Infarcted Brain Tissue Research Articles

Mifepristone alleviates cerebral ischemia-reperfusion injury in rats by stimulating PPAR γ.

To investigate the changes of peroxisome proliferator-activated receptor gamma (PPAR γ) in focal cerebral ischemia-reperfusion injury, and to explore the effect and mechanism of mifepristone on the cerebral ischemia-reperfusion injury. Male Sprague-Dawley (SD) rats were selected, and the middle cerebral artery occlusion and reperfusion (MCAO/R) rat model was constructed using the longa's suture-occluded method. The sham operation group was not inserted with occlusion sutures. All experimental rats were divided into four groups: the sham operation group (SHA group), the MCAO/R model group (MCR group), the mifepristone intervention group (MIF group) (3 mg/kg, intragastric administration), and the mifepristone + bisphenol A diglycidyl ether (BADGE) intervention group (MIF+BAD group) [3 mg/kg mifepristone (intragastric administration) + 30 mg/kg BADGE (intraperitoneal injection)]. The long's scoring method (5 grades) was applied for scoring after reperfusion, at the time when the animals woke up, and at 48 h after awaking before execution, respectively. 48 h after the model was successfully established, triphenyl tetrazolium chloride (TTC) staining was performed to calculate the volume of cerebral infarction, and Nissl staining was conducted to observe the cranial nerve tissue morphology. Meanwhile, immune-histochemical staining was used to detect PPAR γ. Moreover, the protein expression levels of PPAR γ, tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), interleukin-6 (IL-6), matrix metalloproteinase-2 (MMP-2), MMP-9 and tissue inhibitor of metalloproteinase 1 (TIMP-1) were examined by Western blotting (WB). Mifepristone could significantly enhance the neurological function after cerebral ischemia-reperfusion injury, reduce the volume of cerebral infarction, and improve the morphology of nerve tissues in rats. The expression of PPAR γ in the brain tissues of rats after cerebral ischemia-reperfusion injury markedly declined, whereas mifepristone could remarkably increase the protein expression of PPAR γ. After mifepristone intervention, the protein levels of TNF-α, IL-1β, IL-6, MMP-2, and MMP-9 in the infarcted brain tissues of rats were markedly decreased, while the expression of the TIMP-1 protein was increased. When combined with BADGE, the effect of mifepristone was partially offset. Mifepristone acts as a PPAR γ agonist, and relieves cerebral ischemia-reperfusion injury by restoring the balance between MMPs and TIMPs and inhibiting inflammatory cytokines.

Revealing the Penumbra through Imaging Elemental Markers of Cellular Metabolism in an Ischemic Stroke Model.

Stroke exacts a heavy financial and economic burden, is a leading cause of death, and is the leading cause of long-term disability in those who survive. The penumbra surrounds the ischemic core of the stroke lesion and is composed of cells that are stressed and vulnerable to death, which is due to an altered metabolic, oxidative, and ionic environment within the penumbra. Without therapeutic intervention, many cells within the penumbra will die and become part of the growing infarct, however, there is hope that appropriate therapies may allow potential recovery of cells within this tissue region, or at least slow the rate of cell death, therefore, slowing the spread of the ischemic infarct and minimizing the extent of tissue damage. As such, preserving the penumbra to promote functional brain recovery is a central goal in stroke research. While identification of the ischemic infarct, and the infarct/penumbra boundary is relatively trivial using classical histology and microscopy techniques, accurately assessing the penetration of the penumbra zone into undamaged brain tissue, and evaluating the magnitude of chemical alterations in the penumbra, has long been a major challenge to the stroke research field. In this study, we have used synchrotron-based X-ray fluorescence imaging to visualize the elemental changes in undamaged, penumbra, and infarct brain tissue, following ischemic stroke. We have employed a Gaussian mixture model to cluster tissue areas based on their elemental characteristics. The method separates the core of the infarct from healthy tissue, and also demarcates discrete regions encircling the infarct. These regions of interest can be combined with elemental and metabolic data, as well as with conventional histology. The cell populations defined by clustering provide a reproducible means of visualizing the size and extent of the penumbra at the level of the single cell and provide a critically needed tool to track changes in elemental status and penumbra size.

Role of polymorphonuclear neutrophils in the reperfused ischemic brain: insights from cell-type-specific immunodepletion and fluorescence microscopy studies.

Polymorphonuclear neutrophil granulocytes (PMNs) are part of the early post-ischemic immune response that orchestrates the removal of infarcted brain tissue. PMNs contribute to secondary brain injury in experimental stroke models. In human patients, high PMN-to-lymphocyte ratios in peripheral blood are predictive of poor stroke outcome. Following earlier studies indicating that the cerebral microvasculature forms an efficient barrier that impedes PMN brain entry even under conditions of ischemia, more recent studies combining intravital two-photon microscopy and ex vivo immunohistochemistry unequivocally demonstrated the accumulation of PMNs in the ischemic brain parenchyma. In the meantime, transgenic mouse lines, such as mice expressing Cre-recombinase and the red fluorescent reporter protein tdTomato under the highly granulocyte-specific locus for the gene Ly6G (so-called Catchup mice), have become available that allow study of dynamic interactions of PMNs with brain parenchymal cells. These mice will further help us understand how PMNs promote brain injury and disturb brain remodeling and plasticity.

Association between hemorrhagic transformation after endovascular therapy and poststroke seizures.

Endovascular therapy has recently become standard therapy for select patients with acute ischemic stroke. Infarcted brain tissue may undergo hemorrhagic transformation (HT) after endovascular therapy. We investigated the association between HT and occurrence of poststroke seizures in patients treated with endovascular therapy. Consecutive patients treated with endovascular therapy for acute anterior circulation ischemic stroke were included. HT was assessed with computed tomography/magnetic resonance imaging (CT/MRI) at 24 h after stroke onset. Patients were followed for up to 2 years for seizure occurrence. A total of 205 (57.1% male) patients were analyzed. Median age was 69 years (interquartile range [IQR] 57-78). Among patients with HT, 17.9% (10/56) developed poststroke seizures compared with 4.0% (6/149) among those without HT (hazard ratio [HR] 5.52; 95% confidence interval [CI] 2.00-15.22; P = .001). The association remained significant after adjustment for cortical involvement, baseline National Institutes of Health Stroke Scale score, age and use of intravenous tissue plasminogen activator and clot retrieval (HR 4.85; 95% CI 1.60-14.76; P = .005). In patients who developed seizures within the follow-up period, median time to first seizure was 111 days (IQR 28-369) in patients with HT and 36 days (IQR 0.5-183) in patients without HT. A patient who develops HT following endovascular therapy for acute ischemic stroke had a nearly 5 times higher rate of developing poststroke seizures within 2 years. HT may be used as an imaging biomarker for poststroke seizures.

Fumarate decreases edema volume and improves functional outcome after experimental stroke

BackgroundOxidative stress and inflammation exacerbate tissue damage in the brain after ischemic stroke. Dimethyl-fumarate (DMF) and its metabolite monomethyl-fumarate (MMF) are known to stimulate anti-oxidant pathways and modulate inflammatory responses. Considering these dual effects of fumarates, we examined the effect of MMF treatment after ischemic stroke in mice. MethodsPermanent middle cerebral artery occlusion (pMCAO) was performed using adult, male C57BL/6 mice. Thirty minutes after pMCAO, 20mg/kg MMF was administered intravenously. Outcomes were evaluated 6, 24 and 48h after pMCAO. First, we examined whether a bolus of MMF was capable of changing expression of kelch-like erythroid cell-derived protein with CNC homology-associated protein 1 (Keap1) and nuclear factor erythroid 2-related factor (Nrf)2 in the infarcted brain. Next, we studied the effect of MMF on functional recovery. To explore mechanisms potentially influencing functional changes, we examined infarct volumes, edema formation, the expression of heat shock protein (Hsp)72, hydroxycarboxylic acid receptor 2 (Hcar2), and inducible nitric oxide synthase (iNOS) in the infarcted brain using real-time PCR and Western blotting. Concentrations of a panel of pro- and anti-inflammatory cytokines (IFNγ, IL-1β, IL-2, IL-4, IL-5, IL-6, IL-10, IL-12p70, TNF) were examined in both the infarcted brain tissue and plasma samples 6, 24 and 48h after pMCAO using multiplex electrochemoluminiscence analysis. ResultsAdministration of MMF increased the protein level of Nrf2 6h after pMCAO, and improved functional outcome at 24 and 48h after pMCAO. MMF treatment did not influence infarct size, however reduced edema volume at both 24 and 48h after pMCAO. MMF treatment resulted in increased Hsp72 expression in the brain 6h after pMCAO. Hcar2 mRNA levels increased significantly 24h after pMCAO, but were not different between saline- and MMF-treated mice. MMF treatment also increased the level of the anti-inflammatory cytokine IL-10 in the brain and plasma 6h after pMCAO, and additionally reduced the level of the pro-inflammatory cytokine IL-12p70 in the brain at 24 and 48h after pMCAO. ConclusionsA single intravenous bolus of MMF improved sensory-motor function after ischemic stroke, reduced edema formation, and increased the levels of the neuroprotective protein Hsp72 in the brain. The early increase in IL-10 and reduction in IL-12p70 in the brain combined with changes in systemic cytokine levels may also contribute to the functional recovery after pMCAO.

Effects of interleukin 10 gene modified bone marrow mesenchymal stem cells on expression of inflammatory cytokines and neuronal apoptosis in rats after cerebral ischemia reperfusion injury

To explore the effects of interleukin 10 (IL-10) gene modified bone marrow mesenchymal stem cells (BMSCs) on the expression of inflammatory cytokines and neuronal apoptosis in rats after cerebral ischemia reperfusion injury. BMSCs were cultured by whole bone marrow adherence screening method. The properties of BMSCs were identified by immunocytochemical methods. BMSCs at passage 3 were transfected with recombinant adenovirus IL-10 gene (AdIL-10-BMSCs). The model of middle cerebral artery occlusion was made in 40 adult male Sprague Dawley rats by thread embolism method. The rats were randomly divided into 4 groups ( n=10). At 3 hours after modelling, the rats of groups A, B, C, and D received tail intravenous injection of 1 mL L-DMEM medium containing 10% FBS, 61.78 ng IL-10, 1 mL BMSCs suspension (2×10 6 cells/mL), and 1 mL AdIL-10-BMSCs cell suspension (2×10 6 cells/mL), respectively. The cells were labelled with BrdU before cell transplantation in groups C and D. At 7 days after reperfusion, the brain tissue was harvested to detect the expression of OX42 by immunohistochemical assay, to determine the concentration of tumor necrosis factor α (TNF-α) and IL-1β by ELISA, and to detect the apoptosis by TUNEL assay. BrdU labelled cells were observed by immunofluorescence staining in groups C and D. BrdU labelled positive cells with green fluorescence were observed in the brain tissue of groups C and D, which mainly distributed in the striatum, cerebral cortex, and subcortex around the infarction area. The number of OX42 positive cells was significantly less in groups B, C, and D than group A ( P<0.05), and in group D than groups B and C ( P<0.05). Compared with the other 3 groups, the contents of TNF-α and IL-1β significantly decreased in group D ( P<0.05). TUNEL assay showed that the apoptotic cells (TUNEL positive cells) were mainly seen in the striatum and fronto parietal subcortical tissues (equivalent to ischemic penumbra). The number of TUNEL positive cells in group D was significantly less than that in groups A, B, and C ( P<0.05). AdIL-10-BMSCs can inhibit secretion of TNF-α and IL-1β from microglial cells and inhibit the nerve cell apoptosis around infarct brain tissue, which might contribute to its protective role upon cerebral ischemia reperfusion injury.

Abstract 132: Final Infarct Volume is a Critical Determinant of Hospitalization Cost in Anterior Circulation Large Vessel Occlusion Stroke

Background: Anterior circulation large vessel occlusion (ACLVO) stroke, one of the most devastating stroke subtypes, is associated with substantial economic burden. Identifying predictors of increased ACLVO stroke hospitalization cost is essential to developing cost-effective treatment strategies. Methods: We utilized comprehensive patient-level cost-tracking software to calculate hospitalization costs for ACLVO stroke patients at our institution between July 2012-October 2014. Patient demographics and neuroimaging findings were analyzed. Predictors of hospitalization cost were determined using multivariable linear regression. In addition to our primary analysis (all eligible ACLVO patients), we conducted subgroup analyses by treatment (endovascular, IV tPA-only, and no reperfusion therapy) and sensitivity analyses. Results: 341 patients (median age 69 [IQR 57-80], median NIHSS 16 [IQR 13-21], median hospitalization cost $16,446 [IQR $9823-$27,165]) were included in our primary analysis; final infarct volume (FIV), parenchymal hematoma, age, obstructive sleep apnea, and baseline NIHSS were significant predictors of hospitalization cost (Figure). FIV alone accounted for 20.51% of the total variance in hospitalization cost. Notably, FIV was consistently the most robust predictor of increased cost across primary, subgroup, and sensitivity analyses. Over the observed range of FIVs in our cohort, each additional 1cc of infarcted brain tissue increased hospitalization cost by $122.35. Conclusion: FIV is a critical determinant of increased hospitalization cost in ACLVO stroke. Therapies resulting in reduced FIV may not only improve clinical outcomes, but prove cost-effective.

ZW800-1 for Assessment of Blood-Brain Barrier Disruption in a Photothrombotic Stroke Model.

Background: Since it is known that serum albumin-bound dyes can cross the blood-brain barrier (BBB) after ischemia, Evans Blue dye is commonly used to assess BBB disruption because of its rapid binding to serum albumin. In addition, indocyanine green (ICG), a clinically available dye, binds to serum proteins that could also be used for assessment of BBB impairment. Unlike these near-infrared (NIR) dyes, zwitterionic NIR fluorophore (ZW800-1) shows no serum binding, ultralow non-specific tissue uptake, and rapid elimination from the body via renal filtration. In this study, we report the use of ZW800-1 as a NIR fluorescence imaging agent for detecting BBB disruption in rat stroke models.Methods: Three types of NIR fluorophores, Evans Blue, ICG, and ZW800-1, were administered intraperitoneally into rat photothrombotic stroke models by using 4% concentration of each NIR dye. The NIR fluorescence signals in the infarcted brain tissue and biodistribution were observed in real-time using the Mini-FLARE® imaging system up to 24 h post-injection.Results: ZW800-1 provided successful visualization of the ischemic injury site in the brain tissue, while the remaining injected dye was clearly excreted from the body within a certain period of time. Although Evans Blue and ICG provided mapping of the infarcted brain lesions, they exhibited high non-specific uptake in most of the tissues and organs and persisted in the body over 24 h post-injection.Conclusion: Our results suggest the promising application of ZW800-1 as a new strategy in BBB experiments and future therapeutic development.

CT Perfusion in Acute Stroke: "Black Holes" on Time-to-Peak Image Maps Indicate Unsalvageable Brain.

CT perfusion is becoming important in acute stroke imaging to determine optimal patient-management strategies. The purpose of this study was to examine the predictive value of time-to-peak image maps and, specifically, a phenomenon coined a "black hole" for assessing infarcted brain tissue at the time of scan. Acute stroke patients were screened for the presence of black holes and their follow-up imaging (noncontrast CT or MR) was reviewed to assess for infarcted brain tissue. Of the 23 patients with signs of acute ischemia on CT perfusion, all had black holes. The black holes corresponded with areas of infarcted brain on follow-up imaging (specificity 100%). Black holes demonstrated significantly lower cerebral blood volumes (P < .001) and cerebral blood flow (P < .001) compared to immediately adjacent tissue. Black holes on time-to-peak image maps represent areas of unsalvageable brain.

Venlafaxine treatment after endothelin-1-induced cortical stroke modulates growth factor expression and reduces tissue damage in rats

Neuromodulators, such as antidepressants, may contribute to neuroprotection by modulating growth factor expression to exert anti-inflammatory effects and to support neuronal plasticity after stroke. Our objective was to study whether early treatment with venlafaxine, a serotonin-norepinephrine reuptake inhibitor, modulates growth factor expression and positively contributes to reducing the volume of infarcted brain tissue resulting in increased functional recovery.We studied the expression of BDNF, FGF2 and TGF-β1 by examining their mRNA and protein levels and cellular distribution using quantitative confocal microscopy at 5 days after venlafaxine treatment in control and infarcted brains. Venlafaxine treatment did not change the expression of these growth factors in sham rats. In infarcted rats, BDNF mRNA and protein levels were reduced, while the mRNA and protein levels of FGF2 and TGF-β1 were increased. Venlafaxine treatment potentiated all of the changes that were induced by cortical stroke alone. In particular, increased levels of FGF2 and TGF-β1 were observed in astrocytes at 5 days after stroke induction, and these increases were correlated with decreased astrogliosis (measured by GFAP) and increased synaptophysin immunostaining at twenty-one days after stroke in venlafaxine-treated rats. Finally, we show that venlafaxine reduced infarct volume after stroke resulting in increased functional recovery, which was measured using ladder rung motor tests, at 21 days after stroke. Our results indicate that the early oral administration of venlafaxine positively contributes to neuroprotection during the acute and late events that follow stroke.

Effects of Shaoyao-Gancao Decoction on Infarcted Cerebral Cortical Neurons: Suppression of the Inflammatory Response following Cerebral Ischemia-Reperfusion in a Rat Model.

The mechanisms by which Shaoyao-Gancao decoction (SGD) inhibits the production of inflammatory cytokines in serum and brain tissue after cerebral ischemia-reperfusion (CI-RP) in rats were investigated. A right middle cerebral artery occlusion was used to induce CI-RP after which the rats were divided into model (n = 39), SGD (n = 28), clopidogrel (n = 25) and sham operated (n = 34) groups. The Bederson scale was used to evaluate changes in behavioral indices. The levels of IL-1β, TNF-α, MCP-1, IL-10, RANTES, VEGF, and TGF-β1 in the serum and infarcted brain tissues were measured. Nissl body and immunohistochemical staining methods were used to detect biochemical changes in neurons, microglial cells, and astrocytes. Serum levels of VEGF, TNF-α, MCP-1, IL-1β, and IL-10 increased significantly 24 h after CI-RP. In brain tissue, levels of TNF-α and IL-1β significantly increased 24 h after CI-RP, whereas levels of TGF-β1 and MCP-1 were significantly higher 96 h after CI-RP (P < 0.05). SGD or clopidogrel after CI-RP reduced TNF-α and IL-1β levels in brain tissue and serum levels of MCP-1, IL-1β, and IL-10. SGD increased the number of NeuN-positive cells in infarcted brain tissue and reduced the number of IBA1-positive and GFAP-positive cells. The efficacy of SGD was significantly higher than that of clopidogrel.

Expression of Monomeric C-Reactive Protein in Infarcted Brain Tissue from Patients with Alzheimer's Disease.

We have previously shown that monomeric-C-reactive protein is deposited in significant quantities within the brain parenchyma after stroke. Since we have recently identified a possible role of this protein in supporting neurodegeneration and aberrant vascular development we identified a small group of post-mortem brain samples from individuals who had Alzheimer's disease and evidence of tissue infarction/ micro-infarction on histological examination. We used immunohistochemistry staining to identify the monomeric-C-reactive protein expressed in the infarcted brain tissues. We showed that monomeric-C-reactive protein deposition was highest in those regions affected by stroke or vascular disruption, and that within those same areas, there was more interaction and co-localization between major classical proteins of neurodegeneration (β-amyloid and tau). We hypothesise that vascular disruption and concomitant release of monomeric-C-reactive protein within the brain tissue could exacerbate ongoing neurological damage via stimulation of neuro-inflammation and from direct consequences of its action on both neuronal and vascular cells.

Comparisons of Apparent Diffusion Coefficient Values in Penumbra, Infarct, and Normal Brain Regions in Acute Ischemic Stroke: Confirmatory Data Using Bootstrap Confidence Intervals, Analysis of Variance, and Analysis of Means

There is no consensus about apparent diffusion coefficient (ADC) values in acute stroke regions that could be used by clinicians in a day-to-day clinical practice; regional measures using confidence intervals (CIs) and a graphic representation of means are scarce in the literature. Our aim in this study was to compare ADC values in infarct, penumbra, and normal brain regions in patients with acute ischemic stroke (AIS). This is a retrospective study of 100 magnetic resonance imaging data sets from AIS patients. ADC values were measured in the infarct, penumbra, and normal regions. Three hundred measurements underwent 1-way analysis of variance, analysis of means, and calculation of 95% and 84% CIs. There was a statistically significant difference at the P level less than .025 in ADC values for the 3 regions (F[2, 297] = 168.039, P ≤ .001), with no overlap of the CIs for the means among the regions: normal brain (mean [M] = .847, standard deviation [SD] = .103, 95% CI: .825-.866), infarct (M = .533, SD = .157, 95% CI: .501-.563), and penumbra (M = .764, SD = .110, 95% CI: .740-.787). ADC values might be used as reference data in acute stroke-specific populations; CIs would provide radiologists and clinicians with additional quantitative tools to evaluate penumbra, infarct, and normal brain tissue and to tailor follow-up and treatment options for selected patients.

Oxygen Mapping within Healthy and Acutely Infarcted Brain Tissue in Humans Using the NMR Relaxation of Lipids: A Proof-Of-Concept Translational Study.

The clinical applicability of brain oxygenation mapping using the MOBILE (Mapping of Oxygen By Imaging Lipids relaxation Enhancement) magnetic resonance (MR) technique was assessed in the clinical setting of normal brain and of acute cerebral ischemia as a founding proof-of-concept translational study. Changes in the oxygenation level within healthy brain tissue can be detected by analyzing the spin-lattice proton relaxation (‘Global T 1 ’ combining water and lipid protons) because of the paramagnetic properties of molecular oxygen. It was hypothesized that selective measurement of the relaxation of the lipid protons (‘Lipids T 1 ’) would result in enhanced sensitivity of pO2 mapping because of higher solubility of oxygen in lipids than in water, and this was demonstrated in pre-clinical models using the MOBILE technique. In the present study, 12 healthy volunteers and eight patients with acute (48–72 hours) brain infarction were examined with the same clinical 3T MR system. Both Lipids R1 (R1 = 1/T1) and Global R1 were significantly different in the infarcted area and the contralateral unaffected brain tissue, with a higher statistical significance for Lipids R1 (median difference: 0.408 s-1; p<0.0001) than for Global R1 (median difference: 0.154 s-1; p = 0.027). Both Lipids R1 and Global R1 values in the unaffected contralateral brain tissue of stroke patients were not significantly different from the R1 values calculated in the brain tissue of healthy volunteers. The main limitations of the present prototypic version of the MOBILE sequence are the long acquisition time (4 min), hampering robustness of data in uncooperative patients, and a 2 mm slice thickness precluding accurate measurements in small infarcts because of partial volume averaging effects.

Identification of Site-Specific Stroke Biomarker Candidates by Laser Capture Microdissection and Labeled Reference Peptide.

The search to date for accurate protein biomarkers in acute ischemic stroke has taken into consideration the stage and/or the size of infarction, but has not accounted for the site of stroke. In the present study, multiple reaction monitoring using labeled reference peptide (LRP) following laser capture microdissection (LCM) is used to identify site-specific protein biomarker candidates. In middle cerebral artery occlusion (MCAO) rat models, both intact and infarcted brain tissue was collected by LCM, followed by on-film digestion and semi-quantification using triple-quadrupole mass spectrometry. Thirty-four unique peptides were detected for the verification of 12 proteins in both tissue homogenates and LCM-captured samples. Six insoluble proteins, including neurofilament light polypeptide (NEFL), alpha-internexin (INA), microtubule-associated protein 2 (MAP2), myelin basic protein (MBP), myelin proteolipid protein (PLP) and 2′,3′-cyclic-nucleotide 3′-phosphodiesterase (CNP), were found to be site-specific. Soluble proteins, such as neuron-specific enolase (NSE) and ubiquitin carboxyl-terminal hydrolase isozyme L1 (UCHL1), and some insoluble proteins, including neurofilament heavy polypeptide (NEFH), glial fibrillary acidic protein (GFAP), microtubule-associated protein tau (MAPT) and tubulin β-3 chain (TUBB3), were found to be evenly distributed in the brain. Therefore, we conclude that some insoluble protein biomarkers for stroke are site-specific, and would make excellent candidates for the design and analysis of relevant clinical studies in the future.

Expression of neuronal and signaling proteins in penumbra around a photothrombotic infarction core in rat cerebral cortex.

Photodynamic impact on animal cerebral cortex using water-soluble Bengal Rose as a photosensitizer, which does not cross the blood-brain barrier and remains in blood vessels, induces platelet aggregation, vessel occlusion, and brain tissue infarction. This reproduces ischemic stroke. Irreversible cell damage within the infarction core propagates to adjacent tissue and forms a transition zone - the penumbra. Tissue necrosis in the infarction core is too fast (minutes) to be prevented, but much slower penumbral injury (hours) can be limited. We studied the changes in morphology and protein expression profile in penumbra 1h after local photothrombotic infarction induced by laser irradiation of the cerebral cortex after Bengal Rose administration. Morphological study using standard hematoxylin/eosin staining showed a 3-mm infarct core surrounded by 1.5-2.0mm penumbra. Morphological changes in the penumbra were lesser and decreased towards its periphery. Antibody microarrays against 224 neuronal and signaling proteins were used for proteomic study. The observed upregulation of penumbra proteins involved in maintaining neurite integrity and guidance (NAV3, MAP1, CRMP2, PMP22); intercellular interactions (N-cadherin); synaptic transmission (glutamate decarboxylase, tryptophan hydroxylase, Munc-18-1, Munc-18-3, and synphilin-1); mitochondria quality control and mitophagy (PINK1 and Parkin); ubiquitin-mediated proteolysis and tissue clearance (UCHL1, PINK1, Parkin, synphilin-1); and signaling proteins (PKBα and ERK5) could be associated with tissue recovery. Downregulation of PKC, PKCβ1/2, and TDP-43 could also reduce tissue injury. These changes in expression of some neuronal proteins were directed mainly to protection and tissue recovery in the penumbra. Some upregulated proteins might serve as markers of protection processes in a penumbra.

Multiple extra-ischemic hemorrhages following intravenous thrombolysis in a patient with Trousseau syndrome: case study.

BackgroundIntracerebral hemorrhage is the most feared complication of intravenous thrombolysis for acute ischemic stroke. Such hemorrhage usually occurs within or at the margin of ischemic or manifestly infarcted brain tissue. A patient with Trousseau syndrome who developed multiple extra-ischemic hemorrhages following intravenous thrombolysis is described.Case descriptionAn 80-year-old Japanese man with no other underlying disease was diagnosed with unresectable advanced lung cancer (stage IV) without brain metastasis and had not yet been treated. The patient suddenly presented with disturbance of consciousness, right hemiplegia, and total aphasia, and was admitted to our hospital. Magnetic resonance imaging revealed acute cerebral infarction extending from the basal ganglia to the corona radiata of the left cerebrum and multiple small areas of bilateral cerebral cortices. Cardiogenic cerebral embolism was considered among the differential diagnoses, but the brain natriuretic peptide level was within the normal range, and no arrhythmias such as atrial fibrillation were observed. With no other causes, the patient was diagnosed with Trousseau syndrome due to hypercoagulability associated with the advanced lung cancer. The patient received intravenous tissue plasminogen activator (t-PA) at 96 minutes after onset of symptoms. His symptoms partially improved, but they suddenly deteriorated at 84 minutes after the thrombolysis. A computed tomography (CT) scan immediately after the neurological deterioration revealed a subcortical hemorrhage in the left occipital lobe. A repeat CT scan the day after onset showed enlargement of the left occipital hemorrhage and two new subcortical hemorrhages in the right frontal and right temporal lobes. These hemorrhages were located in areas remote from the acute ischemic lesions.ConclusionTo the best of our knowledge, this is the first reported case of multiple extra-ischemic hemorrhages following intravenous thrombolysis in a patient with Trousseau syndrome. The course of this case suggests that intravenous t-PA administration for acute ischemic stroke with Trousseau syndrome may be associated with a higher risk of intracranial hemorrhage.

Triggering receptor expressed on myeloid cells 2 (TREM2) deficiency attenuates phagocytic activities of microglia and exacerbates ischemic damage in experimental stroke.

Clearing cellular debris after brain injury represents an important mechanism in regaining tissue homeostasis and promoting functional recovery. Triggering receptor expressed on myeloid cells-2 (TREM2) is a newly identified receptor expressed on microglia and is thought to phagocytose damaged brain cells. The precise role of TREM2 during ischemic stroke has not been fully understood. We explore TREM2 in both in vitro and in vivo stroke models and identify a potential endogenous TREM2 ligand. TREM2 knockdown in microglia reduced microglial activation to an amoeboid phenotype and decreased the phagocytosis of injured neurons. Phagocytosis and infarcted brain tissue resorption was reduced in TREM2 knock-out (KO) mice compared with wild-type (WT) mice. TREM2 KO mice also had worsened neurological recovery and decreased viable brain tissue in the ipsilateral hemisphere. The numbers of activated microglia and phagocytes in TREM2 KO mice were decreased compared with WT mice, and foamy macrophages were nearly absent in the TREM2 KO mice. Postischemia, TREM2 was highly expressed on microglia and TREM2-Fc fusion protein (used as a probe to identify potential TREM2 binding partners) bound to an unknown TREM2 ligand that colocalized to neurons. Oxygen glucose deprivation-exposed neuronal media, or cellular fractions containing nuclei or purified DNA, but not cytosolic fractions, stimulated signaling through TREM2. TREM2-Fc fusion protein pulled down nucleic acids from ischemic brain lysate. These findings establish the relevance of TREM2 in the phagocytosis of the infarcted brain and emphasize its role in influencing neurological outcomes following stroke. Further, nucleic acids may be one potential ligand of TREM2 in brain ischemia.

Reperfusion therapies of acute ischemic stroke: potentials and failures.

Over the past 20 years, clinical research has focused on the development of reperfusion therapies for acute ischemic stroke (AIS), which include the use of systemic intravenous thrombolytics (alteplase, desmoteplase, or tenecteplase), the augmentation of systemic intravenous recanalization with ultrasound, the bridging of intravenous with intra-arterial thrombolysis, the use of multi-modal approaches to reperfusion including thrombectomy and thromboaspiration with different available retrievers. Clinical trials testing these acute reperfusion therapies provided novel insight regarding the comparative safety and efficacy, but also raised new questions and further uncertainty on the field. Intravenous alteplase (tPA) remains the fastest and easiest way to initiate acute stroke reperfusion treatment, and should continue to be the first-line treatment for patients with AIS within 4.5 h from onset. The use of tenecteplase instead of tPA and the augmentation of systemic thrombolysis with ultrasound are both novel therapeutical modalities that may emerge as significant options in AIS treatment. Endovascular treatments for AIS are rapidly evolving due to technological advances in catheter-based interventions and are currently emphasizing speed in order to result in timely restoration of perfusion of still-salvageable, infarcted brain tissue, since delayed recanalization of proximal intracranial occlusions has not been associated with improved clinical outcomes. Comprehensive imaging protocols in AIS may enable better patient selection for endovascular interventions and for testing multi-modal combinatory strategies.

Intravenous thrombolysis in acute ischemic stroke patients with negative CT perfusion: a case series.

BackgroundComputed tomography perfusion (CTP) is a commonly used modality of neurophysiologic imaging to aid the selection of acute ischemic stroke patients for neuroendovascular intervention by identifying the presence of penumbra versus infarcted brain tissue. However many patients present with evidence of cerebral ischemia with normal CTP, and in that case, should intravenous thrombolytics be given?PurposeTo demonstrate if tissue-type plasminogen activator (tPA)-eligible stroke patients without perfusion defects demonstrated on CTP would benefit from administration of intravenous thrombolytics.Material and MethodsWe retrospectively identified patients presenting with acute ischemic symptoms who received intravenous tPA (IV-tPA) from January to June 2012 without a perfusion defect on CTP. Clinical and radiographic findings including the NIHSS at presentation, 24 h, and at discharge, symptomatic and asymptomatic hemorrhagic transformation, and the modified Rankin score at 30 days were collected. A reduction of NIHSS of greater than 4 points or resolution of symptoms was considered significant.ResultsSeventeen patients were identified with a mean NIHSS of 8.2 prior to administration of intravenous thrombolytics, 3.5 after 24 h, and 2.5 at discharge. Among them, 13 patients had significant improvement of NIHSS with a mean reduction of 6.15 points at 24 h. One patient initially improved but had delayed hemorrhagic transformation and died. Two patients had improvement in NIHSS but were not significant and two patients had increased in NIHSS at 24 h, although one eventually improved at discharge. There was no asymptomatic hemorrhagic transformation. Mean mRS at 3 months is 1.76.ConclusionThe failure to identify a perfusion deficit by CTP should not be used as a contraindication for intravenous thrombolytics. Criteria for administration of intravenous thrombolytics should still be based on time from symptom onset as previously published by NINDS.