Collateral Circulation Augmentation and Neuroprotection as Adjuvant to Mechanical Thrombectomy in Acute Ischemic Stroke

A review: Carrier-based hydrogels containing bioactive molecules and stem cells for ischemic stroke therapy

Ischemic stroke (IS), a cerebrovascular disease, is the leading cause of physical disability and death worldwide. Tissue plasminogen activator (tPA) and thrombectomy are limited by a narrow therapeutic time window. Although strategies such as drug therapies and cellular therapies have been used in preclinical trials, some important issues in clinical translation have not been addressed: low stem cell survival and drug delivery limited by the blood-brain barrier (BBB). Among the therapeutic options currently sought, carrier-based hydrogels hold great promise for the repair and regeneration of neural tissue in the treatment of ischemic stroke. The advantage lies in the ability to deliver drugs and cells to designated parts of the brain in an injectable manner to enhance therapeutic efficacy. Here, this article provides an overview of the use of carrier-based hydrogels in ischemic stroke therapy and focuses on the use of hydrogel scaffolds containing bioactive molecules and stem cells. In addition to this, we provide a more in-depth summary of the composition, physicochemical properties and physiological functions of the materials themselves. Finally, we also outline the prospects and challenges for clinical translation of hydrogel therapy for IS.

Novel Risk Score to Predict Poor Outcome After Endovascular Treatment in Anterior Circulation Occlusive Acute Ischemic Stroke

BACKGROUND

We aimed to develop and validate a prognostic score to predict outcomes after endovascular treatment in acute ischemic stroke.

METHODS

The prognostic score was developed based on the ACTUAL (Endovascular Treatment for Acute Anterior Circulation Ischemic Stroke) registry. The validation cohort was derived from the Captor trial. Independent predictors of poor outcome after endovascular treatment were obtained from the least absolute shrinkage and selection operator regression and multivariable logistic regression. Corresponding regression coefficients were used to generate point scoring system. The area under the receiver operating characteristic curve and the Hosmer-Lemeshow goodness-of-fit test were used to assess model discrimination and calibration. The predictive properties of the developed prognostic score were validated and the discriminative power was compared with other validated tools.

RESULTS

A 17-point Age, Collateral Status, Blood glucose, Alberta Stroke Program Early Computed Tomography Score, and National Institutes of Health Stroke Scale score scale was developed from the set of independent predictors, including age, admission National Institutes of Health Stroke Scale score, Alberta Stroke Program Early Computed Tomography Score on initial computed tomography scan, blood glucose, and collateral status. The scale showed good discrimination in the derivation cohort (area under the receiver operating characteristic curve, 0.79 [95% CI, 0.75-0.82]) and validation cohorts (area under the receiver operating characteristic curve, 0.77 [95% CI, 0.70-0.84]). The scale was well calibrated (Hosmer-Lemeshow test) in the derivation cohort (P=0.57) and validation cohort (P=0.75).

CONCLUSIONS

The Age, Collateral Status, Blood glucose, Alberta Stroke Program Early Computed Tomography score, and National Institutes of Health Stroke Scale score scale is a valid tool for predicting outcomes and may be useful for endovascular stroke treatment in anterior circulation large vessel occlusions.

Collateral blood vessels in stroke and ischemic disease: Formation, physiology, rarefaction, remodeling

Collateral blood vessels are unique, naturally occurring endogenous bypass vessels that provide alternative pathways for oxygen delivery in obstructive arterial conditions and diseases. Surprisingly however, the capacity of the collateral circulation to provide protection varies greatly among individuals, resulting in a significant fraction having poor collateral circulation in their tissues. We recently reviewed evidence that the presence of naturally-occurring polymorphisms in genes that determine the number and diameter of collaterals that form during development (ie, genetic background), is a major contributor to this variation. The purpose of this review is to summarize current understanding of the other determinants of collateral blood flow, drawing on both animal and human studies. These include the level of smooth muscle tone in collaterals, hemodynamic forces, how collaterals form during development (collaterogenesis), de novo formation of additional new collaterals during adulthood, loss of collaterals with aging and cardiovascular risk factor presence (rarefaction), and collateral remodeling (structural lumen enlargement). We also review emerging evidence that collaterals not only provide protection in ischemic conditions but may also serve a physiological function in healthy individuals. Primary focus is on studies conducted in brain, however relevant findings in other tissues are also reviewed, as are questions for future investigation.

Edaravone dexborneol for ischemic stroke with sufficient recanalization after thrombectomy: a randomized phase II trial

This phase II, randomized, double blinded, multi-center study aims to explore whether intravenous edaravone dexborneol (ED) could improve clinical outcomes in patients with anterior circulation stroke with successful endovascular reperfusion (ClinicalTrials.gov: NCT04667637). Eligible patients were randomly (1:1) assigned into ED, which received intravenous ED (37.5 mg, 2/day, for 12 days) or control group, which received placebo. The primary endpoint was favorable functional outcome (a modified Rankin Scale [mRS] of 0-2 at 90 days). Two hundred patients were enrolled, including 97 in ED group and 103 in control group. The proportion of patients with 90-day mRS (0-2) was 58.7% (54/92) in ED group and 52.1% (49/94) in control group (unadjusted odds ratio 1.37, [95% CI 0.76-2.44], P = 0.29). This work suggests that intravenous ED is safe, but do not statistically improve 90-day functional outcomes in patients with anterior circulation stroke with successful endovascular reperfusion.

Mechanism of inflammatory response and therapeutic effects of stem cells in ischemic stroke: current evidence and future perspectives

Ischemic stroke is a leading cause of death and disability worldwide, with an increasing trend and tendency for onset at a younger age. China, in particular, bears a high burden of stroke cases. In recent years, the inflammatory response after stroke has become a research hotspot: understanding the role of inflammatory response in tissue damage and repair following ischemic stroke is an important direction for its treatment. This review summarizes several major cells involved in the inflammatory response following ischemic stroke, including microglia, neutrophils, monocytes, lymphocytes, and astrocytes. Additionally, we have also highlighted the recent progress in various treatments for ischemic stroke, particularly in the field of stem cell therapy. Overall, understanding the complex interactions between inflammation and ischemic stroke can provide valuable insights for developing treatment strategies and improving patient outcomes. Stem cell therapy may potentially become an important component of ischemic stroke treatment.

Treatment of Stroke at a Delayed Timepoint with a Repurposed Drug Targeting Sigma 1 Receptors

Sigma 1 receptors are intracellular chaperone proteins that have been explored as a subacute treatment to enhance post-stroke recovery. We recently identified the antitussive oxeladin as a selective sigma 1 receptor agonist with the ability to stimulate the release of brain-derived neurotrophic factor from neurons in vitro. In this study, we hypothesized that oral oxeladin citrate would stimulate BDNF secretion and improve stroke outcomes when administered to male rats starting 48 h after transient middle cerebral artery occlusion. Oxeladin did not alter blood clotting and crossed the blood brain barrier within 30 min of oral administration. Rats underwent 90 min of transient middle cerebral artery occlusion. Forty-eight hours later rats began receiving daily oxeladin (135 mg/kg) for 11 days. Oxeladin significantly improved neurological function on days 3, 7, and 14 following MCAO. Infarct size was not altered by a single dose, but the final extent of infarct after 14 days was decreased. However, there was no significant reduction in astrogliosis or microgliosis compared to vehicle-treated control rats. In agreement with in vitro studies, oxeladin increased the amount of mature BDNF in the cerebral cortex 2, 6, and 24 h after single oral dose. However, the increase in BDNF did not result in increases in cellular proliferation in the subventricular zone or dentate gyrus when compared to vehicle-treated controls. These results suggest that oxeladin may reduce the extent of infarct expansion in the subacute phase of stroke, although this action does not appear to involve a reduction in inflammation or increased cell proliferation.

Cerebral arterial collateral status, but not venous outflow profiles, modifies the effect of intravenous tissue plasminogen activator in acute ischemic stroke

BACKGROUND

The role of arterial collateral and venous outflow status on the response to intravenous tissue plasminogen activator (IV-tPA) has not been sufficiently clarified in acute major cerebral occlusions.

PATIENTS AND METHODS

A total of 130 patients (mean age: 71 years; 73 females) with acute middle cerebral artery M1/M2 segment or terminal internal carotid artery occlusion treated solely with IV-tPA were analyzed. Regional leptomeningeal score (rLMC) was used for cerebral arterial collateral scoring, and the cortical vein opacification score (COVES) and modified Prognostic Evaluation based on Cortical vein score difference In Stroke (PRECISE) superficial and deep scores were used for venous outflow profile. Exploratory logistic models for response to IV-tPA [positive response: National Institutes of Health Stroke Scale (NIHSS) decrease 4 (or decrease to 0) at 24 h; dramatic response: NIHSS decrease ≥8 (or decrease to 0 or 1)], functional outcome (modified Rankin's score 0-1 as "excellent" and 0-2 "good") and tPA-associated hemorrhagic transformation were constructed.

RESULTS

IV-tPA efficacy was positive in 47% and dramatic in 32%. Dramatic response was linked to better arterial collateral status (exp[B] =1.115 [95% confidence interval (CI), 1.016-1.223]). Excellent outcome was noted in 26% and good in 45%. One-point increase in rLMC score independently increased good prognosis (exp[B] =1.209 [1.034-1.412]). Patients with good prognosis had higher (by 0.5 points) modified PRECISE deep score (P = 0.047) and less frequent nonsufficient modified PRECISE deep score (0-2) (P = 0.017) in univariate analyses. However, these associations failed to survive in multiple regression. Any type tPA-associated cerebral hemorrhagic transformation was observed in 23% and parenchymal hemorrhage type 2 in 5.4%. While rLMC score showed a borderline strength correlation to hemorrhage (exp[B] =0.899 [95% CI, 0.808-1.001]), outflow scores not.

CONCLUSION

While arterial collateral status modifies the effect of tPA in acute anterior circulation major artery occlusions, venous outflow capacity is not so critical.

Predictive value of white matter hyperintensity burden combined with collateral circulation in mechanical thrombectomy for acute anterior circulation large vessel occlusion

OBJECTIVE

To investigate the correlation and predictive value of white matter hyperintensity (WMH) burden in conjunction with collateral circulation during mechanical thrombectomy (MT) for acute anterior circulation occlusion.

METHODS

A database comprising consecutive registrations of patients who underwent mechanical thrombectomy for acute anterior circulation large vessel occlusive cerebral infarction at Nanjing Drum Tower Hospital from January 2018 to December 2021 was analyzed. Collateral circulation was assessed using the American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology (ASITN/SIR) scoring criteria. The good collateral group included ASITN/SIR grades 3 and 4, while the poor collateral group included grades 1 and 2. Additionally, white matter hyperintensity burden was evaluated using white matter hyperintensity volume and the Fazekas scoring system. A favorable functional outcome was defined as a modified Rankin scale (mRS) of 0-2 at 90 days. Multivariable logistic regression analyses and Spearman correlation analysis were employed to assess the correlation between white matter hyperintensity burden and unfavorable outcomes in mechanical thrombectomy.

RESULTS

A total of 123 patients who underwent mechanical thrombectomy for acute anterior circulation occlusion were included (56.9 % male). Favorable outcomes were observed in 45.5 % (56/123) of cases. Those with a low ASITN/SIR scale (r = -1.33, 95 % CI: 0.26 (0.09-0.78), P=0.01; cutoff value = 2.5), low low-density lipoprotein cholesterol (LDL-C) level (r = -1.00, 95 % CI: 0.37 (0.15-0.92), P=0.03; cutoff value = 2.26), and high white matter hyperintense volume (r = 0.28, 95 % CI: 1.33 (1.03-1.71), P=0.03; cutoff value = 10.03) were more likely to experience unfavorable outcomes. Moreover, when compared to ASITN/SIR scale (AUC=89.6, 95 % CI: 0.09-0.78) and LDL level (AUC=62.8, 95 % CI: 0.15-0.92), white matter hyperintense volume demonstrated greater accuracy in predicting poor outcomes (AUC=94.4, 95 % CI: 1.03-1.71). Importantly, white matter hyperintense volume showed a positive correlation with the modified Rankin Scale (mRS) Score (r = 0.8289, P<0.0001). In brief, the burden of white matter hyperintensity is negatively correlated with collateral circulation in mechanical thrombectomy for acute anterior circulation occlusion.

CONCLUSIONS

The higher the burden of white matter hyperintensity, the worse the collateral circulation in mechanical thrombectomy for acute anterior circulation occlusion. The combination of high white matter hyperintensity volume and poor collateral circulation enhances might predict a worse clinical outcome of mechanical thrombectomy with acute anterior circulation occlusion.

The effectiveness and safety of human urinary kallidinogenase in acute ischemic stroke patients undergoing endovascular therapy

The effectiveness and safety of human urinary kallidinogenase (HUK) in acute ischemic stroke (AIS) patients undergoing endovascular therapy (EVT) due to large vessel occlusion (LVO) was unclear. A pooled analysis was performed using individual data from the DEVT and RESCUE BT trials. Patients were divided into two groups based on HUK treatment. The primary outcome was the 90-day modified Rankin Scale (mRS) score. Safety outcomes included 90-day mortality and symptomatic intracranial hemorrhage (sICH) within 48 hours. A total of 1174 patients were included in the study. Of these, 150 (12.8%) patients received HUK. The adjusted common odds ratio (OR) of the mRS score was 1.458 (95% confidence interval [CI] = 1.072-1.983; p = 0.016) favoring HUK. The incidence of sICH (2.0% vs. 8.6%; adjusted OR: 0.198; 95% CI: 0.061-0.638; p = 0.007) and mortality (11.3% vs.18.5%; adjusted OR: 0.496; 95% CI: 0.286-0.862; p = 0.013) was lower in HUK group than non-HUK group. This association was consistent with propensity score-matching and the inverse probability of treatment weighting analysis. In conclusion, HUK was safe and associated with a preferable prognosis in AIS patients due to LVO in the anterior circulation.

Numerical study on the cerebral blood flow regulation in the circle of Willis with the vascular absence and internal carotid artery stenosis

Objectives

This study explores how vascular stenosis and absence affect the regulation of cerebral blood flow in the Circle of Willis (CoW) and the hemodynamic changes downstream of the stenosis.

Materials and Methods

Forty idealized CoW models were simulated to analyze the impact of vascular absence and internal carotid artery (ICA) stenosis on hemodynamics. Inlet conditions were set using a physiological pressure waveform, and outflow boundaries were modeled using three-element Windkessel models.

Results

The absence of vessels such as RP1, LP1, RA1, or LA1 had a comparable effect on total blood flow to a 40% stenosis of the left internal carotid artery (LICA) across the entire CoW. Specifically, when LP1 and RA1 were absent with a 50% LICA stenosis, the total blood flow closely resembled that of a complete CoW with 75% LICA stenosis. In cases of proximal ICA stenosis, downstream regions showed elevated oscillatory shear index (OSI >0.2) and reduced time-averaged wall shear stress (TAWSS <1 Pa). With increasing stenosis severity, areas of high OSI shifted, and regions of low TAWSS expanded notably. At 75% stenosis, the area with TAWSS <1 Pa downstream significantly increased. Until complete occlusion, the area of low TAWSS and high OSI were maximized.

Conclusion

This study underscores how anatomical variations in the CoW, combined with ICA stenosis, impact both total cerebral blood flow and its distribution among different outlets. Moreover, it highlights the potential for increased atherosclerosis development in affected areas. Particularly notable is the finding the absence of LP1 and RA1 vessels alongside 50% LICA stenosis results in blood flow patterns similar to those seen with 75% LICA stenosis in a complete CoW, emphasizing clinical implications for the patient. Hemodynamic changes, including TAWSS and OSI, are most pronounced downstream of the stenosis especially when the stenosis rate exceeds 75%.

Brain-Targeting Emodin Mitigates Ischemic Stroke via Inhibiting AQP4-Mediated Swelling and Neuroinflammation

Failure to achieve target-specific delivery to ischemic brain sites has hampered the clinical efficacy of newly developed therapies for ischemic stroke. Emodin, an active ingredient isolated from traditional Chinese medicine, has been indicated to alleviate ischemic stroke; however, the underlying mechanism remains unclear. In this study, we aimed to achieve brain-targeted delivery of emodin to maximize its therapeutic efficacy and elucidate the mechanisms by which emodin alleviates ischemic stroke. A polyethylene glycol (PEG)/cyclic Arg-Gly-Asp (cRGD)-modified liposome was used to encapsulate emodin. TTC, HE, Nissl staining, and immunofluorescence staining were employed to evaluate the therapeutic efficacy of brain-targeting emodin in MCAO and OGD/R models. Inflammatory cytokine levels were determined using ELISA. Immunoprecipitation, immunoblotting, and RT-qPCR were utilized for clarifying the changes in key downstream signaling. Lentivirus-mediated gene restoration was employed to verify the core effector of emodin for relieving ischemic stroke. Encapsulating emodin in a PEG/cRGD-modified liposome enhanced its accumulation in the infarct region and substantially raised its therapeutic efficacy. Furthermore, we demonstrated that AQP4, the most abundant water transporter subunit expressed in astrocytes, plays a crucial role in mediating the mechanisms by which emodin inhibits astrocyte swelling, neuroinflammatory blood-brain barrier (BBB) breakdown in vivo and in vitro, and brain edema in general. Our study unveiled the critical target of emodin responsible for alleviating ischemic stroke and a localizable drug delivery vehicle in the therapeutic strategy for ischemic stroke and other brain injuries.

Hydrogel-Based Therapies for Ischemic and Hemorrhagic Stroke: A Comprehensive Review

Stroke remains the second leading cause of death and a major cause of disability worldwide, significantly impacting individuals, families, and healthcare systems. This neurological emergency can be triggered by ischemic events, including small vessel arteriolosclerosis, cardioembolism, and large artery atherothromboembolism, as well as hemorrhagic incidents resulting from macrovascular lesions, venous sinus thrombosis, or vascular malformations, leading to significant neuronal damage. The resultant motor impairment, cognitive dysfunction, and emotional disturbances underscore the urgent need for effective therapeutic interventions. Recent advancements in biomaterials, particularly hydrogels, offer promising new avenues for stroke management. Hydrogels, composed of three-dimensional networks of hydrophilic polymers, are notable for their ability to absorb and retain substantial amounts of water. Commonly used polymers in hydrogel formulations include natural polymers like alginate, chitosan, and collagen, as well as synthetic polymers such as polyethylene glycol (PEG), polyvinyl alcohol (PVA), and polyacrylamide. Their customizable characteristics-such as their porosity, swelling behavior, mechanical strength, and degradation rates-make hydrogels ideal for biomedical applications, including drug delivery, cell delivery, tissue engineering, and the controlled release of therapeutic agents. This review comprehensively explores hydrogel-based approaches to both ischemic and hemorrhagic stroke therapy, elucidating the mechanisms by which hydrogels provide neuroprotection. It covers their application in drug delivery systems, their role in reducing inflammation and secondary injury, and their potential to support neurogenesis and angiogenesis. It also discusses current advancements in hydrogel technology and the significant challenges in translating these innovations from research into clinical practice. Additionally, it emphasizes the limited number of clinical trials utilizing hydrogel therapies for stroke and addresses the associated limitations and constraints, underscoring the need for further research in this field.

Blood pressure variability and outcome in atherosclerosis versus cardioembolism cerebral large vessel occlusion after successful thrombectomy

Higher blood pressure variability (BPV) has been proven associated with worse functional outcome after endovascular treatment (EVT). However, this association is not established according to different stroke etiologies. In this study, we compared patients with the two highest proportions of stroke etiologies-cardioembolism (CE) and large-artery atherosclerosis (LAA), aiming to explore appropriate strategies of BP management for different etiologies. We enrolled patients with large vessel occlusion (LVO) in anterior circulation who underwent EVT and achieved successful recanalization retrospectively. 24-h blood pressure (BP) and BPV measured as blood pressure reduction (BPr), standard deviation (SD), coefficient of variation (CV), successive variation (SV), average real variability (ARV) after EVT were collected for systolic blood pressure (SBP) and diastolic blood pressure (DBP). The favorable outcome was defined as functional independence by 90-day modified Rankin Scale (mRS 0-2). In our cohort, higher BPV parameters significantly resulted in 90d functional dependence in CE-LVO patients (SBPSV OR: 1.083, 95%CI = 1.009-1.163; SBPARV OR: 1.121, 95%CI = 1.019-1.233; DBPSD OR: 1.124, 95%CI = 1.007-1.1256; DBPCV OR: 1.078, 95%CI = 1.002-1.161). However, for LAA-LVO patients, no positive results correlated 90d functional dependence with 24-hour BPV. Additionally, 90d functional dependence in CE patients with poor collaterals were significantly dependent on post-procedural BPV (DBPmax OR: 1.044, 95%CI = 1.002-1.087; DBPSD OR: 1.229, 95%CI = 1.022-1.1.479; DBPCV OR: 1.143, 95%CI = 1.009-1.295). Whereas to patients with good collaterals, there did not exist such a correlation. In summary, stroke etiologies should probably be taken into consideration to optimize individualized BP management strategies. In order to achieve better clinical outcomes for patients with acute ischemic stroke due to large vessel occlusion, stricter blood pressure management should be taken in cardioembolic stroke patients in contrast with large artery atherosclerotic stroke patients after successful endovascular therapy.

Normobaric hyperoxia therapy in acute ischemic stroke: A literature review

Background

Ischemic stroke is one of the most severe cerebrovascular diseases that leads to disability and death and seriously endangers health and quality of life. Insufficient oxygen supply is a critical factor leading to ischemic brain injury. However, effective therapies for ischemic stroke are lacking. Oxygen therapy has been shown to increase oxygen supply to ischemic tissues and improve prognosis after cerebral ischemia/reperfusion. Normobaric hyperoxia (NBHO) has been shown to have neuroprotective effects during ischemic stroke and is considered an appropriate neuroprotective therapy for ischemic stroke. Evidence indicates that NBHO plays a neuroprotective role through different mechanisms in acute ischemic stroke. Recent studies have also reported that combinations with other drug therapies can enhance the efficacy of NBHO in ischemic stroke. Here, we aimed to provide a summary of the potential mechanisms underlying the use of NBHO in ischemic stroke and an overview of the benefits of NBHO in ischemic stroke.

Methods

We screened 83 articles on PubMed and other websites. A quick review was conducted, including clinical trials, animal trials, and reviews of studies in the field of NBHO treatment published before July 1, 2023. The results were described and synthesized, and the bias risk and evidence quality of all included studies were assessed.

Results

The results were divided into four categories: the mechanism of NBHO, animal and clinical trials of NBHO, the clinical application and prospects of NBHO, and adverse reactions of NBHO.

Conclusion

NBHO is a simple, non-invasive therapy that may be delivered early after stroke onset, with promising potential for the treatment of acute ischemic stroke. However, the optimal therapeutic regimen remains uncertain. Further studies are needed to confirm its efficacy and safety.

Construction and comparison of short-term prognosis prediction model based on machine learning in acute ischemic stroke

Objective

To construct and compared the short-term prognosis prediction models of acute ischemic stroke (AIS) by machine learning (ML).

Methods

Retrospectively study. The group W (mRS≤3) was clustered, and combined with group P (mRS>3) to form the post-clustering dataset for modeling. The "glmnet", "rpart", "xgboost", "randomForest", "neuralnet" packages were used to construct ML models. The accuracy, sensitivity, specificity, positive predict value (PPV), negative predict value (NPV) among the models were compared. Four external clinical datasets were used for external clinical validation. The optimal prediction model was determined by variable screening ability, model visualization, and external clinical validation performance.

Results

The post-clustering dataset contains 139 patients (group W) and 122 patients (group P). The neutrophil multiplied by D-dimer (NDM) has predictive value in all ML prediction models in this study. In the decision tree model, NDMQ occupies the first tree node, When NDM≤5.62 and the age<74.5, the probability of poor prognosis of AIS is less than 20 %. When NDM>5.62 and accompanied by pneumonia, the incidence of poor prognosis of AIS is about 90 %. In the Random Forest (RF) model, NDMQ had the highest Gini index. The variable combination screened by the RF model had the best performance in the neural network, and the accuracy, sensitivity, specificity, PPV, and NPV of the external validation were 0.800, 0.774, 0.833, 0.857, and 0.741, respectively. The RF model had the best performance in the external clinical validation datasets, with accuracies of 0.646, 0.697, 0.695, and 0.713, respectively.

Conclusions

NDM shows predictive value for AIS short-term prognosis in all ML models in this study. The optimal model in screening characteristic variables and the performance of in external clinical datasets was RF model. In the analysis of medical data with small sample size and outcome as categorical variables, RF could be used as the main algorithm to build a model.

Postoperative fibrinogen-to-albumin ratio acting as an indicator of futile recanalization in patients with successful thrombectomy

BACKGROUND

Timely recognition of futile recanalization might enable a prompter response and thus improve outcomes in patients receiving successful thrombectomy. This study aims to evaluate whether postoperative fibrinogen-to-albumin ratio (FAR) could act as an indicator of futile recanalization.

METHODS

This is a single-center, retrospective analysis of patients with acute anterior circulation large-vessel occlusion and successful thrombectomy between May 2019 and June 2022. FAR was defined as postoperative blood levels of fibrinogen divided by those of albumin, and dichotomized into high and low levels based on the Youden index. Futile recanalization was defined as patients achieving a successful recanalization with a modified Rankin Scale score of 3-6 at 90 days. Multivariable logistic regression was used to assess the association of FAR with futile recanalization.

RESULTS

A total of 255 patients were enrolled, amongst which 87 patients (34.1%) had high postoperative FAR. Futile recanalization was more prevalent among patients with high FAR compared to those with low FAR (74.7% vs. 53.0%, p = .001). After adjusting for potential confounders, high postoperative FAR was found to independently correspond with the occurrence of futile recanalization (adjusted OR 2.40, 95%CI 1.18-4.87, p = .015). This association was consistently observed regardless of prior antithrombotic therapy, treatment of intravenous thrombolysis, occlusion site, time from symptom onset to groin puncture, and reperfusion status.

CONCLUSION

Our findings support high postoperative FAR serving as an indicator of futile recanalization in patients with anterior circulation large-vessel occlusion and successful thrombectomy.

Risk Factors, Pathophysiologic Mechanisms, and Potential Treatment Strategies of Futile Recanalization after Endovascular Therapy in Acute Ischemic Stroke

Endovascular therapy is the first-line treatment for acute ischemic stroke. However, studies have shown that, even with the timely opening of occluded blood vessels, nearly half of all patients treated with endovascular therapy for acute ischemic stroke still have poor functional recovery, a phenomenon called "futile recanalization.". The pathophysiology of futile recanalization is complex and may include tissue no-reflow (microcirculation reperfusion failure despite recanalization of the occluded large artery), early arterial reocclusion (reocclusion of the recanalized artery 24-48 hours post endovascular therapy), poor collateral circulation, hemorrhagic transformation (cerebral bleeding following primary ischemic stroke), impaired cerebrovascular autoregulation, and large hypoperfusion volume. Therapeutic strategies targeting these mechanisms have been attempted in preclinical research; however, translation to the bedside remains to be explored. This review summarizes the risk factors, pathophysiological mechanisms, and targeted therapy strategies of futile recanalization, focusing on the mechanisms and targeted therapy strategies of no-reflow to deepen the understanding of this phenomenon and provide new translational research ideas and potential intervention targets for improving the efficacy of endovascular therapy for acute ischemic stroke.

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.

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.

The Implications of Microglial Regulation in Neuroplasticity-Dependent Stroke Recovery

Stroke causes varying degrees of neurological deficits, leading to corresponding dysfunctions. There are different therapeutic principles for each stage of pathological development. Neuroprotection is the main treatment in the acute phase, and functional recovery becomes primary in the subacute and chronic phases. Neuroplasticity is considered the basis of functional restoration and neurological rehabilitation after stroke, including the remodeling of dendrites and dendritic spines, axonal sprouting, myelin regeneration, synapse shaping, and neurogenesis. Spatiotemporal development affects the spontaneous rewiring of neural circuits and brain networks. Microglia are resident immune cells in the brain that contribute to homeostasis under physiological conditions. Microglia are activated immediately after stroke, and phenotypic polarization changes and phagocytic function are crucial for regulating focal and global brain inflammation and neurological recovery. We have previously shown that the development of neuroplasticity is spatiotemporally consistent with microglial activation, suggesting that microglia may have a profound impact on neuroplasticity after stroke and may be a key therapeutic target for post-stroke rehabilitation. In this review, we explore the impact of neuroplasticity on post-stroke restoration as well as the functions and mechanisms of microglial activation, polarization, and phagocytosis. This is followed by a summary of microglia-targeted rehabilitative interventions that influence neuroplasticity and promote stroke recovery.

Perspective insights into hydrogels and nanomaterials for ischemic stroke

Ischemic stroke (IS) is a neurological disorder prevalent worldwide with a high disability and mortality rate. In the clinic setting, tissue plasminogen activator (tPA) and thrombectomy could restore blood flow of the occlusion region and improve the outcomes of IS patients; however, these therapies are restricted by a narrow time window. Although several preclinical trials have revealed the molecular and cellular mechanisms underlying infarct lesions, the translatability of most findings is unsatisfactory, which contributes to the emergence of new biomaterials, such as hydrogels and nanomaterials, for the treatment of IS. Biomaterials function as structural scaffolds or are combined with other compounds to release therapeutic drugs. Biomaterial-mediated drug delivery approaches could optimize the therapeutic effects based on their brain-targeting property, biocompatibility, and functionality. This review summarizes the advances in biomaterials in the last several years, aiming to discuss the therapeutic potential of new biomaterials from the bench to bedside. The promising prospects of new biomaterials indicate the possibility of an organic combination between materialogy and medicine, which is a novel field under exploration.

Intensive blood pressure control after endovascular thrombectomy for acute ischaemic stroke (ENCHANTED2/MT): a multicentre, open-label, blinded-endpoint, randomised controlled trial

BACKGROUND

The optimum systolic blood pressure after endovascular thrombectomy for acute ischaemic stroke is uncertain. We aimed to compare the safety and efficacy of blood pressure lowering treatment according to more intensive versus less intensive treatment targets in patients with elevated blood pressure after reperfusion with endovascular treatment.

METHODS

We conducted an open-label, blinded-endpoint, randomised controlled trial at 44 tertiary-level hospitals in China. Eligible patients (aged ≥18 years) had persistently elevated systolic blood pressure (≥140 mm Hg for &gt;10 min) following successful reperfusion with endovascular thrombectomy for acute ischaemic stroke from any intracranial large-vessel occlusion. Patients were randomly assigned (1:1, by a central, web-based program with a minimisation algorithm) to more intensive treatment (systolic blood pressure target &lt;120 mm Hg) or less intensive treatment (target 140-180 mm Hg) to be achieved within 1 h and sustained for 72 h. The primary efficacy outcome was functional recovery, assessed according to the distribution in scores on the modified Rankin scale (range 0 [no symptoms] to 6 [death]) at 90 days. Analyses were done according to the modified intention-to-treat principle. Efficacy analyses were performed with proportional odds logistic regression with adjustment for treatment allocation as a fixed effect, site as a random effect, and baseline prognostic factors, and included all randomly assigned patients who provided consent and had available data for the primary outcome. The safety analysis included all randomly assigned patients. The treatment effects were expressed as odds ratios (ORs). This trial is registered at ClinicalTrials.gov, NCT04140110, and the Chinese Clinical Trial Registry, 1900027785; recruitment has stopped at all participating centres.

FINDINGS

Between July 20, 2020, and March 7, 2022, 821 patients were randomly assigned. The trial was stopped after review of the outcome data on June 22, 2022, due to persistent efficacy and safety concerns. 407 participants were assigned to the more intensive treatment group and 409 to the less intensive treatment group, of whom 404 patients in the more intensive treatment group and 406 patients in the less intensive treatment group had primary outcome data available. The likelihood of poor functional outcome was greater in the more intensive treatment group than the less intensive treatment group (common OR 1·37 [95% CI 1·07-1·76]). Compared with the less intensive treatment group, the more intensive treatment group had more early neurological deterioration (common OR 1·53 [95% 1·18-1·97]) and major disability at 90 days (OR 2·07 [95% CI 1·47-2·93]) but there were no significant differences in symptomatic intracerebral haemorrhage. There were no significant differences in serious adverse events or mortality between groups.

INTERPRETATION

Intensive control of systolic blood pressure to lower than 120 mm Hg should be avoided to prevent compromising the functional recovery of patients who have received endovascular thrombectomy for acute ischaemic stroke due to intracranial large-vessel occlusion.

FUNDING

The Shanghai Hospital Development Center; National Health and Medical Research Council of Australia; Medical Research Futures Fund of Australia; China Stroke Prevention; Shanghai Changhai Hospital, Science and Technology Commission of Shanghai Municipality; Takeda China; Hasten Biopharmaceutic; Genesis Medtech; Penumbra.

Neutrophil count multiplied by D-dimer combined with pneumonia may better predict short-term outcomes in patients with acute ischemic stroke

Objective

To investigate the predictive value of neutrophil, D-dimer and diseases associated with stroke for short-term outcomes of acute ischemic stroke (AIS).

Methods

By collecting the subitems of laboratory data especially routine blood and coagulation test in AIS patients, and recording their clinical status, the correlation, regression and predictive value of each subitem with the short-term outcomes of AIS were analyzed. The predict model was constructed.

Results

The neutrophil count multiplied by D-dimer (NDM) had the best predictive value among the subitems, and the area under the receiver operating characteristic (ROC) curve reached 0.804. When clinical information was not considered, the Youden index of NDM was calculated to be 0.48, corresponding to an NDM value of 7.78, a diagnostic sensitivity of 0.79, specificity of 0.69, negative predictive value of 96%. NDM were divided into 5 quintiles, the five grade of NDM (quintile) were < = 1.82, 1.83–2.41, 2.42–3.27, 3.28–4.49, 4.95+, respectively. The multivariate regression analysis was conducted between NDM (quintile), Babinski+, pneumonia, cardiac disease and poor outcomes of AIS. Compared with the first grade of NDM (quintile), the second grade of NDM (quintile) was not significant, but the third grade of NDM (quintile) showed 7.061 times, the fourth grade of NDM (quintile) showed 11.776 times, the fifth grade of NDM (quintile) showed 23.394 times in short-term poor outcomes occurrence. Babinski sign + showed 1.512 times, pneumonia showed 2.995 times, cardiac disease showed 1.936 times in short-term poor outcomes occurrence compared with those negative patients.

Conclusions

NDM combined with pneumonia may better predict short-term outcomes in patients with AIS. Early prevention, regular examination and timely intervention should be emphasized for patients, which may reduce the risk of short-term poor outcomes.

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.