Inhibition of matrix metalloproteinases to reduce blood brain barrier disruption and haemorrhagic transformation in ischaemic stroke: Go broad or go narrow?

Ischaemic stroke characterises impulsive cerebral-region hypoxia due to deep intracerebral arteriole blockage, often accompanied by permanent cerebral infarction and cognitive impairment. Thrombolysis with recombinant tissue plasminogen activator (rtPA) and thrombectomy remain the only guidance-approved therapies. However, emerging data draws clear links between such therapies and haemorrhage transformation, which occur when cerebral vasculature is damaged during ischaemia/reperfusion. Studies have shown that matrix metalloproteinases (MMPs) play a significant role in haemorrhage transformation, by depleting the extracellular matrix (ECM) and disrupting the blood brain barrier (BBB). Inhibitors of MMPs may be used to prevent ischaemic stroke patients from BBB disruption and haemorrhage transformation, particularly for those receiving rtPA treatment. Preclinical studies found that inhibition of MMPs with agents or in knock out mice, effectively reduced BBB disruption and infarct volume, leading to improved ischaemic stroke outcomes. At present, MMP inhibition is not an approved therapy for stroke patients. There remain concerns about timing, dosing, duration of MMP inhibition and selection of either broad spectrum or specific MMP inhibitors for stroke patients. This review aims to summarize current knowledge on MMP inhibition in ischaemic stroke and explore whether a broad spectrum or a specific MMP inhibitor should be used for ischaemic stroke patient treatment. It is crucial to inhibit MMP activities early and sufficiently to ensure BBB intact during ischaemia and reperfusion, but also to reduce side effects of MMP inhibitors to minimum. Recent advance in stroke therapy by thrombectomy could aid in such treatment with intra-arterially delivery of MMP inhibitors (and/or antioxidants).

The protective role of carnosine against type 2 diabetes-induced cognitive impairment.

The morbidity and mortality associated with type 2 diabetes mellitus (T2DM) have grown exponentially over the last 30 years. Together with its associated complications, the mortality rates have increased. One important complication in those living with T2DM is the acceleration of age-related cognitive decline. T2DM-induced cognitive impairment seriously affects memory, executive function, and quality of life. However, there is a lack of effective treatment for both diabetes and cognitive decline. Thus, finding novel treatments which are cheap, effective in both diabetes and cognitive impairment, are easily accessible, are needed to reduce impact on patients with diabetes and health-care systems. Carnosine, a histidine containing dipeptide, plays a protective role in cognitive diseases due to its antioxidant, anti-inflammation, and anti-glycation properties, all of which may slow the development of neurodegenerative diseases and ischemic injury. Furthermore, carnosine is also involved in regulating glucose and insulin in diabetes. Herein, we discuss the neuroprotective role of carnosine and its mechanisms in T2DM-induced cognitive impairment, which may provide a theoretical basis and evidence base to evaluate whether carnosine has therapeutic effects in alleviating cognitive dysfunction in T2DM patients.

Gene Expression Studies in Down Syndrome: What Do They Tell Us about Disease Phenotypes?

Down syndrome is a well-studied aneuploidy condition in humans, which is associated with various disease phenotypes including cardiovascular, neurological, haematological and immunological disease processes. This review paper aims to discuss the research conducted on gene expression studies during fetal development. A descriptive review was conducted, encompassing all papers published on the PubMed database between September 1960 and September 2022. We found that in amniotic fluid, certain genes such as COL6A1 and DSCR1 were found to be affected, resulting in phenotypical craniofacial changes. Additionally, other genes such as GSTT1, CLIC6, ITGB2, C21orf67, C21orf86 and RUNX1 were also identified to be affected in the amniotic fluid. In the placenta, dysregulation of genes like MEST, SNF1LK and LOX was observed, which in turn affected nervous system development. In the brain, dysregulation of genes DYRK1A, DNMT3L, DNMT3B, TBX1, olig2 and AQP4 has been shown to contribute to intellectual disability. In the cardiac tissues, dysregulated expression of genes GART, ETS2 and ERG was found to cause abnormalities. Furthermore, dysregulation of XIST, RUNX1, SON, ERG and STAT1 was observed, contributing to myeloproliferative disorders. Understanding the differential expression of genes provides insights into the genetic consequences of DS. A better understanding of these processes could potentially pave the way for the development of genetic and pharmacological therapies.

Vagus Nerve Stimulation in Ischemic Stroke.

PURPOSE OF REVIEW: Vagus nerve stimulation (VNS) has emerged as a potential therapeutic approach for neurological and psychiatric disorders. In recent years, there has been increasing interest in VNS for treating ischemic stroke. This review discusses the evidence supporting VNS as a treatment option for ischemic stroke and elucidates its underlying mechanisms. RECENT FINDINGS: Preclinical studies investigating VNS in stroke models have shown reduced infarct volumes and improved neurological deficits. Additionally, VNS has been found to reduce reperfusion injury. VNS may promote neuroprotection by reducing inflammation, enhancing cerebral blood flow, and modulating the release of neurotransmitters. Additionally, VNS may stimulate neuroplasticity, thereby facilitating post-stroke recovery. The Food and Drug Administration has approved invasive VNS (iVNS) combined with rehabilitation for ischemic stroke patients with moderate to severe upper limb deficits. However, iVNS is not feasible in acute stroke due to its time-sensitive nature. Non-invasive VNS (nVNS) may be an alternative approach for treating ischemic stroke. While the evidence from preclinical studies and clinical trials of nVNS is promising, the mechanisms through which VNS exerts its beneficial effects on ischemic stroke are still being elucidated. Therefore, further research is needed to better understand the efficacy and underlying mechanisms of nVNS in ischemic stroke. Moreover, large-scale randomized clinical trials are necessary to determine the optimal nVNS protocols, assess its long-term effects on stroke recovery and outcomes, and identify the potential benefits of combining nVNS with other rehabilitation strategies.

Histidine-containing dipeptide supplementation improves delayed recall: a systematic review and meta-analysis.

CONTEXT: Histidine-containing dipeptides (carnosine, anserine, beta-alanine and others) are found in human muscle tissue and other organs like the brain. Data in rodents and humans indicate that administration of exogenous carnosine improved cognitive performance. However, RCTs results vary. OBJECTIVES: To perform a systematic review and meta-analysis of randomized controlled trials (RCTs) of histidine-containing dipeptide (HCD) supplementation on cognitive performance in humans to assess its utility as a cognitive stabiliser. DATA SOURCES: OVID Medline, Medline, EBM Reviews, Embase, and Cumulative Index to Nursing and Allied Health Literature databases from 1/1/1965 to 1/6/2022 for all RCT of HCDs were searched. DATA EXTRACTION: 2653 abstracts were screened, identifying 94 full-text articles which were assessed for eligibility. Ten articles reporting the use of HCD supplementation were meta-analysed. DATA ANALYSIS: The random effects model has been applied using the DerSimonian-Laird method. HCD treatment significantly increased performance on Wechsler Memory Scale (WMS) -2 Delayed recall (Weighted mean difference (WMD) (95% CI (CI)) = 1.5 (0.6, 2.5), P < .01). Treatment with HCDs had no effect on Alzheimer's Disease Assessment Scale-Cognitive (WMD (95% CI) = -0.2 (-1.1, 0.7), P = .65, I2 = 0%), Mini-Mental State Examination (WMD (95% CI) = 0.7 (-0.2, 1.5), P = .14, I2 = 42%), The Wechsler Adult Intelligence Scale (WAIS) Digit span Backward (WMD (95% CI) = 0.1 (-0.3, 0.5), P = .51, I2 = 0%), WAIS digit span Forward (WMD (95% CI) = 0.0 (-0.3, 0.4), P = .85, I2 = 33%) and the WMS-1 Immediate recall (WMD (95% CI) = .7 (-.2, 1.5), P = .11, I2 = 0%). The effect on delayed recall remained in subgroup meta-analysis performed on studies of patients without mild cognitive impairment (MCI), and in those without MCI where average age in the study was above 65. CONCLUSION: HCD, supplementation improved scores on the Delayed recall examination, a neuropsychological test affected early in Alzheimer's disease. Further studies are needed in people with early cognitive impairment with longer follow-up duration and standardization of carnosine doses to delineate the true effect. SYSTEMATIC REVIEW REGISTRATION: PROSPERO registration no. CRD42017075354.

tVNS in Stroke: A Narrative Review on the Current State and the Future.

Ischemic stroke is a leading cause of disability and there is a paucity of therapeutic strategies that promote functional recovery after stroke. Transcutaneous vagus nerve stimulation (tVNS) has shown promising evidence as a tool to reduce infarct size in animal models of hyperacute stroke. In chronic stroke, tVNS paired with limb movements has been shown to enhance neurological recovery. In this review, we summarize the current evidence for tVNS in preclinical models and clinical trials in humans. We highlight the mechanistic pathways involved in the beneficial effects of tVNS. We critically evaluate the current gaps in knowledge and recommend the key areas of research required to translate tVNS into clinical practice in acute and chronic stroke.

Thrombolysis Outcomes in Acute Ischaemic Stroke Patients with Pre-Existing Cognitive Impairment.

BACKGROUND: Thrombolysis treatment for ischaemic stroke in patients with pre-existing disabilities, including cognitive impairment, remains controversial. Previous studies have suggested functional outcomes post-thrombolysis are worse in patients with cognitive impairment. This study aimed to compare and explore factors contributing to thrombolysis outcomes, including haemorrhagic complications, in cognitively and non-cognitively impaired patients with ischaemic stroke. MATERIALS AND METHODS: A retrospective analysis of 428 ischaemic stroke patients who were thrombolysed between January 2016 and February 2021 was performed. Cognitive impairment was defined as a diagnosis of dementia, mild cognitive impairment, or clinical evidence of the condition. The outcome measures included morbidity (using NIHSS and mRS), haemorrhagic complications, and mortality, and were analysed using multivariable logistic regression models. RESULTS: The analysis of the cohort revealed that 62 patients were cognitively impaired. When compared to those without cognitive impairment, this group showed worse functional status at discharge (mRS 4 vs. 3, p < 0.001) and a higher probability of dying within 90 days (OR 3.34, 95% CI 1.85-6.01, p < 0.001). A higher risk of a fatal ICH post-thrombolysis was observed in the cognitively impaired patients, and, after controlling for covariates, cognitive impairment remained a significant predictor of a fatal haemorrhage (OR 4.79, 95% CI 1.24-18.45, p = 0.023). CONCLUSIONS: Cognitively impaired ischaemic stroke patients experience increased morbidity, mortality, and haemorrhagic complications following thrombolytic therapy. However cognitive status is not independently predictive of most outcome measures. Further work is required to elucidate contributing factors to the poor outcomes observed in these patients and help guide thrombolysis decision-making in clinical practice.

The neurology of space flight; How does space flight effect the human nervous system?

RATIONALE AND HYPOTHESIS: Advancements in technology, human adaptability, and funding have increased space exploration and in turn commercial spaceflight. Corporations such as Space X and Blue Origin are exploring methods to make space tourism possible. This could lead to an increase in the number of patients presenting with neurological diseases associated with spaceflight. Therefore, a comprehensive understanding of spaceflight stressors is required to manage neurological disease in high-risk individuals. OBJECTIVES: This review aims to describe the neurological effects of spaceflight and to assess countermeasures such as pre-flight prophylaxis, training, and possible therapeutics to reduce long-term effects. METHODOLOGY: A literature search was performed for experimental studies conducted in astronauts and in animal models that simulated the space environment. Many studies, however, only discussed these with scientific reasoning and did not include any experimental methods. Relevant studies were identified through searching research databases such as PubMed and Google Scholar. No inclusion or exclusion criteria were used. FINDINGS: Analysis of these studies provided a holistic understanding of the acute and chronic neurological changes that occur during space flight. Astronauts are exposed to hazards that include microgravity, cosmic radiation, hypercapnia, isolation, confinement and disrupted circadian rhythms. Microgravity, the absence of a gravitational force, is linked to disturbances in the vestibular system, intracranial and intraocular pressures. Furthermore, microgravity affects near field vision as part of the spaceflight-associated neuro-ocular syndrome. Exposure to cosmic radiation can increase the risk of neurodegenerative conditions and malignancies. It is estimated that cosmic radiation has significantly higher ionising capabilities than the ionising radiation used in medicine. Space travel also has potential benefits to the nervous system, including psychological development and effects on learning and memory. Future work needs to focus on how we can compare a current astronaut to a future space tourist. Potentially the physiological and psychological stresses of space flight might lead to neurological complications in future space travellers that do not have the physiological reserve of current astronauts.

Vagus Nerve Stimulation Paired With Rehabilitation for Upper Limb Motor Impairment and Function After Chronic Ischemic Stroke: Subgroup Analysis of the Randomized, Blinded, Pivotal, VNS-REHAB Device Trial.

BACKGROUND: Vagus Nerve Stimulation (VNS) paired with rehabilitation improved upper extremity impairment and function in a recent pivotal, randomized, triple-blind, sham-controlled trial in people with chronic arm weakness after stroke. OBJECTIVE: We aimed to determine whether treatment effects varied across candidate subgroups, such as younger age or less injury. METHODS: Participants were randomized to receive rehabilitation paired with active VNS or rehabilitation paired with sham stimulation (Control). The primary outcome was the change in impairment measured by the Fugl-Meyer Assessment Upper Extremity (FMA-UE) score on the first day after completion of 6-weeks in-clinic therapy. We explored the effect of VNS treatment by sex, age (≥62 years), time from stroke (>2 years), severity (baseline FMA-UE score >34), paretic side of body, country of enrollment (USA vs UK) and presence of cortical involvement of the index infarction. We assessed whether there was any interaction with treatment. FINDINGS: The primary outcome increased by 5.0 points (SD 4.4) in the VNS group and by 2.4 points (SD 3.8) in the Control group (P = .001, between group difference 2.6, 95% CI 1.03-4.2). The between group difference was similar across all subgroups and there were no significant treatment interactions. There was no important difference in rates of adverse events across subgroups. CONCLUSION: The response was similar across subgroups examined. The findings suggest that the effects of paired VNS observed in the VNS-REHAB trial are likely to be consistent in wide range of stroke survivors with moderate to severe upper extremity impairment.

Neuroprotective efficacy of N-t-butylhydroxylamine (NtBHA) in transient focal ischemia in rats.

The pharmacological or toxicological activities of the degradation products of drug candidates have been unaddressed during the drug development process. Ischemic stroke accounts for 80% of all strokes and is responsible for considerable mortality and disability worldwide. Despite decades of research on neuroprotective agents, tissue plasminogen activators (t-PA), a thrombolytic agent, remains the only approved acute stroke pharmacological therapy. NXY-059, a free radical scavenger, exhibited striking neuroprotective properties in preclinical models and met all the criteria established by the Stroke Academic Industry Roundtable (STAIR) for a neuroprotective agent. In phase 3 clinical trials, NXY-059 exhibited significant neuroprotective effects in one trial (SAINT-I), but not in the second (SAINT-II). Some have hypothesized that N-t-butyl hydroxylamine (NtBHA), a breakdown product of NXY-059 was the actual neuroprotective agent in SAINT-I and that changes to the formulation of NXY-059 to prevent its breakdown to NtBHA in SAINT -II was the reason for the lack of efficacy. We evaluated the neuroprotective effect of NtBHA in N-methyl-D-aspartate (NMDA)-treated primary neurons and in rat focal cerebral ischemia. NtBHA significantly attenuated infarct volume in rat transient focal ischemia, and attenuated NMDA-induced cytotoxicity in primary cortical neurons. NtBHA also reduced free radical generation and exhibited mitochondrial protection.

Antiplatelet Use in Ischemic Stroke.

OBJECTIVE: A literature review of antiplatelet agents for primary and secondary stroke prevention, including mechanism of action, cost, and reasons for lack of benefit. DATA SOURCES: Articles were gathered from MEDLINE, Cochrane Reviews, and PubMed databases (1980-2021). Abstracts from scientific meetings were considered. Search terms included ischemic stroke, aspirin, clopidogrel, dipyridamole, ticagrelor, cilostazol, prasugrel, glycoprotein IIb/IIIa inhibitors. STUDY SELECTION AND DATA EXTRACTION: English-language original and review articles were evaluated. Guidelines from multiple countries were reviewed. Articles were evaluated independently by 2 authors. DATA SYNTHESIS: An abundance of evidence supports aspirin and clopidogrel use for secondary stroke prevention. In the acute phase (first 21 days postinitial stroke), these medications have higher efficacy for preventing further stroke when combined, but long-term combination therapy is associated with higher hemorrhage rates. Antiplatelet treatment failure is influenced by poor adherence and genetic polymorphisms. Antiplatelet agents such as cilostazol may provide extra benefit over clopidogrel and aspirin, in certain racial groups, but further research in more diverse ethnic populations is needed. RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE: This review presents the data available on the use of different antiplatelet agents poststroke. Dual therapy, recurrence after initiation of secondary preventative therapy, and areas for future research are discussed. CONCLUSIONS: Although good evidence exists for the use of certain antiplatelet agents postischemic stroke, there are considerable opportunities for future research to investigate personalized therapies. These include screening patients for platelet polymorphisms that confer antiplatelet resistance and for randomized trials including more racially diverse populations.

Transcutaneous vagus nerve stimulation (tVNS) in stroke: the evidence, challenges and future directions.

Stroke is one of the leading causes of death and disability globally. A significant proportion of stroke survivors are left with long term neurological deficits that have a detrimental effect on personal wellbeing and wider socioeconomic impacts. As such, there is an unmet need for novel therapies that improve neurological recovery after stroke. Invasive vagus nerve stimulation (VNS) paired with rehabilitation has been shown to improve upper limb motor function in chronic stroke. However, invasive VNS requires a surgical procedure and therefore may not be suitable for all stroke patients. Non-invasive, transcutaneous VNS (tVNS) via auricular vagus nerve stimulation in the ear (taVNS) and cervical vagus nerve stimulation in the neck (tcVNS) have been shown to activate similar vagal nerve projections in the central nervous system to invasive VNS. A number of pre-clinical studies indicate that tVNS delivered in acute middle cerebral artery occlusion reduces infarct size through anti-inflammatory effects, reduced excitotoxicity and increased blood-brain barrier integrity. Longer term effects of tVNS in stroke that may mediate neuroplasticity include microglial polarisation, angiogenesis and neurogenesis. Pilot clinical trials of taVNS indicate that taVNS paired with rehabilitation may improve upper limb motor and sensory function in patients with chronic stroke. In this review, we summarise and critically appraise the current pre-clinical and clinical evidence, outline the major ongoing clinical trials and detail the challenges and future directions regarding tVNS in acute and chronic stroke.

Fusion of Higher Order Spectra and Texture Extraction Methods for Automated Stroke Severity Classification with MRI Images.

This paper presents a scientific foundation for automated stroke severity classification. We have constructed and assessed a system which extracts diagnostically relevant information from Magnetic Resonance Imaging (MRI) images. The design was based on 267 images that show the brain from individual subjects after stroke. They were labeled as either Lacunar Syndrome (LACS), Partial Anterior Circulation Syndrome (PACS), or Total Anterior Circulation Stroke (TACS). The labels indicate different physiological processes which manifest themselves in distinct image texture. The processing system was tasked with extracting texture information that could be used to classify a brain MRI image from a stroke survivor into either LACS, PACS, or TACS. We analyzed 6475 features that were obtained with Gray-Level Run Length Matrix (GLRLM), Higher Order Spectra (HOS), as well as a combination of Discrete Wavelet Transform (DWT) and Gray-Level Co-occurrence Matrix (GLCM) methods. The resulting features were ranked based on the p-value extracted with the Analysis Of Variance (ANOVA) algorithm. The ranked features were used to train and test four types of Support Vector Machine (SVM) classification algorithms according to the rules of 10-fold cross-validation. We found that SVM with Radial Basis Function (RBF) kernel achieves: Accuracy (ACC) = 93.62%, Specificity (SPE) = 95.91%, Sensitivity (SEN) = 92.44%, and Dice-score = 0.95. These results indicate that computer aided stroke severity diagnosis support is possible. Such systems might lead to progress in stroke diagnosis by enabling healthcare professionals to improve diagnosis and management of stroke patients with the same resources.

Carnosine Protects against Cerebral Ischemic Injury by Inhibiting Matrix-Metalloproteinases.

Stroke is one of the leading causes of death and disability worldwide. However, treatment options for ischemic stroke remain limited. Matrix-metalloproteinases (MMPs) contribute to brain damage during ischemic strokes by disrupting the blood-brain barrier (BBB) and causing brain edemas. Carnosine, an endogenous dipeptide, was found by us and others to be protective against ischemic brain injury. In this study, we investigated whether carnosine influences MMP activity. Brain MMP levels and activity were measured by gelatin zymography after permanent occlusion of the middle cerebral artery (pMCAO) in rats and in vitro enzyme assays. Carnosine significantly reduced infarct volume and edema. Gelatin zymography and in vitro enzyme assays showed that carnosine inhibited brain MMPs. We showed that carnosine inhibited both MMP-2 and MMP-9 activity by chelating zinc. Carnosine also reduced the ischemia-mediated degradation of the tight junction proteins that comprise the BBB. In summary, our findings show that carnosine inhibits MMP activity by chelating zinc, an essential MMP co-factor, resulting in the reduction of edema and brain injury. We believe that our findings shed new light on the neuroprotective mechanism of carnosine against ischemic brain damage.

Effect of Exercise Interventions on Health-Related Quality of Life After Stroke and Transient Ischemic Attack: A Systematic Review and Meta-Analysis.

Exercise interventions have been shown to help physical fitness, walking, and balance after stroke, but data are lacking on whether such interventions lead to improvements in health-related quality of life (HRQoL). In this systematic review and meta-analysis, 30 randomized controlled trials (n=1836 patients) were found from PubMed, OVID MEDLINE, Web of Science, CINAHL, SCOPUS, The Cochrane Library, and TRIP databases when searched from 1966 to February 2020 that examine the effects of exercise interventions on HRQoL after stroke or transient ischemic attack. Exercise interventions resulted in small to moderate beneficial effects on HRQoL at intervention end (standardized mean difference, -0.23 [95% CI, -0.40 to -0.07]) that appeared to diminish at longer-term follow-up (standardized mean difference, -0.11 [95% CI, -0.26 to 0.04]). Exercise was associated with moderate improvements in physical health (standardized mean difference, -0.33 [95% CI, -0.61 to -0.04]) and mental health (standardized mean difference, -0.29 [95% CI, -0.49 to -0.09]) domains of HRQoL while effects on social or cognitive composites showed little difference. Interventions that were initiated within 6 months, lasted at least 12 weeks in duration, involved at least 150 minutes per week, and included resistance training appeared most effective. Exercise can lead to moderate beneficial effects on HRQoL and should be considered an integral part of stroke rehabilitation.

A Commonly Used Biocide 2-N-octyl-4-isothiazolin-3-oneInduces Blood-Brain Barrier Dysfunction via Cellular Thiol Modification and Mitochondrial Damage.

Isothiazolinone (IT) biocides are potent antibacterial substances commonly used as preservatives or disinfectants, and 2-n-Octyl-4-isothiazolin-3-one (OIT; octhilinone) is a common IT biocide that is present in leather products, glue, paints, and cleaning products. Although humans are exposed to OIT through personal and industrial use, the potentially deleterious effects of OIT on human health are still unknown. To investigate the effects of OIT on the vascular system, which is continuously exposed to xenobiotics through systemic circulation, we treated brain endothelial cells with OIT. OIT treatment significantly activated caspase-3-mediated apoptosis and reduced the bioenergetic function of mitochondria in a bEnd.3 cell-based in vitro blood-brain barrier (BBB) model. Interestingly, OIT significantly altered the thiol redox status, as evidenced by reduced glutathione levels and protein S-nitrosylation. The endothelial barrier function of bEnd.3 cells was significantly impaired by OIT treatment. OIT affected mitochondrial dynamics through mitophagy and altered mitochondrial morphology in bEnd.3 cells. N-acetyl cysteine significantly reversed the effects of OIT on the metabolic capacity and endothelial function of bEnd.3 cells. Taken together, we demonstrated that the alteration of the thiol redox status and mitochondrial damage contributed to OIT-induced BBB dysfunction, and we hope that our findings will improve our understanding of the potential hazardous health effects of IT biocides.

Remote ischaemic conditioning for stroke: unanswered questions and future directions.

Remote ischaemic conditioning (RIC) refers to a process whereby periods of intermittent ischaemia, typically via the cyclical application of a blood pressure cuff to a limb at above systolic pressure, confers systemic protection against ischaemia in spatially distinct vascular territories. The mechanisms underlying this have not been characterised fully but have been shown to involve neural, hormonal and systemic inflammatory signalling cascades. Preclinical and early clinical studies have been promising and suggest beneficial effects of RIC in acute ischaemic stroke, symptomatic intracranial stenosis and vascular cognitive impairment. Through systematic searches of several clinical trials databases we identified 48 active clinical trials of RIC in ischaemic stroke, intracerebral haemorrhage and subarachnoid haemorrhage. We summarise the different RIC protocols and outcome measures studied in ongoing clinical trials and highlight which studies are most likely to elucidate the underlying biological mechanisms of RIC and characterise its efficacy in the near future. We discuss the uncertainties of RIC including the optimal frequency and duration of therapy, target patient groups, cost-effectiveness, the confounding impact of medications and the absence of a clinically meaningful biomarker of the conditioning response. With several large clinical trials of RIC expected to report their outcomes within the next 2 years, this review aims to highlight the most important studies and unanswered questions that will need to be addressed before this potentially widely accessible and low-cost intervention can be used in clinical practice.

Vagus nerve stimulation paired with rehabilitation for upper limb motor function after ischaemic stroke (VNS-REHAB): a randomised, blinded, pivotal, device trial.

BACKGROUND: Long-term loss of arm function after ischaemic stroke is common and might be improved by vagus nerve stimulation paired with rehabilitation. We aimed to determine whether this strategy is a safe and effective treatment for improving arm function after stroke. METHODS: In this pivotal, randomised, triple-blind, sham-controlled trial, done in 19 stroke rehabilitation services in the UK and the USA, participants with moderate-to-severe arm weakness, at least 9 months after ischaemic stroke, were randomly assigned (1:1) to either rehabilitation paired with active vagus nerve stimulation (VNS group) or rehabilitation paired with sham stimulation (control group). Randomisation was done by ResearchPoint Global (Austin, TX, USA) using SAS PROC PLAN (SAS Institute Software, Cary, NC, USA), with stratification by region (USA vs UK), age (≤30 years vs >30 years), and baseline Fugl-Meyer Assessment-Upper Extremity (FMA-UE) score (20-35 vs 36-50). Participants, outcomes assessors, and treating therapists were masked to group assignment. All participants were implanted with a vagus nerve stimulation device. The VNS group received 0·8 mA, 100 µs, 30 Hz stimulation pulses, lasting 0·5 s. The control group received 0 mA pulses. Participants received 6 weeks of in-clinic therapy (three times per week; total of 18 sessions) followed by a home exercise programme. The primary outcome was the change in impairment measured by the FMA-UE score on the first day after completion of in-clinic therapy. FMA-UE response rates were also assessed at 90 days after in-clinic therapy (secondary endpoint). All analyses were by intention to treat. This trial is registered at ClinicalTrials.gov, NCT03131960. FINDINGS: Between Oct 2, 2017, and Sept 12, 2019, 108 participants were randomly assigned to treatment (53 to the VNS group and 55 to the control group). 106 completed the study (one patient for each group did not complete the study). On the first day after completion of in-clinic therapy, the mean FMA-UE score increased by 5·0 points (SD 4·4) in the VNS group and by 2·4 points (3·8) in the control group (between group difference 2·6, 95% CI 1·0-4·2, p=0·0014). 90 days after in-clinic therapy, a clinically meaningful response on the FMA-UE score was achieved in 23 (47%) of 53 patients in the VNS group versus 13 (24%) of 55 patients in the control group (between group difference 24%, 6-41; p=0·0098). There was one serious adverse event related to surgery (vocal cord paresis) in the control group. INTERPRETATION: Vagus nerve stimulation paired with rehabilitation is a novel potential treatment option for people with long-term moderate-to-severe arm impairment after ischaemic stroke. FUNDING: MicroTransponder.

Neural Progenitor Cell-Derived Extracellular Vesicles Enhance Blood-Brain Barrier Integrity by NF-κB (Nuclear Factor-κB)-Dependent Regulation of ABCB1 (ATP-Binding Cassette Transporter B1) in Stroke Mice.

OBJECTIVE: Extracellular vesicles (EVs) derived from neural progenitor cells enhance poststroke neurological recovery, albeit the underlying mechanisms remain elusive. Since previous research described an enhanced poststroke integrity of the blood-brain barrier (BBB) upon systemic transplantation of neural progenitor cells, we examined if neural progenitor cell-derived EVs affect BBB integrity and which cellular mechanisms are involved in the process. Approach and Results: Using in vitro models of primary brain endothelial cell (EC) cultures as well as co-cultures of brain ECs (ECs) and astrocytes exposed to oxygen glucose deprivation, we examined the effects of EVs or vehicle on microvascular integrity. In vitro data were confirmed using a mouse transient middle cerebral artery occlusion model. Cultured ECs displayed increased ABCB1 (ATP-binding cassette transporter B1) levels when exposed to oxygen glucose deprivation, which was reversed by treatment with EVs. The latter was due to an EV-induced inhibition of the NF-κB (nuclear factor-κB) pathway. Using a BBB co-culture model of ECs and astrocytes exposed to oxygen glucose deprivation, EVs stabilized the BBB and ABCB1 levels without affecting the transcellular electrical resistance of ECs. Likewise, EVs yielded reduced Evans blue extravasation, decreased ABCB1 expression as well as an inhibition of the NF-κB pathway, and downstream matrix metalloproteinase 9 (MMP-9) activity in stroke mice. The EV-induced inhibition of the NF-κB pathway resulted in a poststroke modulation of immune responses. CONCLUSIONS: Our findings suggest that EVs enhance poststroke BBB integrity via ABCB1 and MMP-9 regulation, attenuating inflammatory cell recruitment by inhibition of the NF-κB pathway. Graphic Abstract: A graphic abstract is available for this article.