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

Brain targeted polymeric micelles as drug carriers for ischaemic stroke treatment

Ischaemic stroke is a central nervous system disease with high morbidity, recurrence and mortality rates. Thrombolytic and neuroprotective therapies are the main therapeutic strategies for ischaemic stroke, however, the poor delivery efficiency of thrombolytic and neuroprotective drugs to the brain limits their clinical application. So far, the development of nanomedicine has brought opportunities for the above challenges, which can not only realise the effective accumulation of drugs in the target site, but also improve the pharmacokinetic behaviour of the drugs. Among the most rapidly developing nanoparticles, micelles gradually emerging as an effective strategy for ischaemic stroke treatment due to their own unique advantages. This review provided an overview of targeted and response-release micelles based on the physicochemical properties of the ischaemic stroke microenvironment, summarised the targeting strategies for delivering micellar formulations to the thrombus, blood-brain barrier, and brain parenchyma, and finally described the potentials and challenges of polymeric micelles in the treatment of ischaemic stroke.

Cerebral Infarct Growth: Pathophysiology, Pragmatic Assessment, and Clinical Implications

Cerebral ischemic injury occurs when blood flow drops below a critical level, resulting in an energy failure. The progressive transformation of hypoperfused viable tissue, the ischemic penumbra, into infarction is a mechanism shared by patients with ischemic stroke if timely reperfusion is not achieved. Yet, the pace at which this transformation occurs, known as the infarct growth rate (IGR), exhibits remarkable heterogeneity among patients, brain regions, and over time, reflecting differences in compensatory collateral flow and ischemic tolerance. We review (1) the pathophysiology of infarct growth, (2) the advantages and pitfalls of different approaches of IGR measurement, (3) research gaps for future studies, and (4) the clinical implications of stroke progressor phenotypes. The estimated average IGR in patients with acute large vessel occlusion stroke is 5.4 mL/h although there is wide variability based on ischemic stroke subtype, occlusion location, presence of collaterals, and patient baseline status. The IGR can be calculated using various pragmatic strategies, mostly either quantifying the extension of the infarct at a particular time and dividing this measure by the time that elapsed from symptom onset to imaging assessment or by using collateral blood flow status as a radiological surrogate marker. The IGR defines a spectrum of clinical stroke phenotypes, often dichotomized into fast and slow progressors. An IGR ≥10 mL/h and the perfusion metric hypoperfusion intensity ratio ≥0.5 are commonly used definitions of fast progressors. A nuanced understanding of the IGR and stroke progressor phenotypes could have clinical implications, including informing prognostication, acute decision-making in peripheral-to-comprehensive transfer patients eligible for thrombectomy, and selection for adjuvant neuroprotective agents.

MiR-146a-5p downregulated TRAF6/NF-κB p65 pathway to attenuate the injury of HT-22 cells induced by oxygen-glucose deprivation/reoxygenation

MicroRNA-146a-5p (miR-146a-5p) actively participates in the process of cerebral ischemia-reperfusion (CI/R) injury. Dysregulation of the tumor necrosis factor receptor-associated factor 6 (TRAF6)/nuclear factor kappa-B (NF-κB) p65 axis is closely associated with inflammatory response. This study aimed to investigate the potential involvement of miR-146a-5p and TRAF6/NF-κB p65 in mediating CI/R progression in vitro. HT-22 cells were challenged with oxygen-glucose deprivation/reoxygenation (OGD/R) to simulate CI/R in vitro. HT-22 cells were transfected with miR-146a-5p mimics or TRAF6 overexpression constructs. The impact of miR-146a-5p on apoptosis, inflammation, and TRAF6/NF-κB p65 activation were investigated. OGD/R inhibited HT-22 cell viability, induced apoptosis, reduced miR-146a-5p levels and activated the TRAF6/NF-κB p65 pathway. MiR-146a-5p mimics reduced pro-inflammatory factor release, limited apoptosis-related protein expression, and inactivated the TRAF6/NF-κB p65 pathway in OGD/R-challenged HT-22 cells. Mechanistically, miR-146a-5p was verified to bind to TRAF6 3'UTR. TRAF6 overexpression reversed the beneficial effects of miR-146a-5p mimics on apoptosis, inflammation, and TRAF6/NF-κB p65 activation. This work revealed that miR-146a-5p targeted TRAF6 and suppressed the TRAF6/NF-κB p65 pathway, thereby reducing OGD/R-induced inflammation and apoptosis in HT-22 cells. These findings suggest the potential of the miR-146a-5p/TRAF6/NF-κB p65 axis in the treatment of CI/R.

X-ray fluorescence mapping of brain tissue reveals the profound extent of trace element dysregulation in stroke pathophysiology

The brain is a privileged organ with regard to its trace element composition and maintains a robust barrier system to sequester this specialized environment from the rest of the body and the vascular system. Stroke is caused by loss of adequate blood flow to a region of the brain. Without adequate blood flow ischaemic changes begin almost immediately, triggering an ischaemic cascade, characterized by ion dysregulation, loss of function, oxidative damage, cellular degradation, and breakdown of the barrier that helps maintain this environment. Ion dysregulation is a hallmark of stroke pathophysiology and we observe that most elements in the brain are dysregulated after stroke. X-ray fluorescence-based detection of physiological changes in the neurometallome after stroke reveals profound ion dysregulation within the lesion and surrounding tissue. Not only are most elements significantly dysregulated after stroke, but the level of dysregulation cannot be predicted from a cell-level description of dysregulation. X-ray fluorescence imaging reveals that the stroke lesion retains <25% of essential K+ after stroke, but this element is not concomitantly elevated elsewhere in the organ. Moreover, elements like Na+, Ca2+, and Cl- are vastly elevated above levels available in normal brain tissue (>400%, >200%, and >150%, respectively). We hypothesize that weakening of the blood-brain barrier after stroke allows elements to freely diffuse down their concentration gradient so that the stroke lesion is in equilibrium with blood (and the compartments containing brain interstitial fluid and cerebrospinal fluid). The change observed for the neurometallome likely has consequences for the potential to rescue infarcted tissue, but also presents specific targets for treatment.

Ischemia/reperfusion injury in acute human and experimental stroke: focus on thrombo-inflammatory mechanisms and treatments

BACKGROUND

Despite high recanalization rates of > 90% after endovascular thrombectomy (EVT) clinical outcome in around 50% of treated acute ischemic stroke (AIS) patients is still poor. Novel treatments augmenting the beneficial effects of recanalization are eagerly awaited, but this requires mechanistic insights to explain and overcome futile recanalization.

MAIN BODY

At least two mechanisms contribute to futile recanalization after cerebral large vessel occlusions (LVO): (i) the no reflow phenomenon as evidenced by randomly distributed areas without return of blood flow despite reperfusion of large cerebral arteries, and (ii) ischemia/reperfusion (I/R) injury, the paradoxically harmful aspect of blood flow return in transiently ischemic organs. There is accumulating evidence from experimental stroke models that platelets and leukocytes interact and partly obstruct the microvasculature under LVO, and that platelet-driven inflammation (designated thrombo-inflammation) extends into the reperfusion phase and causes I/R injury. Blocking of platelet glycoprotein receptors (GP) Ib and GPVI ameliorated inflammation and I/R injury providing novel therapeutic options. Recently, MRI studies confirmed a significant, up to 40% infarct expansion after recanalization in AIS thereby proofing the existance of I/R injury in the human brain. Moreover, analysis of minute samples of ischemic arterial blood aspirated directly from the pial cerebral collateral circulation under LVO during the routine EVT procedure confirmed platelet activation and platelet-driven leukocyte accumulation in AIS and, thus, the principal transferability of pathophysiological stroke mechanisms from rodents to man. Two recently published clinical phase 1b/2a trials targeted (thrombo-) inflammation in AIS: The ACTIMIS trial targeting platelet GPVI by glenzocimab provided encouraging safety signals in AIS similar to the ApTOLL trial targeting toll-like receptor 4, a central receptor guiding stroke-induced innate immunity. However, both studies were not powered to show clinical efficacy.

CONCLUSIONS

The fact that the significance of I/R injury in AIS has recently been formally established and given the decisive role of platelet-leukocytes interactions herein, new avenues for adjunct stroke treatments emerge. Adjusted study designs to increase the probability of success are of outmost importance and we look forward from what can be learned from the so far unpublished, presumbably negative ACTISAFE and MOST trials.

Polyphenols for stroke therapy: the role of oxidative stress regulation

Stroke is associated with a high incidence and disability rate, which seriously endangers human health. Oxidative stress (OS) plays a crucial role in the underlying pathologic progression of cerebral damage in stroke. Emerging experimental studies suggest that polyphenols have antioxidant potential and express protective effects after different types of strokes, but no breakthrough has been achieved in clinical studies. Nanomaterials, due to small characteristic sizes, can be used to deliver drugs, and have shown excellent performance in the treatment of various diseases. The drug delivery capability of nanomaterials has significant implications for the clinical translation and application of polyphenols. This comprehensive review introduces the mechanism of oxidative stress in stroke, and also summarizes the antioxidant effects of polyphenols on reactive oxygen species generation and oxidative stress after stroke. Also, the application characteristics and research progress of nanomaterials in the treatment of stroke with antioxidants are presented.

Deciphering the mechanistic impact of acupuncture on the neurovascular unit in acute ischemic stroke: Insights from basic research in a narrative review

Ischemic stroke(IS), a severe acute cerebrovascular disease, not only imposes a heavy economic burden on society but also presents numerous challenges in treatment. During the acute phase, while thrombolysis and thrombectomy serve as primary treatments, these approaches are restricted by a narrow therapeutic window. During rehabilitation, commonly used neuroprotective agents struggle with their low drug delivery efficiency and inadequate preclinical testing, and the long-term pharmacological and toxicity effects of nanomedicines remain undefined. Meanwhile, acupuncture as a therapeutic approach is widely acknowledged for its effectiveness in treating IS and has been recommended by the World Health Organization (WHO) as an alternative and complementary therapy, even though its exact mechanisms remain unclear. This review aims to summarize the known mechanisms of acupuncture and electroacupuncture (EA) in the treatment of IS. Research shows that acupuncture treatment mainly protects the neurovascular unit through five mechanisms: 1) reducing neuronal apoptosis and promoting neuronal repair and proliferation; 2) maintaining the integrity of the blood-brain barrier (BBB); 3) inhibiting the overactivation and polarization imbalance of microglia; 4) regulating the movement of vascular smooth muscle (VSM) cells; 5) promoting the proliferation of oligodendrocyte precursors. Through an in-depth analysis, this review reveals the multi-level, multi-dimensional impact of acupuncture treatment on the neurovascular unit (NVU) following IS, providing stronger evidence and a theoretical basis for its clinical application.

Before, during, and after: An Argument for Safety and Improved Outcome of Thrombolysis in Acute Ischemic Stroke with Direct Oral Anticoagulant Treatment

Direct oral anticoagulants are the primary stroke prevention option in patients with atrial fibrillation. Anticoagulant use before stroke, however, might inhibit clinician comfort with thrombolysis if a stroke does occur. Resuming anticoagulants after ischemic stroke is also problematic for fear of hemorrhage. We describe extensive literature showing that thrombolysis is safe after stroke with direct anticoagulant use. Early reinstitution of direct anticoagulant treatment is associated with lower risk of embolic recurrence and lower hemorrhage risk. The use of direct anticoagulants before, during, and after thrombolysis appears to be safe and is likely to promote improved outcomes after ischemic stroke. ANN NEUROL 2024;96:871-886.

Clinical significance and prevalence of subarachnoid hyperdensities on flat detector CT after mechanical thrombectomy: does it really matter?

BACKGROUND

Subarachnoid hyperdensities after mechanical thrombectomy (MT) are a common finding. However, it is often regarded as clinically insignificant.

OBJECTIVE

With this single-center investigation, to identify the prevalence of subarachnoid hyperdensities following MT, associated predictors, and the impact on the clinical outcome of the patients.

METHODS

383 patients from the stroke registry were analyzed for the presence of subarachnoid hyperdensities on flat detector CT (FDCT) directly after the completion of MT, and on follow-up dual-energy CT, then classified according to a visual grading scale. 178 patients were included with anterior circulation occlusions. Regression analysis was performed to identify significant predictors, and Kruskal-Wallis analysis and Χ2 test were performed to test the variables among the different groups. The primary outcome was the modified Rankin Scale (mRS) score at 90 days and was analyzed with the Wilcoxon-Mann-Whitney rank-sum test.

RESULTS

The prevalence of subarachnoid hyperdensities on FDCT was (66/178, 37.1%) with patients experiencing a significant unfavorable outcome (P=0.035). Significantly fewer patients with subarachnoid hyperdensities achieved a mRS score of ≤3 at 90 days 25/66 (37.9%) vs 60/112 (53.6%), P=0.043). In addition, mortality was significantly higher in the subarachnoid hyperdensities group (34.8% vs 19.6%, P=0.024). Distal occlusions and a higher number of device passes were significantly associated with subarachnoid hyperdensities (P=0.026) and (P=0.001), respectively. Patients who received intravenous tissue plasminogen activator had significantly fewer subarachnoid hyperdensities (P=0.029).

CONCLUSIONS

Postinterventional subarachnoid hyperdensities are a frequent finding after MT and are associated with neurological decline and worse functional outcome. They are more common with distal occlusions and multiple device passes.

The positive role of transforming growth factor-β1 in ischemic stroke

Ischemic stroke is one of the most disabling and fatal diseases around the world. The damaged brain tissues will undergo excessive autophagy, vascular endothelial cells injury, blood-brain barrier (BBB) impairment and neuroinflammation after ischemic stroke. However, there is no unified viewpoint on the underlying mechanism of brain damage. Transforming growth factor-β1 (TGF-β1), as a multi-functional cytokine, plays a crucial role in the intricate pathological processes and helps maintain the physiological homeostasis of brain tissues through various signaling pathways after ischemic stroke. In this review, we summarize the protective role of TGF-β1 in autophagic flux, BBB, vascular remodeling, neuroinflammation and other aspects after ischemic stroke. Based on the review, we believe that TGF-β1 could serve as a key target for treating ischemic stroke.

β-elemene promotes microglial M2-like polarization against ischemic stroke via AKT/mTOR signaling axis-mediated autophagy

BACKGROUND

Resident microglia- and peripheric macrophage-mediated neuroinflammation plays a predominant role in the occurrence and development of ischemic stroke. Microglia undergo polarization to M1/M2-like phenotype under stress stimulation, which mediates intracellular inflammatory response. β-elemene is a natural sesquiterpene and possesses potent anti-inflammatory activity. This study aimed to investigate the anti-inflammatory efficacy and mechanism of β-elemene in ischemic stroke from the perspective of balancing microglia M1/M2-like polarization.

METHODS

The middle cerebral artery occlusion (MCAO) model and photothrombotic stroke model were established to explore the regulation effect of β-elemene on the cerebral ischemic injury. The LPS and IFN-γ stimulated BV-2 cells were used to demonstrate the anti-inflammatory effects and potential mechanism of β-elemene regulating M1/M2-like polarization in vitro.

RESULTS

In C57BL/6 J mice subjected to MCAO model and photothrombotic stroke model, β-elemene attenuated neurological deficit, reduced the infarction volume and neuroinflammation, thus improving ischemic stroke injury. β-elemene promoted the phenotype transformation of microglia from M1-like to M2-like, which prevented neurons from oxygen and glucose deprivation/reoxygenation (OGD/R) injury by inhibiting inflammatory factor release, thereby reducing neuronal apoptosis. Mechanically, β-elemene prevented the activation of TLR4/NF-κΒ and MAPK signaling pathway and increased AKT/mTOR mediated-autophagy, thereby promoting M2-like polarization of microglia.

CONCLUSIONS

These results indicated that β-elemene improved cerebral ischemic injury and promoted the transformation of microglia phenotype from M1-like to M2-like, at least in part, through AKT/mTOR-mediated autophagy. This study demonstrated that β-elemene might serve as a promising drug for alleviating ischemic stroke injury.

Geraniol attenuates oxygen-glucose deprivation/reoxygenation-induced ROS-dependent apoptosis and permeability of human brain microvascular endothelial cells by activating the Nrf-2/HO-1 pathway

Blood-brain barrier breakdown and ROS overproduction are important events during the progression of ischemic stroke aggravating brain damage. Geraniol, a natural monoterpenoid, possesses anti-apoptotic, cytoprotective, anti-oxidant, and anti-inflammatory activities. Our study aimed to investigate the effect and underlying mechanisms of geraniol in oxygen-glucose deprivation/reoxygenation (OGD/R)-induced human brain microvascular endothelial cells (HBMECs). Apoptosis, caspase-3 activity, and cytotoxicity of HBMECs were evaluated using TUNEL, caspase-3 activity, and CCK-8 assays, respectively. The permeability of HBMECs was examined using FITC-dextran assay. Reactive oxygen species (ROS) production was measured using the fluorescent probe DCFH-DA. The protein levels of zonula occludens-1 (ZO-1), occludin, claudin-5, β-catenin, nuclear factor erythroid 2-related factor 2 (Nrf2), and heme oxygenase-1 (HO-1) were determined by western blotting. Geraniol showed no cytotoxicity in HBMECs. Geraniol and ROS scavenger N-acetylcysteine (NAC) both attenuated OGD/R-induced apoptosis and increase of caspase-3 activity and the permeability to FITC-dextran in HBMECs. Geraniol relieved OGD/R-induced ROS accumulation and decrease of expression of ZO-1, occludin, claudin-5, and β-catenin in HBMECs. Furthermore, we found that geraniol activated Nrf2/HO-1 pathway to inhibit ROS in HBMECs. In conclusion, geraniol attenuated OGD/R-induced ROS-dependent apoptosis and permeability in HBMECs through activating the Nrf2/HO-1 pathway.

Aquaporins alteration revealed kidney damages in cerebral ischemia/reperfusion rats

Background

Restoration of blood supply is a desired goal for the treatment of acute ischemic stroke. However, the restoration often leads to cerebral ischemia-reperfusion injury (CIR/I), which greatly increases the risk of non-neural organ damage. In particular, the acute kidney injury might be one of the most common complications.

Aims

The study aimed to understand the damage occurred and the potential molecular mechanisms.

Methods

The study was explored on the CIR/I rats generated by performing middle cerebral artery occlusion/reperfusion (MCAO/Reperfusion). The rats were evaluated with injury on the brains, followed by the non-neural organs including kidneys, livers, colons and stomachs. They were examined further with histopathological changes, and gene expression alterations by using RT-qPCR of ten aquaporins (Aqps) subtypes including Aqp1～Aqp9 and Aqp11. Furthermore, the Aqps expression profiles were constructed for each organ and analyzed by performing Principle Component Analysis. In addition, immunohistochemistry was explored to look at the protein expression of Aqp1, Aqp2, Aqp3 and Aqp4 in the rat kidneys.

Results

There was a prominent down-regulation profile in the MCAO/Reperfusion rat kidneys. The protein expression of Aqp1, Aqp2, Aqp3 and Aqp4 was decreased in the kidneys of the MCAO/Reperfusion rats. We suggested that the kidney was in the highest risk to be damaged following the CIR/I. Down-regulation of Aqp2, Aqp3 and Aqp4 was involved in the acute kidney injury induced by the CIR/I.

Differential Vulnerability and Response to Injury among Brain Cell Types Comprising the Neurovascular Unit

The neurovascular unit (NVU) includes multiple different cell types, including neurons, astrocytes, endothelial cells, and pericytes, which respond to insults on very different time or dose scales. We defined differential vulnerability among these cell types, using response to two different insults: oxygen-glucose deprivation (OGD) and thrombin-mediated cytotoxicity. We found that neurons are most vulnerable, followed by endothelial cells and astrocytes. After temporary focal cerebral ischemia in male rats, we found significantly more injured neurons, compared with astrocytes in the ischemic area, consistent with differential vulnerability in vivo. We sought to illustrate different and shared mechanisms across all cell types during response to insult. We found that gene expression profiles in response to OGD differed among the cell types, with a paucity of gene responses shared by all types. All cell types activated genes relating to autophagy, apoptosis, and necroptosis, but the specific genes differed. Astrocytes and endothelial cells also activated pathways connected to DNA repair and antiapoptosis. Taken together, the data support the concept of differential vulnerability in the NVU and suggest that different elements of the unit will evolve from salvageable to irretrievable on different time scales while residing in the same brain region and receiving the same (ischemic) blood flow. Future work will focus on the mechanisms of these differences. These data suggest future stroke therapy development should target different elements of the NVU differently.

Advanced Nano-Drug Delivery Systems in the Treatment of Ischemic Stroke

In recent years, the frequency of strokes has been on the rise year by year and has become the second leading cause of death around the world, which is characterized by a high mortality rate, high recurrence rate, and high disability rate. Ischemic strokes account for a large percentage of strokes. A reperfusion injury in ischemic strokes is a complex cascade of oxidative stress, neuroinflammation, immune infiltration, and mitochondrial damage. Conventional treatments are ineffective, and the presence of the blood-brain barrier (BBB) leads to inefficient drug delivery utilization, so researchers are turning their attention to nano-drug delivery systems. Functionalized nano-drug delivery systems have been widely studied and applied to the study of cerebral ischemic diseases due to their favorable biocompatibility, high efficiency, strong specificity, and specific targeting ability. In this paper, we briefly describe the pathological process of reperfusion injuries in strokes and focus on the therapeutic research progress of nano-drug delivery systems in ischemic strokes, aiming to provide certain references to understand the progress of research on nano-drug delivery systems (NDDSs).

Remote Ischemic Conditioning With Medical Management or Reperfusion Therapy for Acute Ischemic Stroke: A Systematic Review and Meta-Analysis

BACKGROUND AND OBJECTIVES

Remote ischemic conditioning (RIC) is a low-cost, accessible, and noninvasive neuroprotective treatment strategy, but its efficacy and safety in acute ischemic stroke are controversial. With the publication of several randomized controlled trials (RCTs) and the recent results of the RESIST trial, it may be possible to identify the patient population that may (or may not) benefit from RIC. This systematic review and meta-analysis aims to evaluate the effectiveness and safety of RIC in patients with ischemic stroke receiving different treatments by pooling data of all randomized controlled studies to date.

METHODS

We searched the PubMed, Embase, Cochrane, Elsevier, and Web of Science databases to obtain articles in all languages from inception until May 25, 2023. The primary outcome was the modified Rankin Scale (mRS) score at the specified endpoint time in the trial. The secondary outcomes were change in NIH Stroke Scale (NIHSS) and recurrence of stroke events. The safety outcomes were cardiovascular events, cerebral hemorrhage, and mortality. The quality of articles was evaluated through the Cochrane risk assessment tool. This study was registered in PROSPERO (CRD42023430073).

RESULTS

There were 7,657 patients from 22 RCTs included. Compared with the control group, patients who received RIC did not have improved mRS functional outcomes, regardless of whether they received medical management, reperfusion therapy with intravenous thrombolysis (IVT), or mechanical thrombectomy (MT). In the medical management group, patients who received RIC had decreased incidence of stroke recurrence (risk ratio 0.63, 95% CI 0.43-0.92, p = 0.02) and lower follow-up NIHSS score by 1.72 points compared with the control group (p < 0.00001). There was no increased risk of adverse events including death or cerebral hemorrhage in the IVT or medical management group.

DISCUSSION

In patients with ischemic stroke who are not eligible for reperfusion therapy, RIC did not affect mRS functional outcomes but significantly improved the NIHSS score at the follow-up endpoint and reduced stroke recurrence, without increasing the risk of cerebral hemorrhage or death. In patients who received IVT or MT, the benefit of RIC was not observed.

Molecular Mechanisms of Ischemic Stroke: A Review Integrating Clinical Imaging and Therapeutic Perspectives

Ischemic stroke poses a significant global health challenge, necessitating ongoing exploration of its pathophysiology and treatment strategies. This comprehensive review integrates various aspects of ischemic stroke research, emphasizing crucial mechanisms, therapeutic approaches, and the role of clinical imaging in disease management. It discusses the multifaceted role of Netrin-1, highlighting its potential in promoting neurovascular repair and mitigating post-stroke neurological decline. It also examines the impact of blood-brain barrier permeability on stroke outcomes and explores alternative therapeutic targets such as statins and sphingosine-1-phosphate signaling. Neurocardiology investigations underscore the contribution of cardiac factors to post-stroke mortality, emphasizing the importance of understanding the brain-heart axis for targeted interventions. Additionally, the review advocates for early reperfusion and neuroprotective agents to counter-time-dependent excitotoxicity and inflammation, aiming to preserve tissue viability. Advanced imaging techniques, including DWI, PI, and MR angiography, are discussed for their role in evaluating ischemic penumbra evolution and guiding therapeutic decisions. By integrating molecular insights with imaging modalities, this interdisciplinary approach enhances our understanding of ischemic stroke and offers promising avenues for future research and clinical interventions to improve patient outcomes.

Integrated transcriptomic and proteomic profiling reveals the key molecular signatures of brain endothelial reperfusion injury

BACKGROUND

Reperfusion therapy after ischemic stroke often causes brain microvascular injury. However, the underlying mechanisms are unclear.

METHODS

Transcriptomic and proteomic analyses were performed on human cerebral microvascular endothelial cells following oxygen-glucose deprivation (OGD) or OGD plus recovery (OGD/R) to identify molecules and signaling pathways dysregulated by reperfusion. Major findings were further validated in a mouse model of cerebral ischemia and reperfusion.

RESULTS

Transcriptomic analysis identified 390 differentially expressed genes (DEGs) between the OGD/R and OGD group. Pathway analysis indicated that these genes were mostly associated with inflammation, including the TNF signaling pathway, TGF-β signaling pathway, cytokine-cytokine receptor interaction, NOD-like receptor signaling pathway, and NF-κB signaling pathway. Proteomic analysis identified 201 differentially expressed proteins (DEPs), which were primarily associated with extracellular matrix destruction and remodeling, impairment of endothelial transport function, and inflammatory responses. Six genes (DUSP1, JUNB, NFKBIA, NR4A1, SERPINE1, and THBS1) were upregulated by OGD/R at both the mRNA and protein levels. In mice with cerebral ischemia and reperfusion, brain TNF signaling pathway was activated by reperfusion, and inhibiting TNF-α with adalimumab significantly attenuated reperfusion-induced brain endothelial inflammation. In addition, the protein level of THBS1 was substantially upregulated upon reperfusion in brain endothelial cells and the peri-endothelial area in mice receiving cerebral ischemia.

CONCLUSION

Our study reveals the key molecular signatures of brain endothelial reperfusion injury and provides potential therapeutic targets for the treatment of brain microvascular injury after reperfusion therapy in ischemic stroke.

Demethylnobiletin ameliorates cerebral ischemia-reperfusion injury in rats through Nrf2/HO-1 signaling pathway

BACKGROUND

Demethylnobiletin (DN), with a variety of biological activities, is a polymethoxy-flavanone (PMF) found in citrus. In the present study, we explored the biological activities and potential mechanism of DN to improve cerebral ischemia reperfusion injury (CIRI) in rats, and identified DN as a novel neuroprotective agent for patients with ischemic brain injury.

METHODS

Rat CIRI models were established via middle cerebral artery occlusion (MCAO). Primary nerve cells were isolated and cultured in fetal rat cerebral cortex in vitro, and oxygen-glucose deprivation/reperfusion (OGD/R) models of primary nerve cells were induced. After intervention with DN with different concentrations in MCAO rats and OGD/R nerve cells, 2,3,5-triphenyltetrazolium chloride staining was used to quantify cerebral infarction size in CIRI rats. Modified neurological severity score was utilized to assess neurological performance. Histopathologic staining and live/dead cell-viability staining was used to observe apoptosis. Levels of glutathione (GSH), superoxide dismutase (SOD), reactive oxygen species (ROS) and malondialdehyde (MDA) in tissues and cells were detected using commercial kits. DN level in serum and cerebrospinal fluid of MCAO rats were measured by liquid chromatography tandem mass spectrometry. In addition, expression levels of proteins like Kelch like ECH associated protein 1 (Keap1), nuclear factor erythroid 2-related factor 2 (Nfr2) and heme oxygenase 1 (HO-1) in the Nrf2/HO-1 pathway, and apoptosis-related proteins like Cleaved caspase-3, BCL-2-associated X protein (Bax) and B-cell lymphoma-2 (Bcl-2) were determined by Western blot and immunofluorescence.

RESULTS

DN can significantly enhance neurological function recovery by reducing cerebral infarction size and weakening neurocytes apoptosis in MCAO rats. It was further found that DN could improve oxidative stress (OS) injury of nerve cells by bringing down MDA and ROS levels and increasing SOD and GSH levels. Notably, DN exerts its pharmacological influences through entering blood-brain barrier. Mechanically, DN can reduce Keap1 expression while activate Nrf2 and HO-1 expression in neurocytes.

CONCLUSIONS

The protective effect of DN on neurocytes have been demonstrated in both in vitro and in vivo circumstances. It deserves to be developed as a potential neuroprotective agent through regulating the Nrf2/HO-1 signaling pathway to ameliorate neurocytes impairment caused by OS.

Hyperperfusion profiles after recanalization differentially associate with outcomes in a rat ischemic stroke model

Futile recanalization hampers prognoses of ischemic stroke after successful mechanical thrombectomy, hypothetically through post-recanalization perfusion deficits, onset-to-groin delays and sex effects. Clinically, acute multiparametric imaging studies remain challenging. We assessed possible relationships between these factors and disease outcome after experimental cerebral ischemia-reperfusion, using translational MRI, behavioral testing and multi-model inference analyses. Male and female rats (N = 60) were subjected to 45-/90-min filament-induced transient middle cerebral artery occlusion. Diffusion, T2- and perfusion-weighted MRI at occlusion, 0.5 h and four days after recanalization, enabled tracking of tissue fate, and relative regional cerebral blood flow (rrCBF) and -volume (rrCBV). Lesion areas were parcellated into core, salvageable tissue and delayed injury, verified by histology. Recanalization resulted in acute-to-subacute lesion volume reductions, most apparently in females (n = 19). Hyperacute normo-to-hyperperfusion in the post-ischemic lesion augmented towards day four, particularly in males (n = 23). Tissue suffering delayed injury contained higher ratios of hypoperfused voxels early after recanalization. Regressed against acute-to-subacute lesion volume change, increased rrCBF associated with lesion growth, but increased rrCBV with lesion reduction. Similar relationships were detected for behavioral outcome. Post-ischemic hyperperfusion may develop differentially in males and females, and can be beneficial or detrimental to disease outcome, depending on which perfusion parameter is used as explanatory variable.

Implications of Post-recanalization Perfusion Deficit After Acute Ischemic Stroke: a Scoping Review of Clinical and Preclinical Imaging Studies

The goal of reperfusion therapy for acute ischemic stroke (AIS) is to restore cerebral blood flow through recanalization of the occluded vessel. Unfortunately, successful recanalization does not always result in favorable clinical outcome. Post-recanalization perfusion deficits (PRPDs), constituted by cerebral hypo- or hyperperfusion, may contribute to lagging patient recovery rates, but its clinical significance remains unclear. This scoping review provides an overview of clinical and preclinical findings on post-ischemic reperfusion, aiming to elucidate the pattern and consequences of PRPD from a translational perspective. The MEDLINE database was searched for quantitative clinical and preclinical studies of AIS reporting PRPD based on cerebral circulation parameters acquired by translational tomographic imaging methods. PRPD and stroke outcome were mapped on a charting table, creating an overview of PRPD after AIS. Twenty-two clinical and twenty-two preclinical studies were included. Post-recanalization hypoperfusion is rarely reported in clinical studies (4/22) but unequivocally associated with detrimental outcome. Post-recanalization hyperperfusion is more commonly reported (18/22 clinical studies) and may be associated with positive or negative outcome. PRPD has been replicated in animal studies, offering mechanistic insights into causes and consequences of PRPD and allowing delineation of possible courses of PRPD. Complex relationships exist between PRPD and stroke outcome. Diversity in methods and lack of standardized definitions in reperfusion studies complicate the characterization of reperfusion patterns. Recommendations are made to advance the understanding of PRPD mechanisms and to further disentangle the relation between PRPD and disease outcome.

Incidence, severity and impact on functional outcome of persistent hypoperfusion despite large-vessel recanalization, a potential marker of impaired microvascular reperfusion: Systematic review of the clinical literature

The reported incidence of persistent hypoperfusion despite complete recanalization as surrogate for impaired microvascular reperfusion (IMR) has varied widely among clinical studies, possibly due to differences in i) definition of complete recanalization, with only recent Thrombolysis in Cerebral Infarction (TICI) grading schemes allowing distinction between complete (TICI3) and partial recanalization with distal occlusions (TICI2c); ii) operational definition of IMR; and iii) consideration of potential alternative causes for hypoperfusion, notably carotid stenosis, re-occlusion and post-thrombectomy hemorrhage. We performed a systematic review to identify clinical studies that carried out brain perfusion imaging within 72 hrs post-thrombectomy for anterior circulation stroke and reported hypoperfusion rates separately for TICI3 and TICI2c grades. Authors were contacted if this data was missing. We identified eight eligible articles, altogether reporting 636 patients. The incidence of IMR after complete recanalization (i.e., TICI3) tended to decrease with the number of considered alternative causes of hypoperfusion: range 12.5-42.9%, 0-31.6% and 0-9.1% in articles that considered none, two or all three causes, respectively. No study reported the impact of IMR on functional outcome separately for TICI-3 patients. Based on this systematic review, IMR in true complete recanalization appears relatively rare, and reported incidence highly depends on definition used and consideration of confounding factors.

Early mortality of emergency surgery for acute type A aortic dissection in octogenarians and nonagenarians: A multi-center retrospective study

OBJECTIVES

The clinical data on postoperative mortality and central nervous system (CNS) complications in older adults who underwent acute type A aortic dissection are limited. Thus, in this study we aimed to evaluate the association between age and early postoperative mortality and occurrence of CNS complications.

METHODS

This multicentric retrospective cohort study included 5 tertiary hospitals in Japan. All patients who underwent emergency surgery for acute type A aortic dissection between October 1998 and December 2019 were enrolled. The multilevel Cox proportional hazards model, which considered years as level 1, institutions as level 2, and surgeons as level 3, was used to evaluate the association between age and early postoperative hospital mortality and occurrence of CNS complications.

RESULTS

Of the 1037 patients, 227 (21.9%) were ≥80 years old and 810 (78.1%) were <80 years old. Overall, 134 patients (12.9%) died within 30 days postoperatively; among them, 42/227 (18.5%) and 92/810 (11.4%) were aged ≥80 and <80 years, respectively (hazard ratio [HR], 1.63; P = .0046). CNS complications within 30 days postoperatively occurred in 140/1037 (13.5%) patients; among them, 42/227 (18.5%) and 98/810 (12.1%) were aged ≥80 and <80 years, respectively (HR, 1.63; P = .011). In multivariate analysis, age ≥80 years was associated with mortality within 30 days postoperatively (adjusted HR, 2.37; 95% CI, 1.23-4.57; P = .01) but not with CNS complications (adjusted HR, 1.58; 95% CI, 0.93-2.69; P = .091).

CONCLUSIONS

The early postoperative mortality in older patients was approximately 50% higher than in the younger population. A thorough discussion regarding the surgical indications should be done.

"No-reflow" phenomenon in acute ischemic stroke

Acute ischemic stroke (AIS) afflicts millions of individuals worldwide. Despite the advancements in thrombolysis and thrombectomy facilitating proximal large artery recanalization, the resultant distal hypoperfusion, referred to "no-reflow" phenomenon, often impedes the neurological function restoration in patients. Over half a century of scientific inquiry has validated the existence of cerebral "no-reflow" in both animal models and human subjects. Furthermore, the correlation between "no-reflow" and adverse clinical outcomes underscores the necessity to address this phenomenon as a pivotal strategy for enhancing AIS prognoses. The underlying mechanisms of "no-reflow" are multifaceted, encompassing the formation of microemboli, microvascular compression and contraction. Moreover, a myriad of complex mechanisms warrant further investigation. Insights gleaned from mechanistic exploration have prompted advancements in "no-reflow" treatment, including microthrombosis therapy, which has demonstrated clinical efficacy in improving patient prognoses. The stagnation in current "no-reflow" diagnostic methods imposes limitations on the timely application of combined therapy on "no-reflow" post-recanalization. This narrative review will traverse the historical journey of the "no-reflow" phenomenon, delve into its underpinnings in AIS, and elucidate potential therapeutic and diagnostic strategies. Our aim is to equip readers with a swift comprehension of the "no-reflow" phenomenon and highlight critical points for future research endeavors.

Reperfusion by endovascular thrombectomy and early cerebral edema in anterior circulation stroke: Results from the SITS-International Stroke Thrombectomy Registry

BACKGROUND

A large infarct and expanding cerebral edema (CED) due to a middle cerebral artery occlusion confers a 70% mortality unless treated surgically. There is still conflicting evidence whether reperfusion is associated with a lower risk for CED in acute ischemic stroke.

AIM

To investigate the association of reperfusion with development of early CED after stroke thrombectomy.

METHODS

From the SITS-International Stroke Thrombectomy Registry, we selected patients with occlusion of the intracranial internal carotid or middle cerebral artery (M1 or M2). Successful reperfusion was defined as mTICI ⩾ 2b. Primary outcome was moderate or severe CED, defined as focal brain swelling ⩾1/3 of the hemisphere on imaging scans at 24 h. We used regression methods while adjusting for baseline variables. Effect modification by severe early neurological deficits, as indicators of large infarct at baseline and at 24 h, were explored.

RESULTS

In total, 4640 patients, median age 70 years and median National Institutes of Health Stroke Score (NIHSS) 16, were included. Of these, 86% had successful reperfusion. Moderate or severe CED was less frequent among patients who had reperfusion compared to patients without reperfusion: 12.5% versus 29.6%, p < 0.05, crude risk ratio (RR) 0.42 (95% confidence interval (CI): 0.37-0.49), and adjusted RR 0.50 (95% CI: 0.44-0.57). Analysis of effect modification indicated that severe neurological deficits weakened the association between reperfusion and lower risk of CED. The RR reduction was less favorable in patients with severe neurological deficits, defined as NIHSS score 15 or more at baseline and at 24 h, used as an indicator for larger infarction.

CONCLUSION

In patients with large artery anterior circulation occlusion stroke who underwent thrombectomy, successful reperfusion was associated with approximately 50% lower risk for early CED. Severe neurological deficit at baseline seems to be a predictor for moderate or severe CED also in patients with successful reperfusion by thrombectomy.

IV thrombolysis plus thrombectomy versus IV thrombolysis alone for minor stroke with anterior circulation large vessel occlusion from the IRETAS and Italian SITS-ISTR cohorts

INTRODUCTION

The aim of this study was to compare the outcomes of patients treated with intravenous thrombolysis (IVT) <4.5 h after symptom onset plus mechanical thrombectomy (MT) <6 h with those treated with IVT alone <4.5 h for minor stroke (NIHSS ≤5) with large vessel occlusion (LVO) in the anterior circulation.

PATIENTS AND METHODS

Patients enrolled in the Italian Registry of Endovascular Treatment in Acute Stroke (IRETAS) and in the Italian centers included in the SITS-ISTR were analyzed.

RESULTS

Among the patients with complete data on 24-h ICH type, 236 received IVT plus MT and 382 received IVT alone. IVT plus MT was significantly associated with unfavorable shift on 24-h ICH types (from no ICH to PH-2) (OR, 2.130; 95% CI, 1.173-3.868; p=0.013) and higher rate of PH (OR, 4.363; 95% CI, 1.579-12.055; p=0.005), sICH per ECASS II definition (OR, 5.527; 95% CI, 1.378-22.167; p=0.016), and sICH per NINDS definition (OR, 3.805; 95% CI, 1.310-11.046; p=0.014). Among the patients with complete data on 3-month mRS score, 226 received IVT plus MT and 262 received IVT alone. No significant difference was reported between IVT plus MT and IVT alone on mRS score 0-1 (72.1% versus 69.1%), mRS score 0-2 (79.6% versus 79%), and death (6.2% versus 6.1%).

CONCLUSIONS

Compared with IVT alone, IVT plus MT was associated with unfavorable shift on 24-h ICH types and higher rate of 24-h PH and sICH in patients with minor stroke and LVO in the anterior circulation. However, no difference was reported between the groups on 3-month functional outcome measures.

Predictors for hemorrhagic transformation and cerebral edema in stroke patients with first-pass complete recanalization

BACKGROUND

Predictors of radiological complications attributable to reperfusion injury remain unknown when baseline setting is optimal for endovascular treatment and procedural setting is the best in stroke patients with large vessel occlusion (LVO).

AIMS

To identify clinical and radiological/procedural predictors for hemorrhagic transformation (HT) and cerebral edema (CED) at 24 hr in patients obtaining complete recanalization in one pass of thrombectomy for ischemic stroke ⩽ 6 h from symptom onset with intra-cranial anterior circulation LVO and ASPECTS ⩾ 6.

METHODS

We conducted a cohort study on prospectively collected data from 1400 patients enrolled in the Italian Registry of Endovascular Treatment in Acute Stroke.

RESULTS

HT was reported in 248 (18%) patients and early CED was reported in 260 (19.2%) patients. In the logistic regression model including predictors from a first model with clinical variables and from a second model with radiological/procedural variables, diabetes mellitus (odds ratio (OR) = 1.832, 95% confidence interval (CI) = 1.201-2.795), higher National Institutes of Health Stroke Scale (NIHSS) (OR = 1.076, 95% CI = 1.044-1.110), lower Alberta Stroke Program Early CT (ASPECTS) (OR = 0.815, 95% CI = 0.694-0.957), and longer onset-to-groin time (OR = 1.005, 95% CI = 1.002-1.007) were predictors of HT, whereas general anesthesia was inversely associated with HT (OR = 0.540, 95% CI = 0.355-0.820). Higher NIHSS (OR = 1.049, 95% CI = 1.021-1.077), lower ASPECTS (OR = 0.700, 95% CI = 0.613-0.801), intravenous thrombolysis (OR = 1.464, 95% CI = 1.061-2.020), longer onset-to-groin time (OR = 1.002, 95% CI = 1.001-1.005), and longer procedure time (OR = 1.009, 95% CI = 1.004-1.015) were predictors of early CED. After repeating a fourth logistic regression model including also good collaterals, the same variables remained predictors for HT and/or early CED, except diabetes mellitus and thrombolysis, while good collaterals were inversely associated with early CED (OR = 0.385, 95% CI = 0.248-0.599).

CONCLUSIONS

Higher NIHSS, lower ASPECTS, and longer onset-to-groin time were predictors for both HT and early CED. General anesthesia and good collaterals were inversely associated with HT and early CED, respectively. Longer procedure time was predictor of early CED.

Cerebral Ischemic Reperfusion Injury: Preventative and Therapeutic Strategies

Acute ischemic stroke is a leading cause of morbidity and mortality in the United States. Treatment goals remain focused on restoring blood flow to compromised areas. However, a major concern arises after reperfusion occurs. Cerebral ischemic reperfusion injury is defined as damage to otherwise salvageable brain tissue occurring with the reestablishment of the vascular supply to that region. The pool of eligible patients for revascularization continues to grow, especially with the recently expanded endovascular therapeutic window. Neurointensivists should understand and manage complications of successful recanalization. In this review, we examine the pathophysiology, diagnosis, and potential management strategies in cerebral ischemic reperfusion injury.

ALDH2 activation attenuates oxygen-glucose deprivation/reoxygenation-induced cell apoptosis, pyroptosis, ferroptosis and autophagy

PURPOSE

It is previously reported that aldehyde dehydrogenase 2 family member (ALDH2) shows neuroprotective effects in cerebral ischemia/reperfusion injury. However, whether the protective effects are through mediating the programmed cell death is yet to be fully elucidated.

METHODS

In vitro oxygen-glucose deprivation/reoxygenation (OGD/R) model was established in HT22 cells and mouse cortical neurons. Subsequently, ALDH2 expression were assessed by qRT-PCR and western blot. The methylation status was examined by methylation-specific PCR (MS-PCR). Then, ALDH2 expression was promoted and suppressed to explore the role of ALDH2 in OGD/R-treated cells. CCK-8 assay was applied to detect cell viability, and flow cytometry was applied to evaluate cell apoptosis. Western blot was applied to detect the apoptosis-related proteins (Caspase 3, Bcl-2 and Bax), necroptosis-related proteins (RIP3 and MLKL), pyroptosis-related proteins (NLRP3 and GSDMD), ferroptosis-related protein (ACSL4 and GPX4), and autophagy-related proteins (LC3B, and p62). IL-1β and IL-18 production was evaluated by ELISA assay. Reactive oxygen species production and Fe2+ content were evaluated by the corresponding detection kit.

RESULTS

In OGD/R-treated cells, ALDH2 expression was decreased, which was due to the hypermethylation of ALDH2 in the promoter region. ALDH2 overexpression improved cell viability and ALDH2 knockdown suppressed cell viability in OGD/R-treated cells. We also found that ALDH2 overexpression attenuated OGD/R-induced cell apoptosis, pyroptosis, ferroptosis and autophagy, while ALDH2 knockdown facilitated the OGD/R-induced cell apoptosis, pyroptosis, ferroptosis and autophagy.

CONCLUSIONS

Collectively, our results implied that ALDH2 attenuated OGD/R-induced cell apoptosis, pyroptosis, ferroptosis and autophagy to promote cell viability in HT22 cells and mouse cortical neurons.

No-reflow phenomenon following stroke recanalization therapy: Clinical assessment advances: A narrative review

The no-reflow phenomenon (NRP) after successful vascular recanalization in acute ischemic stroke (AIS) has become a major cause of poor clinical prognosis and ineffective recanalization. However, there is currently no clear definition or unified clinical assessment method for the NRP. Therefore, it is urgent to clarify the clinical evaluation criteria for the NRP and develop new no-reflow evaluation techniques so that remedial treatment can be applied to AIS patients suffering from the NRP. In this brief review, a variety of NRP assessment methods and defining criteria for clinical practice are presented.

From static to dynamic: live observation of the support system after ischemic stroke by two photon-excited fluorescence laser-scanning microscopy

Ischemic stroke is one of the most common causes of mortality and disability worldwide. However, treatment efficacy and the progress of research remain unsatisfactory. As the critical support system and essential components in neurovascular units, glial cells and blood vessels (including the blood-brain barrier) together maintain an optimal microenvironment for neuronal function. They provide nutrients, regulate neuronal excitability, and prevent harmful substances from entering brain tissue. The highly dynamic networks of this support system play an essential role in ischemic stroke through processes including brain homeostasis, supporting neuronal function, and reacting to injuries. However, most studies have focused on postmortem animals, which inevitably lack critical information about the dynamic changes that occur after ischemic stroke. Therefore, a high-precision technique for research in living animals is urgently needed. Two-photon fluorescence laser-scanning microscopy is a powerful imaging technique that can facilitate live imaging at high spatiotemporal resolutions. Two-photon fluorescence laser-scanning microscopy can provide images of the whole-cortex vascular 3D structure, information on multicellular component interactions, and provide images of structure and function in the cranial window. This technique shifts the existing research paradigm from static to dynamic, from flat to stereoscopic, and from single-cell function to multicellular intercommunication, thus providing direct and reliable evidence to identify the pathophysiological mechanisms following ischemic stroke in an intact brain. In this review, we discuss exciting findings from research on the support system after ischemic stroke using two-photon fluorescence laser-scanning microscopy, highlighting the importance of dynamic observations of cellular behavior and interactions in the networks of the brain's support systems. We show the excellent application prospects and advantages of two-photon fluorescence laser-scanning microscopy and predict future research developments and directions in the study of ischemic stroke.

Understanding the Neuroplastic Effects of Auricular Vagus Nerve Stimulation in Animal Models of Stroke: A Systematic Review and Meta-Analysis

BACKGROUND

Transauricular vagus nerve stimulation (taVNS) is being studied as a feasible intervention for stroke, but the mechanisms by which this non-invasive technique acts in the cortex are still broadly unknown.

OBJECTIVES

This study aimed to systematically review the current pre-clinical evidence in the auricular vagus nerve stimulation (aVNS) neuroplastic effects in stroke.

METHODS

We searched, in December of 2022, in Medline, Cochrane, Embase, and Lilacs databases. The authors executed the extraction of the data on Excel. The risk of bias was evaluated by adapted Cochrane Collaboration's tool for animal studies (SYRCLES's RoB tool).

RESULTS

A total of 8 studies published between 2015 and 2022 were included in this review, including 391 animal models. In general, aVNS demonstrated a reduction in neurological deficits (SMD = -1.97, 95% CI -2.57 to -1.36, I2 = 44%), in time to perform the adhesive removal test (SMD = -2.26, 95% CI -4.45 to -0.08, I2 = 81%), and infarct size (SMD = -1.51, 95% CI -2.42 to -0.60, I2 = 58%). Regarding the neuroplasticity markers, aVNS showed to increase microcapillary density, CD31 proliferation, and BDNF protein levels and RNA expression.

CONCLUSIONS

The studies analyzed show a trend of results that demonstrate a significant effect of the auricular vagal nerve stimulation in stroke animal models. Although the aggregated results show high heterogeneity and high risk of bias. More studies are needed to create solid conclusions.

Sulforaphane protects microvascular endothelial cells in lower limb ischemia/reperfusion injury mice

Background: Microvascular damage is a key pathological factor in acute lower limb ischemia/reperfusion (I/R) injury. Current evidence suggests that sulforaphane (SFN) protects tissue from I/R injury. However, the role of SFN in acute lower limb I/R injury remains elusive. This study aimed to investigate the role and potential mechanism of SFN in I/R-related microvascular damage in the limb. Methods: Limb viability was evaluated by laser Doppler imaging, tissue edema analysis and histological analysis. Western blotting and immunofluorescence were applied to analyze the levels of apoptosis, oxidative stress, autophagy, transcription factor EB (TFEB) activity and mucolipin 1 (MCOLN1)-calcineurin signaling pathway. Results: SFN administration significantly ameliorated I/R-induced hypoperfusion, tissue edema, skeletal muscle fiber injury and endothelial cell (EC) damage in the limb. Pharmacological inhibition of NFE2L2 (nuclear factor, erythroid 2 like 2) reversed the anti-oxidation and anti-apoptosis effects of SFN on ECs. Additionally, silencing of TFEB by interfering RNA abolished the SFN-induced autophagy restoration, anti-oxidant response and anti-apoptosis effects on ECs. Furthermore, silencing of MCOLN1 by interfering RNA and pharmacological inhibition of calcineurin inhibited the activity of TFEB induced by SFN, demonstrating that SFN regulates the activity of TFEB through the MCOLN1-calcineurin signaling pathway. Conclusion: SFN protects microvascular ECs against I/R injury by TFEB-mediated autophagy restoration and anti-oxidant response.

Serum amyloid A is a potential predictor of prognosis in acute ischemic stroke patients after intravenous thrombolysis

Objectives

Inflammation shows a notable relationship to acute ischemic stroke's (AIS) occurrence and prognosis. However, existing research has confirmed that serum amyloid A (SAA) is an inflammatory biomarker. The aim of this paper was to investigate the association between SAA and the three-month clinical results of acute AIS patients after intravenous thrombolysis (IVT).

Methods

The evaluation of AIS patients with complete medical records was carried out by prospectively investigating patients hospitalized in our department between January 2020 and February 2023. The SAA levels were examined with the use of an immunosorbent assay kit that shows a relationship with the enzyme (Invitrogen Corp). Patients were dichotomized into favorable (mRS score of 0, 1 or 2) and unfavorable (mRS score of 3, 4, 5, or 6) results with the use of the modified Rankin Scale (mRS).

Results

A total of 405 AIS patients who were subjected to IVT therapy were prospectively covered. To be specific, 121 (29.88%) patients had an unfavorable prognosis during the follow-up for 3 months. On that basis, patients achieving unfavorable results gained notably greater SAA levels (39.77 (IQR 38.32-46.23) vs.31.23 (IQR 27.44-34.47), p < 0.001) during hospitalization in comparison to patients with a better result. In the analysis with multiple variates, SAA was adopted to achieve the independent prediction of the three-month unfavorable clinical results of acute AIS patients after IVT [OR:2.874 (95% CI, 1.764-4.321), p < 0.001]. When the fundamental confounding factors were regulated, the odds ratio (OR) of unfavorable prognosis after AIS patients undergoing IVT therapy was 4.127 (95% CI = 1.695-10.464, p = 0.032) for the maximum tertile of SAA in terms of the minimal tertile. With an AUC of 0.703 (95% CI, 0.649-0.757), SAA revealed a notably more effective discriminating capability in terms of CRP, NLR, EMR, and WBC. SAA as a predictor in terms of the prediction of three-month unfavorable results after AIS patients undergoing IVT therapy achieved specificity and sensitivity of 84.45% and 77.23%, as well as an optimal cut-off value (COV) of 37.39.

Conclusion

SAA level that is up-regulated during hospitalization is capable of serving as an effective marker in terms of the prediction of unfavorable three-month results in AIS patients after IVT.

Hypothermic neuroprotection by targeted cold autologous blood transfusion in a non-human primate stroke model

Over decades, nearly all attempts to translate the benefits of therapeutic hypothermia in stroke models of lower-order species to stroke patients have failed. Potentially overlooked reasons may be biological gaps between different species and the mismatched initiation of therapeutic hypothermia in translational studies. Here, we introduce a novel strategy of selective therapeutic hypothermia in a non-human primate ischemia-reperfusion model, in which autologous blood was cooled ex vivo and the cool blood transfusion was administered at the middle cerebral artery just after the onset of reperfusion. Cold autologous blood cooled the targeted brain rapidly to below 34 °C while the rectal temperature remained around 36 °C with the assistance of a heat blanket during a 2-h hypothermic process. Therapeutic hypothermia or extracorporeal-circulation related complications were not observed. Cold autologous blood treatment reduced infarct sizes, preserved white matter integrity, and improved functional outcomes. Together, our results suggest that therapeutic hypothermia, induced by cold autologous blood transfusion, was achieved in a feasible, swift, and safe way in a non-human primate model of stroke. More importantly, this novel hypothermic approach conferred neuroprotection in a clinically relevant model of ischemic stroke due to reduced brain damage and improved neurofunction. This study reveals an underappreciated potential for this novel hypothermic modality for acute ischemic stroke in the era of effective reperfusion.

Optimizing intra-arterial hypothermia scheme for acute ischemic stroke in an MCAO/R rat model

Hypothermia is a promising neuroprotective treatment. This study aims to explore and optimize the intervention scheme of intra-arterial hypothermia (IAH) in a middle cerebral artery occlusion and reperfusion (MCAO/R) rat model. The MCAO/R model was established with a thread that could be retracted 2 h after occlusion. Cold normal saline was injected into the internal carotid artery (ICA) through a microcatheter in different infusion conditions. Grouping followed an orthogonal design (L₉[3⁴]) based on three critical factors closely associated with IAH: perfusate temperature (4, 10, 15 °C), infusion flow rate (1/3, 1/2, 2/3 blood flow rate of ICA), and duration (10, 20, 30 min), resulting in 9 subgroups (H₁, H₂ to H₉). A myriad of indexes were monitored, such as vital signs, blood parameters, changes in local ischemic brain tissue temperature (T_b), ipsilateral jugular venous bulb temperature (T_jvb), and the core temperature of the anus (T_core). After 24 h and 72 h of cerebral ischemia, cerebral infarction volume, cerebral water content, and neurological function were assessed to explore the optimal IAH conditions. The results revealed that the three critical factors were independent predictors for cerebral infarction volume, cerebral water content, and neurological function. The optimal perfusion conditions were 4 °C, 2/3 R_ICA (0.50 ml/min) for 20 min, and there was a significant correlation between T_b and T_jvb (R = 0.994, P < 0.001). The vital signs, blood routine tests and biochemical indexes showed no significant abnormal changes. These findings revealed that IAH was safe and feasible with the optimized scheme in an MCAO/R rat model.

Efficacy and safety of remote ischemic conditioning for acute ischemic stroke: A comprehensive meta-analysis from randomized controlled trials

BACKGROUND AND PURPOSE

Remote ischemic conditioning (RIC) is a remote, transient, and noninvasive procedure providing temporary ischemia and reperfusion. However, there is no comprehensive literature investigating the efficacy and safety of RIC for the treatment of acute ischemic stroke. In the present study, we performed a comprehensive meta-analysis of the available studies.

METHODS

MEDLINE, Embase, the Cochrane Library database (CENTRAL), and ClinicalTrials.gov were searched before Sep 7, 2022. The data were analyzed using Review Manager 5.4.1 software, Stata version 16.0 software, and R 4.2.0 software. Odds ratio (OR), mean difference (MD), and corresponding 95% CIs were pooled using fixed-effects meta-analysis.

RESULTS

We pooled 6392 patients from 17 randomized controlled trials. Chronic RIC could reduce the recurrence of ischemic stroke at the endpoints (OR 0.67, 95% CI [0.51, 0.87]). RIC could also improve the prognosis of patients at 90 days as assessed by mRS score (mRS 0-1: OR 1.29, 95% CI [1.09, 1.52]; mRS 0-2: OR 1.22, 95% CI [1.01, 1.48]) and at the endpoints assessed by NIHSS score (MD -0.99, 95% CI [-1.45, -0.53]). RIC would not cause additional adverse events such as death (p = 0.72), intracerebral hemorrhage events (p = 0.69), pneumonia (p = 0.75), and TIA (p = 0.24) but would inevitably cause RIC-related adverse events (OR 26.79, 95% CI [12.08, 59.38]).

CONCLUSIONS

RIC could reduce the stroke recurrence and improve patients' prognosis. Intervention on bilateral upper limbs, 5 cycles, and a length of 50 min in each intervention might be an optimal protocol for RIC at present. RIC could be an effective therapy for patients not eligible for reperfusion therapy. RIC would not cause other adverse events except for relatively benign RIC-related adverse events.

Microvascular Leakage as Therapeutic Target for Ischemia and Reperfusion Injury

Reperfusion injury is a very common complication of various indicated therapies such as the re-opening of vessels in the myocardium or brain as well as reflow in hemodynamic shutdown (cardiac arrest, severe trauma, aortic cross-clamping). The treatment and prevention of reperfusion injury has therefore been a topic of immense interest in terms of mechanistic understanding, the exploration of interventions in animal models and in the clinical setting in major prospective studies. While a wealth of encouraging results has been obtained in the lab, the translation into clinical success has met with mixed outcomes at best. Considering the still very high medical need, progress continues to be urgently needed. Multi-target approaches rationally linking interference with pathophysiological pathways as well as a renewed focus on aspects of microvascular dysfunction, especially on the role of microvascular leakage, are likely to provide new insights.

The role of protein glycosylation in the occurrence and outcome of acute ischemic stroke

Acute ischemic stroke (AIS) is a serious and life-threatening disease worldwide. Despite thrombolysis or endovascular thrombectomy, a sizeable fraction of patients with AIS have adverse clinical outcomes. In addition, existing secondary prevention strategies with antiplatelet and anticoagulant drugs therapy are not able to adequately decrease the risk of ischemic stroke recurrence. Thus, exploring novel mechanisms for doing so represents an urgent need for the prevention and treatment of AIS. Recent studies have discovered that protein glycosylation plays a critical role in the occurrence and outcome of AIS. As a common co- and post-translational modification, protein glycosylation participates in a wide variety of physiological and pathological processes by regulating the activity and function of proteins or enzymes. Protein glycosylation is involved in two causes of cerebral emboli in ischemic stroke: atherosclerosis and atrial fibrillation. Following ischemic stroke, the level of brain protein glycosylation becomes dynamically regulated, which significantly affects stroke outcome through influencing inflammatory response, excitotoxicity, neuronal apoptosis, and blood-brain barrier disruption. Drugs targeting glycosylation in the occurrence and progression of stroke may represent a novel therapeutic idea. In this review, we focus on possible perspectives about how glycosylation affects the occurrence and outcome of AIS. We then propose the potential of glycosylation as a therapeutic drug target and prognostic marker for AIS patients in the future.

The relationship between antiplatelet therapies and the outcome of endovascular treatment for acute ischemic stroke

PURPOSE

We conducted this study to investigate the safety and efficacy of antiplatelet therapies (APT) for acute ischemic patients received endovascular treatment (EVT).

METHODS

The population of our study was derived from a nationwide multicentered registry conducted by 111 centers in China. Patients were divided to groups of no APT, single APT (SAPT) or dual APT (DAPT) according to the APT received at 24 h after EVT. The primary outcome was 90-day functional independence, and the safety outcomes included the symptomatic intracranial hemorrhage (sICH), any type of intracranial hemorrhage, and all-caused death within 90 days. Patient characteristics, procedural data, and outcomes were analyzed.

RESULTS

A total of 1679 patients were included in this study, 71.42% of whom received oral APT at 24 h after EVT, and the initial time was 20.53(13.94-27.17) hours after recanalization or the end of procedure. 90-day functional independence was significantly more observed in patients with DAPT (54.02% vs. 33.64%; adjusted odds ratio [OR] 1.940, 95% CI 1.444-2.606), but not in SAPT (40.75% vs. 33.64%; adjusted OR 1.280, 95% CI 0.907-1.804) compared with patients without APT. APT increased the risk of sICH (1.14% vs. 0, p = 0.036). Both the application of DAPT (adjusted OR 0.264, 95% CI 0.178-0.392, p < 0.001) and SAPT (adjusted OR 0.341, 95% CI 0.213-0.545, p < 0.001) could reduce the 90-day mortality.

CONCLUSIONS

In this uncontrolled series of patients APT at 24 h after EVT showed improvement of the patients' functional independence and reduction of mortality, even though the rate of sICH was increased, especially in the DAPT-group.

Kinsenoside alleviates oxidative stress-induced blood-brain barrier dysfunction via promoting Nrf2/HO-1 pathway in ischemic stroke

An ischemic stroke usually causes blood-brain barrier (BBB) damage and excessive oxidative stress (OS) levels. Kinsenoside (KD), a major effective compound extracted in Chinese herbal medicine Anoectochilus roxburghii (Orchidaceae), has anti-OS effects. The present study focused on exploring KD's protection against OS-mediated cerebral endothelial cell damage and BBB damage within the mouse model. Intracerebroventricular administration of KD upon reperfusion after 1 h ischemia decreased infarct volumes, neurological deficit, brain edema, neuronal loss, and apoptosis 72 h post-ischemic stroke. KD improved BBB structure and function, as evidenced by a lower 18F-fluorodeoxyglucose pass rate of the BBB and upregulation of tight junction (TJ) proteins such as occludin, claudin-5, and zonula occludens-1 (ZO-1). KD protected bEnd.3 endothelial cells from oxygen and glucose deprivation/reoxygenation (OGD/R) injury in an in-vitro study. Meanwhile, OGD/R reduced transepithelial electronic resistance, whereas KD significantly increased TJ protein levels. Furthermore, based on in-vivo and in-vitro research, KD alleviated OS in endothelial cells, which is related to nuclear factor, erythroid 2 like 2 (Nrf2) nuclear translocation as well as Nrf2/haem oxygenase 1 signaling protein stimulation. Our findings demonstrated that KD might serve as a potential compound for treating ischemic stroke involving antioxidant mechanisms.

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.

Cell Therapy: A New Technology for Cerebral Circulation Restoration after Ischemia/Reperfusion

Cell therapy with mesenchymal stem cells (MSCs) may be a promising technique for cerebral blood flow restoration after transient ischemia. Before a practical application of the cell material, 7-9 days are required for its cultivation. We studied the efficacy of human MSC (hMSC) transplantation performed 7 days after cerebral ischemia/reperfusion (I/R) to help recover cerebral circulation. The intravital micrograph technique was used to comparatively evaluate the vasculature density in the pia mater and the reactivity of the pial arteries in response to acetylcholine (ACh) in rats after I/R (clamping of both carotid arteries and a simultaneous decrease in and strict maintenance of the mean BP at 45 ± 2 mm Hg for 12 min) and with/without hMSC transplantation. Perfusion (P) in the sensorimotor cortex was assessed using laser dopplerography. After 14 and 21 days, the vasculature density in I/R-affected rats was 1.2- to 1.4-fold and 1.2- to 1.3-fold lower, respectively, than that in the controls. The number of ACh-dilated arteries decreased 1.6- to 1.9-fold and 1.2- to 1.7-fold 14 and 21 days after I/R, respectively. After 21 days, the P level decreased 1.6-fold, on average. Administration of hMSCs on day 7 after I/R resulted in complete recovery of the vasculature density by day 14. ACh-mediated dilatation fully recovered only in arteries of less than 40 μm in diameter within 21 days. After 21 days, the P level was 1.2-fold lower than that in the controls but significantly higher than that in rats after I/R without hMSCs. Delayed administration of MSCs after a transient cerebral ischemic attack affords the time for the procedures required to prepare cell material for transplantation and provides a good therapeutic response in the pial microvasculature.

An MMP-9 exclusive neutralizing antibody attenuates blood-brain barrier breakdown in mice with stroke and reduces stroke patient-derived MMP-9 activity

Rapid upregulation of matrix metalloproteinase 9 (MMP-9) leads to blood-brain barrier (BBB) breakdown following stroke, but no MMP-9 inhibitors have been approved in clinic largely due to their low specificities and side effects. Here, we explored the therapeutic potential of a human IgG monoclonal antibody (mAb), L13, which was recently developed with exclusive neutralizing specificity to MMP-9, nanomolar potency, and biological function, using mouse stroke models and stroke patient samples. We found that L13 treatment at the onset of reperfusion following cerebral ischemia or after intracranial hemorrhage (ICH) significantly reduced brain tissue injury and improved the neurological outcomes of mice. Compared to control IgG, L13 substantially attenuated BBB breakdown in both types of stroke model by inhibiting MMP-9 activity-mediated degradations of basement membrane and endothelial tight junction proteins. Importantly, these BBB-protective and neuroprotective effects of L13 in wild-type mice were comparable to Mmp9 genetic deletion and fully abolished in Mmp9 knockout mice, highlighting the in vivo target specificity of L13. Meanwhile, ex vivo co-incubation with L13 significantly neutralized the enzymatic activities of human MMP-9 in the sera of ischemic and hemorrhagic stroke patients, or in the peri-hematoma brain tissues from hemorrhagic stroke patients. Overall, we demonstrated that MMP-9 exclusive neutralizing mAbs constitute a potential feasible therapeutic approach for both ischemic and hemorrhagic stroke.

Development of sertraline analogues as potential anti-ischemic stroke agents

Ischemic stroke (IS) is harmful to human health and social development, and there is no medicine available at present. To find the hit compound for treating ischemic stroke, we screened 28 FDA approved nervous system drugs by using an in vitro OGD-induced stroke model. Notably, our in vitro and in vivo studies demonstrated that low-dose sertraline had good neuroprotective activities, while high-dose sertraline showed significant toxicity. Interestingly, the same high-dose sertraline in the control group did not exhibit any obvious toxic effect. Therefore, it is important to modify the structure of sertraline to improve the activity and reduce the toxicity. Stereoisomers of sertraline were first investigated to analyze the influence of stereochemistry on the neuroprotective activities, which showed no obvious difference. Then we evaluated the activity of our previously reported sertraline analogues and found that introducing amide or alkane groups to the amino moiety might be beneficial to enhance the activity and reduce the toxicity. Thus, 10 new analogues were designed, synthesized, and evaluated. Among them, compound OY-201 showed the best safety and neuroprotective activity in both in vitro and in vivo models. Moreover, it exhibited good blood-brain barrier (BBB) permeability, indicating its potential for the development of anti-ischemic stroke drugs.

Neuroprotective Effects and Metabolomics Study of Protopanaxatriol (PPT) on Cerebral Ischemia/Reperfusion Injury In Vitro and In Vivo

Stroke, one of the leading causes of disability and death worldwide, is a severe neurological disease that threatens human life. Protopanaxatriol (PPT), panaxatriol-type saponin aglycone, is a rare saponin that exists in Panax ginseng and Panax Noto-ginseng. In this study, we established an oxygen-glucose deprivation (OGD)-PC12 cell model and middle cerebral artery occlusion/reperfusion (MCAO/R) model to evaluate the neuroprotective effects of PPT in vitro and in vivo. In addition, metabolomics analysis was performed on rat plasma and brain tissue samples to find relevant biomarkers and metabolic pathways. The results showed that PPT could significantly regulate the levels of LDH, MDA, SOD, TNF-α and IL-6 factors in OGD-PC12 cells in vitro. PPT can reduce the neurological deficit score and infarct volume of brain tissue in rats, restore the integrity of the blood-brain barrier, reduce pathological damage, and regulate TNF-α, IL-1β, IL-6, MDA, and SOD factors. In addition, the results of metabolomics found that PPT can regulate 19 biomarkers involving five metabolic pathways, including amino acid metabolism, arachidonic acid metabolism, sphingolipid metabolism, and glycerophospholipid metabolism. Thus, it could be inferred that PPT might serve as a novel natural agent for MCAO/R treatment.

Association between Infarct Location and Hemorrhagic Transformation of Acute Ischemic Stroke following Successful Recanalization after Mechanical Thrombectomy

BACKGROUND AND PURPOSE

The association between infarct location and hemorrhagic transformation of acute ischemic stroke after mechanical thrombectomy is not understood. We aimed to evaluate the association between CTP-based ischemic core variables at admission and hemorrhagic transformation after a successful thrombectomy.

MATERIALS AND METHODS

We retrospectively analyzed patients who underwent endovascular thrombectomy for acute anterior circulation large-vessel occlusion between October 2019 and June 2021. We enrolled 146 patients with visible ischemic core on pretreatment CTP who had successful reperfusion. The ischemic core infarct territories were classified into the cortical and subcortical areas and then qualitatively and quantitatively analyzed by CTP. Logistic regression and receiver operating characteristic curve analyses were performed to determine the association between ischemic core variables and hemorrhagic transformation.

RESULTS

Of the 146 patients analyzed, 72 (49.3%) had hemorrhagic transformation and 23 (15.8%) had symptomatic intracerebral hemorrhage. Multivariate analysis showed that subcortical infarcts were independently associated with hemorrhagic transformation (OR, 8.06; 95% CI, 2.31-28.10; P = .001) and subcortical infarct volume was independently linked to symptomatic intracerebral hemorrhage (OR, 1.05; 95% CI, 1.01-1.09; P = .039). The receiver operating characteristic curve indicated that subcortical infarcts can predict hemorrhagic transformation accurately (area under the curve = 0.755; 95% CI, 0.68-0.82; P < .001) and subcortical infarct volume can predict symptomatic intracerebral hemorrhage (area under the curve = 0.694; 95% CI, 0.61-0.77; P = .002).

CONCLUSIONS

Subcortical infarcts seen on CTP at admission are associated with hemorrhagic transformation in patients after successful thrombectomy, and subcortical infarct volume may influence the risk of symptomatic intracerebral hemorrhage.

Acidosis in arterial blood gas testing is associated with clinical outcomes after endovascular thrombectomy

Background

Despite recanalization, some of the patients undergoing endovascular thrombectomy (EVT) still suffer from unfavorable outcomes. Patients with poor prognoses are often accompanied by acidosis in arterial blood gas (ABG) testing. We, therefore, explored the ABG testing results in the early phase of recanalization and analyzed their association with poor prognosis.

Patients and methods

We identified all patients with ischemic stroke and successful endovascular recanalization for anterior circulation vessel occlusion between June 2019 and May 2022. ABG testing was performed in all patients within 0-30 min and 8 h after endovascular therapy. We investigated the relationship between the ABG testing results with symptomatic intracerebral hemorrhage (sICH), hemicraniectomy, and mortality.

Results

A total of 123 patients with stroke after endovascular thrombectomy were analyzed. Of those, eight (6.5%) patients had postinterventional sICH. Acidosis was associated with sICH. Decreased HCO 3 - levels and HCO 3 - levels at 8 h after EVT were independently related to a higher risk of sICH. Twelve (9.8%) patients underwent hemicraniectomy for postischemic malignant edema and similar results were found for hemicraniectomy. Increased lactate at 8 h after EVT and decreased HCO 3 - levels at 8 h after EVT were closely associated with hemicraniectomy. Twenty-two (17.9%) patients died within 3 months. Decreased HCO 3 - levels were independently related to mortality, as were decreased pH levels at 8 h after EVT and decreased HCO 3 - levels at 8 h after EVT.

Conclusion

Acidosis is associated with clinical outcomes after endovascular therapy and may help to select patients with poor prognosis in the acute early phase of recanalization.