice with photothrombosis (PT) at 7 Tesla. PT represents a model of focal cerebral ischemia exhibiting acute vessel occlusion and delayed neuroinflammation. Methods/Principal Findings Perfluorocarbons (PFC) or superparamagnetic iron oxide particles (SPIO) were injected intravenously at different time points after photothrombotic infarction. While administration of PFC directly after PT induction led to a strong \(^{19}\)F signal throughout the entire lesion, two hours delayed application resulted in a rim-like \(^{19}\)F signal at the outer edge of the lesion. These findings closely resembled the distribution of signal loss on T2-weighted MRI seen after SPIO injection reflecting intravascular accumulation of iron particles trapped in vessel thrombi as confirmed histologically. By sequential administration of two chemically shifted PFC compounds 0 and 2 hours after illumination the different spatial distribution of the \(^{19}\)F markers (infarct core/rim) could be visualized in the same animal. When PFC were applied at day 6 the fluorine marker was only detected after long acquisition times ex vivo. SPIO-enhanced MRI showed slight signal loss in vivo which was much more prominent ex vivo indicative for neuroinflammation at this late lesion stage. Conclusion Our study shows that vessel occlusion can be followed in vivo by \(^{19}\)F and SPIO-enhanced high-field MRI while in vivo imaging of neuroinflammation remains challenging. The timing of contrast agent application was the major determinant of the underlying processes depicted by both imaging techniques. Importantly, sequential application of different PFC compounds allowed depiction of ongoing vessel occlusion from the core to the margin of the ischemic lesions in a single MRI measurement. KW - in vivo imaging KW - magnetic resonance imaging KW - macrophages KW - emulsions KW - infarction KW - fluorine KW - prefrontal cortex KW - developmental signaling Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-137792 VL - 6 IS - 12 ER -