Revisiting Cerebral Postischemic Reperfusion Injury: New Insights in Understanding Reperfusion Failure, Hemorrhage, and Edema

Gene Expression Dynamics at the Neurovascular Unit During Early Regeneration After Cerebral Ischemia/Reperfusion Injury in Mice

With increasing distribution of endovascular stroke therapies, transient middle cerebral artery occlusion (tMCAO) in mice now more than ever depicts a relevant patient population with recanalized M1 occlusion. In this case, the desired therapeutic effect of blood flow restauration is accompanied by breakdown of the blood-brain barrier (BBB) and secondary reperfusion injury. The aim of this study was to elucidate short and intermediate-term transcriptional patterns and the involved pathways covering the different cellular players at the neurovascular unit after transient large vessel occlusion. To achieve this, male C57Bl/6J mice were treated according to an intensive post-stroke care protocol after 60 min occlusion of the middle cerebral artery or sham surgery to allow a high survival rate. After 24 h or 7 days, RNA from microvessel fragments from the ipsilateral and the contralateral hemispheres was isolated and used for mRNA sequencing. Bioinformatic analyses allowed us to depict gene expression changes at two timepoints of neurovascular post-stroke injury and regeneration. We validated our dataset by quantitative real time PCR of BBB-associated targets with well-characterized post-stroke dynamics. Hence, this study provides a well-controlled transcriptome dataset of a translationally relevant mouse model 24 h and 7 days after stroke which might help to discover future therapeutic targets in cerebral ischemia/reperfusion injury.

Enhancing Glycolysis Protects against Ischemia-Reperfusion Injury by Reducing ROS Production

After myocardial ischemia-reperfusion, fatty acid oxidation shows fast recovery while glucose oxidation rates remain depressed. A metabolic shift aimed at increasing glucose oxidation has shown to be beneficial in models of myocardial ischemia-reperfusion. However, strategies aimed at increasing glucose consumption in the clinic have provided mixed results and have not yet reached routine clinical practice. A better understanding of the mechanisms underlying the protection afforded by increased glucose oxidation may facilitate the transfer to the clinic. The purpose of this study was to evaluate if the modulation of reactive oxygen species (ROS) was involved in the protection afforded by increased glucose oxidation. Firstly, we characterized an H9C2 cellular model in which the use of glucose or galactose as substrates can modulate glycolysis and oxidative phosphorylation pathways. In this model, there were no differences in morphology, cell number, or ATP and PCr levels. However, galactose-grown cells consumed more oxygen and had an increased Krebs cycle turnover, while cells grown in glucose had increased aerobic glycolysis rate as demonstrated by higher lactate and alanine production. Increased aerobic glycolysis was associated with reduced ROS levels and protected the cells against simulated ischemia-reperfusion injury. Furthermore, ROS scavenger N-acetyl cysteine (NAC) was able to reduce the amount of ROS and to prevent cell death. Lastly, cells grown in galactose showed higher activation of mTOR/Akt signaling pathways. In conclusion, our results provide evidence indicating that metabolic shift towards increased glycolysis reduces mitochondrial ROS production and prevents cell death during ischemia-reperfusion injury.

Intra- and extra-hospital improvement in ischemic stroke patients: influence of reperfusion therapy and molecular mechanisms

Neuroprotective treatments in ischemic stroke are focused to reduce the pernicious effect of excitotoxicity, oxidative stress and inflammation. However, those cellular and molecular mechanisms may also have beneficial effects, especially during the late stages of the ischemic stroke. The objective of this study was to investigate the relationship between the clinical improvement of ischemic stroke patients and the time-dependent excitotoxicity and inflammation. We included 4295 ischemic stroke patients in a retrospective study. The main outcomes were intra and extra-hospital improvement. High glutamate and IL-6 levels at 24 hours were associated with a worse intra-hospital improvement (OR:0.993, 95%CI: 0.990–0.996 and OR:0.990, 95%CI: 0.985–0.995). High glutamate and IL-6 levels at 24 hours were associated with better extra-hospital improvement (OR:1.13 95%CI, 1.07–1.12 and OR:1.14, 95%CI, 1.09–1.18). Effective reperfusion after recanalization showed the best clinical outcome. However, the long term recovery is less marked in patients with an effective reperfusion. The variations of glutamate and IL6 levels in the first 24 hours clearly showed a relationship between the molecular components of the ischemic cascade and the clinical outcome of patients. Our findings suggest that the rapid reperfusion after recanalization treatment blocks the molecular response to ischemia that is associated with restorative processes.

Neuroprotection by selective endovascular brain cooling - the TwinFlo™ Catheter

The neuroprotective effects of hypothermia have been demonstrated in experimental models and clinical trials. Experimental studies indicate that improved efficacy and broadened indications can be achieved with moderate to deep hypothermia. The TwinFlo catheter was designed to provide very rapid, deep and selective brain cooling with faster cooling rates, and temperatures much lower than those which can be achieved by any other hypothermia device and technique. This report describes the experimental in vivo studies and initial clinical experience with the TwinFlo catheter.

Infusion warm during selective hypothermia in acute ischemic stroke

INTRODUCTION

Mechanical thrombectomy (MT) has dramatically improved the prognosis for acute ischemic stroke (AIS) patients. Despite high recanalization rates, up to half of the patients will not present a good neurological outcome after MT. Therapeutic hypothermia is perhaps the most robust neuroprotectant studied preclinically.

MATERIALS AND METHODS

We explored various warming effects that can reduce the effectiveness or potency of selective hypothermia during AIS under conditions similar to actual clinical care. Four different selective hypothermia layouts were chosen. Layouts 1 and 2 used a single catheter without and with an insulated IV bag. Layouts 3 and 4 used two catheters arrange coaxially, without and with an insulated IV bag. Independent variables measured were IV bag exit temperature, catheter inlet temperature, and catheter outlet temperature at four different flow rates ranging from 8 to 25 ml/min over an infusion duration of 20 min.

RESULTS

Dominant warming occurs along the catheter pathway compared to warming along the infusion line pathway, ranging from 66% to 72%. Coaxial configurations provided an approximate 4°C cooler temperature benefit on delivered infusate over a single catheter. Brain tissue temperature predictions show that the maximum cooling layout, Layout 4 at maximum flow provides a 1°C within 5 min.

CONCLUSION

Significant rewarming effects occur along the infusate flow path from IV bag to site of injury in the brain. Previous selective hypothermia clinical work, using flow rates and equipment at conditions similar to our study, likely produced rapid but not deep tissue cooling in the brain (~ 1°C).

Effect of Recanalization on Cerebral Edema in Ischemic Stroke Treated With Thrombolysis and/or Endovascular Therapy

Background and Purpose- A large infarct and expanding cerebral edema (CED) due to a middle cerebral artery occlusion confers a 70% mortality unless treated surgically. Reperfusion may cause blood-brain barrier disruption and a risk for cerebral edema and secondary parenchymal hemorrhage (PH). We aimed to investigate the effect of recanalization on development of early CED and PH after recanalization therapy. Methods- From the SITS-International Stroke Treatment Registry, we selected patients with signs of artery occlusion at baseline (either Hyperdense Artery Sign or computed tomography/magnetic resonance imaging angiographic occlusion). We defined recanalization as the disappearance of radiological signs of occlusion at 22 to 36 hours. Primary outcome was moderate to severe CED and secondary outcome was PH on 22- to 36-hour imaging scans. We used logistic regression with adjustment for baseline variables and PH. Results- Twenty two thousand one hundred eighty-four patients fulfilled the inclusion criteria (n=18 318 received intravenous thrombolysis, n=3071 received intravenous thrombolysis+thrombectomy, n=795 received thrombectomy). Recanalization occurred in 64.1%. Median age was 71 versus 71 years and National Institutes of Health Stroke Scale score 15 versus 16 in the recanalized versus nonrecanalized patients respectively. Recanalized patients had a lower risk for CED (13.0% versus 23.6%), adjusted odds ratio (aOR), 0.52 (95% CI, 0.46-0.59), and a higher risk for PH (8.9% versus 6.5%), adjusted odds ratio, 1.37 (95% CI, 1.22-1.55), than nonrecanalized patients. Conclusions- In patients with acute ischemic stroke, recanalization was associated with a lower risk for early CED even after adjustment for higher rate for PH in recanalized patients.

Assessing the Effects of Cytoprotectants on Selective Neuronal Loss, Sensorimotor Deficit and Microglial Activation after Temporary Middle Cerebral Occlusion

Although early reperfusion after stroke salvages the still-viable ischemic tissue, peri-infarct selective neuronal loss (SNL) can cause sensorimotor deficits (SMD). We designed a longitudinal protocol to assess the effects of cytoprotectants on SMD, microglial activation (MA) and SNL, and specifically tested whether the KCa3.1-blocker TRAM-34 would prevent SNL. Spontaneously hypertensive rats underwent 15 min middle-cerebral artery occlusion and were randomized into control or treatment group, which received TRAM-34 intraperitoneally for 4 weeks starting 12 h after reperfusion. SMD was assessed longitudinally using the sticky-label test. MA was quantified at day 14 using in vivo [¹¹C]-PK111195 positron emission tomography (PET), and again across the same regions-of-interest template by immunofluorescence together with SNL at day 28. SMD recovered significantly faster in the treated group (p = 0.004). On PET, MA was present in 5/6 rats in each group, with no significant between-group difference. On immunofluorescence, both SNL and MA were present in 5/6 control rats and 4/6 TRAM-34 rats, with a non-significantly lower degree of MA but a significantly (p = 0.009) lower degree of SNL in the treated group. These findings document the utility of our longitudinal protocol and suggest that TRAM-34 reduces SNL and hastens behavioural recovery without marked MA blocking at the assessed time-points.

Ischaemic stroke

Stroke is the second highest cause of death globally and a leading cause of disability, with an increasing incidence in developing countries. Ischaemic stroke caused by arterial occlusion is responsible for the majority of strokes. Management focuses on rapid reperfusion with intravenous thrombolysis and endovascular thrombectomy, which both reduce disability but are time-critical. Accordingly, improving the system of care to reduce treatment delays is key to maximizing the benefits of reperfusion therapies. Intravenous thrombolysis reduces disability when administered within 4.5 h of the onset of stroke. Thrombolysis also benefits selected patients with evidence from perfusion imaging of salvageable brain tissue for up to 9 h and in patients who awake with stroke symptoms. Endovascular thrombectomy reduces disability in a broad group of patients with large vessel occlusion when performed within 6 h of stroke onset and in patients selected by perfusion imaging up to 24 h following stroke onset. Secondary prevention of ischaemic stroke shares many common elements with cardiovascular risk management in other fields, including blood pressure control, cholesterol management and antithrombotic medications. Other preventative interventions are tailored to the mechanism of stroke, such as anticoagulation for atrial fibrillation and carotid endarterectomy for severe symptomatic carotid artery stenosis.

Differential effects of hypothermia on neurovascular unit determine protective or toxic results: Toward optimized therapeutic hypothermia

Therapeutic hypothermia (TH) benefits survivors of cardiac arrest and neonatal hypoxic-ischemic injury and may benefit stroke patients. Large TH clinical trials, however, have shown mixed results. Given the substantial pre-clinical literature supporting TH, we explored possible mechanisms for clinical trial variability. Using a standard rodent stroke model (n = 20 per group), we found smaller infarctions after 2 h pre- or post-reperfusion TH compared to 4 h. To explore the mechanism of this discrepancy, we used primary cell cultures of rodent neurons, astrocytes, or endothelial cells subjected to oxygen-glucose deprivation (OGD). Then, cells were randomly assigned to 33℃, 35℃ or 37℃ for varying durations after varying delay times. Both 33 and 35℃ TH effectively preserved all cell types, although 33℃ was superior. Longer cooling durations overcame moderate delays to cooling initiation. In contrast, TH interfered with astrocyte paracrine protection of neurons in a temperature-dependent manner. These findings suggest that longer TH is needed to overcome delays to TH onset, but shorter TH durations may be superior to longer, perhaps due to suppression of astrocytic paracrine support of neurons during injury. We propose a scheme for optimizing TH after cerebral injury to stimulate further studies of cardiac arrest and stroke.

Protecting the ischaemic penumbra as an adjunct to thrombectomy for acute stroke

After ischaemic stroke, brain damage can be curtailed by rescuing the 'ischaemic penumbra' - that is, the severely hypoperfused, at-risk but not yet infarcted tissue. Current evidence-based treatments involve restoration of blood flow so as to salvage the penumbra before it evolves into irreversibly damaged tissue, termed the 'core'. Intravenous thrombolysis (IVT) can salvage the penumbra if given within 4.5 h after stroke onset; however, the early recanalization rate is only ~30%. Direct removal of the occluding clot by mechanical thrombectomy considerably improves outcomes over IVT alone, but despite early recanalization in > 80% of cases, ~50% of patients who receive this treatment do not enjoy functional independence, usually because the core is already too large at the time of recanalization. Novel therapies aiming to 'freeze' the penumbra - that is, prevent core growth until recanalization is complete - hold potential as adjuncts to mechanical thrombectomy. This Review focuses on nonpharmacological approaches that aim to restore the physiological balance between oxygen delivery to and oxygen demand of the penumbra. Particular emphasis is placed on normobaric oxygen therapy, hypothermia and sensory stimulation. Preclinical evidence and early pilot clinical trials are critically reviewed, and future directions, including clinical translation and trial design issues, are discussed.

Effect of HMGB1 and RAGE on brain injury and the protective mechanism of glycyrrhizin in intracranial‑sinus occlusion followed by mechanical thrombectomy recanalization

The key to successful treatment of cerebral venous-sinus occlusion (CVO) is the rapid recanalization of the sinus following venous-sinus occlusion; however, rapid recanalization of the sinus may also cause secondary cerebral injury. The present study examined mechanical thrombectomy-related brain injury and the possible molecular mechanisms following CVO recanalization, and investigated the protective effect of glycyrrhizin (GL) in CVO recanalization. The cerebral venous sinus thrombosis (CVST) model was induced in rats using 40% FeCl₃. Mechanical thrombectomy was performed at 6 h post-thrombosis. GL was administered to rats following thromboembolism. Neurological function and brain water content were measured prior to sacrifice of the rats. Serum malondialdehyde, superoxide dismutase and nitric-oxide synthase concentrations were measured. The expression levels of high-mobility group box 1 (HMGB1) and receptor of advanced glycation end products (RAGE) and its downstream inflammatory mediators were measured in serum and brain tissues. Rapid CVO recanalization caused brain injury, and the brain parenchymal damage and neurological deficits caused by CVO were not completely restored following recanalization. Similarly, following rapid recanalization in the venous sinus, the expression levels of HMGB1 and RAGE were lower than those in the CVST group, but remained significantly higher than those of the sham group. The combination of mechanical thrombectomy and GL improved cerebral infarction and cerebral edema in rats, and inhibited the extracellular transport of HMGB1, and the expression of downstream inflammatory factors and oxidative-stress products. The administration of exogenous recombinant HMGB1 reversed the neural protective effects of GL. In conclusion, mechanical thrombectomy subsequent to CVO in rats can cause brain injury following recanalization. HMGB1 and RAGE promote inflammation in the process of brain injury following recanalization. GL has a relatively reliable neuroprotective effect on brain injury by inhibiting HMGB1 and its downstream inflammatory factors, and decreasing oxidative stress.

Oxycodone suppresses the apoptosis of hippocampal neurons induced by oxygen-glucose deprivation/recovery through caspase-dependent and caspase-independent pathways via κ- and δ-opioid receptors in rats

Cerebral ischemia/reperfusion injury (CIRI) can lead to perioperative neurocognitive disorders (PND) during clinical recanalization procedures in cerebral vessels, principally due to neuronal apoptosis in the hippocampus. Oxycodone appears to be a multiple opioid receptor agonist and exerts intrinsic antinociception activity via κ-opioid receptor (KOR). Recent evidence has revealed that activation of both δ-opioid receptor (DOR) and KOR can provide neuroprotection against CIRI in vivo and in vitro. In our study, we established an oxygen-glucose deprivation/recovery (OGD/R) model with fetal hippocampal neurons and found that oxycodone could induce CIRI tolerance in these neurons, primarily through KOR and DOR. Possible mechanisms might involve the regulatory effect of oxycodone on the MAPK-Bcl2/Bax-caspase-9-caspase-3 pathway, as well as its inhibitory effect on cellular reactive oxygen species (ROS) production and mitochondrial membrane potential activation. Taken together, our findings may indicate a potential method for the prevention and treatment of PND associated with CIRI.

Measurement of collateral perfusion in acute stroke: a vessel-encoded arterial spin labeling study

Collateral perfusion is important for sustaining tissue viability in acute ischemic stroke. Conventional techniques for its visualization are invasive, require contrast agents and demonstrate collateral vessels, rather than measuring perfusion directly. In this study we utilize a non-invasive, non-contrast magnetic resonance imaging (MRI)-based method to directly quantify collateral perfusion in acute stroke patients. Vessel-encoded multi-postlabeling delay arterial spin labeling (ASL) was used to separately quantify the blood flow and blood arrival time from four arteries supplying the brain in patients presenting within 18 hours of stroke onset. Twenty-nine acute ischemic stroke patients were scanned with a median time of onset to first MRI of 3 hours. Collateral perfusion at presentation was associated with tissue fate at 1-week. It sustained tissue prior to reperfusion, but was less effective than direct blood flow at maintaining tissue viability in patients who did not reperfuse. Delay in the blood arrival around the ischemic region was found at presentation and reduced over time but was not consistently associated with collateral perfusion. Vessel-encoded multi-postlabeling delay ASL provides a non-invasive tool for direct measurement of collateral perfusion and delayed blood arrival in acute stroke patients.

Early hemodynamic predictors of good outcome and reperfusion injury after endovascular treatment

Objective

To find early hemodynamic predictors of outcome and reperfusion injury in patients with acute ischemic stroke due to anterior circulation large artery occlusion (LAO) after endovascular treatment (EVT).

Methods

Serial transcranial color-coded sonography examinations assessed the vessel status and cerebral hemodynamics of 185 (109 [58.9%] men, mean age 69.5 ± 12.3 years) consecutive patients with acute anterior circulation LAO soon after, at 48 hours after, and 1 week after EVT.

Results

Successful recanalization (odds ratio [OR] 0.25, 95% confidence interval [CI] 0.11–0.61) and normal peak systolic velocity (PSV) ratio (PSV of recanalized middle cerebral artery/PSV of contralateral middle cerebral artery) at 48 hours (OR 0.22, 95% CI 0.15–0.64) and after 1 week (OR 0.11, 95% CI 0.07–0.31) from EVT were independent predictors of good outcome at 3 months. Thrombectomy failure (OR 10.22, 95% CI 1.47–45.53) and pathologic PSV ratio at 1 week from EVT (OR 15.23, 95% CI 4.54–46.72) were associated with a worse 90-day outcome. Patients who subsequently developed postinterventional intracranial hemorrhage (ICH) showed a higher mean PSV ratio (3.5 ± 0.2 vs 2.4 ± 0.1, p < 0.0001) soon after successful recanalization. In multivariate analysis, early PSV ratio was independently associated with postprocedural ICH (OR 8.474, 95% CI 3.066–45.122, p < 0.01]. At 1 week from EVT, 15 of 21 (71.4%) patients with ICH who resumed normal PSV values had a better 90-day outcome (modified Rankin Scale score 0–2: 40% vs 0%).

Conclusion

Post-EVT ultrasound monitoring of stroke patients might be an effective bedside method for assessing treatment efficacy, shedding light on outcome variability and identifying patients at increased risk of ICH.

Croix CM, Alexander H, Gibson GA, Loughran PA, Kirisci L, Clark RSB, Kochanek PM, Vazquez AL, Manole MD. Cerebral microcirculatory alterations and the no-reflow phenomenon in vivo after experimental pediatric cardiac arrest

Decreased cerebral blood flow (CBF) after cardiac arrest (CA) contributes to secondary ischemic injury in infants and children. We previously reported cortical hypoperfusion with tissue hypoxia early in a pediatric rat model of asphyxial CA. In order to identify specific alterations as potential therapeutic targets to improve cortical hypoperfusion post-CA, we characterize the CBF alterations at the cortical microvascular level in vivo using multiphoton microscopy. We hypothesize that microvascular constriction and disturbances of capillary red blood cell (RBC) flow contribute to cortical hypoperfusion post-CA. After resuscitation from 9 min asphyxial CA, transient dilation of capillaries and venules at 5 min was followed by pial arteriolar constriction at 30 and 60 min (19.6 ± 1.3, 19.3 ± 1.2 µm at 30, 60 min vs. 22.0 ± 1.2 µm at baseline, p < 0.05). At the capillary level, microcirculatory disturbances were highly heterogeneous, with RBC stasis observed in 25.4% of capillaries at 30 min post-CA. Overall, the capillary plasma mean transit time was increased post-CA by 139.7 ± 51.5%, p < 0.05. In conclusion, pial arteriolar constriction, the no-reflow phenomenon and increased plasma transit time were observed post-CA. Our results detail the microvascular disturbances in a pediatric asphyxial CA model and provide a powerful platform for assessing specific vascular-targeted therapies.

Microthrombus-Targeting Micelles for Neurovascular Remodeling and Enhanced Microcirculatory Perfusion in Acute Ischemic Stroke

Reperfusion injury exists as the major obstacle to full recovery of neuron functions after ischemic stroke onset and clinical thrombolytic therapies. Complex cellular cascades including oxidative stress, neuroinflammation, and brain vascular impairment occur within neurovascular units, leading to microthrombus formation and ultimate neuron death. In this work, a multitarget micelle system is developed to simultaneously modulate various cell types involved in these events. Briefly, rapamycin is encapsulated in self-assembled micelles that are consisted of reactive oxygen species (ROS)-responsive and fibrin-binding polymers to achieve micelle retention and controlled drug release within the ischemic lesion. Neuron survival is reinforced by the combination of micelle facilitated ROS elimination and antistress signaling pathway interference under ischemia conditions. In vivo results demonstrate an overall remodeling of neurovascular unit through micelle polarized M2 microglia repair and blood-brain barrier preservation, leading to enhanced neuroprotection and blood perfusion. This strategy gives a proof of concept that neurovascular units can serve as an integrated target for ischemic stroke treatment with nanomedicines.

Eventual analysis of global cerebral ischemia-reperfusion injury in rat brain: a paradigm of a shift in stress and its influence on cognitive functions

Cognitive issues in stroke arise as a result of reperfusion of a clogged artery, which is reported to exacerbate the injury in the brain leading to oxidative stress. Through the present work, we try to understand the regional variations across brain regions mainly cortex and striatum associated with the progression of ischemia-reperfusion injury (IRI). In a rat model of IRI, the influence of varying ischemia and reperfusion times on the biochemical phases across the brain regions were monitored. IRI resulted in the blood-brain barrier disruption and developed mild areas of risk. The brain's tolerance towards IRI indicated a progressive trend in the injury and apoptosis from ischemia to reperfusion that was supported by the activities of plasma lactate dehydrogenase and tissue caspase-3. Cognitive impairment in these rats was an implication of cellular oxidative stress (higher lipid peroxidation and lower antioxidant enzyme activity) that persisted by 24-h reperfusion. The oxidative stress was prominent in the cortex than the striatum and was supported by the lower ATP level. Upregulated Mn-SOD expression leading to a preserved mitochondria in the striatum could be attributed to the regional protection. Overall, a progression of IRI was observed from striatum to cortex leading to 5-day cognitive decline.

Outcome estimation based on multimodal computed tomography examination in acute ischaemic stroke patients treated with mechanical thrombectomy

Introduction

Reperfusion therapy for acute ischaemic stroke used within a time window of 6 h following symptom onset, although currently the treatment of choice, is characterised by certain limitations and carries certain risks.

Aim

To assess the potential for predicting the risks and limitations of reperfusion therapy by means of advanced neuroimaging.

Material and methods

For this purpose, the baseline CT scans of patients with ischaemic stroke treated by means of mechanical thrombectomy were assessed retrospectively using the Combined Multimodal Computed Tomography Score (CMCTS), modified to account for the perfusion examination of a limited area. These data were then combined with radiological and clinical outcomes, in particular haemorrhagic stroke transformation and scoring on a modified Rankin scale (mRS).

Results

Based on material from 85 patients, the scoring system we employed enabled us to distinguish a group that did not benefit from treatment with specificity and a positive predictive value of 100%, and a negative predictive value of 64%. Neither the relationship between the score and early haemorrhagic complications, nor the effectiveness or severity of the course of the thrombectomy procedure itself was confirmed.

Conclusions

There is no justification for the use of reperfusion procedures in acute ischaemic stroke in the anterior circulation in patients with initially unfavourable multimodal computed tomography scores.

The effect of repeated remote ischemic postconditioning on infarct size in patients with an ischemic stroke (REPOST): study protocol for a randomized clinical trial

Background

Remote ischemic postconditioning (rIPostC) refers to the observation that repeated, short periods of ischemia protect remote areas against tissue damage during and after prolonged ischemia. Based on previous observations of a potential neuroprotective effect of rIPostC, the aim of this study is to evaluate whether repeated rIPostC after an ischemic stroke can reduce infarct size, which could be translated to an improvement in clinical outcomes.

Methods/design

We will enroll 200 ischemic stroke patients to daily rIPostC or sham conditioning during hospitalization into a randomized single-blind placebo-controlled trial. The intervention consists of twice daily exposure to four cycles of 5-min cuff inflation around the upper arm to > 20 mmHg above systolic blood pressure (i.e., rIPostC) or 50 mmHg (i.e., control), followed by 5 minutes of deflation. The primary outcome is infarct size, measured using an MRI diffusion-weighted image at the end of hospitalization. Secondary outcomes include the Modified Rankin Scale, National Institutes of Health Stroke Scale, quality of life, and cardiovascular and cerebrovascular morbidity and mortality. To explore possible underlying mechanisms of rIPostC, venous blood will be sampled to assess biomarkers of inflammation and vascular health.

Discussion

Previous studies in animals and humans, using a single bout of remote ischemic conditioning, report a potential effect of rIPostC in attenuating neural damage. Although repeated rIPostC has been investigated for cardiovascular disease patients and preclinical stroke models, no previous study has explored the potential physiological and clinical effects of repeatedly applying rIPostC during the hospitalization phase after a stroke.

Trial registration

Netherlands Trial Register, NTR6880. Registered on 8 December 2017.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3264-0) contains supplementary material, which is available to authorized users.

Neuroprotection and vasculoprotection using genetically targeted protease-ligands

Thrombin and activated protein C (APC) are known coagulation factors that exhibit profound effects in brain by acting on the protease activated receptor (PAR). The wild type (WT) proteases appear to impact cell survival powerfully, and therapeutic forms of APC are under development. Engineered recombinant thrombin or APC were designed to separate their procoagulant or anticoagulant effects from their cytoprotective properties. We measured vascular disruption and neuronal degeneration after a standard rodent filament stroke model. For comparison to a robust anticoagulant, we used a GpIIb/IIIa inhibitor, GR144053. During 2 h MCAo both WT murine APC and its mutant, 5A-APC, significantly decreased neuronal death 30 min after reperfusion. During 4 h MCAo, only 5A-APC significantly protected neurons but both WT-APC and 5A-APC exacerbated vascular disruption during 4 h MCAo. Human APC mutants appeared to reduce 24 h neuronal injury significantly when given after 2 h delay after MCAo. In contrast, 24 h vascular damage was worsened by high doses of WT and mutant APCs, although only statistically significantly for high dose 3K3A-APC. Mutated thrombin worsened vascular damage significantly without affecting neuron damage. GR144053 failed to ameliorate vascular disruption or neuronal injury despite significant anticoagulation. Differential effects on neurons and the vasculature were demonstrated using wild-type and mutated proteases. The mutants murine 3K3A-APC and 5A-APC protected neurons in this rodent model but in high doses worsened vascular leakage. Cytoactive effects of plasma proteases may be separated from their coagulation effects. Further studies should explore impact of dose and timing on cytoactive and vasculoactive properties of these drugs.

Late-onset "white cord syndrome" in an elderly patient after posterior cervical decompression and fusion: a case report

Introduction

In 2013, a rare early complication following cervical decompression the so-called "white cord syndrome" (WCS) was described for first time. This designation was given on the basis of the postoperative appearance of intramedullary hypertense areas in T2-MRI, resulting in devastating neurological damage. To our knowledge, only three cases of WCS have been published; we hereby present the fourth case, but the first one with late-onset presentation of this syndrome.

Case presentation

A 79-year-old male patient with Nurick grade 3 CSM was referred to our institution. He had already had a double-level C4-C6 anterior cervical decompression and fusion (ACDF) 2 years ago in another institution. The patient underwent posterior decompression from C3 to C6 plus C2-C7 lateral mass screw fusion. Within the first 24 h following surgery, he gradually developed C6 incomplete paraplegia (ASIA B). Cervical MRI disclosed a hypertensive signal in T2-weighted sequences at C6-C7 levels and the diagnosis of WCS was suspected. Revision surgery was made 30 h following our first surgery, with wider posterior decompression accompanied by intravenous methylprednisolone. The patient's neurologic status was improved, but the final neurologic outcome was worse (Nurick 4) than the preoperative status and subsequently did not change at all.

Discussion

To the best of our knowledge, this is the first report of a late-onset WCS and the fourth case of WCS per se. Spine surgeons should be aware of this rare but serious complication. We highlight possible risk factors and review the literature on the hypotheses about the pathophysiology of WCS.

Management of Blood Pressure During and After Recanalization Therapy for Acute Ischemic Stroke

Ischemic stroke is a common neurologic condition and can lead to significant long term disability and death. Observational studies have demonstrated worse outcomes in patients presenting with the extremes of blood pressure as well as with hemodynamic variability. Despite these associations, optimal hemodynamic management in the immediate period of ischemic stroke remains an unresolved issue, particularly in the modern era of revascularization therapies. While guidelines exist for BP thresholds during and after thrombolytic therapy, there is substantially less data to guide management during mechanical thrombectomy. Ideal blood pressure targets after attempted recanalization depend both on the degree of reperfusion achieved as well as the extent of infarction present. Following complete reperfusion, lower blood pressure targets may be warranted to prevent reperfusion injury and promote penumbra recovery however prospective clinical trials addressing this issue are warranted.

Ultrasound Identification of Patients at Increased Risk of Intracranial Hemorrhage After Successful Endovascular Recanalization for Acute Ischemic Stroke

BACKGROUND

Intracranial hemorrhage (ICH) is the most feared complication of endovascular treatment (EVT) for acute ischemic stroke because of anterior circulation large vessel occlusion (LVO). The purpose of this study was to identify cerebral hemodynamic predictors of ICH and poor outcome in patients with successful recanalization.

METHODS

Serial transcranial color-coded sonography (TCCS) examinations assessed vessel status and cerebral hemodynamics of 226 (mean age, 69.8 ± 12.5 years; 130 men [57.5%]) consecutive patients with acute anterior circulation LVO at 48 hours and 1 week after EVT. Middle cerebral artery peak systolic velocity (PSV_MCA) and PSV_MCA ratio (recanalized PSV_MCA/contralateral PSV_MCA) were recorded.

RESULTS

Out of 180 successfully recanalized patients (79.6%), 28 patients (15.5%) had ICH. They more often had arterial hypertension (25/28 [89.3%] vs. 106/152 [69.7%], P = 0.04), a more severe stroke syndrome (18 [range, 10-23] vs. 16 [range, 5-26], P = 0.01), a worse clinical outcome (90-day modified Rankin Scale [mRS] score 3-5: 16/28 [57.1%] vs. 42/152 [27.6%], P = 0.004), and soon after EVT showed a significantly higher mean PSV_MCA ratio (3.4 ± 0.1 vs. 2.4 ± 0.1, P < 0.0001) than patients without ICH, respectively. In multivariate analysis, early PSV_MCA ratio was independently associated with postinterventional ICH (odds ratio, 13.379; 95% confidence interval, 2.466-50.372; P < 0.01). The patients with ICH (19/28 [67.9%]) who resumed normal PSV_MCA values at 1 week after EVT had a better outcome (90-day mRS score 0-2: 8/19 [42.1%] vs. 0/9 [0%], respectively).

CONCLUSIONS

Early TCCS detection of a high PSV_MCA ratio in successfully recanalized stroke patients indicates an increased risk of ICH, whereas cerebral hemodynamics normalization at 1 week in patients with postinterventional ICH predicts a relatively better 3-month outcome.

Pharmacodynamic Effect of Luteolin Micelles on Alleviating Cerebral Ischemia Reperfusion Injury

Oxidative stress and inflammation are important mechanisms of cerebral ischemia reperfusion (IR) injury. Luteolin (Lu), one of the major active components in the classical Tibetan prescription, which has been used in the treatment of cardiovascular diseases since 700 BC, has potential for IR injury therapy. Its hydrophobicity has impeded its further applications. In this study, we first prepared Lu micelles (M-Lu) by self-assembling with an amphiphilic copolymer via the thin film hydration method to improve the dispersion of Lu in water. The obtained M-Lu was about 30 nm, with a narrow particle size distribution, and a 5% (w/w) of Lu. The bioavailability of the micelles was further evaluated in vitro and in vivo. Compared to free Lu, M-Lu had a better penetration efficiency, which enhanced its therapeutic effect in IR injury restoration. M-Lu further strengthened the protection of nerve cells through the nuclear factor-κ-gene binding κ (NF-κB) and mitogen-activated protein kinases (MAPK) pathways and inhibited the apoptosis of cells by adjusting the expression of B-cell lymphoma-2 (Bcl-2) and Bcl-2 associated X protein (Bax) in the case of oxidative stress damage. M-Lu induced stem cells to differentiate into neuron-like cells to promote the repair and regeneration of neurons. The results of in vivo pharmacodynamics of Lu on occlusion of the middle cerebral artery model further demonstrated that M-Lu better inhibited inflammation and the oxidative stress response by the down-regulation of the inflammatory cytokine, including tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6, and the up-regulation of the activity of anti-oxidant kinase, such as superoxide dismutase (SOD) and glutathione peroxidase (GSH-px), which further ameliorated the degree of IR injury. The M-Lu could be a new strategy for IR injury therapy.

Bone marrow mesenchymal stem cell transplantation exerts neuroprotective effects following cerebral ischemia/reperfusion injury by inhibiting autophagy via the PI3K/Akt pathway

Although cerebral ischemia itself is associated with a high rate of disability, secondary cerebral ischemia/reperfusion (I/R) injury following recanalization is associated with much more severe outcomes. The mechanisms underlying cerebral I/R injury are complex, involving neuronal death caused by apoptosis and autophagy. Autophagy is critical for cell survival and plays an important role in the pathogenesis of cerebral I/R injury. Research has indicated that transplantation of bone marrow mesenchymal stem cells (BMSCs) is effective in repairing and reconstructing brain tissue, and that this effect may be associated with the regulation of autophagy. To explore this hypothesis, we intravenously transplanted BMSCs into a rat model of cerebral I/R injury (middle cerebral artery occlusion [MCAO]). Our results indicated that BMSCs transplantation promoted behavioral recovery, reduced cerebral infarction volume, and decreased the number of apoptotic cells in rats exposed to cerebral I/R injury. Moreover, this effect was associated with reduced expression of the autophagy-associated proteins microtubule-associated protein 1 light chain 3 (LC3) and Beclin-1. Furthermore, BMSCs remarkably increased the expression of p-Akt and p-mTOR following cerebral I/R injury. Expression of LC3 also increased when the PI3K pathway was blocked using LY294002. In summary, our results indicated that the protective effects of BMSCs in cerebral I/R injury may be associated with the inhibition of autophagy via the activation of the PI3K/Akt/mTOR signaling pathway.

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.

Antioxidant-mediated neuroprotection by Allium schoenoprasum L. leaf extract against ischemia reperfusion-induced cerebral injury in mice

Background Oxidative stress is strongly implicated in ischemia reperfusion (IR)-mediated functional and neuronal impairment. Therefore, strategies employing antioxidants to reverse the damage due to IR are being investigated. Allium schoenoprasum L. is a culinary medicine whose antioxidant properties are well documented but whose neuroprotective potential has not been examined. Hence, the present study was designed to evaluate the effect of A. schoenoprasum leaf extract (ASLE) on functional deficit against IR-induced cerebral injury in mice. Methods Acute toxicity studies of ASLE were performed following the Organisation for Economic Co-operation and Development Guideline 423. IR injury was induced by bilateral common carotid artery occlusion (BCCAO) for 15 min followed by 24-h reperfusion. Animals were treated for 7 days with ASLE (200 and 400 mg/kg, p.o. once daily) after IR injury. Functional outcomes (memory and sensorimotor functions) were measured using Morris water maze and neurological severity score, respectively. Cerebral infarct size and oxidative stress (thiobarbituric acid reactive species (TBARS), reduced glutathione (GSH), and superoxide dismutase (SOD) activity) were measured in order to elucidate the neuroprotective mechanism of ASLE. Results No toxic effects of ASLE were observed in mice. Oral treatment with ASLE for 7 days significantly attenuated IR-mediated memory and sensorimotor function deficit in the animals. The extract also reduced the cerebral infarct size and rise in brain TBARS levels, and restored the GSH levels and SOD activity. Conclusions The results of the present study suggest that ASLE is safe and effective in improving functional outcomes. It demonstrates neuroprotective effect by enhancing the antioxidant defence against IR injury.

The 10th Biennial Hatter Cardiovascular Institute workshop: cellular protection-evaluating new directions in the setting of myocardial infarction, ischaemic stroke, and cardio-oncology

Due to its poor capacity for regeneration, the heart is particularly sensitive to the loss of contractile cardiomyocytes. The onslaught of damage caused by ischaemia and reperfusion, occurring during an acute myocardial infarction and the subsequent reperfusion therapy, can wipe out upwards of a billion cardiomyocytes. A similar program of cell death can cause the irreversible loss of neurons in ischaemic stroke. Similar pathways of lethal cell injury can contribute to other pathologies such as left ventricular dysfunction and heart failure caused by cancer therapy. Consequently, strategies designed to protect the heart from lethal cell injury have the potential to be applicable across all three pathologies. The investigators meeting at the 10th Hatter Cardiovascular Institute workshop examined the parallels between ST-segment elevation myocardial infarction (STEMI), ischaemic stroke, and other pathologies that cause the loss of cardiomyocytes including cancer therapeutic cardiotoxicity. They examined the prospects for protection by remote ischaemic conditioning (RIC) in each scenario, and evaluated impasses and novel opportunities for cellular protection, with the future landscape for RIC in the clinical setting to be determined by the outcome of the large ERIC-PPCI/CONDI2 study. It was agreed that the way forward must include measures to improve experimental methodologies, such that they better reflect the clinical scenario and to judiciously select combinations of therapies targeting specific pathways of cellular death and injury.

Evidence from functional ultrasound imaging of enhanced contralesional microvascular response to somatosensory stimulation in acute middle cerebral artery occlusion/reperfusion in rats: A marker of ultra-early network reorganization?

Following middle cerebral artery (MCA) stroke, enhanced contralesional evoked responses have been consistently reported both in man and rodents as part of plastic processes thought to influence motor recovery. How early this marker of large-scale network reorganization develops has however been little addressed, yet has clinical relevance for rehabilitation strategies targeting plasticity. Previous work in mice has reported enhanced contralesional responses to unaffected-side forepaw stimulation as early as 45 min after MCA small branch occlusion. Using functional ultrasound imaging (fUSi) in anesthetized rats subjected to distal temporary MCA occlusion (MCAo), we assessed here (i) whether enhanced contralesional responses also occurred with unaffected-side whisker pad stimulation, and if so, how early after MCAo; and (ii) the time course of this abnormal response during occlusion and after reperfusion. We replicate in a more proximal MCA occlusion model the earlier findings of ultra-early enhanced contralesional evoked responses. In addition, we document this phenomenon within minutes after MCAo, and its persistence throughout the entire 90-min occlusion as well as 90-min reperfusion periods studied. These findings suggest that plastic processes may start within minutes following MCAo in rodents. If replicated in man, they might have implications regarding how early plasticity-enhancing therapies can be initiated after stroke.

Emergent Uric Acid Treatment is Synergistic with Mechanical Recanalization in Improving Stroke Outcomes in Male and Female Rats

Preclinical and clinical studies support a promising, albeit not definitive, neuroprotective effect of emergent uric acid (UA) administration in ischemic stroke. We assessed the effects of UA in an ischemic stroke model relevant to the current treatment paradigm of mechanical thrombectomy within the STAIR/RIGOR recommendations. A cohort of male and female Wistar rats was subjected to ischemic stroke with mechanical recanalization under physiological monitoring. The effects of transient middle cerebral artery occlusion (tMCAO) with adjunctive UA (IV, 16 mg/kg) or vehicle treatment were assessed at 24 h and 7 days. Outcomes included neurofunctional impairment, brain infarct (TTC staining, MRI imaging and cresyl violet staining) and edema. At 24 h after tMCAO, neurofunctional scores and brain infarct were significantly reduced in rats subjected to UA treatment compared to vehicle, with a selective effect of UA on cortical infarct. No differential effect of UA between male and female rats was evidenced, as no significant interaction of sex with stroke outcomes was found. Rats achieving higher reperfusion levels after tMCAO showed superior reduction of neurofunctional impairment, cortical infarct and edema by UA. After a 7-day follow-up, male rats subjected to UA treatment still showed reductions in neurofunctional impairment and infarct size, compared to vehicle treatment. In conclusion, UA treatment immediately after transient ischemia results in a sex-independent, maintained reduction of brain damage and neurological impairment, better manifested in hyperperfusion conditions. This synergistic effect of UA with mechanical recanalization supports additional clinical testing of UA as an adjunctive treatment to mechanical thrombectomy.

Remote ischaemic conditioning for preventing and treating ischaemic stroke

BACKGROUND

Remote ischaemic conditioning (RIC) has been developed as a neuroprotective strategy to prevent and treat ischaemic stroke. It usually involves restricting blood flow to limbs and then releasing the ischaemic blood to promote a neuroprotective effect. Preclinical studies have suggested that RIC may have beneficial effects in ischaemic stroke patients and those at risk of ischaemic stroke. However, existing evidence is insufficient to demonstrate the efficacy and safety of RIC in preventing and treating ischaemic stroke.

OBJECTIVES

To assess the benefits and harms of RIC for preventing ischaemic stroke and for treating people with ischaemic stroke and those at risk for ischaemic stroke.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (16 January 2018), the Cochrane Central Register of Controlled Trials (CENTRAL; 2017, Issue 12) in the Cochrane Library (January 2018), MEDLINE Ovid (1946 to January 2018), Embase Ovid (1974 to January 2018), Web of Science Core Collection (1950 to January 2018) and three Chinese databases (January 2018). We also searched four ongoing trials registers, reference lists, and conference proceedings.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing RIC with sham RIC or medical management in people with ischaemic stroke or at risk of ischaemic stroke.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies, assessed trial quality and risk of bias, and extracted data. We used the GRADE approach to assess the quality of the evidence.

MAIN RESULTS

We included seven trials, involving 735 participants, in this review. We analysed the effects of RIC on preventing and treating ischaemic stroke respectively.We evaluated risk of bias and judged it to be low for generation of allocation sequence in six studies and unclear in one study; unclear for allocation concealment in four studies and low in three studies; high for incomplete outcome data (attrition bias) in five studies and low in two studies; high for blinding in three studies and low in four studies; low for selective reporting; and high for other sources of bias in six studies and low in one study.We included three trials (involving 371 participants) in the analysis of the effects of RIC on ischaemic stroke prevention. In people with symptomatic intracerebral artery stenosis, recurrent stroke was significantly reduced by RIC (risk ratio (RR) 0.32, 95% confidence interval (CI) 0.12 to 0.83; 2 trials, 182 participants, low-quality evidence). In people with carotid stenosis undergoing carotid stenting, there was no significant difference in the incidence of ischaemic stroke between participants treated with RIC and non-RIC (RR 0.22, 95% CI 0.01 to 4.03; 1 trial, 189 participants, low-quality evidence); however the stroke severity (assessed by infarct volume) was significantly lower in participants treated with RIC (mean difference (MD) -0.17 mL, 95% CI -0.23 to -0.11; 1 trial, 189 participants, low-quality evidence). Adverse events associated with RIC were significantly higher in participants treated with RIC (RR 10.91; 95% CI 2.01 to 59.28; 3 trials, 371 participants, low-quality evidence), but no severe adverse event was attributable to RIC treatment. No participants experienced death or cardiovascular events during the period of the studies; and no trial reported haemorrhagic stroke or improvement in neurological, phycological or cognitive impairment.We included four trials (involving 364 participants) in the analysis of the effects of RIC on ischaemic stroke treatment. In acute ischaemic stroke, for people receiving intravenous thrombolysis, the rate of death or dependency was significantly increased by RIC treatment compared with non-RIC treatment (RR 2.34; 95% 1.19 to 4.61; 1 trial, 285 participants, low-quality evidence). In people with acute ischaemic stroke, there was no significant difference between RIC and non-RIC for reducing stroke severity as assessed by the National Institutes of Health Stroke Scale score and the final infarct volume (standardised mean difference (SMD) -0.24 mL, 95% CI -1.02 to 0.54; 2 trials, 175 participants, very low quality evidence). There was no significant difference between RIC and non-RIC for improving the psychological impairment (SMD -0.37 points, 95% CI -1.15 to 0.41; 1 trial, 26 participants, very low quality evidence) and the cognitive impairment (SMD -0.26 points; 95% CI -0.72 to 0.21; 3 trials, 79 participants, low-quality evidence) in people with acute ischaemic stroke and cerebral small vessel disease. No trial reported ischaemic stroke, recurrent ischaemic stroke, improvement in neurological impairment, hemorrhagic stroke, cardiovascular events, and RIC associated adverse events.

AUTHORS' CONCLUSIONS

We found low-quality evidence that RIC may reduce the risk of recurrent stroke in participants with intracerebral artery stenosis and reduce stroke severity in participants undergoing carotid stenting, but it may increase death or dependence in participants with acute ischaemic stroke who are undergoing intravenous thrombolysis. However, there is considerable uncertainty about these conclusions because of the small number of studies and low quality of the evidence.

Bicuculline Reverts the Neuroprotective Effects of Meloxicam in an Oxygen and Glucose Deprivation (OGD) Model of Organotypic Hippocampal Slice Cultures

We previously demonstrated that the non-steroidal anti-inflammatory agent meloxicam has neuroprotective effects in an oxygen and glucose deprivation model (OGD) of rat organotypic hippocampal slice cultures. We wondered if GABAergic transmission changed the neuroprotective effects of meloxicam and if meloxicam was able to modulate endoplasmic reticulum stress (ER stress) in this model. Mortality was measured using propidium iodide. Western blot assays were performed to measure levels of cleaved and non-cleaved caspase-3 to quantify apoptosis, while levels of GRP78, GRP94 and phosphorylated eIF2α were used to detect unfolded protein response (UPR). Transcript levels of GRP78, GRP94 and GABAergic receptor α, β, and γ subunits were measured by real-time quantitative polymerase chain reaction (qPCR). In the present study, we show that the presence of meloxicam in a 30 min OGD assay, followed by 24 h of normoxic conditions, presented an antiapoptotic effect. The simultaneous presence of the GABA_A receptor antagonist, bicuculline, in combination with meloxicam blocked the neuroprotective effect provided by the latter. However, in light of its effects on caspase 3 and PARP, bicuculline did not seem to promote the apoptotic pathway. Our results also showed that meloxicam modified the unfolded protein response (UPR), as well as the transcriptional response of different genes, including the GABA_A receptor, alpha1, beta3 and gamma2 subunits. We concluded that meloxicam has a neuroprotective anti-apoptotic action, is able to enhance the UPR independently of the systemic anti-inflammatory response and its neuroprotective effect can be inhibited by blocking GABA_A receptors.

Sema3E/PlexinD1 inhibition is a therapeutic strategy for improving cerebral perfusion and restoring functional loss after stroke in aged rats

Brain tissue survival and functional recovery after ischemic stroke greatly depend on cerebral vessel perfusion and functional collateral circulation in the ischemic area. Semaphorin 3E (Sema3E), one of the class 3 secreted semaphorins, has been demonstrated to be a critical regulator in embryonic and postnatal vascular formation via binding to its receptor PlexinD1. However, whether Sema3E/PlexinD1 signaling is involved in poststroke neovascularization remains unknown. To determine the contribution of Sema3E/PlexinD1 signaling to poststroke recovery, aged rats (18 months) were subjected to a transient middle cerebral artery occlusion. We found that depletion of Sema3E/PlexinD1 signaling with lentivirus-mediated PlexinD1-specific-shRNA improves tissue survival and functional outcome. Sema3E/PlexinD1 inhibition not only increases cortical perfusion but also ameliorates blood-brain barrier damage, as determined by positron emission tomography and magnetic resonance imaging. Mechanistically, we demonstrated that Sema3E suppresses endothelial cell proliferation and angiogenic capacity. More importantly, Sema3E/PlexinD1 signaling inhibits recruitment of pericytes by decreasing production of platelet derived growth factor-BB in endothelial cells. Overall, our study revealed that inhibition of Sema3E/PlexinD1 signaling in the ischemic penumbra, which increases both endothelial angiogenic capacity and recruitment of pericytes, contributed to functional neovascularization and blood-brain barrier integrity in the aged rats. Our findings imply that Sema3E/PlexinD1 signaling is a novel therapeutic target for improving brain tissue survival and functional recovery after ischemic stroke.

Underlying mechanism of subcortical brain protection during hypoxia and reoxygenation in a sheep model - Influence of α1-adrenergic signalling

While the cerebral autoregulation sufficiently protects subcortical brain regions during hypoxia or asphyxia, the cerebral cortex is not as adequately protected, which suggests that regulation of the cerebral blood flow (CBF) is area-specific. Hypoxia was induced by inhalation of 5% oxygen, for reoxygenation 100% oxygen was used. Cortical and subcortical CBF (by laser Doppler flowmetry), blood gases, mean arterial blood pressure (MABP), heart rate and renal blood flow were constantly monitored. Low dosed urapidil was used for α1A-adrenergic receptor blockade. Western blotting was used to determine adrenergic receptor signalling mediators in brain arterioles. During hypoxia cortical CBF decreased to 72 ± 11% (mean reduction 11 ± 3%, p < 0.001) of baseline, whereas subcortical CBF increased to 168±18% (mean increase 43 ± 5%, p < 0.001). Reoxygenation led to peak CBF of 194 ± 27% in the subcortex, and restored cortical CBF. α1A-Adrenergic blockade led to minor changes in cortical CBF, but massively reduced subcortical CBF during hypoxia and reoxygenation–almost aligning CBF in both brain regions. Correlation analyses revealed that α1A-adrenergic blockade renders all CBF-responses pressure-passive during hypoxia and reoxygenation, and confirmed the necessity of α1A-adrenergic signalling for coupling of CBF-responses to oxygen saturation. Expression levels and activation state of key signalling-mediators of α1-receptors (NOSs, CREB, ERK1/2) did not differ between cortex and subcortex. The dichotomy between subcortical and cortical CBF during hypoxia and reoxygenation critically depends on α1A-adrenergic receptors, but not on differential expression of signalling-mediators: signalling through the α1A-subtype is a prerequisite for cortical/subcortical redistribution of CBF.

Reperfusion Injury after ischemic Stroke Study (RISKS): single-centre (Florence, Italy), prospective observational protocol study

INTRODUCTION

Treatments aiming at reperfusion of the acutely ischaemic brain tissue may result futile or even detrimental because of the so-called reperfusion injury. The processes contributing to reperfusion injury involve a number of factors, ranging from blood-brain barrier (BBB) disruption to circulating biomarkers. Our aim is to evaluate the relative effect of imaging and circulating biomarkers in relation to reperfusion injury.

METHODS AND ANALYSIS

Observational hospital-based study that will include 140 patients who had ischaemic stroke, treated with systemic thrombolysis, endovascular treatment or both. BBB disruption will be assessed with CT perfusion (CTP) before treatment, and levels of a large panel of biomarkers will be measured before intervention and after 24 hours. Relevant outcomes will include: (1) reperfusion injury, defined as radiologically relevant haemorrhagic transformation at 24 hours and (2) clinical status 3 months after the index stroke. We will investigate the separate and combined effect of pretreatment BBB disruption and circulating biomarkers on reperfusion injury and clinical status at 3 months. Study protocol is registered at http://www.clinicaltrials.gov (ClinicalTrials.gov ID: NCT03041753).

ETHICS AND DISSEMINATION

The study protocol has been approved by ethics committee of the Azienda Ospedaliero Universitaria Careggi (Università degli Studi di Firenze). Informed consent is obtained by each patient at time of enrolment or deferred when the participant lacks the capacity to provide consent during the acute phase. Researchers interested in testing hypotheses with the data are encouraged to contact the corresponding author. Results from the study will be disseminated at national and international conferences and in medical thesis.

TRIAL REGISTRATION NUMBER

NCT03041753.

Remote Ischemic Conditioning in Cerebral Diseases and Neurointerventional Procedures: Recent Research Progress

Cerebral ischemia and stroke are increasing in prevalence and are among the leading causes of morbidity and mortality in both developed and developing countries. Despite the progress in endovascular treatment, ischemia/reperfusion (IR) injury is an important contributor to post-surgical mortality and morbidity affecting a wide range of neurointerventional procedures. However, pharmacological recruitment of effective cerebral protective signaling has been largely disappointing to date. In remote ischemic conditioning (RIC), repetitive transient mechanical obstruction of vessels at a limb remote from the IR injury site protects vital organs from IR injury and confers infarction size reduction following prolonged arterial occlusion. Results of pharmacologic agents appear to be species specific, while RIC is based on the neuroprotective influences of phosphorylated protein kinase B, signaling proteins, nitric oxide, and transcriptional activators, the benefits of which have been confirmed in many species. Inducing RIC protection in patients undergoing cerebral vascular surgery or those who are at high risk of brain injury has been the subject of research and has been enacted in clinical settings. Its simplicity and non-invasive nature, as well as the flexibility of the timing of RIC stimulus, also makes it feasible to apply alongside neurointerventional procedures. Furthermore, despite nonuniform RIC protocols, emerging literature demonstrates improved clinical outcomes. The aims of this article are to summarize the potential mechanisms underlying different forms of conditioning, to explore the current translation of this paradigm from laboratory to neurovascular diseases, and to outline applications for patient care.

Hydroxysafflor yellow a protects brain microvascular endothelial cells against oxygen glucose deprivation/reoxygenation injury: Involvement of inhibiting autophagy via class I PI3K/Akt/mTOR signaling pathway

The present study aimed to test whether Hydroxysafflor yellow A (HSYA) protects the brain microvascular endothelial cells (BMECs) injury induced by oxygen glucose deprivation/reoxygenation (OGD/R) via the PI3K/Akt/mTOR autophagy signaling pathway. Primary rat BMECs were cultured and identified by the expression of factor VIII-related antigen before being exposed to OGD/R to imitate ischemia/reperfusion (I/R) damage in vitro. The protective effect of HSYA was evaluated by assessing (1) cellular morphologic and ultrastructural changes; (2) cell viability and cytotoxicity; (3) transendothelial electrical resistance (TEER) of monolayer BMECs; (4) cell apoptosis; (5) fluorescence intensity of LC3B; (6) LC3 mRNA expression; (7) protein expressions of LC3, Beclin-1, Zonula occludens-1 (ZO-1), phospho-Akt (p-Akt), Akt, phospho-mTOR (p-mTOR) and mTOR. It was found that HSYA (20, 40, and 80 μM) and 3-MA effectively reversed the cellular morphological and ultrastructural changes, increased cell survival, normalized the permeability of BMECs, and suppressed apoptosis induced by OGD/R (2 h OGD followed by 24 h reoxygenation). Concurrently, HSYA and 3-MA also inhibited OGD/R-induced autophagy evidenced by the decreased number of autophagosomes and down-regulated levels of LC3 and Beclin-1 proteins and mRNAs. HSYA (80 μM), in combination with 3-MA showed a synergistic effect. Mechanistic studies revealed that HSYA (80 μM) markedly increased the levels of p-Akt and p-mTOR proteins. Blockade of PI3K activity by ZSTK474 abolished its anti-autophagic and pro-survival effect and lowered both Akt and mTOR phosphorylation levels. Taken together, these results suggest that HSYA protects BMECs against OGD/R-induced injury by inhibiting autophagy via the Class I PI3K/Akt/mTOR signaling pathway.

Early Blood-Brain Barrier Disruption after Mechanical Thrombectomy in Acute Ischemic Stroke

BACKGROUND AND PURPOSE

The impact of blood-brain barrier (BBB) disruption can be detected by intraparenchymal hyperdense lesion on the computed tomography (CT) scan after endovascular stroke therapy. The purpose of this study was to determine whether early BBB disruption predicts intracranial hemorrhage and poor outcome in patients with acute ischemic stroke treated with mechanical thrombectomy.

METHODS

We analyzed patients with anterior circulation stroke treated with mechanical thrombectomy and identified BBB disruption on the noncontrast CT images immediately after endovascular treatment. Follow-up CT or magnetic resonance imaging scan was performed at 24 hours to assess intracranial hemorrhage. We dichotomized patients into those with moderate BBB disruption versus those with minor BBB disruption and no BBB disruption. We evaluated the association of moderate BBB disruption after mechanical thrombectomy with intracranial hemorrhage and clinical outcomes.

RESULTS

Moderate BBB disruption after mechanical thrombectomy was found in 56 of 210 patients (26.7%). Moderate BBB disruption was independently associated with higher rates of hemorrhagic transformation (OR 25.33; 95% CI 9.93-64.65; P < .001), parenchymal hematoma (OR 20.57; 95% CI 5.64-74.99; P < .001), and poor outcome at discharge (OR 2.35; 95% CI 1.09-5.07; P = .03). The association of BBB disruption with intracranial hemorrhage remained in patients with successful reperfusion after mechanical thrombectomy. The location of BBB disruption was not associated with intracranial hemorrhage and poor outcome.

CONCLUSIONS

Moderate BBB disruption is common after mechanical thrombectomy in a quarter of patients with acute ischemic stroke and increases the risk of intracranial hemorrhage and poor outcome.

Atherothrombosis and Thromboembolism: Position Paper from the Second Maastricht Consensus Conference on Thrombosis

Atherothrombosis is a leading cause of cardiovascular mortality and long-term morbidity. Platelets and coagulation proteases, interacting with circulating cells and in different vascular beds, modify several complex pathologies including atherosclerosis. In the second Maastricht Consensus Conference on Thrombosis, this theme was addressed by diverse scientists from bench to bedside. All presentations were discussed with audience members and the results of these discussions were incorporated in the final document that presents a state-of-the-art reflection of expert opinions and consensus recommendations regarding the following five topics: 1. Risk factors, biomarkers and plaque instability: In atherothrombosis research, more focus on the contribution of specific risk factors like ectopic fat needs to be considered; definitions of atherothrombosis are important distinguishing different phases of disease, including plaque (in)stability; proteomic and metabolomics data are to be added to genetic information. 2. Circulating cells including platelets and atherothrombosis: Mechanisms of leukocyte and macrophage plasticity, migration, and transformation in murine atherosclerosis need to be considered; disease mechanism-based biomarkers need to be identified; experimental systems are needed that incorporate whole-blood flow to understand how red blood cells influence thrombus formation and stability; knowledge on platelet heterogeneity and priming conditions needs to be translated toward the in vivo situation. 3. Coagulation proteases, fibrin(ogen) and thrombus formation: The role of factor (F) XI in thrombosis including the lower margins of this factor related to safe and effective antithrombotic therapy needs to be established; FXI is a key regulator in linking platelets, thrombin generation, and inflammatory mechanisms in a renin-angiotensin dependent manner; however, the impact on thrombin-dependent PAR signaling needs further study; the fundamental mechanisms in FXIII biology and biochemistry and its impact on thrombus biophysical characteristics need to be explored; the interactions of red cells and fibrin formation and its consequences for thrombus formation and lysis need to be addressed. Platelet-fibrin interactions are pivotal determinants of clot formation and stability with potential therapeutic consequences. 4. Preventive and acute treatment of atherothrombosis and arterial embolism; novel ways and tailoring? The role of protease-activated receptor (PAR)-4 vis à vis PAR-1 as target for antithrombotic therapy merits study; ongoing trials on platelet function test-based antiplatelet therapy adjustment support development of practically feasible tests; risk scores for patients with atrial fibrillation need refinement, taking new biomarkers including coagulation into account; risk scores that consider organ system differences in bleeding may have added value; all forms of oral anticoagulant treatment require better organization, including education and emergency access; laboratory testing still needs rapidly available sensitive tests with short turnaround time. 5. Pleiotropy of coagulation proteases, thrombus resolution and ischaemia-reperfusion: Biobanks specifically for thrombus storage and analysis are needed; further studies on novel modified activated protein C-based agents are required including its cytoprotective properties; new avenues for optimizing treatment of patients with ischaemic stroke are needed, also including novel agents that modify fibrinolytic activity (aimed at plasminogen activator inhibitor-1 and thrombin activatable fibrinolysis inhibitor.

Increased middle cerebral artery mean blood flow velocity index after stroke thrombectomy indicates increased risk for intracranial hemorrhage

Background and purpose

Cerebral hyperperfusion has been related to the risk of intracranial hemorrhage (ICH) in stroke patients after vessel recanalization therapy. We hypothesized that after successful mechanical thrombectomy for acute anterior circulation stroke, hemodynamics detectable by transcranial Duplex (TCD) sonography would vary, and that increased blood flow velocities would be associated with ICH.

Methods

We retrospectively identified all ischemic stroke patients with successful endovascular recanalization for anterior circulation vessel occlusion (Thrombolysis in Cerebral Infarction 2b–3) between 2010 and 2017. We reviewed their postinterventional TCD examinations for mean blood flow (MBF) velocities of the recanalized and contralateral middle cerebral artery (MCA) and searched for an association with postinterventional ICH and clinical outcome.

Results

123 stroke patients (mean age 63±14 years, 40% women) with successful anterior circulation thrombectomy were analyzed. Of those, 18 patients had postinterventional ICH. ICH patients had an increased MCA MBF velocity index (=MBF velocity of the recanalized divided by the contralateral MCA) compared with non-ICH patients (1.32±0.39 vs 1.02±0.32, P<0.001). In multivariate analysis, a higher MCA MBF velocity index was associated with postinterventional ICH and poor 90 day outcome.

Conclusions

A high MCA MBF velocity index on TCD after successful recanalization therapy for anterior circulation stroke indicates a risk for postinterventional ICH and worse prognosis.

Recanalization, reperfusion, and recirculation in stroke

Recirculation, from arterial inflow routes through venous outflow pathways, was conceptualized in stroke research 50 years ago. As new technologies were developed, blocked arteries could be reopened, capillaries could be reperfused, and the use of recanalization and reperfusion grew to dominate therapeutic strategies. These approaches overwhelmingly focused on restoration of arterial and capillary inflow, but not on veins even though venous disorders may initiate or exacerbate brain injury. In this commentary, we advance the term "recirculation" after "recanalization" and "reperfusion" as a primary concept of stroke pathophysiology that targets the restoration of both the arterial and venous cerebral circulations.