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Ischemic stroke is becoming one of the most common causes of death and disability in developed countries. Since current therapeutic options are quite limited, focused on acute reperfusion therapies that are hampered by a very narrow therapeutic time window, it is essential to discover novel treatments that not only stop the progression of the ischemic cascade during the acute phase, but also improve the recovery of stroke patients during the sub-acute or chronic phase. In this regard, several studies have shown that endothelial progenitor cells (EPCs) can repair damaged vessels as well as generate new ones following cerebrovascular damage. EPCs are circulating cells with characteristics of both endothelial cells and adult stem cells presenting the ability to differentiate into mature endothelial cells and self-renew, respectively. Moreover, EPCs have the advantage of being already present in healthy conditions as circulating cells that participate in the maintenance of the endothelium in a direct and paracrine way. In this scenario, EPCs appear as a promising target to tackle stroke by self-promoting re-endothelization, angiogenesis and vasculogenesis. Based on clinical data showing a better neurological and functional outcome in ischemic stroke patients with higher levels of circulating EPCs, novel and promising therapeutic approaches would be pharmacological treatment promoting EPCs-generation as well as EPCs-based therapies. Here, we will review the latest advances in preclinical as well as clinical research on EPCs application following stroke, not only as a single treatment but also in combination with new therapeutic approaches. [ABSTRACT FROM AUTHOR]

Ischemic stroke is a leading cause of death and disability worldwide. Following an ischemic insult, cells undergo endoplasmic reticulum (ER) stress, which increases the ER's protein-folding and degradative capacities and blocks the global synthesis of proteins by phosphorylating the eukaryotic translation initiation factor 2-alpha (eIF2α). Phosphorylation of eIF2α is directly related to the dynamics of stress granules (SGs), which are membraneless organelles composed of RNA-binding proteins and mRNA. SGs play a critical role in mRNA metabolism and translational control. Other translation factors are also linked to cellular pathways, including SG dynamics following a stroke. Because the formation of SGs is closely connected to mRNA translation, it is interesting to study the relationship between SG dynamics and cellular outcome in cases of ischemic damage. Therefore, in this review, we focus on the role of SG dynamics during cerebral ischemia. [ABSTRACT FROM AUTHOR]

Photobiomodulation (PBM) therapy is a promising therapeutic approach for several pathologies, including stroke. The biological effects of PBM for the treatment of cerebral ischemia have previously been explored as a neuroprotective strategy using different light sources, wavelengths, and incident light powers. However, the capability of PBM as a novel alternative therapy to stimulate the recovery of the injured neuronal tissue after ischemic stroke has been poorly explored. The aim of this study was to investigate the low-level light irradiation therapy by using Light Emitting Diodes (LEDs) as potential therapeutic strategy for stroke. The LED photobiomodulation (continuous wave, 830 nm, 0.2–0.6 J/cm2) was firstly evaluated at different energy densities in C17.2 immortalized mouse neural progenitor cell lines, in order to observe if this treatment had any effect on cells, in terms of proliferation and viability. Then, the PBM-LED effect (continuous wave, 830 nm, 0.28 J/cm2 at brain cortex) on long-term recovery (12 weeks) was analyzed in ischemic animal model by means lesion reduction, behavioral deficits, and functional magnetic resonance imaging (fMRI). Analysis of cellular proliferation after PBM was significantly increased (1 mW) in all different exposure times used; however, this effect could not be replicated in vivo experimental conditions, as PBM did not show an infarct reduction or functional recovery. Despite the promising therapeutic effect described for PBM, further preclinical studies are necessary to optimize the therapeutic window of this novel therapy, in terms of the mechanism associated to neurorecovery and to reduce the risk of failure in futures clinical trials. [ABSTRACT FROM AUTHOR]

Several observational studies have suggested an association between periodontitis and cerebral ischemia. This meta-analysis aimed to investigate whether this link exists, and if so, the degree to which it is significant. The Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guideline for systematic review was used. The search strategy included using electronic databases and hand searching works published up to March 2015. MEDLINE via PubMed, EMBASE, Proceedings Web of Science and Current Contents Connect were searched by two independent reviewers. Case-control, cross-sectional or cohort studies including patients with measures of periodontitis and ischemic stroke were eligible to be included in the analysis. Quality assessments of selected studies were performed. From a total of 414 titles and abstracts, 57 potentially relevant full text papers were identified. After inclusion criteria were applied, 8 studies were included in the present systematic review (5 case-control and 3 cohort studies). Although it was not the intention, cross-sectional studies were excluded due to eligibility criteria were not accomplished. Therefore, meta-analyses were conducted with data retrieved from the 8 studies included. These meta-analyses showed statistically significant association between periodontitis and ischemic stroke in both cohort pooled relative risks at 2.52 (1.77-3.58), and case-control studies pooled relative risks at 3.04 (1.10-8.43). In conclusion, the present meta-analysis demonstrated an association between periodontitis and ischemic stroke. However, well-designed prospective studies should be carried out to provide robust evidence of the link between both diseases. In regards to ischemic stroke subtypes, further case-control studies should be carried out to investigate whether there is any association between the different subtypes of cerebral infarcts and periodontitis. [ABSTRACT FROM AUTHOR]

Background: Neuroserpin has shown neuroprotective effects in animal models of cerebral ischemia and has been associated with functional outcome after ischemic stroke. Our aim was to study whether neuroserpin serum levels could be associated to biomarkers of excitotoxicity, inflammation and blood brain barrier disruption.Methods: We prospectively included 129 patients with ischemic stroke (58.1% male; mean age, 72.4 ± 9.6 years) not treated with tPA within 12 hours (h) of symptoms onset (mean time, 4.7 ± 2.1 h). Poor functional outcome at 3 months was considered as a modified Rankin scale score >2. Serum levels of neuroserpin, Interleukin 6 (IL-6), Intercellular adhesion molecule-1 (ICAM-1), active Matrix metalloproteinase 9 (MMP-9), and cellular fibronectin (cFn) (determined by ELISA) and glutamate (determined by HPLC) were measured on admission, 24 and 72 h. The main variable was considered the decrease of neuroserpin levels within the first 24 h. ROC analysis was used to select the best predictive value for neuroserpin to predict poor functional outcome due to a lack of linearity.Results: The decrease of neuroserpin levels within the first 24 h was negatively correlated with serum levels at 24 hours of glutamate (r = -0.642), IL-6 (r = -0.678), ICAM-1 (r = -0.345), MMP-9 (r = -0.554) and cFn (r = -0.703) (all P < 0.0001). In the multivariate analysis, serum levels of glutamate (OR, 1.04; CI95%, 1.01-1.06, p = 0.001); IL-6 (OR, 1.4; CI95%, 1.1-1.7, p = 0.001); and cFn (OR, 1.3; CI95%, 1.1-1.6, p = 0.002) were independently associated with a decrease of neuroserpin levels <70 ng/mL at 24 h after adjusting for confounding factors.Conclusions: These findings suggest that neuroprotective properties of neuroserpin may be related to the inhibition of excitotoxicity, inflammation, as well as blood brain barrier disruption that occur after acute ischemic stroke. [ABSTRACT FROM AUTHOR]

Stroke triggers an intense inflammatory response that could be a consequence of Toll-like receptors (TLRs) activation. However, the clinical significance and the therapeutic possibilities of TLR in stroke is not completely clear. In this study, we analyze the association between the expression of TLR2 and TLR4, inflammatory molecules and endogenous ligands, and clinical outcome of ischemic stroke patients, and we test the potential of TLR2/TLR4 and their endogenous ligands as therapeutic targets. For this purpose, we included 110 patients with ischemic stroke finding that TLR2 and TLR4 are independently associated to poor outcome and correlated with higher serum levels of interleukin (IL)1β, IL6, tumor necrosis factor α, and VCAM1, and that TLR4 was independently associated to lesion volume. In addition, we have developed an in vitro model to test the potential therapeutic value of blocking TLR2/TLR4 or their endogenous ligands. Cultured cells (monocytes and human umbilical vein endothelial cells) were treated with serum from ischemic stroke patients, showing a strong inflammatory response that was blocked when TLR2/4 or cellular fibronectin (cFN) or HSP60 were blocked. In conclusion, TLR2 and TLR4 are associated to outcome in stroke patients and TLR2/4 or their endogenous ligands, cFN/HSP60 could be new therapeutic targets for ischemic stroke. [ABSTRACT FROM AUTHOR]

Neuronal death produced by cerebral ischemia activates innate immunity by Toll-like receptors and triggers inflammatory response. This response is necessary to remove cell debris and to start regenerative process. However, inflammatory response could exacerbate cerebral damage and it is involved in secondary brain damage. Therefore, organisms have developed different mechanisms to regulate inflammatory response. An accurate balance between inflammation and anti-inflammation is necessary to assure the removal of cell debris and to avoid secondary cell damage. New therapeutic targets could be designed to obtain a correct modulation of the immune system and to reduce cerebral brain damage after cerebral ischemia. In this paper, we review the function of the immune system in cerebral ischemia, particularly inflammation and immunomodulation. Copyright © 2009 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Vascular damage occurring after cerebral ischemia may lead to a worse outcome in patients with ischemic stroke, as it facilitates edema formation and hemorrhagic transformation. There are several phases in the development of vascular injury (acute, subacute and chronic) and different mediators act in each one. Therapeutic options to avoid vascular injury must be focused on acting in each phase. However, even though experimental studies have demonstrated the benefit of therapeutic interventions both in the acute and chronic phases of cerebral ischemia, only the chronic phase offers a therapeutic window sufficiently wide enough to provide vascular protection in clinical practice. Several drugs including erythropoietin and HMG-CoA reductase inhibitors (statins), antihypertensive (angiotensin modulators), antibiotics (minocycline) and antihyperglycemic drugs (thiazolidinediones) have been proved to provide vascular protection in patients with ischemic stroke. Anti-inflammatory, antioxidant, and antiapoptotic actions are responsible for the vascular protective effect related to these drugs. Copyright © 2006 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Stroke is the second to third leading cause of death and the main cause of severe, long-term disability in adults. However, treatment is almost reduced to fibrinolysis, a therapy useful in a low percentage of patients. Given that the immediate treatment for stroke is often unfeasible in the clinical setting, the need for new therapy strategies is imperative. After stroke, the remaining impairment in functions essential for routine activities, such as movement programming and execution, sensorimotor integration, language and other cognitive functions have a deep and life-long impact on the quality of life. An interesting point is that a slow but consistent recovery can be observed in the clinical practice over a period of weeks and months. Whereas the recovery in the first few days likely results from edema resolution and/or from reperfusion of the ischemic penumbra, a large part of the recovery afterwards is due mainly to brain plasticity, by which some regions of the brain assume the functions previously performed by the damaged areas. Neurogenesis and angiogenesis are other possible mechanisms of recovery after stroke. An understanding of the mechanisms underlying functional recovery may shed light on strategies for neurorepair, an alternative with a wide therapeutic window when compared with neuroprotective strategies. Copyright © 2006 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

A short ischemic event (ischemic preconditioning (IPC)) can result in subsequent resistance to severe ischemic injury (ischemic tolerance (IT)). The expression and neuroprotective role of tumor necrosis factor (TNF-α) have been described in models of IPC and we have showed the participation of its processing enzyme, the TNF-α convertase enzyme (TACE) in this process. We have now decided to explore the expression and localization of TNF receptors (TNFR) as well as other signalling mechanisms involved in IT. A period of 10 mins of temporary middle cerebral artery occlusion (tMCAO) was used for focal IPC. To evaluate the ability of IPC to produce IT, permanent MCAO was performed 48 hours after IPC. Ischemic preconditioning produced a reduction in infarct volume, as we showed previously. Ischemic preconditioning caused upregulation of neuronal TNFR1 that was reduced by the selective TACE inhibitor BB1101. Intracerebral administration of TNFR1 antisense oligodeoxynucleotide, which caused a reduction in TNFR1 expression, inhibited the IPC-induced protective effect, showing that TNFR1 upregulation is implicated in IT. Moreover, treatment with BB1101, TNFR1 antisense and lactacystin—a specific proteasome inhibitor—blocked IPC-induced NF-κB. Immunohistochemical studies showed the expression of TACE and TNFR1 in neurons. In summary, these data show that IPC produces neuronal upregulation of TACE and TNFR1, and that the pathway TACE/TNF-α/TNFR1/NF-κB is involved in IT.Journal of Cerebral Blood Flow & Metabolism (2005) 25, 193–203. doi:10.1038/sj.jcbfm.9600019 Published online 5 January 2005 [ABSTRACT FROM AUTHOR]

In this work, we report our study of protein expression in rat peri-infarct tissue, 48 h after the induction of permanent focal cerebral ischemia. Two proteomic approaches, gel electrophoresis with mass spectrometry and combined fractional diagonal chromatography (COFRADIC), were performed using tissue samples from the periphery of the induced cerebral ischemic lesions, using tissue from the contra-lateral hemisphere as a control. Several protein spots (3408) were identified by gel electrophoresis, and 11 showed significant differences in expression between peri-infarct and contra-lateral tissues (at least 3-fold, p < 0.05). Using COFRADIC, 5412 proteins were identified, with 72 showing a difference in expression. Apart from blood-related proteins (such as serum albumin), both techniques showed that the 70 kDa family of heat shock proteins were highly expressed in the peri-infarct tissue. Further studies by 1D and 2D western blotting and immunohistochemistry revealed that only one member of this family (the inducible form, HSP72 or HSP70i) is specifically expressed by the peri-infarct tissue, while the majority of this family (the constitutive form, HSC70 or HSP70c) is expressed in the whole brain. Our data support that HSP72 is a suitable biomarker of peri-infarct tissue in the ischemic brain. [ABSTRACT FROM AUTHOR]

Aims Dexmedetomidine is a selective agonist of α 2 -adrenergic receptors with clinical anesthetic and analgesic properties that has also shown neuroprotective effects on several models of brain injury. Because perioperative stroke and brain damage are frequent causes of death in critical care units, we aimed to investigate neuroprotective properties of dexmedetomidine using an in vitro model of cerebral ischemia. Main methods Primary mixed rat brain cortical cultures were subjected to oxygen and glucose deprivation and treated with different doses of dexmedetomidine in order to analyze three conditioning strategies: preconditioning, intraconditioning and postconditioning. Key findings All dexmedetomidine pre-, intra- and postconditioning treatments showed neuroprotective effects reducing brain cell necrosis, although only preconditioning showed antiapoptotic effects. Dexmedetomidine treatments also reduced IL-6 and TNF-α levels, especially in the preconditioning groups. Oxidative stress was attenuated with all dexmedetomidine preconditioning treatments, but only with the higher dose in the intraconditioning group, and no effects were observed in the postconditioning. All conditioning strategies increased BDNF levels. Significance Dexmedetomidine-mediated neuroprotective effects in an in vitro model of cerebral ischemia involve the attenuation of inflammation and oxidative stress and the increment of BDNF expression. [ABSTRACT FROM AUTHOR]

Abstract: Endothelin-1 (ET-1) is involved on the development of cerebral edema in acute ischemic stroke. As edema is a therapeutic target in cerebral ischemia, our aim was to study the effect of antagonists for ET-1 receptors (Clazosentan® and BQ-788, specific antagonists for receptors A and B, respectively) on the development of edema, infarct volume and sensorial-motor deficits in rats subjected to ischemia by occlusion of the middle cerebral artery (MCAO). We used Wistar rats (280–320 g) submitted to ischemia by intraluminal transient (90 min) MCAO. After ischemia, rats were randomized into 4 groups (n = 6) treated with; 1) control group (saline), 2) Clazosentan® group (10 mg/kg iv), 3) BQ-788 group (3 mg/kg iv), and 4) combined treatment (Clazosentan® 10 mg/kg plus BQ-788 3 mg/kg iv). We observed that rats treated with Clazosentan® showed a reduction of edema, measured by MRI, at 72 h (hours) and at day 7 (both p < 0.0001), and a decrease in the serum levels of ET-1 at 72 h (p < 0.0001) and at day 7 (p = 0.009). The combined treatment also induced a reduction of edema at 24 h (p = 0.004), 72 h (p < 0.0001) and at day 7 (p < 0.0001), a reduction on infarct volume, measured by MRI, at 24 and 72 h, and at day 7 (all p < 0.01), and a better sensorimotor recovery at 24 and 72 h, and at day 7 (all p < 0.01). Moreover, Clazosentan® induced a decrease in AQP4 expression, while BQ-788 induced an increase in AQP9 expression. These results suggest that antagonists for ET-1 receptors may be a good therapeutic target for cerebral ischemia. [Copyright &y& Elsevier]

Abstract: Liposome encapsulation of active principles enhances their bioavailability to the brain. We investigated whether encapsulation of citicoline in liposomes increases its therapeutic effects in ischemia, performing a longitudinal MRI study of lesion volumes and edema in an animal model of stroke. Nineteen rats were submitted to permanent occlusion of the middle cerebral artery and treated with: (1) saline, (2) intraperitoneal citicoline (500mg/kg), (3) intravenous citicoline (48mg/kg), and (4) intravenous liposome-encapsulated citicoline (48mg/kg). Lesion volumes were measured by MRI at days 0, 1, 3 and 7 following surgery. Encapsulation in liposomes increased the therapeutic effects of citicoline, as reflected by a 32% reduction of the infarct sizes at day 7, in contrast with controls where infarct sizes at day 7 increased by 39%, respect to values at day 0. Intravenously injected citicoline reduced infarct sizes by 9% while intraperitoneal citicoline resulted in an increase of infarct sizes by 10%. A slight (not significant) reduction of edema formation was observed for animals treated with citicoline, in all of its delivery forms. Liposome-encapsulated citicoline causes a noticeable reduction in lesion volumes as compared to free citicoline (either i.p. or i.v.) at days 1, 3 and 7 following permanent stroke. [ABSTRACT FROM AUTHOR]

Abstract: Besides its role as a thrombolytic agent, tissue plasminogen activator (tPA) triggers harmful effects in the brain parenchyma after stroke, such as inflammation, excitotoxicity and basal lamina degradation. Neuroserpin, a natural inhibitor of tPA, has shown neuroprotective effects in animal models of brain infarct. However, the molecular mechanisms of neuroserpin-mediated neuroprotection after brain ischemia remain to be well characterized. Then, our aim was to investigate such mechanisms in primary mixed cortical cell cultures after oxygen and glucose deprivation (OGD). Primary rat mixed cortical cultures containing both astrocytes and neurons were subjected to OGD for 150min and subsequently treated with either tPA (5μg/mL), neuroserpin (0.125, 0.25, 0.5 or 1μM), and tPA together with neuroserpin at the mentioned doses. Twenty-four hours after treatment, LDH release, caspase-3 activity, MCP-1, MIP-2, active MMP-9, GRO/KC and COX-2 were measured. Statistical differences were analyzed using Student''s t-test or one-way ANOVA as appropriate. Treatment with tPA after OGD increased LDH release, active MMP-9, MCP-1 and MIP-2 (all p ≤0.05), but not caspase-3, GRO/KC or COX-2 compared to control. Treatment with neuroserpin after OGD decreased LDH release and active MMP-9 (all p ≤0.05). It had no effect on caspase-3 activity, or on MCP-1, MIP-2, GRO/KC or COX-2 expression compared to control. Administration of tPA together with neuroserpin decreased LDH release, active MMP-9 and MIP-2 (all p ≤0.05) and showed no effect on MCP-1, GRO/KC or COX-2 compared to control. Our results suggest that neuroprotective activity of neuroserpin involves attenuation on tPA-mediated mechanisms of inflammation and BBB disruption after brain ischemia. [Copyright &y& Elsevier]

Experimental and clinical data suggest an important role of iron in cerebral ischaemia. We measured infarct volume and analysed the oxidative stress, and also the excitatory and inflammatory responses to brain injury in a rat stroke model after an increased oral iron intake. Permanent middle cerebral artery occlusion (MCAO) was performed in ten male Wistar rats fed with a diet containing 2.5% carbonyl iron for 9 weeks, and in ten control animals. Glutamate, interleukin-6 (IL-6) and tumour necrosis factor-α (TNF-α) were determined in blood samples before and at 2, 4, 6, 8, 24 and 48 h after MCAO, and thiobarbituric acid reaction substances (TBARS) were analysed at 48 h. Infarct volume was measured at 48 h by image analysis on brain slices stained with 1% TTC. Tissue iron was measured by atomic absorption spectrophotometry. Infarct volume was 66% greater in the iron fed rats than in the control group (178±49 mm3 versus 107±53 mm3, P<0.01). Significant higher levels of glutamate, IL-6 and TNF-α were observed in the group with iron intake (peak values were obtained at 6, 8 and 4 h, respectively). Iron-fed animals also showed significantly higher levels of TBARS than those receiving a normal diet (6.52±0.59 vs. 5.62±0.86 μmol/l, P=0.033) Liver iron stores (3500±199 vs. 352±28 μg Fe/g, P<0.0001), but not brain iron stores (131 vs. 139 μg Fe/g, P=0.617), were significantly higher in the iron fed rats group. These results suggest that iron intake is associated with larger infarct volumes after MCAO in the rat. This effect seems to be associated with higher oxidative stress, excitotoxicity and inflammatory responses. [Copyright &y& Elsevier]