Acute ischemic stroke: time, penumbra, and reperfusion

Clinical outcome prediction after thrombectomy of proximal middle cerebral artery occlusions by the appearance of lenticulostriate arteries on magnetic resonance angiography: A retrospective analysis

Post-ischemic vasodynamic changes in infarcted brain parenchyma are common and range from hypo- to hyperperfusion. In the present study, appearance of the lenticulostriate arteries (LSAs) on postinterventional 3T time-of-flight (TOF)-MRA suggestive for altered post-stroke vasodynamics following thrombectomy was investigated. Patients who underwent thrombectomy for a proximal MCA occlusion and for whom postinterventional 3T TOF-MRA (median at day 3) was available, were included in this retrospective analysis (n=98). LSA appearance was categorized into presence (LSA-sign⁺) or absence (LSA-sign^-) of vasodilatation in the ischemic hemisphere. Functional outcome was determined using the modified Rankin scale (mRS). LSA-sign⁺ was observed in 64/98 patients. Hypertension (adjusted OR: 0.171, 95% CI: 0.046-0.645) and preinterventional IV rtPA (adjusted OR: 0.265, 95% CI: 0.088-0.798) were associated with absence of the LSA-sign⁺. In multivariate logistic regression, LSA-sign⁺ was associated with substantial neurologic improvement (adjusted OR: 10.18, 95% CI: 2.69-38.57) and good functional outcome (discharge-mRS ≤ 2, adjusted OR: 7.127, 95% CI: 1.913-26.551 and day 90 mRS ≤ 2, adjusted OR: 3.786, 95% CI: 1.026-13.973) after correcting for relevant confounders. For all clinical endpoints, model fit improved when including the LSA-sign term (p<0.05). Asymmetrical dilatation of LSAs following successful thrombectomy indicates favorable neurologic and mid-term functional outcomes. This may indicate preserved cerebral blood flow regulatory mechanisms.

Systematic review and meta-analysis on outcome differences among patients with TICI2b versus TICI3 reperfusions: success revisited

OBJECTIVE

A reperfusion quality of thrombolysis in cerebral infarction (TICI)≥2b has been set as the therapeutic angiography target for interventions in patients with acute ischaemic stroke. This study addresses whether the distinction between TICI2b and TICI3 reperfusions shows a clinically relevant difference on functional outcome.

METHODS

A systematic literature review and meta-analysis was carried out and presented in conformity with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria to test the primary hypothesis that TICI2b and TICI3 reperfusions are associated with different rates of modified Rankin Scale (mRS) ≤2 at day 90. Secondary endpoints included rates of haemorrhagic transformations, mortality and excellent functional outcome (mRS ≤1). Summary estimates of ORs (sOR) with 95% CI were calculated using the inverse variance heterogeneity model accounting for multiple true effect sizes.

RESULTS

Fourteen studies on 2379 successfully reperfused patients were included (1131 TICI3, 1248 TICI2b). TICI3 reperfusions were associated with higher rates of functional independence (1.74, 95% CI 1.44 to 2.10) and excellent functional outcomes (2.01, 95% CI 1.60 to 2.53), also after including adjusted estimates. The safety profile of patients with TICI3 was superior, as demonstrated by lower rates of mortality (sOR 0.59, 95% CI 0.37 to 0.92) and symptomatic intracranial haemorrhages (sOR 0.42, 95% CI 0.25 to 0.71).

CONCLUSION

TICI3 reperfusions are associated with superior outcome and better safety profiles than TICI2b reperfusions. This effect seems to be independent of time and collaterals. As reperfusion quality is the most important modifiable predictor of patients' outcome, a more conservative definition of successful therapy and further evaluation of treatment approaches geared towards achieving TICI3 reperfusions are desirable.

NCCT and CTA-based imaging protocol for endovascular treatment selection in late presenting or wake-up strokes

Introduction

Recently, the benefit of selecting patients for endovascular treatment (EVT) beyond the 6-hour time window using a tissue-based approach was demonstrated in two randomized trials. The optimal imaging protocol for selecting patients is under debate, and it is still unknown if a simpler and faster protocol may adequately select patients with wake-up stroke (WUS) and late-presenting stroke (LPS) for EVT.

Objective

To compare outcomes of patients submitted to EVT presenting within 6 hours of symptom onset or 6–24 hours after last seen well, selected using non-contrast computed tomography (NCCT) and CT angiography (CTA).

Methods

An observational study was performed, which included consecutive patients with anterior circulation ischemic stroke with large vessel occlusion treated with EVT. Patients presenting within 6 hours were treated if their NIH Stroke Scale (NIHSS) score was ≥6 and Alberta Stroke Program Early CT score (ASPECTS) was ≥6, while patients presenting with WUS or 6–24 hours after last seen well (WUS/LPS) were treated if their NIHSSscore was ≥12 and ASPECTS was ≥7.

Results

249 patients were included, 63 of whom were in the WUS/LPS group. Baseline characteristics were similar between groups, except for longer symptom-recanalization time, lower admission NIHSS (16 vs 17, P=0.038), more frequent tandem occlusions (25.4% vs 11.8%, P=0.010), and large artery atherosclerosis etiology (22.2% vs 11.8%, P=0.043) in the WUS/LPS group. No differences in symptomatic intracranial hemorrhage, peri-procedural complications or mortality were found between groups. Three-month functional independence was similar in both groups (65.1% in WUS/LPS vs 57.0% in ≤6 hours, P=0.259) and no differences were found after adjustment for confounders.

Conclusions

This real-world observational study suggests that EVT may be safe and effective in patients with WUS and LPS selected using clinical-core mismatch (high NIHSS/high ASPECTS in NCCT).

Mechanical recanalization in ischemic anterior circulation stroke within an 8-hour time window: a real-world experience

PURPOSE

We aimed to assess the safety and effectiveness of mechanical recanalization in patients with ischemic stroke in the anterior circulation within 8 h since symptoms onset and with unknown onset time. We compared time intervals <6 h vs. 6-8 h/unknown onset time, as only limited data are available for a time window beyond 6 h.

METHODS

Our cohort included 110 consecutive patients (44 males; mean age, 73.0±11.5 years) with ischemic stroke in the anterior circulation due to the acute occlusion of a large intracranial artery who underwent mechanical recanalization within an 8-hour time window or with unknown onset time. All patients underwent unenhanced computed tomography (CT) of the brain, CT angiography of the cervical and intracranial arteries and digital subtraction angiography. Perfusion CT was performed in patients beyond a 6-hour time window/with unknown onset time. We collected the following data: baseline characteristics, presence of risk factors, neurologic deficit at the time of treatment, time to therapy, recanalization rate, and 3-month clinical outcome. Successful recanalization was defined as Thrombolysis in Cerebral Infarction score of 2b/3 and good clinical outcome as modified Rankin scale value of 0-2 points.

RESULTS

Successful recanalization was achieved in 82 patients (74.5%): in 61 patients treated within 6 h (73.5%), 7 patients treated within 6-8 h (63.6%), and 13 patients with unknown onset time (81.3%). Good 3-month clinical outcome was achieved in 61 patients (55.5%): in 46 patients treated within 6 h (55.4%), 5 patients treated within 6-8 h (45.5%), and 10 patients with unknown onset time (62.5%). Recanalization success or clinical outcome were not significantly different between patients treated at different time windows.

CONCLUSION

Our data confirms the safety and effectiveness of mechanical recanalization performed in carefully selected patients with ischemic stroke in the anterior circulation within 8 h of stroke onset or with unknown onset time in everyday practice.

Neuroprotective effects of Yiqihuoxue calm wind capsule on ischemic stroke in rats

Stroke remains the third leading cause of death and of adult disability worldwide. Vascular occlusion, followed by ischemic cascade, leads to irreversible tissue injury. Recombinant tissue plasminogen activator is the only FDA approved drug for the current treatment of acute ischemic stroke. However, traditional Chinese medicine has a long history and rich clinical experience in the treatment and rehabilitation of ischemic stroke. Using a classical middle cerebral artery occlusion (MCAO) stroke model, we tested the effectiveness of Yiqihuoxue calm wind (YCW) capsule on neurological function, gross pathology and oxidative stress status in MCAO rats. YCW capsule (3.36 and 6.72 g·kg^-1 of crude drug) could significantly lower Longa's score and superoxide dismutase (SOD) level, together with less necrotic cells and infarcted area. In addition to elevated MDA and downregulated iNOS expression, YCW capsule exhibited its neuroprotective effects via free radical scavenging and NO inhibition.

Molecular Magnetic Resonance Imaging of Endothelial Activation in the Central Nervous System

Endothelial cells of the central nervous system over-express surface proteins during neurological disorders, either as a cause, or a consequence, of the disease. Since the cerebral vasculature is easily accessible by large contrast-carrying particles, it constitutes a target of choice for molecular magnetic resonance imaging (MRI). In this review, we highlight the most recent advances in molecular MRI of brain endothelial activation and focus on the development of micro-sized particles of iron oxide (MPIO) targeting adhesion molecules including intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1), P-Selectin and E-Selectin. We also discuss the perspectives and challenges for the clinical application of this technology in neurovascular disorders (ischemic stroke, intracranial hemorrhage, subarachnoid hemorrhage, diabetes mellitus), neuroinflammatory disorders (multiple sclerosis, brain infectious diseases, sepsis), neurodegenerative disorders (Alzheimer's disease, vascular dementia, aging) and brain cancers (primitive neoplasms, metastasis).

Paradigm Change? Cardiac Output Better Associates with Cerebral Perfusion than Blood Pressure in Ischemic Stroke

Introduction

In patients with acute ischemic stroke, penumbral perfusion is maintained by collateral flow and so far is maintained by normal mean arterial pressure (MAP) levels. Since MAP is dependent on cardiac function, optimization of cardiac output might be a valuable hemodynamic goal in order to optimize cerebral perfusion (CP).

Methods

Cerebral perfusion was assessed by transcranial color-coded duplex and transcranial perfusion sonography in 10 patients with acute large hemispheric stroke. Time-to-peak (TTP) values of defined regions of interest (ROI) within the middle cerebral artery (MCA) territory were assessed bilaterally in addition to mean flow velocities of the MCA. Via semi-invasive advanced hemodynamic monitoring systemic hemodynamic parameters were assessed, including MAP and cardiac index (CI). Patients received sonographic follow-up after optimizing CI.

Results

TTP values of the deeply located ROIs of the non-affected as well as the affected hemisphere correlated highly significantly with CI (in affected side r = −0.827, p = 0.002; and in non-affected side r = −0.908, p < 0.0001). This demonstrates dependence of CP on CI, while correlation with MAP was not detected. Neither CI nor MAP revealed significant correlation with MCA velocity.

Influence of Renal Function on Treatment Results after Stroke Thrombectomy

Background: Renal dysfunction (RD) may be associated with poor outcome in ischemic stroke patients treated with mechanical thrombectomy (MT), but data concerning this important and emerging comorbidity do not exist so far. Here, we investigated the influence of RD on postprocedural intracerebral hemorrhage (ICH), clinical outcome, and mortality in a large prospectively collected cohort of acute ischemic stroke patients treated with MT. Methods: Consecutive patients with anterior-circulation stroke treated with MT between October 2010 and January 2016 were included. RD was defined as glomerular filtration rate (GFR) <60 mL/min/1.73 m2. In a prospective database, clinical characteristics were recorded and brain images were analyzed for the presence of ICH after treatment in all patients. Clinical outcome was assessed by the modified Rankin Scale (mRS) after 3 months. To evaluate associations between clinical factors and outcomes uni- and multivariate regression analyses were conducted. Results: In total, 505 patients fulfilled all inclusion criteria (female: 49.7%, mean age: 71.0 years). RD at admission was present in 20.2%. RD patients were older and had cardiovascular risk factors more often. Multivariate regression analysis after adjustment for age, stroke severity, diabetes, hypertension, GFR, previous stroke, MT alone, or additional thrombolysis and recanalization results revealed that lower GFR was not independently associated with poor outcome (mRS 3-6; OR 1.13, 95% CI 0.99-1.28; p = 0.072) or ICH. However, lower GFR at admission was associated with a higher risk of mortality (OR 1.15, 95% CI 1.01-1.31; p = 0.038). Compared to admission, GFR values were higher at discharge (mean: 77.9 vs. 80.8 mL/min/1.73 m2; p = 0.046). Conclusions: We did not find evidence for an association of lower GFR with an increased risk of poor outcome and ICH, but lower GFR was a determinant of 90-day mortality after endovascular stroke treatment. Our findings encourage also performing MT in this relevant subgroup of acute ischemic stroke patients.

Optimizing Cardiac Out-Put to Increase Cerebral Penumbral Perfusion in Large Middle Cerebral Artery Ischemic Lesion-OPTIMAL Study

INTRODUCTION

In unsuccessful vessel recanalization, clinical outcome of acute stroke patients depends on early improvement of penumbral perfusion. So far, mean arterial blood pressure (MAP) is the target hemodynamic parameter. However, the correlations of MAP to cardiac output (CO) and cerebral perfusion are volume state dependent. In severe subarachnoid hemorrhage, optimizing CO leads to a reduction of delayed ischemic neurological deficits and improvement of clinical outcome. This study aims to investigate the effect of standard versus advanced cardiac monitoring with optimization of CO on the clinical outcome in patients with large ischemic stroke.

METHODS AND ANALYSIS

The OPTIMAL study is a prospective, multicenter, open, into two arms (1:1) randomized, controlled trial. Sample size estimate: sample sizes of 150 for each treatment group (300 in total) ensure an 80% power to detect a difference of 16% of a dichotomized level of functional clinical outcome at 3 months at a significance level of 0.05. Study outcomes: the primary endpoint is the functional outcome at 3 months. The secondary endpoints include functional outcome at 6 months follow-up, and complications related to hemodynamic monitoring and therapies.

DISCUSSION

The results of this trial will provide data on the safety and efficacy of advanced hemodynamic monitoring on clinical outcome.

ETHICS AND DISSEMINATION

The trial was approved by the leading ethics committee of Freiburg University, Germany (438/14, 2015) and the local ethics committees of the participating centers. The study is performed in accordance with the Declaration of Helsinki and the guidelines of Good Clinical Practice. It is registered in the German Clinical Trial register (DRKS; DRKS00007805). Dissemination will include submission to peer-reviewed professional journals and presentation at congresses. Hemodynamic monitoring may be altered in a specific stroke patient cohort if the study shows that advanced monitoring is safe and improves the functional outcome.

Role of Transporters in Central Nervous System Drug Delivery and Blood-Brain Barrier Protection: Relevance to Treatment of Stroke

Ischemic stroke is a leading cause of morbidity and mortality in the United States. The only approved pharmacologic treatment for ischemic stroke is thrombolysis via recombinant tissue plasminogen activator (r-tPA). A short therapeutic window and serious adverse events (ie, hemorrhage, excitotoxicity) greatly limit r-tPA therapy, which indicates an essential need to develop novel stroke treatment paradigms. Transporters expressed at the blood-brain barrier (BBB) provide a significant opportunity to advance stroke therapy via central nervous system delivery of drugs that have neuroprotective properties. Examples of such transporters include organic anion–transporting polypeptides (Oatps) and organic cation transporters (Octs). In addition, multidrug resistance proteins (Mrps) are transporter targets in brain microvascular endothelial cells that can be exploited to preserve BBB integrity in the setting of stroke. Here, we review current knowledge on stroke pharmacotherapy and demonstrate how endogenous BBB transporters can be targeted for improvement of ischemic stroke treatment.

Collateral blood flow in different cerebrovascular hierarchy provides endogenous protection in cerebral ischemia

Collateral blood flow as vascular adaptions to focal cerebral ischemia is well recognized. However, few studies directly investigate the dynamics of collateral vessel recruitment in vivo and little is known about the effect of collateral blood flow in different cerebrovascular hierarchy on the neuropathology after focal ischemic stroke. Here, we report that collateral blood flow is critically involved in blood vessel compensations following regional ischemia. We occluded a pial arteriole using femtosecond laser ablating under the intact thinned skull and documented the changes of collateral flow around the surface communication network and between the surface communication network and subsurface microcirculation network using in vivo two photon microscopy imaging. Occlusion of the pial arteriole apparently increased the diameter and collateral blood flow of its leptomeningeal anastomoses, which significantly reduced the cortical infarction size. This result suggests that the collateral flow via surface communicating network connected with leptomeningeal anastomoses could greatly impact on the extent of infarction. We then further occluded the target pial arteriole and all of its leptomeningeal anastomoses. Notably, this type of occlusion led to reversals of blood flow in the penetrating arterioles mainly proximal to the occluded pial arteriole in a direction from the subsurface microcirculation network to surface arterioles. Interesting, the cell death in the area of ischemic penumbra was accelerated when we performed occlusion to cease the reversed blood flow in those penetrating arterioles, suggesting that the collateral blood flow from subsurface microcirculation network exerts protective roles in delaying cell death in the ischemic penumbra. In conclusion, we provide the first experimental evidence that collateral blood vessels at different cerebrovascular hierarchy are endogenously compensatory mechanisms in brain ischemia.

Oxidative stress and apoptosis after acute respiratory hypoxia and reoxygenation in rat brain

Acute hypoxia increases the formation of reactive oxygen species (ROS) in the brain. However, the effect of reoxygenation, unavoidable to achieve full recovery of the hypoxic organ, has not been clearly established. The aim of the present study was to evaluate the effects of exposition to acute severe respiratory hypoxia followed by reoxygenation on the evolution of oxidative stress and apoptosis in the brain. We investigated the effect of in vivo acute severe normobaric hypoxia (rats exposed to 7% O₂ for 6 h) and reoxygenation in normoxia (21% O₂ for 24 h or 48 h) on oxidative stress markers, the antioxidant system and apoptosis in the brain. After respiratory hypoxia we found increased levels of HIF-1α expression, lipid peroxidation, protein oxidation and nitric oxide in brain extracts. Antioxidant defence systems such as superoxide dismutase (SOD), reduced glutathione (GSH) and glutathione peroxidase (GPx) and the reduced/oxidized glutathione (GSH/GSSG) ratio were significantly decreased in the brain. After 24 h of reoxygenation, oxidative stress parameters and the anti-oxidant system returned to control values. Regarding the apoptosis parameters, acute hypoxia increased cytochrome c, AIF and caspase 3 activity in the brain. The apoptotic effect is greatest after 24 h of reoxygenation. Immunohistochemistry suggests that CA3 and dentate gyrus in the hippocampus seem more susceptible to hypoxia than the cortex. Severe acute hypoxia increases oxidative damage, which in turn could activate apoptotic mechanisms. Our work is the first to demonstrate that after 24 h of reoxygenation oxidative stress is attenuated, while apoptosis is maintained mainly in the hippocampus, which may, in fact, be the cause of impaired brain function.

No space left for intravenous thrombolysis in acute stroke: PROS

Five recently published RCTs (MR CLEAN, EXTEND-IA, SWIFT PRIME, REVASCAT and ESCAPE) employing mechanical thrombectomy with modern stent retriever devices clearly demonstrated the superiority of endovascular treatment compared to thrombolysis alone, which is now considered standard first-line therapy for selected patients with acute severe ischemic stroke and large vessel in the anterior circulation. RCT results led to recommendations outlined in "Mechanical thrombectomy in acute ischemic stroke by ESO-Karolinska Stroke Update 2014/2015, supported by ESO, ESMINT, ESNR and EAN". Moreover, endovascular procedures in the 5 RCTs to date were performed at high-volume referral centers with, in some trials, rigid requirements for the interventionalist to participate, which may have contributed substantially to the excellent results, supporting the concept of centralization of intra-arterial thrombolysis resources and expertise. Therefore, patients with suspected large-artery occlusion and deemed candidates for thrombectomy, should be treated at a Comprehensive Stroke Centre with 24/7 endovascular treatment services. There seems to be limited space left for intravenous thrombolysis alone in acute stroke patients with large-vessel occlusions as thrombectomy plus thrombolysis continues to be reported as being superior with regard to outcome.

The VWF-GPIb axis in ischaemic stroke: lessons from animal models

Stroke is a leading cause of death and long-term disability worldwide. Ischaemic stroke is caused by a blood clot that obstructs cerebral blood flow. Current treatment mainly consists of achieving fast reperfusion, either via pharmacological thrombolysis using tissue plasminogen activator or via endovascular thrombectomy. Unfortunately, reperfusion therapy is only available to a limited group of patients and reperfusion injury can further aggravate brain damage. Hence, there is an urgent need for better understanding of ischaemic stroke pathophysiology in order to develop novel therapeutic strategies. In recent years, the pathophysiological importance of von Willebrand factor (VWF) in ischaemic stroke has become clear from both clinical and experimental studies. In particular, binding of VWF to platelet glycoprotein Ib (GPIb) has become an interesting target for ischaemic stroke therapy. Recent insights show that inhibting the VWF-GPIb interaction could result in a pro-thrombolytic activity improving cerebral reperfusion rates and concurrently reducing cerebral ischaemia/reperfusion damage. This review gives an overview of the experimental evidence that illustrates the crucial role of the VWF-GPIb axis in ischaemic stroke.

Is mean arterial pressure the best parameter in ischemic stroke?

This case series of 27 patients with large stroke challenges the current state of the art guiding hemodynamic management by blood pressure levels. The results show that assumed correlations of blood pressure, cardiac output, and systemic vascular resistance do not exist. Therefore, hemodynamic therapy may better be guided by cardiac output.

The "inflammatory penumbra" in ischemic stroke: From clinical data to experimental evidence

Purpose

The objective of the present review is to provide an overview of the available clinical and preclinical data supporting the existence of an "inflammatory penumbra" in ischemic stroke.

Findings

Recent data from clinical trials suggest the existence of an inflammatory area at risk, surrounding the initial ischemic lesion and secondarily infiltrated by lymphocytes, that is ultimately recruited by the ischemic core: called the "inflammatory penumbra." Experimental results support this concept. Lymphocytes, especially T-cells, enter the brain in the perilesional area in a vascular-cell adhesion molecule-1 dependent manner and participate in delayed neuronal cell death.

Methods

For writing this review, we used the more recent publications in the field, including the preclinical and clinical studies. We have also used our own experise in the field of in vivo imaging of inflammatory processes.

Discussion

Consequently, the intensity of the inflammatory reaction and the size of the inflammatory penumbra may vary considerably in patients, as it is the case in experimental stroke models in mice. By analogy with the ischemic penumbra of the acute phase of stroke, this secondary inflammatory penumbra represents a therapeutic opportunity during the subacute phase of stroke. Large clinical trials that target lymphocyte trafficking are currently taking place. However, to improve the benefit of such therapeutic strategies, adequate patient selection may be mandatory.

Conclusion

In this context, innovative imaging methods including magnetic resonance imaging of adhesion molecules may contribute to noninvasively detect this inflammatory penumbra and thus to select patients eligible for such therapy.

Focal cerebral ischemia and neurovascular protection: a bench-to-bedside update

PURPOSE OF REVIEW

To date, many pharmacological approaches, or combination of approaches, have been applied to experimental models of focal cerebral ischemia (FCI), but their translation to clinically effective agents has proved unsuccessful. To date, only thrombolysis with recombinant tissue-type plasminogen activator, or other 'clot-breaking' or 'clot-removal' approaches, have proved effective for acute stroke. This review, therefore, focuses on the 'vascular' phenomena involved in the development of FCI.

RECENT FINDINGS

Recent advances in the experimental literature on FCI describe the microvascular characteristics of the ischemic penumbra, the consequences of cortical spreading depression on impairing cerebral perfusion, and the potential neuroprotective mechanisms of ischemic preconditioning via antithrombotic effects on the neurovascular unit.

SUMMARY

This review provides a perspective about the neurovascular components contributing to the pathophysiology of FCI, and some relevant clinical strategies available on the horizon that hold promise for improved cerebral perfusion in FCI.

Characteristic Changes of Astrocyte and Microglia in Rat Striatum Induced by 3-NP and MCAO

Our previous studies had confirmed that both 3-NP and MCAO induced the behavioral defect as well as striatal neuronal injury and loss in experimental rats. This study aimed to examine different response forms of striatal astrocyte and microglia in 3-NP and MCAO rat models. The present results showed that the immunoreaction for GFAP was extremely weak in the lesioned core of striatum, but in the transition zone of 3-NP model and the penumbra zone of MCAO model, GFAP+ cells showed strong hypertrophic and proliferative changes. Statistical analysis for the number, size and integral optical density (IOD) of GFAP+ cells showed significant differences when compared with their controls and compared between the core and the transition zone or the penumbra zone, respectively, but no differences between the 3-NP and MCAO groups. However, Iba-1+ cells showed obvious hypertrophy and proliferation in the injured striatum in the 3-NP and the MCAO models, especially in the transition zone of 3-NP model and the penumbra zone of MCAO model. These Iba-1+ cells displayed two characteristic forms as branching cells with thick processes and amoeboid cells with thin processes. Statistical analysis showed that the number, size and IOD of Iba-1+ cells were significantly increased in the cores and the transition zone of 3-NP group and the penumbra zone of MCAO group than that of the controls, and the immune response of Iba-1 was stronger in the MCAO group than in the 3-NP group. The present results suggested that characteristic responses of astrocyte and microglia in the 3-NP and the MCAO models display their different effects on the pathological process of brain injury.

PreSSUB II: The prehospital stroke study at the Universitair Ziekenhuis Brussel II

RATIONALE

Stroke is a time-critical medical emergency requiring specialized treatment. Prehospital delay contributes significantly to delayed or missed treatment opportunities. In-ambulance telemedicine can bring stroke expertise to the prehospital arena and facilitate this complex diagnostic and therapeutic process.

AIMS

This study evaluates the efficacy, safety, feasibility, reliability and cost-effectiveness of in-ambulance telemedicine for patients with suspicion of acute stroke. We hypothesize that this approach will reduce the delay to in-hospital treatment by streamlining the diagnostic process and that prehospital stroke care will be improved by expert stroke support via telemedicine during the ambulance transportation.

DESIGN

PreSSUB II is an interventional, prospective, randomized, open-blinded, end-point, single-center trial comparing standard emergency care by the Paramedic Intervention Team of the Universitair Ziekenhuis Brussel (control) with standard emergency care complemented with in-ambulance teleconsultation service by stroke experts (PreSSUB).

STUDY OUTCOMES

The primary efficacy endpoint is the call-to-brain imaging time. Secondary endpoints for the efficacy analysis include the prevalence of medical events diagnosed and corrected during in-ambulance teleconsultation, the proportion of patients with ischemic stroke receiving recanalization therapy, the assessment of disability, functional status, quality of life and overall well-being. Mortality at 90 days after stroke is the primary safety endpoint. Secondary safety analysis will involve the registration of any adverse event. Other analyses include assessment of feasibility and reliability and a health economic evaluation.

Endovascular stent thrombectomy: the new standard of care for large vessel ischaemic stroke

BACKGROUND

Results of initial randomised trials of endovascular treatment for ischaemic stroke, published in 2013, were neutral but limited by the selection criteria used, early-generation devices with modest efficacy, non-consecutive enrollment, and treatment delays.

RECENT DEVELOPMENTS

In the past year, six positive trials of endovascular thrombectomy for ischaemic stroke have provided level 1 evidence for improved patient outcome compared with standard care. In most patients, thrombectomy was performed in addition to thrombolysis with intravenous alteplase, but benefits were also reported in patients ineligible for alteplase treatment. Despite differences in the details of eligibility requirements, all these trials required proof of major vessel occlusion on non-invasive imaging and most used some imaging technique to exclude patients with a large area of irreversibly injured brain tissue. The results indicate that modern thrombectomy devices achieve faster and more complete reperfusion than do older devices, leading to improved clinical outcomes compared with intravenous alteplase alone. The number needed to treat to achieve one additional patient with independent functional outcome was in the range of 3·2-7·1 and, in most patients, was in addition to the substantial efficacy of intravenous alteplase. No major safety concerns were noted, with low rates of procedural complications and no increase in symptomatic intracerebral haemorrhage. WHERE NEXT?: Thrombectomy benefits patients across a range of ages and levels of clinical severity. A planned meta-analysis of individual patient data might clarify effects in under-represented subgroups, such as those with mild initial stroke severity or elderly patients. Imaging-based selection, used in some of the recent trials to exclude patients with large areas of irreversible brain injury, probably contributed to the proportion of patients with favourable outcomes. The challenge is how best to implement imaging in clinical practice to maximise benefit for the entire population and to avoid exclusion of patients with smaller yet clinically important potential to benefit. Although favourable imaging identifies patients who might benefit despite long delays from symptom onset to treatment, the proportion of patients with favourable imaging decreases with time. Health systems therefore need to be reorganised to deliver treatment as quickly as possible to maximise benefits. On the basis of available trial data, intravenous alteplase remains the initial treatment for all eligible patients within 4·5 h of stroke symptom onset. Those patients with major vessel occlusion should, in parallel, proceed to endovascular thrombectomy immediately rather than waiting for an assessment of response to alteplase, because minimising time to reperfusion is the ultimate aim of treatment.

Deciphering the pharmacological mechanism of the Chinese formula huanglian-jie-du decoction in the treatment of ischemic stroke using a systems biology-based strategy

AIM

Huanglian-jie-du decoction (HLJDD) is an important multiherb remedy in TCM, which is recently demonstrated to be effective to treat ischemic stroke. Here, we aimed to investigate the pharmacological mechanisms of HLJDD in the treatment of ischemic stroke using systems biology approaches.

METHODS

Putative targets of HLJDD were predicted using MetaDrug. An interaction network of putative HLJDD targets and known therapeutic targets for the treatment of ischemic stroke was then constructed, and candidate HLJDD targets were identified by calculating topological features, including 'Degree', 'Node-betweenness', 'Closeness', and 'K-coreness'. The binding efficiencies of the candidate HLJDD targets with the corresponding compositive compounds were further validated by a molecular docking simulation.

RESULTS

A total of 809 putative targets were obtained for 168 compositive compounds in HLJDD. Additionally, 39 putative targets were common to all four herbs of HLJDD. Next, 49 major nodes were identified as candidate HLJDD targets due to their network topological importance. The enrichment analysis based on the Gene Ontology (GO) annotation system and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway demonstrated that candidate HLJDD targets were more frequently involved in G-protein-coupled receptor signaling pathways, neuroactive ligand-receptor interactions and gap junctions, which all played important roles in the progression of ischemic stroke. Finally, the molecular docking simulation showed that 170 pairs of chemical components and candidate HLJDD targets had strong binding efficiencies.

CONCLUSION

This study has developed for the first time a comprehensive systems approach integrating drug target prediction, network analysis and molecular docking simulation to reveal the relationships between the herbs contained in HLJDD and their putative targets and ischemic stroke-related pathways.

A Systems Biology Perspective on the Molecular Mechanisms Underlying the Therapeutic Effects of Buyang Huanwu Decoction on Ischemic Stroke

Ischemic stroke is the leading cause of adult disability worldwide. The outcome is worse in older patients, especially in terms of disability. Buyang Huanwu decoction (BHD), a famous traditional Chinese medicine formula, has been used extensively in the treatment of ischemic stroke for centuries. However, its pharmacological mechanisms have not been fully elucidated. In this study, 82 putative targets for 411 composite compounds contained in BHD were predicted on the basis of our previously developed target prediction system. On the basis of large-scale molecular docking, more than 80% compound-putative target pairs had medium to strong binding efficiency. The pharmacological networks of BHD were built according to relationships among herbs, putative targets, and known therapeutic targets for ischemic stroke, and 121 major nodes were identified by calculating three topological features-degree, node betweenness, and closeness. Importantly, the pathway enrichment analysis identified several signaling pathways involved with major putative targets of BHD, such as the calcium signaling pathway, vascular smooth muscle contraction, and nucleotide-binding oligomerization domain (NOD)-like receptor signaling pathway, which have not hitherto been reported. These data are expected to help find new therapeutic effects of BHD and optimize clinical use of this formula. Collectively, our study developed a comprehensive systems approach integrating drug target prediction and network and functional analyses to reveal the relationships of the herbs in BHD with their putative targets, and for the first time with ischemic stroke-related pathway systems. This is a pilot study based on bioinformatics analysis; thus, further experimental studies are required to validate our findings.

Clinical outcomes of patients with acute minor stroke receiving rescue IA therapy following early neurological deterioration

Background

Patients presenting with minor ischemic stroke frequently have early neurological deterioration (END) and poor final outcome. The optimal management of patients with END has not been determined.

Objective

To investigate rescue IA therapy (IAT) when patients with acute minor ischemic stroke develop END.

Methods

This was a retrospective study of consecutively registered patients with acute minor stroke and END. ‘END’ was defined as an increase in National Institutes of Health Stroke Scale (NIHSS) scores by 1 or more points (or development of new neurological symptoms) and ‘ΔEND−NIHSS’ was defined as numerical difference between NIHSS scores at the time of END and before END. Rescue IAT following END was adjusted for the covariates to evaluate the association between IAT and favorable outcome at 3 months.

Results

Among 982 patients with acute minor ischemic stroke, END occurred in 232 (23.6%). Of the 209 patients with END with full data available, 87 (41.6%) had favorable outcomes at 3 months. Rescue IAT following END was performed in 28 (13.4%). Favorable 3-month outcomes were seen in 50% of patients undergoing rescue IAT, including 8/19 (42.1%) undergoing rescue IAT beyond 8 h. By multivariate logistic regression analysis, rescue IAT following END was independently associated with favorable outcome at 3 months (OR=10.9; 95% CI 3.06 to 38.84; p<0.001).

Conclusions

The results suggest that rescue IAT may be safe and effective when END occurs in selected patients with acute minor ischemic stroke. Further prospective and randomized studies are needed to confirm our results.

Overexpression of glyceraldehyde 3-phosphate dehydrogenase prevents neurovascular degeneration after retinal injury

Ischemia and reperfusion (I/R) injury is a common cause of many vascular and neuronal diseases. Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) has been found down-regulated or dysfunctional in several tissues upon I/R injury. To investigate the role of GAPDH in retinal I/R injury-induced neurovascular degeneration, the injured retinas of GAPDH transgenic (Tg) mice and wild-type (WT) littermates were analyzed. I/R injury induced neurovascular degeneration, energy failure, DNA damage, and necroptosis in the retinas of WT mice. In contrast, the GAPDH Tg mice showed resistance to all of these injury-induced abnormalities. In addition, I/R-induced effects were further examined in a neuroblastoma cell line and an endothelial cell line, which were transfected with a vector encoding human GAPDH or a control vector. After I/R challenge, energy failure, DNA damage, and elevation of receptor-interacting serine/threonine-protein kinase (RIP) 1/3 were observed in the cells transfected with the control vector. However, overexpression of GAPDH in these cells prevented the injury-induced RIP3 up-regulation by restoring energy production and preventing DNA damage. Together, the protective role of GAPDH in retinal neurovascular degeneration after I/R injury provides a better understanding of the underlying mechanism of I/R injury and a potential therapeutic target to attenuate I/R injury-related diseases.

Neuroprotective effects of SMADs in a rat model of cerebral ischemia/reperfusion

Previous studies have shown that up-regulation of transforming growth factor β1 results in neuroprotective effects. However, the role of the transforming growth factor β1 downstream molecule, SMAD2/3, following ischemia/reperfusion remains unclear. Here, we investigated the neuroprotective effects of SMAD2/3 by analyzing the relationships between SMAD2/3 expression and cell apoptosis and inflammation in the brain of a rat model of cerebral ischemia/reperfusion. Levels of SMAD2/3 mRNA were up-regulated in the ischemic penumbra 6 hours after cerebral ischemia/reperfusion, reached a peak after 72 hours and were then decreased at 7 days. Phosphorylated SMAD2/3 protein levels at the aforementioned time points were consistent with the mRNA levels. Over-expression of SMAD3 in the brains of the ischemia/reperfusion model rats via delivery of an adeno-associated virus containing the SMAD3 gene could reduce tumor necrosis factor-α and interleukin-1β mRNA levels, down-regulate expression of the pro-apoptotic gene, capase-3, and up-regulate expression of the anti-apoptotic protein, Bcl-2. The SMAD3 protein level was negatively correlated with cell apoptosis. These findings indicate that SMAD3 exhibits neuroprotective effects on the brain after ischemia/reperfusion through anti-inflammatory and anti-apoptotic pathways.

Protosappanin B protects PC12 cells against oxygen-glucose deprivation-induced neuronal death by maintaining mitochondrial homeostasis via induction of ubiquitin-dependent p53 protein degradation

Protosappanin B (PTB) is a bioactive dibenzoxocin derivative isolated from Caesalpinia sappan L. Here, we investigated the neuroprotective effects and the potential mechanisms of PTB on oxygen-glucose deprivation (OGD)-injured PC12 cells. Results showed that PTB significantly increased cell viability, inhibited cell apoptosis and up-regulated the expression of growth-associated protein 43 (a marker of neural outgrowth). Moreover, our study revealed that PTB effectively maintained mitochondrial homeostasis by up-regulation of mitochondrial membrane potential (MMP), inhibition of cytochrome c release from mitochondria and inactivation of mitochondrial caspase-9/3 apoptosis pathway. Further study showed that PTB significantly promoted cytoplasmic component degradation of p53 protein, a key negative regulator for mitochondrial function, resulting in a release of Bcl-2 from p53-Bcl-2 complex and an enhancing translocation of Bcl-2 to mitochondrial outer membrane. Finally, we found the degradation of p53 protein was induced by PTB via activation of a MDM2-dependent ubiquitination process. Taken together, our findings provided a new viewpoint of neuronal protection strategy for anoxia and ischemic injury with natural small molecular dibenzoxocin derivative by activating ubiquitin-dependent p53 protein degradation as well as increasing mitochondrial function.

Endovascular stroke therapy at nighttime and on weekends-as fast and effective as during normal business hours?

INTRODUCTION

There is only limited data on the influence of the admission time (normal business hours versus nighttime and weekends) on procedural timings, revascularization efficacy, and outcome after mechanical thrombectomy. We investigated whether the admission time has an impact on the above-mentioned factors.

METHODS

Our neurointerventional database was screened for all mechanical thrombectomies in anterior circulation acute ischemic stroke between 07/13 and 06/14. Outcome measures were procedural timings and clinical and demographic data; we compared patients who were admitted at normal business hours (Monday to Friday 8:00-18:00) to those admitted at night or at the weekend.

RESULTS

98 patients were identified. Of them, 52 (53%) were admitted during normal business hours, the remainder at night or at weekend. There was no statistically significant difference between the groups regarding the time from symptom-onset to admission, baseline National Institutes of Health Stroke Scale (NIHSS) or IVT-rate. There was a significant difference between groups for door-to-reperfusion timing, favoring patients admitted during normal business hours (146 versus 165 min, p = 0.02). Door-to-groin-puncture and groin-puncture-to-reperfusion time did not differ significantly. The rate of successful revascularizations (mTICI ≥ 2b) and the rate of favorable clinical outcome at discharge (mRS ≤ 2) did not differ between groups (77% versus 78% and 37% versus 35%, respectively).

CONCLUSIONS

There was a statistically significant prolongation of door-to-reperfusion timings for patients admitted during nighttime and weekends; it went along neither with a lower rate of successful revascularizations nor with a lower rate of favorable outcome in our series.

ABBREVIATIONS

AFatrial fibrillationAISacute ischemic strokeCTAcomputed tomography angiographyDMdiabetes mellitusENTembolization to new territoryEVTendovascular therapyHLPhyperlipoproteinemiaHTNhypertensionIQRinter-quartile rangeIVTintravenous thrombolysismRSmodified Rankin ScaleMTmechanical thrombectomyNIHSSNational Institutes of Health Stroke Scalen.s.not significantsICHsymptomatic intracranial hemorrhage.

Cerebral collateral flow defines topography and evolution of molecular penumbra in experimental ischemic stroke

Intracranial collaterals are dynamically recruited after arterial occlusion and are emerging as a strong determinant of tissue outcome in both human and experimental ischemic stroke. The relationship between collateral flow and ischemic penumbra remains largely unexplored in pre-clinical studies. The aim of the present study was to investigate the pattern of collateral flow with regard to penumbral tissue after transient middle cerebral artery (MCA) occlusion in rats. MCA was transiently occluded (90min) by intraluminal filament in adult male Wistar rats (n=25). Intracranial collateral flow was studied in terms of perfusion deficit and biosignal fluctuation analyses using multi-site laser Doppler monitoring. Molecular penumbra was defined by topographical mapping and quantitative signal analysis of Heat Shock Protein 70kDa (HSP70) immunohistochemistry. Functional deficit and infarct volume were assessed 24h after ischemia induction. The results show that functional performance of intracranial collaterals during MCA occlusion inversely correlated with HSP70 immunoreactive areas in both the cortex and the striatum, as well as with infarct size and functional deficit. Intracranial collateral flow was associated with reduced areas of both molecular penumbra and ischemic core and increased areas of intact tissue in rats subjected to MCA occlusion followed by reperfusion. Our findings prompt the development of collateral therapeutics to provide tissue-saving strategies in the hyper-acute phase of ischemic stroke prior to recanalization therapy.

[Endovascular therapy in the treatment of acute ischemic stroke: what the cardiologist should know]

INTRODUCTION

Interventional cardiology procedures are regularly exposed to ischemic neurological complications. IV fibrinolysis is the only approved treatment in ischemic stroke but is very often contraindicated in these situations. Many techniques of interventional neuroradiology (mechanical thrombectomy) have been developed over the past years and are used to treat these patients.

OBSERVATION

We report the case of two patients who were admitted in emergency for ischemic stroke with contraindication to IV fibrinolysis (cardioversion for atrial fibrillation under anticoagulation; 24 hours after carotid surgery). These patients were treated by endovascular thrombectomy procedure.

DISCUSSION

After validation of IV fibrinolysis within 4.5 hours after stroke onset, techniques of mechanical thrombectomy have gradually been developed, either as a complementary treatment or as an alternative in the case of CI to fibrinolysis. These endovascular thrombectomy devices currently allow recanalization of proximal cerebral occlusions, which correlates with a favorable clinical prognosis. A review of the literature is provided, along with a discussion about the techniques currently being improved, their advantages and disadvantages and the selection of patients that can benefit from endovascular procedures.

CONCLUSION

In the case of a sudden occurrence of a neurological deficit during a cardiovascular procedure, a "thrombolysis alert" should be triggered. This will permit the rapid establishment of a clinico-radiological report for selecting stroke patients eligible for a procedure of recanalization by thrombolysis and/or mechanical thrombectomy.

Cytoprotective-selective activated protein C therapy for ischaemic stroke

Despite years of research and efforts to translate stroke research to clinical therapy, ischaemic stroke remains a major cause of death, disability, and diminished quality of life. Primary and secondary preventive measures combined with improved quality of care have made significant progress. However, no novel drug for ischaemic stroke therapy has been approved in the past decade. Numerous studies have shown beneficial effects of activated protein C (APC) in rodent stroke models. In addition to its natural anticoagulant functions, APC conveys multiple direct cytoprotective effects on many different cell types that involve multiple receptors including protease activated receptor (PAR) 1, PAR3, and the endothelial protein C receptor (EPCR). Application of molecular engineered APC variants with altered selectivity profiles to rodent stroke models demonstrated that the beneficial effects of APC primarily require its cytoprotective activities but not its anticoagulant activities. Extensive basic, preclinical, and clinical research provided a compelling rationale based on strong evidence for translation of APC therapy that has led to the clinical development of the cytoprotective-selective APC variant, 3K3A-APC, for ischaemic stroke. Recent identification of non-canonical PAR1 and PAR3 activation by APC that give rise to novel tethered-ligands capable of inducing biased cytoprotective signalling as opposed to the canonical signalling provides a mechanistic explanation for how APC-mediated PAR activation can selectively induce cytoprotective signalling pathways. Collectively, these paradigm-shifting discoveries provide detailed insights into the receptor targets and the molecular mechanisms for neuroprotection by cytoprotective-selective 3K3A-APC, which is currently a biologic drug in clinical trials for ischaemic stroke.

Exendin-4 reduces ischemic brain injury in normal and aged type 2 diabetic mice and promotes microglial M2 polarization

Exendin-4 is a glucagon-like receptor 1 agonist clinically used against type 2 diabetes that has also shown neuroprotective effects in experimental stroke models. However, while the neuroprotective efficacy of Exendin-4 has been thoroughly investigated if the pharmacological treatment starts before stroke, the therapeutic potential of the Exendin-4 if the treatment starts acutely after stroke has not been clearly determined. Further, a comparison of the neuroprotective efficacy in normal and aged diabetic mice has not been performed. Finally, the cellular mechanisms behind the efficacy of Exendin-4 have been only partially studied. The main objective of this study was to determine the neuroprotective efficacy of Exendin-4 in normal and aged type 2 diabetic mice if the treatment started after stroke in a clinically relevant setting. Furthermore we characterized the Exendin-4 effects on stroke-induced neuroinflammation. Two-month-old healthy and 14-month-old type 2 diabetic/obese mice were subjected to middle cerebral artery occlusion. 5 or 50 µg/kg Exendin-4 was administered intraperitoneally at 1.5, 3 or 4.5 hours thereafter. The treatment was continued (0.2 µg/kg/day) for 1 week. The neuroprotective efficacy was assessed by stroke volume measurement and stereological counting of NeuN-positive neurons. Neuroinflammation was determined by gene expression analysis of M1/M2 microglia subtypes and pro-inflammatory cytokines. We show neuroprotective efficacy of 50 µg/kg Exendin-4 at 1.5 and 3 hours after stroke in both young healthy and aged diabetic/obese mice. The 5 µg/kg dose was neuroprotective at 1.5 hour only. Proinflammatory markers and M1 phenotype were not impacted by Exendin-4 treatment while M2 markers were significantly up regulated. Our results support the use of Exendin-4 to reduce stroke-damage in the prehospital/early hospitalization setting irrespectively of age/diabetes. The results indicate the polarization of microglia/macrophages towards the M2 reparative phenotype as a potential mechanism of neuroprotection.

Improving neurovascular outcomes with bilateral forepaw stimulation in a rat photothrombotic ischemic stroke model

Restoring perfusion to the penumbra during the hyperacute phase of ischemic stroke is a key goal of neuroprotection. Thrombolysis is currently the only approved treatment for ischemic stroke. However, its use is limited by the narrow therapeutic window and side effect of bleeding. Therefore, other interventions are desired that could potentially increase the perfusion of the penumbra. Here, we hypothesized that bilateral peripheral electrical stimulation will improve cerebral perfusion and restore cortical neurovascular response. We assess the outcomes of bilateral forepaw electrical stimulation at intensities of 2 and 4 mA, administered either unilaterally or bilaterally. We developed a combined electrocorticogram (ECoG)-functional photoacoustic microscopy (fPAM) system to evaluate the relative changes in cerebral hemodynamic function and electrophysiologic response to acute, focal stroke. The fPAM system is used for cerebral blood volume (CBV) and hemoglobin oxygen saturation ([Formula: see text]) and the ECoG for neural activity, namely somatosensory-evoked potential (SSEP), interhemispheric coherence, and alpha-delta ratio (ADR) in response to forepaw stimulation. Our results confirmed the neuroprotective effect of bilateral forepaw stimulation at 2 mA as indicated by the 82% recovery of ADR and 95% improvement in perfusion into the region of penumbra. This experimental model can be used to study other potential interventions such as therapeutic hypertension and hypercarbia.

Disparity among neural injury models and the unfolded protein response

Endoplasmic reticulum stress is activated following both stroke and traumatic brain injury producing reactive oxgygen species, increasing intracellular calcium levels, and inducing inflammation; however, the timing and duration of activation varies between injuries. Preventing the immediate effects of ischemic/reperfusion injury or traumatic brain injury is challenging due to short onset of injury, but mitigating the secondary effects is a therapeutically targetable option. Preventative therapies using pharmacological agents have been utilized in pre-clinical models of neural injury to ameliorate secondary effects such as apoptosis and neurodegeneration. The connection between ER stress activation, apoptosis, and subsequent neurodegeneration has been proposed, but not yet causally linked. Researchers are now pursuing effective treatment strategies to suppress the secondary effects of neural injury in order to mitigate the development of chronic deficits. Secondary effects such as endoplasimic reticulum stress and neuroinflammation can be prevented in pre-clinical models, but the results have yet to translate to meaningful treatment options for patients. Evidence suggests that targeting the right transcription factors, at the right time, will aid in the prevention of apoptosis and neurodegenerative disease development following neural injury. In this review, we examine therapeutic approaches that target secondary injury and how these may correlate to better treatment options for patients.