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

Evaluating post-thrombectomy effective connectivity changes in anterior circulation stroke

OBJECTIVE

Granger causal analysis (GCA) and amplitude of low-frequency fluctuation (ALFF) are commonly used to evaluate functional alterations in brain disorders. By combining the GCA and ALFF, this study aimed to investigate the effective connectivity (EC) changes in patients with acute ischemic stroke (AIS) and anterior circulation occlusion after mechanical thrombectomy (MT).

METHODS

Resting-state functional magnetic resonance imaging (rs-fMRI) data were collected from 43 AIS patients with anterior circulation occlusion within 1 week post-MT and 37 healthy controls. ALFF and GCA were calculated for each participant. Patients were further divided into groups based on prognosis and perfusion levels. The differences in ALFF and EC were compared between AIS patients and healthy controls and between subgroups of patients. Pearson correlations between EC, ALFF values, and clinical characteristics of patients were calculated.

RESULTS

Compared to healthy controls, post-MT, AIS patients exhibited significant ALFF increases in the left precuneus and decreases in the left fusiform gyrus and right caudate. Increased EC from the contralesional lingual gyrus, contralesional putamen, ipsilesional thalamus, and contralesional thalamus to the contralesional caudate was obsrved, while decrease in EC were found for contralesional caudate to the ipsilesional thalamus and medial superior frontal gyrus. EC differences were particularly notable between perfusion groups, with significantly lower EC in the poorly perfused group. EC values were also positively correlated with National Institutes of Health Stroke Scale (NIHSS) scores pre-MT.

INTERPRETATION

In AIS patients, the caudate nucleus was central to the observed EC changes post-MT, characterized by decreased outputs and increased inputs. These changes indicate functional remodeling within the cortico-basal ganglia-thalamic-cortical pathway.

Associations of arterial oxygen partial pressure with all‑cause mortality in critically ill ischemic stroke patients: a retrospective cohort study from MIMIC IV 2.2

BACKGROUND

As a supportive treatment, the effectiveness of oxygen therapy in ischemic stroke (IS) patients remains unclear. This study aimed to evaluate the relationships between arterial partial pressure of oxygen (PaO2) and both consciousness at discharge and all-cause mortality risk in ICU IS patients.

METHODS

Blood gas measurements for all patients diagnosed with IS were extracted from the MIMIC-IV database. Patients were classified into four groups based on their average PaO2 during the first ICU day: hypoxemia (PaO2 < 80 mmHg), normoxemia (PaO2 80-120 mmHg), mild hyperoxemia (PaO2 121-199 mmHg), and moderate/severe hyperoxemia (PaO2 ≥ 200 mmHg). The primary endpoint was 90-day all-cause mortality. Secondary outcomes included the level of consciousness at discharge, assessed by the Glasgow Coma Scale (GCS), and 30-day all-cause mortality. Multivariate Cox regression and Restricted cubic spline (RCS) analysis were used to investigate the relationship between mean PaO2 and mortality, and to assess the nonlinear association between exposure and outcomes.

RESULTS

This study included a total of 946 IS patients. The cumulative incidence of 30-day and 90-day all-cause mortality increased with decreasing PaO2 levels. RCS analysis revealed a nonlinear relationship between PaO2 and the risk of 30-day all-cause mortality (nonlinear P < 0.0001, overall P < 0.0001), as well as a nonlinear association between PaO2 and 90-day all-cause mortality (nonlinear P < 0.0001, overall P < 0.0001). The results remained consistent after excluding the small subset of patients who received reperfusion therapy. Sensitivity analysis indicated that the favorable impact on survival tends to increase with the extended duration of elevated PaO2.

CONCLUSIONS

For IS patients who do not receive reperfusion therapy or whose recanalization status is unknown, a lower PaO2 early during ICU admission is considered an independent risk factor for short-term and recent mortality. Adjusting respiratory parameters to maintain supraphysiological levels of PaO2 appears to be beneficial for survival, although this finding requires further validation through additional studies.

TRIAL REGISTRATION

Not applicable.

Escape of Kdm6a from X chromosome is detrimental to ischemic brains via IRF5 signaling

The role of chromatin biology and epigenetics in disease progression is gaining increasing recognition. Genes that escape X chromosome inactivation (XCI) can impact neuroinflammation through epigenetic mechanisms. Our prior research has suggested that the X escapee genes Kdm6a and Kdm5c are involved in microglial activation after stroke in aged mice. However, the underlying mechanisms remain unclear. We hypothesized that Kdm6a/5c demethylate H3K27Me3/H3K4Me3 in microglia respectively, and mediate the transcription of interferon regulatory factor 5 (IRF5) and IRF4, leading to microglial pro-inflammatory responses and exacerbated stroke injury. Aged (17-20 months) Kdm6a/5c microglial conditional knockout (CKO) female mice (one allele of the gene) were subjected to a 60-min middle cerebral artery occlusion (MCAO). Gene floxed females (two alleles) and males (one allele) were included as controls. Infarct volume and behavioral deficits were quantified 3 days after stroke. Immune responses including microglial activation and infiltration of peripheral leukocytes in the ischemic brain were assessed by flow cytometry. Epigenetic modification of IRF5/4 by Kdm6a/5c were analyzed by CUT&RUN assay. The demethylation of H3K27Me3 by kdm6a increased IRF5 transcription; meanwhile Kdm5c demethylated H3K4Me3 to repress IRF5. Both Kdm6a fl/fl and Kdm5c fl/fl mice had worse stroke outcomes compared to fl/y and CKO mice. Gene floxed females showed more robust expression of CD68 in microglia, elevated brain and plasma levels of IL-1β or TNF-α, after stroke. We concluded that IRF5 signaling plays a critical role in mediating the deleterious effect of Kdm6a; whereas Kdm5c's effect is independent of IRF5.

General In Situ Engineering of Carbon-Based Materials on Carbon Fiber for In Vivo Neurochemical Sensing

Developing real-time, dynamic, and in situ analytical methods with high spatial and temporal resolutions is crucial for exploring biochemical processes in the brain. Although in vivo electrochemical methods based on carbon fiber (CF) microelectrodes are effective in monitoring neurochemical dynamics during physiological and pathological processes, complex post modification hinders large-scale productions and widespread neuroscience applications. Herein, we develop a general strategy for the in situ engineering of carbon-based materials to mass-produce functional CFs by introducing polydopamine to anchor zeolitic imidazolate frameworks as precursors, followed by one-step pyrolysis. This strategy demonstrates exceptional universality and design flexibility, overcoming complex post-modification procedures and avoiding the delamination of the modification layer. This simplifies the fabrication and integration of functional CF-based microelectrodes. Moreover, we design highly stable and selective H+, O2, and ascorbate microsensors and monitor the influence of CO2 exposure on the O2 content of the cerebral tissue during physiological and ischemia-reperfusion pathological processes.

Irisin in ischemic stroke, Alzheimer's disease and depression: a Narrative Review

Irisin is a glycosylated protein formed from the hydrolysis of fibronectin type III domain-containing protein 5 (FNDC5). Irisin is widely involved in the regulation of glucose and lipid metabolism. In addition, recent studies have demonstrated that Irisin can inhibit inflammation, restrain oxidative stress and have neuroprotective effects, which suggests that Irisin may have a good therapeutic effect on central nervous system diseases. Therefore, this review summarizes the role of Irisin in central nervous system diseases, including its signal pathways and possible mechanisms, etc. Irisin may be a potential candidate drug for the treatment of central nervous system diseases.

Clinical change during inter-hospital transfer for thrombectomy: Incidence, associated factors, and relationship with outcome

BACKGROUND

Patients with acute ischemic stroke with a large vessel occlusion (LVO) admitted to non endovascular-capable centers often require inter-hospital transfer for thrombectomy. We aimed to describe the incidence of substantial clinical change during transfer, the factors associated with clinical change, and its relationship with 3-month outcome.

METHODS

We analyzed data from two cohorts of acute stroke patients transferred for thrombectomy to a comprehensive center (Stanford, USA, November 2019 to January 2023; Montpellier, France, January 2015 to January 2017), regardless of whether thrombectomy was eventually attempted. Patients were included if they had evidence of an LVO at the referring hospital and had a National Institute of Health Stroke Scale (NIHSS) score documented before and immediately after transfer. Inter-hospital clinical change was categorized as improvement (⩾4 points and ⩾25% decrease between the NIHSS score in the referring hospital and upon comprehensive center arrival), deterioration (⩾4 points and ⩾25% increase), or stability (neither improvement nor deterioration). The stable group was considered as the reference and was compared to the improvement or deterioration groups separately.

RESULTS

A total of 504 patients were included, of whom 22% experienced inter-hospital improvement, 14% deterioration, and 64% were stable. Pre-transfer variables independently associated with clinical improvement were intravenous thrombolysis use, more distal occlusions, and lower serum glucose; variables associated with deterioration included more proximal occlusions and higher serum glucose. On post-transfer imaging, clinical improvement was associated with arterial recanalization and smaller infarct growth and deterioration with larger infarct growth. As compared to stable patients, those with clinical improvement had better 3-month functional outcome (adjusted common odds ratio (cOR) = 2.43; 95% confidence interval (CI) = 1.59-3.71; p < 0.001), while those with deterioration had worse outcome (adjusted cOR = 0.60; 95% CI = 0.37-0.98; p = 0.044).

CONCLUSION

Substantial inter-hospital clinical changes are frequently observed in LVO-related ischemic strokes, with significant impact on functional outcome. There is a need to develop treatments that improves the clinical status during transfer.

DATA ACCESS STATEMENT

The data that support the findings of this study are available upon reasonable request.

Efficacy analysis of mechanical thrombectomy combined with prolonged mild hypothermia in the treatment of acute middle cerebral artery occlusion: a single-center retrospective cohort study

Objective

To determine the efficacy of mechanical thrombectomy combined with prolonged mild hypothermia compared with conventional treatment in managing acute middle cerebral artery occlusion, and to explore whether extending the duration of hypothermia can improve neurological function.

Method

From 2018 to June 2023, a retrospective analysis was conducted on 45 patients with acute middle cerebral artery occlusion treated at the NICU of Suzhou Kowloon Hospital, affiliated with Shanghai Jiao Tong University School of Medicine. After thrombectomy, patients were admitted to the neurological intensive care unit (NICU) for targeted temperature management. Patients were divided into two groups: the mild hypothermia group (34.5-35.9°C) receiving 5-7 days of treatment, and the normothermia group (control group) whose body temperature was kept between 36 and 37.5°C using pharmacological and physical cooling methods. Baseline characteristics and temperature changes were compared between the two groups of patients. The primary outcome was the modified Rankin Scale (mRS) score at 3 month after surgery, and the secondary outcomes were related complications and mortality rate. Prognostic risk factors were investigated using both univariate and multivariate logistic regression analyses.

Results

Among 45 patients, 21 underwent prolonged mild hypothermia, and 24 received normothermia, with no significant differences in baseline characteristics between the two groups. The duration of mild hypothermia ranged from 5 to 7 days. The incidence of chills (33.3% vs. 8.3%, p = 0.031) and constipation (57.1% vs. 20.8%, p = 0.028) was significantly higher in the mild hypothermia group compared with the control group. There was no significant difference in mortality rates between the mild hypothermia and the control group (4.76% vs. 8.33%, p = 1.000, OR = 1.75, 95% CI, 0.171-17.949). At 3 month, there was no significant difference in the modified mRS (0-3) score between the mild hypothermia and control groups (52.4% vs. 25%, p = 0.114, OR = 0.477, 95% CI, 0.214-1.066). Infarct core volume was an independent risk factor for adverse neurological outcomes.

Conclusion

Prolonged mild hypothermia following mechanical thrombectomy had no severe complications and shows a trend to improve the prognosis of neurological function. The Infarct core volume on CTP was an independent risk factor for predicting neurological function.

Inter-hospital transfer for thrombectomy: transfer time is brain

BACKGROUND AND PURPOSE

Patients with acute ischaemic stroke and a large vessel occlusion who present to a non-endovascular-capable centre often require inter-hospital transfer for thrombectomy. Whether the inter-hospital transfer time is associated with 3-month functional outcome is poorly known.

METHODS

Acute stroke patients enrolled between January 2015 and December 2022 in the prospective French multicentre Endovascular Treatment of Ischaemic Stroke registry were retrospectively analysed. Patients with an anterior circulation large vessel occlusion transferred from a non-endovascular to a comprehensive stroke centre for thrombectomy were eligible. Inter-hospital transfer time was defined as the time between imaging in the referring hospital and groin puncture for thrombectomy. The relationship between transfer time and favourable 3-month functional outcome (modified Rankin Scale 0-2) was assessed through a mixed logistic regression model adjusting for centre and symptom-onset-to-referring-hospital imaging time, age, sex, diabetes, referring hospital National Institutes of Health Stroke Scale score, Alberta Stroke Programme Early Computed Tomography Score, occlusion site and intravenous thrombolysis use.

RESULTS

Overall, 3769 patients were included (median inter-hospital transfer time 161 min, interquartile range 128-195; 46% with favourable outcome). A longer transfer time was independently associated with lower rates of favourable outcome (p < 0.001). Compared to patients with transfer time below 120 min, there was a 15% reduction in the odds of achieving favourable outcome for transfer times between 120 and 180 min (adjusted odds ratio 0.85; 95% confidence interval 0.67-1.07), and a 36% reduction for transfer times beyond 180 min (adjusted odds ratio 0.64; 95% confidence interval 0.50-0.81).

CONCLUSIONS

A shorter inter-hospital transfer time is strongly associated with favourable 3-month functional outcome. A speedier inter-hospital transfer is of critical importance to improve outcome.

Acupuncture modulates the AMPK/PGC-1 signaling pathway to facilitate mitochondrial biogenesis and neural recovery in ischemic stroke rats

Aims

The main objective of this study was to investigate the role and mechanism of acupuncture on anti-nerve injury in the acute phase by regulating mitochondrial energy metabolism via monophosphate-activated protein kinase (AMPK)/peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α) axis in rat ischemic stroke.

Main methods

Middle cerebral artery occlusion (MCAO) was established by middle cerebral artery occlusion/reperfusion. One-week of acupuncture was performed during the acute phase of ischemic stroke. The neurological function and brain tissue integrity were evaluated. Mitochondrial function (intracellular ATP level and the activity of mitochondrial respiratory chain complex I) and the level of NADH oxidase (NOX) were detected by enzymatic chemistry. Next, the potential molecular mechanisms were explored by western blotting, fluorescence quantitative PCR and immunohistochemistry method.

Key findings

(1) Acupuncture treatment for MCAO/R rats showed a significant improvement in the infarcted tissue accompanied by functional recovery in Zea-Longa score and balance beam score outcomes, motor function performances. (2) Acupuncture increased the levels of ATP and mitochondrial respiratory chain complex I, decreased the NOX levels in cerebral ischemia established by suture-occluded method. (3) Acupuncture reduced the necrosis dissolution of neuronal cells and meningeal edema, while promoting angiogenesis. (4) Quantitative immunohistochemical staining results showed acupuncture can increase the expression of AMPK, p-AMPK and the mitochondrial transcription factor PGC-1α, NRF2, TFAM and uncoupling protein 2 (UCP2). Meanwhile, acupuncture treatment up-regulated the expression of the corresponding protein. (5) Subsequently, acupuncture enhanced AMPK phosphorylation as well as the expression of PGC-1α, NRF2, TFAM and UCP2, implicated in mitochondrial synthesis and cellular apoptosis. (6) Finally, injections of AMPK antagonists and activators confirmed AMPK as a therapeutic target for the anti-nerve damage effects of acupuncture.

Significance

Acupuncture intervention relieved ischemic stroke progression in MCAO rats by promoting energy metabolism and mitochondrial biogenesis in the brain and alleviating neuronal apoptosis, which was mediated by eliciting AMPK/PGC-1α axis, among them AMPK is a therapeutic target.

Penumbra-targeted CircOGDH siRNA-loaded nanoparticles alleviate neuronal apoptosis in focal brain ischaemia

BACKGROUND

Nanoparticles (NPs) are a class of substances that can be loaded with therapeutic agents delivered to specific areas. In our earlier research, we identified a neuron-derived circular RNA (circRNA), circular oxoglutarate dehydrogenase (CircOGDH), as a promising therapeutic target for acute ischaemic stroke. This study dedicated to explore a prospective preliminary strategy of CircOGDH-based NP delivered to the ischaemic penumbra region in middle cerebral artery occlusion/reperfusion (MCAO/R) mice.

METHODS

Immunofluorescence in primary cortex neurons and in vivo fluorescence imaging revealed endocytosis of Poly(lactide-co-glycolide) (PLGA) poly amidoamine(PAMAM)@CircOGDH small interfering RNA (siRNA) NPs. Western blotting analysis and CCK8 assay were performed to evaluate the apoptotic level in ischaemic neurons treated with PLGA-PAMAM@CircOGDH siRNA NPs. Quantitative reverse transcription PCR experiments, mice behaviour test, T2 MRI analysis, Nissl and TdT-mediated dUTP nick end labeling (TUNEL) co-staining were performed to evaluate the apoptosis level of ischaemic penumbra neurons in MCAO/R mice. Biosafety evaluation of NPs in MCAO/R mice was detected by blood routine examination, liver and kidney function examination and HE staining.

RESULTS

PLGA-PAMAM@CircOGDH siRNA NPs were successfully assembled. Endocytosis of PLGA-PAMAM@CircOGDH siRNA NPs in ischaemic neurons alleviated neuronal apoptotic level in vitro and in vivo. Furthermore, mice behaviour test showed that the neurological defects of MCAO/R mice were significantly alleviated after the tail injection of PLGA-PAMAM@CircOGDH siRNA NPs, and no toxic effects were observed.

CONCLUSION

In conclusion, our results suggest that PLGA-PAMAM@CircOGDH siRNA NPs can be delivered to the ischaemic penumbra region and alleviate neuron apoptosis in MCAO/R mice and in ischaemic neurons; therefore, our study provides a desirable approach for using circRNA-based NPs for the treatment of ischaemic stroke.

Fluorescence and magnetic resonance imaging of ONL-93 cells in a rat model of ischemic

OBJECTIVES

The current methods for detecting myelin changes in ischemic stroke are indirect and cannot accurately reflect their status. This study aimed to develop a novel fluorescent-magnetic resonance dual-modal molecular imaging probe for direct imaging of myelin.

METHODS

Compounds 7a and 7b were synthesized by linking the MeDAS group and Gadolinium (III) 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate. Compound 7a was selected for characterization and further study. Cell uptake, cytotoxicity, and magnetic resonance imaging scans were performed on cells. In vitro experiments on frozen brain sections from 7-day-old, 8-week-old, and ischemic stroke rats were compared with commercially available Luxol Fast Blue staining. After HPLC and MR scanning, brain tissue was soaked in 7a and scanned using T1WI and T1maps sequences.

RESULTS

Spectrophotometer results showed that compounds 7a and 7b had fluorescent properties. MR scans indicated that the compounds had contrast agent properties. Cells could uptake 7a and exhibited high signals in imaging scans. Compound 7a brain tissue staining showed more fluorescence in myelin-rich regions and identified injury sites in ischemic stroke rats. MR scanning of brain sections provided clear myelin contrast.

CONCLUSION

A novel fluorescent-magnetic resonance dual-modal molecular imaging probe for direct imaging of myelin was successfully developed and tested in rats with ischemic stroke. These findings provide new insights for the clinical diagnosis of demyelinating diseases.

Edaravone-loaded poly(amino acid) nanogel inhibits ferroptosis for neuroprotection in cerebral ischemia injury

Neurological injury caused by ischemic stroke is a major cause of permanent disability and death. The currently available neuroprotective drugs fail to achieve desired therapeutic efficacy mainly due to short circulation half-life and poor blood-brain barrier (BBB) permeability. For that, an edaravone-loaded pH/glutathione (pH/GSH) dual-responsive poly(amino acid) nanogel (NG/EDA) was developed to improve the neuroprotection of EDA. The nanogel was triggered by acidic and EDA-induced high-level GSH microenvironments, which enabled the selective and sustained release of EDA at the site of ischemic injury. NG/EDA exhibited a uniform sub-spherical morphology with a mean hydrodynamic diameter of 112.3 ± 8.2 nm. NG/EDA efficiently accumulated at the cerebral ischemic injury site of permanent middle cerebral artery occlusion (pMCAO) mice, showing an efficient BBB crossing feature. Notably, NG/EDA with 50 µM EDA significantly increased neuron survival (29.3%) following oxygen and glucose deprivation by inhibiting ferroptosis. In addition, administering NG/EDA for 7 d significantly reduced infarct volume to 22.2% ± 7.2% and decreased neurobehavioral scores from 9.0 ± 0.6 to 2.0 ± 0.8. Such a pH/GSH dual-responsive nanoplatform might provide a unique and promising modality for neuroprotection in ischemic stroke and other central nervous system diseases.

The Change in Fibrinogen is Associated with Outcome in Patients with Acute Ischemic Stroke Treated with Endovascular Thrombectomy

BACKGROUND

Fibrinogen has been identified as a modulator of the coagulation and inflammatory process. There is uncertainty about the relationship between the dynamic profile of fibrinogen levels and its impact on clinical outcomes in patients with acute ischemic stroke treated with endovascular thrombectomy.

METHODS

We consecutively enrolled patients with acute ischemic stroke who underwent endovascular thrombectomy. Fibrinogen was measured on admission and during hospitalization. The change in fibrinogen (Δfibrinogen) was calculated as the highest follow-up fibrinogen minus admission fibrinogen, with a positive Δfibrinogen indicating an increase in fibrinogen level. Functional outcome was assessed by the modified Rankin Scale at 3 months. Poor outcome was defined as modified Rankin Scale > 2.

RESULTS

A total of 346 patients were included (mean age 67.4 ± 13.6 years, 52.31% men). The median fibrinogen on admission was 2.77 g/L (interquartile range 2.30-3.39 g/L). The median Δfibrinogen was 1.38 g/L (interquartile range 0.27-2.79 g/L). Hyperfibrinogenemia (> 4.5 g/L) on admission was associated with an increased risk of poor outcome [odds ratio (OR) 5.93, 95% confidence interval (CI) 1.44-24.41, p = 0.014]. There was a possible U-shaped association of Δfibrinogen with outcomes, with an inflection point of - 0.43 g/L (p = 0.04). When Δfibrinogen was <  - 0.43 g/L, a higher decrease in fibrinogen (lower Δfibrinogen value) was associated with a higher risk of poor outcome (OR 0.22, 95% CI 0.02-2.48, p = 0.219). When Δfibrinogen was >  - 0.43 g/L, the risk of poor outcome increased with increasing fibrinogen (OR 1.27, 95% CI 1.04-1.54, p = 0.016).

CONCLUSIONS

In patients with endovascular thrombectomy, hyperfibrinogenemia on admission was associated with poor functional outcomes at 3 months, whereas Δfibrinogen was associated with poor 3-month outcomes in a possible U-shaped manner.

Does imaging of the ischemic penumbra have value in acute ischemic stroke with large vessel occlusion?

PURPOSE OF REVIEW

In this review, we summarize current evidence regarding potential benefits and limitations of using perfusion imaging to estimate presence and extent of irreversibly injured ischemic brain tissue ('core') and severely ischemic yet salvageable tissue ('penumbra') in acute stroke patients with large vessel occlusion (LVO).

RECENT FINDINGS

Core and penumbra volumes are strong prognostic biomarkers in LVO patients. Greater benefits of both intravenous thrombolysis and endovascular therapy (EVT) are observed in patients with small core and large penumbra volumes. However, some current definitions of clinically relevant penumbra may be too restrictive and exclude patients who may benefit from reperfusion therapies. Alongside other clinical and radiological factors, penumbral imaging may enhance the discussion regarding the benefit/risk ratio of EVT in common clinical situations, such as patients with large core - for whom EVT's benefit is established but associated with a high rate of severe disability -, or patients with mild symptoms or medium vessel occlusions - for whom EVT's benefit is currently unknown. Beyond penumbral evaluation, perfusion imaging is clinically relevant for optimizing patient's selection for neuroprotection trials.

SUMMARY

In an emerging era of precision medicine, perfusion imaging is a valuable tool in LVO-related acute stroke.

Penumbral Rescue by normobaric O = O administration in patients with ischemic stroke and target mismatch proFile (PROOF): Study protocol of a phase IIb trial

RATIONALE

Oxygen is essential for cellular energy metabolism. Neurons are particularly vulnerable to hypoxia. Increasing oxygen supply shortly after stroke onset could preserve the ischemic penumbra until revascularization occurs.

AIMS

PROOF investigates the use of normobaric oxygen (NBO) therapy within 6 h of symptom onset/notice for brain-protective bridging until endovascular revascularization of acute intracranial anterior-circulation occlusion.

METHODS AND DESIGN

Randomized (1:1), standard treatment-controlled, open-label, blinded endpoint, multicenter adaptive phase IIb trial.

STUDY OUTCOMES

Primary outcome is ischemic core growth (mL) from baseline to 24 h (intention-to-treat analysis). Secondary efficacy outcomes include change in NIHSS from baseline to 24 h, mRS at 90 days, cognitive and emotional function, and quality of life. Safety outcomes include mortality, intracranial hemorrhage, and respiratory failure. Exploratory analyses of imaging and blood biomarkers will be conducted.

SAMPLE SIZE

Using an adaptive design with interim analysis at 80 patients per arm, up to 456 participants (228 per arm) would be needed for 80% power (one-sided alpha 0.05) to detect a mean reduction of ischemic core growth by 6.68 mL, assuming 21.4 mL standard deviation.

DISCUSSION

By enrolling endovascular thrombectomy candidates in an early time window, the trial replicates insights from preclinical studies in which NBO showed beneficial effects, namely early initiation of near 100% inspired oxygen during short temporary ischemia. Primary outcome assessment at 24 h on follow-up imaging reduces variability due to withdrawal of care and early clinical confounders such as delayed extubation and aspiration pneumonia.

TRIAL REGISTRATIONS

ClinicalTrials.gov: NCT03500939; EudraCT: 2017-001355-31.

Automated advanced imaging in acute ischemic stroke. Certainties and uncertainties

The purpose of this is study was to review pearls and pitfalls of advanced imaging, such as computed tomography perfusion and diffusion-weighed imaging and perfusion-weighted imaging in the selection of acute ischemic stroke (AIS) patients suitable for endovascular treatment (EVT) in the late time window (6-24 h from symptom onset). Advanced imaging can quantify infarct core and ischemic penumbra using specific threshold values and provides optimal selection parameters, collectively called target mismatch. More precisely, target mismatch criteria consist of core volume and/or penumbra volume and mismatch ratio (the ratio between total hypoperfusion and core volumes) with precise cut-off values. The parameters of target mismatch are automatically calculated with dedicated software packages that allow a quick and standardized interpretation of advanced imaging. However, this approach has several limitations leading to a misclassification of core and penumbra volumes. In fact, automatic software platforms are affected by technical artifacts and are not interchangeable due to a remarkable vendor-dependent variability, resulting in different estimate of target mismatch parameters. In addition, advanced imaging is not completely accurate in detecting infarct core, that can be under- or overestimated. Finally, the selection of candidates for EVT remains currently suboptimal due to the high rates of futile reperfusion and overselection caused by the use of very stringent inclusion criteria. For these reasons, some investigators recently proposed to replace advanced with conventional imaging in the selection for EVT, after the demonstration that non-contrast CT ASPECTS and computed tomography angiography collateral evaluation are not inferior to advanced images in predicting outcome in AIS patients treated with EVT. However, other authors confirmed that CTP and PWI/DWI postprocessed images are superior to conventional imaging in establishing the eligibility of patients for EVT. Therefore, the routine application of automatic assessment of advanced imaging remains a matter of debate. Recent findings suggest that the combination of conventional and advanced imaging might improving our selection criteria.

A multimodal pipeline for image correction and registration of mass spectrometry imaging with microscopy

The integration of matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) and histology plays a pivotal role in advancing our understanding of complex heterogeneous tissues, which provides a comprehensive description of biological tissue with both wide molecule coverage and high lateral resolution. Herein, we proposed a novel strategy for the correction and registration of MALDI MSI data with hematoxylin & eosin (H&E) staining images. To overcome the challenges of discrepancies in spatial resolution towards the unification of the two imaging modalities, a deep learning-based interpolation algorithm for MALDI MSI data was constructed, which enables spatial coherence and the following orientation matching between images. Coupled with the affine transformation (AT) and the subsequent moving least squares algorithm, the two types of images from one rat brain tissue section were aligned automatically with high accuracy. Moreover, we demonstrated the practicality of the developed pipeline by projecting it to a rat cerebral ischemia-reperfusion injury model, which would help decipher the link between molecular metabolism and pathological interpretation towards microregion. This new approach offers the chance for other types of bioimaging to boost the field of multimodal image fusion.

pH/Temperature Dual-Responsive Protein-Polymer Conjugates for Potential Therapeutic Hypothermia in Ischemic Stroke

Thrombolytic therapy for ischemic stroke still has several limitations, such as a narrow therapeutic time window and adverse effects. Therapeutic hypothermia is a neuroprotective strategy for stroke. In this study, we developed pH/temperature dual-responsive protein-polymer conjugates (PEG-uPA-PEG-PPG-PEG) by modifying a urokinase-type plasminogen activator (uPA) with polyethylene glycol (PEG) and poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEG-PPG-PEG, a thermosensitive polymer) via pH-sensitive imine bonds and disulfide bonds, respectively. At 37 °C and pH 7.4 (normothermia and physiological pH), PEG-uPA-PEG-PPG-PEG exhibits antiprotease hydrolysis and masked bioactivity of uPA due to the protective effect of the polymer segments wrapped around the protein surface. However, at 33 °C and pH 6.0 (hypothermia and pH at the thrombotic site), uPA loses the protective effect and recovers its bioactivity due to PEG dissociation and PEG-PPG-PEG stretching. The masked bioactivity of uPA at normothermia and physiological pH could reduce the risk of acute hemorrhage complication, and the recovery of protein activity at acidic pH and 33 °C is of great significance for thrombolytic therapy at mild hypothermia. Thus, PEG-uPA-PEG-PPG-PEG provides promising potential for therapeutic hypothermia in ischemic stroke.

Normobaric Hyperoxia (NBHO): An Adjunctive Therapy to Cerebrovascular Recanalization in Ischemic Stroke

Acute ischemic stroke (AIS) is a serious neurological disease. Normobaric hyperoxia (NBHO) is both a non-invasive and easy method that seems to be able to improve outcomes after cerebral ischemia/reperfusion. In clinical trials, normal low-flow oxygen has been shown to be ineffective, but NBHO has been shown to have a transient brain-protective effect. Today, NBHO combined with recanalization is the best treatment available. NBHO combined with thrombolysis is considered to improve neurological scores and long-term outcomes. Large randomized controlled trials (RCTs), however, are still needed to determine the role they will have in stroke treatment. RCTs of NBHO combined with thrombectomy have both improved infarct volume at 24 hours and the long-term prognosis. These two mechanisms most likely play key roles in the neuroprotective actions of NBHO after recanalization, including the increase in penumbra oxygen supply and the integrity of the blood-brain barrier (BBB). Considering the mechanism of action of NBHO, oxygen should be given as early as possible to increase the duration of oxygen therapy before recanalization is initiated. NBHO can further prolong the existence time of penumbra, so that more patients may benefit from it. Overall, however, recanalization therapy is still essential.

Possible Influence of Ethnicity on Computed Tomography Perfusion Parameter Thresholds in Acute Ischaemic Stroke

INTRODUCTION

Tissue at risk, as estimated by CT perfusion utilizing Tmax+6, correlates with final infarct volume (FIV) in acute ischaemic stroke (AIS) without reperfusion. Tmax thresholds are derived from Western ethnic populations but not from ethnic Asian populations. We aimed to investigate the influence of ethnicity on Tmax thresholds.

METHODS

From a clinical-imaging registry of Australian and Indonesian stroke patients, we selected a participant subgroup with the following inclusion criteria: AIS under 24 h and absence of reperfusion therapy. Clinical data included demographics, time metrics, stroke severity, pre-morbid, and 3-month Modified Rankin Score. Baseline computed tomography perfusion and MRI <72 h were performed. Volumes of Tmax utilizing different thresholds and FIVs were calculated. Spearman correlation was used to evaluate relationship involving ordinal variables and calculate the optimal Tmax threshold against FIV in both populations.

RESULTS

Two hundred patients were included in the study sample, 100 in Jakarta and 100 in Geelong. The median National Institutes of Health Stroke Scale (IQR) were 6 (3-11) and 3 (1-5), respectively. The median Tmax+6 (IQR) was 0 (0-46.5) in Jakarta group and 0 (0-7.5) in Geelong group. The median FIV (IQR) was 0 (0-30.5) and 0 (0-5.5). Tmax+8 s in Jakarta population against FIV showed Spearman's coefficient ρ = 0.72, representing the optimal Tmax threshold. Tmax+6 s showed Spearman's coefficient ρ = 0.51 against FIV in the Geelong population.

CONCLUSION

Tmax thresholds approximating FIV were possibly different in the Asian when compared with the non-Asian populations. Future studies are required to extend and confirm the validity of our findings.

Normobaric Hyperoxia Combined with Endovascular Treatment in Patients with Acute Ischemic Stroke (OPENS-2) Trial: Protocol for a Prospective, Multicenter, Randomized Controlled Study

Normobaric hyperoxia (NBO) is a potentially promising stroke treatment strategy that could protect the ischemic penumbra and could be administered as an adjunct before vascular recanalization. However, the efficacy and safety of NBO have not been confirmed by randomized controlled trials. The study aims to assess the efficacy and safety of NBO for ischemic stroke due to large artery occlusion (LVO) of acute anterior circulation among patients who had endovascular treatment (EVT) and were randomized within 6 h from symptom onset. Based on the data of the modified Rankin Scale (mRS) score at 90 days from the normobaric hyperoxia combined with EVT for acute ischemic stroke (OPENS: NCT03620370) trial, 284 patients will be included to achieve a 90% power by using Wilcoxon-Mann-Whitney test and the proportional odds model to calculate the sample size. The study is a prospective, multicenter, blinded, randomized controlled trial. The NBO group is administered with mask oxygen therapy of 10 L/min, while the sham NBO group is with that of 1 L/min. The primary outcome is the mRS score at 90 days. Secondary endpoints include cerebral infarct volume at 24-48 h, functional independence (mRS ≤2) at 90 days, and improvement in neurological function at 24 h. Safety outcomes include 90-day mortality, oxygen-related adverse events, and serious adverse events. This study will indicate whether NBO combined with EVT is superior to EVT alone for acute ischemic stroke caused by LVO in subjects randomized within 6 h from symptom onset and will provide some evidence for NBO intervention as an adjunct to thrombectomy for acute stroke.

Transcutaneous Electrical Nerve Stimulation (TENS) Alleviates Brain Ischemic Injury by Regulating Neuronal Oxidative Stress, Pyroptosis, and Mitophagy

Background

As a noninvasive treatment, transcutaneous electrical nerve stimulation (TENS) has been utilized to treat various diseases in clinic. However, whether TENS can be an effective intervention in the acute stage of ischemic stroke still remains unclear. In the present study, we aimed to explore whether TENS could alleviate brain infarct volume, reduce oxidative stress and neuronal pyroptosis, and activate mitophagy following ischemic stroke.

Methods

TENS was performed at 24 h after middle cerebral artery occlusion/reperfusion (MCAO/R) in rats for 3 consecutive days. Neurological scores, the volume of infarction, and the activity of SOD, MDA, GSH, and GSH-px were measured. Moreover, western blot was performed to detect the related protein expression, including Bcl-2, Bax, TXNIP, GSDMD, caspase-1, NLRP3, BRCC3, HIF-1α, BNIP3, LC3, and P62. Real-time PCR was performed to detect NLRP3 expression. Immunofluorescence was performed to detect the levels of LC3.

Results

There was no significant difference of neurological deficit scores between the MCAO group and the TENS group at 2 h after MCAO/R operation (P > 0.05), while the neurological deficit scores of TENS group significantly decreased in comparison with MCAO group at 72 h following MACO/R injury (P < 0.05). Similarly, TENS treatment significantly reduced the brain infarct volume compared with the MCAO group (P < 0.05). Moreover, TENS decreased the expression of Bax, TXNIP, GSDMD, caspase-1, BRCC3, NLRP3, and P62 and the activity of MDA as well as increasing the level of Bcl-2, HIF-1α, BNIP3, and LC3 and the activity of SOD, GSH, and GSH-px (P < 0.05).

Conclusions

In conclusion, our results indicated that TENS alleviated brain damage following ischemic stroke via inhibiting neuronal oxidative stress and pyroptosis and activating mitophagy, possibly via the regulation of TXNIP, BRCC3/NLRP3, and HIF-1α/BNIP3 pathways.

Combined Therapeutics: Future Opportunities for Co-therapy with Thrombectomy

Stroke is an urgent public health issue with millions of patients worldwide living with its devastating effects. The advent of thrombolysis and endovascular thrombectomy has transformed the hyperacute care of these patients. However, a significant proportion of patients receiving these therapies still goes on to have unfavorable outcomes and many more remain ineligible for these therapies based on our current guidelines. The future of stroke care will depend on an expansion of the scope of thrombolysis and endovascular thrombectomy to patients outside traditional time windows, more distal occlusions, and large vessel occlusions with mild clinical deficits, for whom clinical trial results have not proven therapeutic efficacy. Novel cytoprotective therapies targeting the ischemic cascade and reperfusion injury therapy, in combination with our existing treatment modalities, should be explored to further improve outcomes for these patients with acute ischemic stroke. In this review, we will review the current status of thrombolysis and thrombectomy, suggest additional data that is needed to enhance these therapies, and discuss how cytoprotection might be combined with thrombectomy.

Thrombolysis for acute ischaemic stroke: current status and future perspectives

Alteplase is currently the only approved thrombolytic agent for treatment of acute ischaemic stroke, but interest is burgeoning in the development of new thrombolytic agents for systemic reperfusion with an improved safety profile, increased efficacy, and convenient delivery. Tenecteplase has emerged as a potential alternative thrombolytic agent that might be preferred over alteplase because of its ease of administration and reported efficacy in patients with large vessel occlusion. Ongoing research efforts are also looking at potential improvements in recanalisation with the use of adjunct therapies to intravenous thrombolysis. New treatment strategies are also emerging that aim to reduce the risk of vessel reocclusion after intravenous thrombolysis administration. Other research endeavors are looking at the use of intra-arterial thrombolysis after mechanical thrombectomy to induce tissue reperfusion. The growing implementation of mobile stroke units and advanced neuroimaging could boost the number of patients who can receive intravenous thrombolysis by shortening onset-to-treatment times and identifying patients with salvageable penumbra. Continued improvements in this area will be essential to facilitate the ongoing research endeavors and to improve delivery of new interventions.

Determinants of Infarct Core Growth During Inter-hospital Transfer for Thrombectomy

OBJECTIVE

Patients with acute ischemic stroke harboring a large vessel occlusion who present to primary stroke centers often require inter-hospital transfer for thrombectomy. We aimed to determine clinical and imaging factors independently associated with fast infarct growth (IG) during inter-hospital transfer.

METHODS

We retrospectively analyzed data from acute stroke patients with a large vessel occlusion transferred for thrombectomy from a primary stroke center to one of three French comprehensive stroke centers, with an MRI obtained at both the primary and comprehensive center before thrombectomy. Inter-hospital IG rate was defined as the difference in infarct volumes on diffusion-weighted imaging between the primary and comprehensive center, divided by the delay between the two MRI scans. The primary outcome was identification of fast progressors, defined as IG rate ≥5 mL/hour. The hypoperfusion intensity ratio (HIR), a surrogate marker of collateral blood flow, was automatically measured on perfusion imaging.

RESULTS

A total of 233 patients were included, of whom 27% patients were fast progressors. The percentage of fast progressors was 3% among patients with HIR < 0.40 and 71% among those with HIR ≥ 0.40. In multivariable analysis, fast progression was independently associated with HIR, intracranial carotid artery occlusion, and exclusively deep infarct location at the primary center (C-statistic = 0.95; 95% confidence interval [CI], 0.93-0.98). IG rate was independently associated with good functional outcome (adjusted OR = 0.91; 95% CI, 0.83-0.99; P = 0.037).

INTERPRETATION

Our findings show that a HIR > 0.40 is a powerful indicator of fast inter-hospital IG. These results have implication for neuroprotection trial design, as well as informing triage decisions at primary stroke centers. ANN NEUROL 2023.

Opportunities and barriers to translating the hibernation phenotype for neurocritical care

Targeted temperature management (TTM) is standard of care for neonatal hypoxic ischemic encephalopathy (HIE). Prevention of fever, not excluding cooling core body temperature to 33°C, is standard of care for brain injury post cardiac arrest. Although TTM is beneficial, HIE and cardiac arrest still carry significant risk of death and severe disability. Mammalian hibernation is a gold standard of neuroprotective metabolic suppression, that if better understood might make TTM more accessible, improve efficacy of TTM and identify adjunctive therapies to protect and regenerate neurons after hypoxic ischemia brain injury. Hibernating species tolerate cerebral ischemia/reperfusion better than humans and better than other models of cerebral ischemia tolerance. Such tolerance limits risk of transitions into and out of hibernation torpor and suggests that a barrier to translate hibernation torpor may be human vulnerability to these transitions. At the same time, understanding how hibernating mammals protect their brains is an opportunity to identify adjunctive therapies for TTM. Here we summarize what is known about the hemodynamics of hibernation and how the hibernating brain resists injury to identify opportunities to translate these mechanisms for neurocritical care.

Tetramethylpyrazine Attenuates Oxygen-glucose Deprivation-induced Neuronal Damage through Inhibition of the HIF-1α/BNIP3 Pathway: from Network Pharmacological Finding to Experimental Validation

AIMS

A network pharmacological analysis combined with experimental validation was used to investigate the neuroprotective mechanism of the natural product Tetramethylpyrazine(TMP).

BACKGROUND

Protecting neurons is critical for acute ischemic stroke treatment. Tetramethylpyrazine is a bioactive component extracted from Chuanxiong. The neuroprotective potential of TMP has been reported, but a systematic analysis of its mechanism has not been performed.

OBJECTIVE

Based on the hints of network pharmacology and bioinformatics analysis, the mechanism by which TMP alleviates oxygen-glucose deprivation-induced neuronal damage through inhibition of the HIF-1α/BNIP3 pathway was verified.

METHOD

In this study, we initially used network pharmacology and bioinformatics analyses to elucidate the mechanisms involved in TMP's predictive targets on a system level. The HIF-1α/BNIP3 pathway mediating the cellular response to hypoxia and apoptosis was considered worthy of focus in the bioinformatic analysis. An oxygen-glucose deprivation (OGD)-induced PC12 cell injury model was established for functional and mechanical validation. Cell viability, lactate dehydrogenase leakage, intracellular reactive oxygen species, percentage of apoptotic cells, and Caspase-3 activity were determined to assess the TMP's protective effects. Transfection with siRNA/HIF-1α or pcDNA/HIF-1α plasmids to silence or overexpress hypoxia-inducible factor 1α(HIF-1α). The role of HIF-1α in OGD-injured cells was observed first. After that, TMP's regulation of the HIF-1α/BNIP3 pathway was investigated. The pcDNA3.1/HIF-1α-positive plasmids were applied in rescue experiments.

RESULT

The results showed that TMP dose-dependently attenuated OGD-induced cell injury. The expression levels of HIF-1α, BNIP3, and the Bax/Bcl-2 increased significantly with increasing OGD duration. Overexpression of HIF-1α decreased cell viability, increased BNIP3 expression, and Bax/Bcl-2 ratio; siRNA-HIF-1α showed the opposite effect. TMP treatment suppressed HIF-1α, BNIP3 expression, and the Bax/Bcl-2 ratio and was reversed by HIF-1α overexpression.

CONCLUSION

Our study shows that TMP protects OGD-damaged PC12 cells by inhibiting the HIF-1α/BNIP3 pathway, which provides new insights into the mechanism of TMP and its neuroprotective potential.

OIP5-AS1 Inhibits Oxidative Stress and Inflammation in Ischemic Stroke Through miR-155-5p/IRF2BP2 Axis

BACKGROUND

Ischemic stroke is a very dangerous disease with high incidence, fatality and disability rate in human beings. Massive evidence has indicated that oxidative stress and inflammation are intimately correlated with progression of ischemic stroke. Additionally, LncRNAs were reported to be involved in ischemic stroke. Here, we aim to explore the effects and molecular mechanism of lncRNA OIP5-AS1 on oxidative stress and inflammation in ischemic stroke.

METHODS

HMC3 and SH-SY5Y cells were under the condition of oxygen-glucose deprivation/reoxygenation (OGD/R) treatment to establish cell models of ischemic stroke. Commercial kits were employed to detect the indicators of oxidative stress including ROS, MDA and SOD. The expression of OIP5-AS1, miR-155-5p and IRF2BP2 mRNA was determined using RT-qPCR. The protein levels of inflammatory factors including TNF-α, IL-1β and IL-6 and IRF2BP2 were assessed by western blot and/or ELISA. Luciferase activity assay was employed to validate their correlations among OIP5-AS1, miR-155-5p and IRF2BP2.

RESULTS

In OGD/R-induced HMC3 and SH-SY5Y cells, the expression of OIP5-AS1 and IRF2BP2 was reduced while miR-155-5p was elevated. OGD/R induction promoted oxidative stress and inflammatory response in HMC3 and SH-SY5Y cells, while OIP5-AS1 or IRF2BP2 sufficiency as well as miR-155-5p inhibitor attenuated OGD/R-induced these influences. In addition, IRF2BP2 knockdown abolished the suppressive impacts of OIP5-AS1 overexpression on oxidative stress and inflammatory response in OGD/R-induced HMC3 and SH-SY5Y cells. Mechanistically, OIP5-AS1 enhanced IRF2BP2 expression via sponging miR-155-5p.

CONCLUSION

OIP5-AS1 suppressed oxidative stress and inflammatory response to alleviate cell injury caused by OGD/R induction in HMC3 and SH-SY5Y cells through regulating miR-155-5p/IRF2BP2 axis, which might offer novel targeted molecules for ischemic stroke therapy.

Loureirin C ameliorates ischemia and reperfusion injury in rats by inhibiting the activation of the TLR4/NF-κB pathway and promoting TLR4 degradation

Ischemic stroke is a leading cause of death and disability worldwide. Post-ischemia, microglia respond immediately to the alternations in neuronal activity and mediate inflammation. Toll-like receptor 4 (TLR4) plays a key role in this phenomenon. To explore the effect of loureirin C, an effective compound from Chinese Dragon's blood, on ischemic stroke, Sprague-Dawley rats were subjected to middle cerebral artery occlusion/reperfusion (MCAO/R) with/without intragastric administration of loureirin C (7, 14, and 28 mg/kg). Loureirin C alleviated MCAO/R-induced brain impairment evaluated by neurological scores (p < 0.001), brain water content (p < 0.001), and cerebral infarct volume (p = 0.001). The neuroprotective (p < 0.001) and inhibitory effects on microglial activation (p < 0.001) of loureirin C were revealed by immunofluorescence. Rescue studies with TLR4 overexpression in BV-2 microglia showed that the antiinflammatory effect of loureirin C was attributable to the inhibition of TLR4 protein expression. Moreover, co-immunoprecipitation assays showed that the binding of Triad3A, an E3 ubiquitin ligase of TLR4, was increased by loureirin C (p = 0.003). Our study demonstrates that loureirin C could be a promising therapeutic agent for the management of ischemic stroke by inhibiting microglial activation, potentially by Triad3A-mediated promotion of TLR4 ubiquitination and degradation.

Epigenetic mechanisms and potential therapeutic targets in stroke

Accumulating evidence indicates a central role for epigenetic modifications in the progression of stroke pathology. These epigenetic mechanisms are involved in complex and dynamic processes that modulate post-stroke gene expression, cellular injury response, motor function, and cognitive ability. Despite decades of research, stroke continues to be classified as a leading cause of death and disability worldwide with limited clinical interventions. Thus, technological advances in the field of epigenetics may provide innovative targets to develop new stroke therapies. This review presents the evidence on the impact of epigenomic readers, writers, and erasers in both ischemic and hemorrhagic stroke pathophysiology. We specifically explore the role of DNA methylation, DNA hydroxymethylation, histone modifications, and epigenomic regulation by long non-coding RNAs in modulating gene expression and functional outcome after stroke. Furthermore, we highlight promising pharmacological approaches and biomarkers in relation to epigenetics for translational therapeutic applications.

Potential mechanisms of acupuncture in enhancing cerebral perfusion of ischemic stroke

Ischemic stroke is the predominant cause of long-term disability and death worldwide. It is attributable to the sudden interruption of regional cerebral blood flow, resulting in brain cell death and neurological impairment. Acupuncture is a widely used adjuvant treatment for ischemic stroke in China and shows promising efficacy in clinical practice. This review mainly focused on the evidence to illustrate several possible mechanisms of acupuncture therapy on cerebral perfusion in ischemic stroke. Studies have shown that acupuncture is probably effective in the enhancement of cerebral perfusion after ischemic stroke. It promotes the improvement of hemodynamics, the release of vasoactive substances, the formation of new blood vessels, as well as the restitution of microcirculation. Multiple factors may contribute to the variability in acupuncture's therapeutic effects, including the acupoint selection, stimulation frequency and intensity, and retaining needle time. Acupuncture has the potential to become a non-pharmacological adjuvant approach to enhance cerebral perfusion in ischemic stroke. Future studies are required to gain our insight into acupuncture as well as accelerate its clinical translation.

The BE COOL Treatments (Batroxobin, oxygEn, Conditioning, and cOOLing): Emerging Adjunct Therapies for Ischemic Cerebrovascular Disease

Ischemic cerebrovascular disease (ICD), the most common neurological disease worldwide, can be classified based on the onset time (acute/chronic) and the type of cerebral blood vessel involved (artery or venous sinus). Classifications include acute ischemic stroke (AIS)/transient ischemic attack (TIA), chronic cerebral circulation insufficiency (CCCI), acute cerebral venous sinus thrombosis (CVST), and chronic cerebrospinal venous insufficiency (CCSVI). The pathogenesis of cerebral arterial ischemia may be correlated with cerebral venous ischemia through decreased cerebral perfusion. The core treatment goals for both arterial and venous ICDs include perfusion recovery, reduction of cerebral ischemic injury, and preservation of the neuronal integrity of the involved region as soon as possible; however, therapy based on the current guidelines for either acute ischemic events or chronic cerebral ischemia is not ideal because the recurrence rate of AIS or CVST is still very high. Therefore, this review discusses the neuroprotective effects of four novel potential ICD treatments with high translation rates, known as the BE COOL treatments (Batroxobin, oxygEn, Conditioning, and cOOLing), and subsequently analyzes how BE COOL treatments are used in clinical settings. The combination of batroxobin, oxygen, conditioning, and cooling may be a promising intervention for preserving ischemic tissues.

Oxygen saturation before and after mechanical thrombectomy and functional outcome in patients with acute ischemic stroke

Background and purpose

Currently, there is a lack of effective neuroprotective strategies to break the ceiling effect of mechanical thrombectomy (MT), and one of the most promising is normobaric oxygen treatment. However, the impact of pre- and post-MT oxygen saturation on clinical outcomes in patients with acute ischemic stroke (AIS) remains unclear. We aimed to determine the influence of preoperative and postoperative oxygen saturation on 3-month poor outcome in patients with AIS.

Methods

A total of 239 consecutive stroke patients with successful recanalization by MT between May 2017 and March 2021 were analyzed. Oxygen saturation was measured non-invasively by pulse oximetry at baseline and continually after MT. Regression analysis was used to assess the association of preoperative and postoperative oxygen saturation with a 3-month poor outcome (modified Rankin Scale score: 3–6).

Results

Decreased preoperative oxygen saturation level was associated with an increased risk of poor outcome (odds ratio, 0.85; 95% CI, 0.73–0.98; P = 0.0293). Postoperative oxygen saturation had the opposite effect on poor outcome (odds ratio, 1.60; 95% CI, 1.13–2.27; P = 0.0088).

Conclusion

Preoperative and postoperative oxygen saturation have different impacts on 3-month poor outcome in patients with AIS with successful recanalization by MT.

Rho-Kinase inhibition decreases focal cerebral ischemia-induced glial activation in rats

Background

Rho-kinase inhibition in a rat middle cerebral artery occlusion (MCAO) model is reported to improve neurological functions and decrease infarction size.

Objective

The objective of this study is to investigate the underlying mechanisms of such improvement by evaluating the effects of Rho-kinase inhibition on astrocytes and microglial accumulation and activation in this condition.

Methods

Adult male Sprague-Dawley (SD) rats were used to generate the MCAO model, which received an I.P injection of a chemical Rho-kinase inhibitor (Fasudil- 5 mg/kg/day) or vehicle (PBS) for 2 and 4 days.

Results

Fasudil treatment significantly decreased the stroke volumes and water content in the lesion areas, as revealed by MRI. Immunostaining and Western blotting results demonstrated that Fasudil significantly decreased the levels of Aquaporin-4, a water channel protein. The number of GFAP⁺ astrocytes and Iba-1⁺ macrophage/microglia was decreased in the lesion areas. Proinflammatory transcription factor NF-κB protein levels were decreased in the Fasudil group 2 days after MCAO. Also, proinflammatory mediators including TNF-α, IL-1β, and iNOS levels were decreased. In vitro migration study using a human microglial cell line (HMO6) confirmed the inhibitory effects of Fasudil on the process. Fasudil also decreased combined IL-1β and IFNγ-induced NF-κB nuclear translocation in HMO6. Moreover, Fasudil transiently decreased combined IL-1β and IFNγ-induced iNOS, TNFα, and IL-1β mRNA levels in HMO6.

Conclusion

Our study demonstrates the inhibitory effects of Rho-kinase on NF-κB-mediated glial activation and cerebral edema, which might be a promising therapeutic target in acute cerebral ischemia conditions.

Early effect of thrombolysis on structural brain network organisation after anterior‐circulation stroke in the randomized WAKE‐UP trial

The symptoms of acute ischemic stroke can be attributed to disruption of the brain network architecture. Systemic thrombolysis is an effective treatment that preserves structural connectivity in the first days after the event. Its effect on the evolution of global network organisation is, however, not well understood. We present a secondary analysis of 269 patients from the randomized WAKE‐UP trial, comparing 127 imaging‐selected patients treated with alteplase with 142 controls who received placebo. We used indirect network mapping to quantify the impact of ischemic lesions on structural brain network organisation in terms of both global parameters of segregation and integration, and local disruption of individual connections. Network damage was estimated before randomization and again 22 to 36 h after administration of either alteplase or placebo. Evolution of structural network organisation was characterised by a loss in integration and gain in segregation, and this trajectory was attenuated by the administration of alteplase. Preserved brain network organization was associated with excellent functional outcome. Furthermore, the protective effect of alteplase was spatio‐topologically nonuniform, concentrating on a subnetwork of high centrality supported in the salvageable white matter surrounding the ischemic cores. This interplay between the location of the lesion, the pathophysiology of the ischemic penumbra, and the spatial embedding of the brain network explains the observed potential of thrombolysis to attenuate topological network damage early after stroke. Our findings might, in the future, lead to new brain network‐informed imaging biomarkers and improved prognostication in ischemic stroke.

Correlation of Serum IL-1β, IL-6, and hsCRP levels with Infarct Core and Ischemic Penumbra Volume in Acute Ischemic Stroke.. [DOI: 10.21203/rs.3.rs-1882454/v2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Background During cerebral ischemia, inflammatory factors such as tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and IL-1β released from the ischemic core may trigger neuronal death in the ischemic penumbra, influencing infarct volume. This study aimed to understand the relationship between serum IL-1β, IL-6, and high-sensitivity C-reactive protein (hs-CRP) levels with infarct core and ischemic penumbra volume in patients with acute ischemic stroke (AIS) and its influence on prognosis. Methods The serum levels of IL-1β, IL-6, and hs-CRP were measured in 65 patients within 24h of AIS onset. The infarcts of the patients were imaged with magnetic resonance imaging and magnetic resonance angiography. Alberta Stroke Program Early Computed Tomography Score (ASPECTS) and core volume on computed tomography perfusion or perfusion-weighted imaging were used to calculate infarct volume and ischemic penumbra volume. The Tan collateral score was calculated with Neusoft Brain Clinical Assistant Ration Evaluate (NeuBrainCARE). Results We found a significant correlation between infarct core volume and serum hs-CRP levels (P < 0.05) and between penumbra volume and IL-6 levels (P < 0.05). Serum IL-6 and hs-CRP levels were positively correlated with NIHSS scores at admission, discharge, and 3 months after discharge. IL-1β levels, Tan collateral score, and ASPECTS showed no correlation with the infarct core volume. Conclusion A significant correlation between hs-CRP and IL-6 levels and infarct and ischemic penumbra volume, respectively, and with NIHSS score shows that these two factors might prove helpful in predicting the extent of neurological damage in AIS patients after 3 months of onset, opening new avenues for treatment.

Normobaric Hyperoxia Combined With Endovascular Treatment for Patients With Acute Ischemic Stroke: A Randomized Controlled Clinical Trial

BACKGROUND AND OBJECTIVES

To investigate the safety and efficacy of normobaric hyperoxia (NBO) combined with endovascular treatment (EVT) in patients with acute ischemic stroke (AIS).

METHODS

In this single-center, proof-of-concept, assessor-blinded, randomized, controlled pilot study, patients with AIS in the acute anterior circulation with large vessel occlusion who had an indication for EVT were randomly assigned to the EVT group or the NBO + EVT group. The NBO + EVT group was given 100% oxygen through a face mask initiated before vascular recanalization (10L/min for 4 hours), while the EVT group was given room air. The primary endpoint was infarct volume measured by MRI within 24-48 hours after randomization.

RESULTS

A total of 231 patients were screened, and 86 patients were randomized into a ratio of 1:1 (EVT group, n = 43; NBO + EVT group, n = 43). The median infarction volume of the NBO + EVT group at 24-48 hours after randomization was significantly smaller than that of the EVT group (median 20.1 vs 37.7 mL, p < 0.01). The median mRS score at 90 days was 2 for the NBO + EVT group when compared with 3 for the EVT group (adjusted value 1.8, 95% CI 1.3-4.2; p = 0.038). Compared with the EVT group, the NBO + EVT group had a lower incidence of symptomatic intracranial hemorrhagic (7% vs 12%), mortality (9% vs 16%), and adverse events (33% vs 42%); however, such a difference was not statistically significant.

DISCUSSION

NBO in combination with EVT seems to be a safe and feasible treatment strategy that could significantly reduce infarct volume, improve short-term neurobehavioral test score, and enhance clinical outcomes at 90 days when compared with EVT alone in patients with AIS. These observations need to be further confirmed by a large, multicenter, randomized clinical trial.

CLINICAL TRIALS REGISTRATION

NCT03620370.

CLASSIFICATION OF EVIDENCE

This pilot study provides Class I evidence that NBO combined with standard EVT decreases infarction volume in patients with acute anterior circulation stroke.

Exosome in Crosstalk between Inflammation and Angiogenesis: A Potential Therapeutic Strategy for Stroke

The endothelial dysfunction, associated with inflammation and vascular permeability, remains the key event in the pathogenesis of cerebral ischemic stroke. Angiogenesis is essential for neuroprotection and neural repair following stroke. The neuroinflammatory reaction plays a vital role in stroke, and inhibition of inflammation contributes to establishing an appropriate external environment for angiogenesis. Exosomes are the heterogeneous population of extracellular vesicles which play critical roles in intercellular communication through transmitting various proteins and nucleic acids to nearby and distant recipient cells by body fluids and circulation. Recent reports have shown that exosomal therapy is a valuable and potential treatment strategy for stroke. In this review, we discussed the exosomes in complex interaction mechanisms of angiogenesis and inflammation following stroke as well as the challenges of exosomal studies such as secretion, uptake, modification, and application.

The crosstalk signals of Sodium Tanshinone ⅡA Sulfonate in rats with cerebral ischemic stroke: Insights from proteomics

BACKGROUND

Stroke could cause long-term disability, even mortality around the world. Recently, Sodium tanshinone IIA sulfonate (STS), identified from Salvia miltiorrhiza Bunge and was found to have unique efficiency in clinical practice as a potential therapeutic agent for ischemic cerebral infarction. However, systematic investigation about the biological mechanism is still lacking. Herein, we utilized high-throughput proteomics approach to identify the underlying targets for the treatment of STS in stroke.

METHODS

We investigated the effect of STS on stroke outcomes on rat model of the Middle Cerebral Artery Occlusion and Reperfusion (MCAO/R), assessing by Z-Longa score, infarct volume and HE staining. Pharmacoproteomic profiling of ischemic penumbra in cortical (IPC) was performed using DIA-based label-free liquid chromatography-tandem mass spectrometry (LC-MS/MS) technique. Bioinformatics analysis was processed for further investigation. The expression of core proteins was semi-quantified by DIA, and the major protein correlating with stroke was examined using parallel reaction monitoring (PRM).

RESULTS

Rats in the MCAO/R group showed neurological function deterioration, which was improved by STS. There were 423 differentially expressed proteins (DEPs) in IPC being detected and quantified in both the sham group and the MCAO/R group. Meanwhile, 285 proteins were significantly changed in the STS treated group, compared to the MCAO/R model. Protein-protein interaction (PPI) network, pathway and biological function enrichment were processed for the DEPs across each two groups, the results of which were integrated for analysis. Alb, mTOR, Dync1h1, Stxbp1, Cltc, and Sptan1 were contained as the core proteins. Altered molecules were discovered to be enriched in 18 signal pathways such as phosphatidylinositol signaling system, PI3K/AKT signal pathway and HIF-1 signal pathway. The results also showed the correlation with sleep disturbances and depression post-stroke.

CONCLUSIONS

We concluded that STS could prevent penumbra from progressively ongoing damage and improve neurological deficits in MCAO/R model rats. The intersected pathways and protein networks predicted by proteomics might provide much more detailed information for the therapeutic mechanisms of STS in the treatment of CIS.

Normobaric hyperoxia plays a neuroprotective role after cerebral ischemia by maintaining the redox homeostasis and the level of connexin43 in astrocytes

Introduction

Acute cerebral ischemia is caused by an insufficient blood supply to brain tissue. Oxygen therapy, which is able to aid diffusion to reach the ischemic region, has been regarded as a possible treatment for cerebral ischemia. Recent animal and pilot clinical studies have reported that normobaric hyperoxia (NBO) showed neuroprotective effects if started soon after the onset of stroke. However, little is known about the role and mechanism of NBO treatment in astrocytes. Connexin43, one of the main gap junction proteins in astrocytes, is extremely sensitive to hypoxia and oxidative stress after cerebral ischemia.

Aims

In the present study, we used sutures to develop an ischemia/reperfusion model in rats to mimic clinical recanalization and investigated the role of connexin43 in NBO‐treated stroke rats, as well as the underlying mechanism of NBO therapy.

Results

Normobaric hyperoxia treatment maintained the homeostasis of oxidoreductases: glutathione peroxidase 4 (GPX4) and NADPH oxidase 4 (two important oxidoreductases) and rescued the ischemia/reperfusion‐induced downregulation of connexin43 protein in astrocytes. Furthermore, NBO treatment attenuated cerebral ischemia‐induced cytochrome c release from mitochondria and was involved in neuroprotective effects by regulating the GPX4 and connexin43 pathway, using Ferrostatin‐1 (an activator of GPX4) or Gap27 (an inhibitor of connexin43).

Conclusions

This study showed the neuroprotective effects of NBO treatment by reducing oxidative stress and maintaining the level of connexin43 in astrocytes, which could be used for the clinical treatment of ischemic stroke.

Quest for Quality in Translational Stroke Research-A New Dawn for Neuroprotection?

Despite tremendous progress in modern-day stroke therapy, ischemic stroke remains a disease associated with a high socioeconomic burden in industrialized countries. In light of demographic change, these health care costs are expected to increase even further. The current causal therapeutic treatment paradigms focus on successful thrombolysis or thrombectomy, but only a fraction of patients qualify for these recanalization therapies because of therapeutic time window restrictions or contraindications. Hence, adjuvant therapeutic concepts such as neuroprotection are urgently needed. A bench-to-bedside transfer of neuroprotective approaches under stroke conditions, however, has not been established after more than twenty years of research, albeit a great many data have demonstrated several neuroprotective drugs to be effective in preclinical stroke settings. Prominent examples of substances supported by extensive preclinical evidence but which failed clinical trials are tirilazad and disodium 2,4-sulphophenyl-N-tert-butylnitrone (NXY-059). The NXY-059 trial, for instance, was retrospectively shown to have a seriously weak study design, a trial of insufficient quality and a poor statistical analysis, although it initially met the recommendations of the STAIR committee. In light of currently ongoing novel neuroprotective stroke trials, such as ESCAPE-NA, and to avoid the mistakes made in the past, an improvement in study quality in the field of stroke neuroprotection is urgently needed. In the present review, animal models closely reflecting the "typical" stroke patient, occlusion techniques and the appropriate choice of time windows are discussed. In this context, the STAIR recommendations could provide a useful orientation. Taking all of this into account, a new dawn for neuroprotection might be possible.

Neuronal chemokine-like-factor 1 (CKLF1) up-regulation promotes M1 polarization of microglia in rat brain after stroke

The phenotypic transformation of microglia in the ischemic penumbra determines the outcomes of ischemic stroke. Our previous study has shown that chemokine-like-factor 1 (CKLF1) promotes M1-type polarization of microglia. In this study, we investigated the cellular source and transcriptional regulation of CKLF1, as well as the biological function of CKLF1 in ischemic penumbra of rat brain. We showed that CKLF1 was significantly up-regulated in cultured rat cortical neurons subjected to oxygen-glucose deprivation/reoxygenation (ODG/R) injury, but not in cultured rat microglia, astrocytes and oligodendrocytes. In a rat model of middle cerebral artery occlusion, we found that CKLF1 was up-regulated and co-localized with neurons in ischemic penumbra. Furthermore, the up-regulated CKLF1 was accompanied by the enhanced nuclear accumulation of NF-κB. The transcriptional activity of CKLF1 was improved by overexpression of NF-κB in HEK293T cells, whereas application of NF-κB inhibitor Bay 11-7082 (1 μM) abolished it, caused by OGD/R. By using chromatin-immunoprecipitation (ChIP) assay we demonstrated that NF-κB directly bound to the promoter of CKLF1 (at a binding site located at -249 bp to -239 bp of CKLF1 promoter region), and regulated the transcription of human CKLF1. Moreover, neuronal conditional medium collected after OGD/R injury or CKLF1-C27 (a peptide obtained from secreted CKLF1) induced the M1-type polarization of microglia, whereas the CKLF1-neutralizing antibody (αCKLF1) or NF-κB inhibitor Bay 11-7082 abolished the M1-type polarization of microglia. Specific knockout of neuronal CKLF1 in ischemic penumbra attenuated neuronal impairments and M1-type polarization of microglia caused by ischemic/reperfusion injury, evidenced by inhibited levels of M1 marker CD16/32 and increased expression of M2 marker CD206. Application of CKLF1-C27 (200 nM) promoted the phosphorylation of p38 and JNK in microglia, whereas specific depletion of neuronal CKLF1 in ischemic penumbra abolished ischemic/reperfusion-induced p38 and JNK phosphorylation. In summary, CKLF1 up-regulation in neurons regulated by NF-κB is one of the crucial mechanisms to promote M1-type polarization of microglia in ischemic penumbra.

Inhibition of the enzyme autotaxin reduces cortical excitability and ameliorates the outcome in stroke

Stroke penumbra injury caused by excess glutamate is an important factor in determining stroke outcome; however, several therapeutic approaches aiming to rescue the penumbra have failed, likely due to unspecific targeting and persistent excitotoxicity, which continued far beyond the primary stroke event. Synaptic lipid signaling can modulate glutamatergic transmission via presynaptic lysophosphatidic acid (LPA) 2 receptors modulated by the LPA-synthesizing molecule autotaxin (ATX) present in astrocytic perisynaptic processes. Here, we detected long-lasting increases in brain ATX concentrations after experimental stroke. In humans, cerebrospinal fluid ATX concentration was increased up to 14 days after stroke. Using astrocyte-specific deletion and pharmacological inhibition of ATX at different time points after experimental stroke, we showed that inhibition of LPA-related cortical excitability improved stroke outcome. In transgenic mice and in individuals expressing a single-nucleotide polymorphism that increased LPA-related glutamatergic transmission, we found dysregulated synaptic LPA signaling and subsequent negative stroke outcome. Moreover, ATX inhibition in the animal model ameliorated stroke outcome, suggesting that this approach might have translational potential for improving the outcome after stroke.

Inhalation of Atmospheric-Pressure Gas Plasma Attenuates Brain Infarction in Rats With Experimental Ischemic Stroke

Previous studies suggest the potential efficacy of neuroprotective effects of gaseous atmospheric-pressure plasma (APP) treatment on neuronal cells. However, it remains unclear if the neuroprotective properties of the gas plasmas benefit the ischemic stroke treatment, and how to use the plasmas in the in vivo ischemic stroke models. Rats were subjected to 90 min middle cerebral artery occlusion (MCAO) to establish the ischemic stroke model and then intermittently inhaled the plasma for 2 min at 60 min MCAO. The regional cerebral blood flow (CBF) was monitored. Animal behavior scoring, magnetic resonance imaging (MRI), 2,3,5-triphenyltetrazolium chloride (TTC) staining, and hematoxylin and eosin (HE) staining were performed to evaluate the therapeutic efficacy of the gas plasma inhalation on MCAO rats. Intermittent gas plasma inhalation by rats with experimental ischemic stroke could improve neurological function, increase regional CBF, and decrease brain infarction. Further MRI tests showed that the gas plasma inhalation could limit the ischemic lesion progression, which was beneficial to improve the outcomes of the MCAO rats. Post-stroke treatment with intermittent gas plasma inhalation could reduce the ischemic lesion progression and decrease cerebral infarction volume, which might provide a new promising strategy for ischemic stroke treatment.

Clinical Imaging of the Penumbra in Ischemic Stroke: From the Concept to the Era of Mechanical Thrombectomy

The ischemic penumbra is defined as the severely hypoperfused, functionally impaired, at-risk but not yet infarcted tissue that will be progressively recruited into the infarct core. Early reperfusion aims to save the ischemic penumbra by preventing infarct core expansion and is the mainstay of acute ischemic stroke therapy. Intravenous thrombolysis and mechanical thrombectomy for selected patients with large vessel occlusion has been shown to improve functional outcome. Given the varying speed of infarct core progression among individuals, a therapeutic window tailored to each patient has recently been proposed. Recent studies have demonstrated that reperfusion therapies are beneficial in patients with a persistent ischemic penumbra, beyond conventional time windows. As a result, mapping the penumbra has become crucial in emergency settings for guiding personalized therapy. The penumbra was first characterized as an area with a reduced cerebral blood flow, increased oxygen extraction fraction and preserved cerebral metabolic rate of oxygen using positron emission tomography (PET) with radiolabeled O₂. Because this imaging method is not feasible in an acute clinical setting, the magnetic resonance imaging (MRI) mismatch between perfusion-weighted imaging and diffusion-weighted imaging, as well as computed tomography perfusion have been proposed as surrogate markers to identify the penumbra in acute ischemic stroke patients. Transversal studies comparing PET and MRI or using longitudinal assessment of a limited sample of patients have been used to define perfusion thresholds. However, in the era of mechanical thrombectomy, these thresholds are debatable. Using various MRI methods, the original penumbra definition has recently gained a significant interest. The aim of this review is to provide an overview of the evolution of the ischemic penumbra imaging methods, including their respective strengths and limitations, as well as to map the current intellectual structure of the field using bibliometric analysis and explore future directions.

Mechanisms of Flow-Mediated Dilation of Pial Collaterals and the Effect of Hypertension

Leptomeningeal anastomoses are small distal anastomotic vessels also known as pial collaterals in the brain. These vessels redirect blood flow during an occlusion and are important for stroke treatment and outcome. Pial collaterals have unique hemodynamic forces and experience significantly increased luminal flow and shear stress after the onset of ischemic stroke. However, there is limited knowledge of how pial collaterals respond to flow and shear stress, and whether this response is altered in chronic hypertension. Using an in vitro system, pial collaterals from normotensive and hypertensive rats (n=6-8/group) were isolated and luminal flow was induced with intravascular pressure maintained at 40 mm Hg. Collateral lumen diameter was measured following each flow rate in the absence or presence of pharmacological inhibitors and activators. Collaterals from male and female Wistar rats dilated similarly to increased flow (2 µL/minute: 58.4±18.7% versus 67.9±7.4%; P=0.275), and this response was prevented by inhibition of the transient receptor potential vanilloid type 4 channel, as well as inhibitors of nitric oxide and intermediate-conductance calcium-activated potassium channels, suggesting shear stress-induced activation of this pathway was involved. However, the vasodilation was significantly impaired in hypertensive rats (2 µL/minute: 17.7±7.7%), which was restored by inhibitors of reactive oxygen species and mimicked by angiotensin II. Thus, flow- and shear stress-induced vasodilation of pial collaterals appears to be an important stimulus for increasing collateral flow during large vessel occlusion. Impairment of this response during chronic hypertension may be related to poorly engaged pial collaterals during ischemic stroke in hypertensive subjects.

New tools for shaping plasticity to enhance recovery after stroke

Stroke is the second most common cause of death worldwide and its prevalence is projected to increase in the coming years in parallel with the increase of life expectancy. Despite the great improvements in the management of the acute phase of stroke, some residual disability persists in most patients thus requiring rehabilitation. One third of patients do not reach the maximal recovery potential and different approaches have been explored with the aim to boost up recovery. In this regard, noninvasive brain stimulation techniques have been widely used to induce neuroplasticity phenomena. Different protocols of repetitive transcranial magnetic stimulation (rTMS) and transcranial electrical stimulation (tES) can induce short- and long-term changes of synaptic excitability and are promising tools for enhancing recovery in stroke patients. New options for neuromodulation are currently under investigation. They include: vagal nerve stimulation (VNS) that can be delivered invasively, with implanted stimulators and noninvasively with transcutaneous VNS (tVNS); and extremely low-frequency (1-300Hz) magnetic fields. This chapter will provide an overview on the new techniques that are used for neuroprotection and for enhancing recovery after stroke.