Neuroprotection for ischaemic stroke: translation from the bench to the bedside

Duration of Remote Ischemic Conditioning and Outcome in Acute Ischemic Stroke

BACKGROUND

Remote ischemic conditioning has been found to be effective in improving functional outcomes in acute ischemic stroke. We conducted a post hoc analysis of the RICAMIS (Remote Ischemic Conditioning for Acute Moderate Ischemic Stroke) trial to determine whether long-term remote ischemic conditioning duration after stroke onset is associated with better clinical outcomes in ischemic stroke.

METHODS AND RESULTS

Patients from the full analysis set were included in this secondary analysis. The primary outcome was the proportion of patients with an excellent functional outcome at 90 days, defined as a modified Rankin Scale score of 0 to 1. Among the 1776 patients, there were 55 patients in the 1 to 7 days remote ischemic conditioning group, 345 in the 8 to 10 days group, 412 in the 11 to 13 days group, 51 in the 14 to 16 days group, and 913 in the control group. Compared with the control group, a significantly higher proportion of excellent functional outcomes at 90 days was found in the 11 to 13 days remote ischemic conditioning group (adjusted absolute difference, 9.1% [95% CI, 3.7%-14.5%]; P =0.001), which was attenuated in the other groups (adjusted absolute difference in the 8-10 days group, 2.0% [95% CI, -4.0% to 8.0%]; P=0.51; adjusted absolute difference in the 14-16 days group, 7.4% [95% CI, -5.8% to 20.5%]; P=0.27), but compared to the control group, there was lower proportion of excellent functional outcomes in the 1 to 7 days group (adjusted absolute difference, -14.4% [95% CI, -27.8% to 0.0%]; P=0.05).

CONCLUSIONS

Among patients with acute moderate ischemic stroke, a higher likelihood of excellent clinical outcome was found in patients with longer duration of remote ischemic conditioning.

Age and efficacy of remote ischemic conditioning in acute ischemic stroke

AIMS

A post hoc analysis of RICAMIS trial to evaluate functional outcomes in relation to patient age.

METHODS

Patients in RICAMIS were divided into six age groups. The primary outcome was excellent functional outcome at 90 days, defined as modified Rankin Scale (mRS) score of 0-1. Compared with patients receiving usual care alone, we investigated the association of remote ischemic conditioning (RIC) effect with functional outcomes in each group and the interaction between RIC effect and age.

RESULTS

Of 1776 patients, 498 were assigned to <60 years, 326 to 60 to <65 years, 325 to 65 to <70 years, 278 to 70 to <75 years, 206 to 75 to <80 years, and 143 to ≥80 years. Higher proportions of primary outcome were found associated with RIC in <60 years group (72.6% vs. 64.8%; adjusted risk difference [RD], 6.8%; 95% CI, -1.6% to 15.1%; p = 0.11), 60 to <65 years group (70.7% vs. 67.1%; adjusted RD, 3.1%; 95% CI, -7.2% to 13.3%; p = 0.56), 65 to <70 years group (70.5% vs. 63.6%; adjusted RD, 3.5%; 95% CI, -6.8% to 13.8%; p = 0.51), 70 to <75 years group (59.7% vs. 54.9%; adjusted RD, 4.7%; 95% CI, -7.1% to 16.4%; p = 0.61), 75 to <80 years group (61.5% vs. 55.9%; adjusted RD, 5.7%; 95% CI, -7.8% to 19.1%; p = 0.41), and ≥ 80 years group (59.2% vs. 59.7%; adjusted RD, -2.6%; 95% CI, -18.8% to 13.5%; p = 0.75). No significant interaction between RIC effect and age was found among groups.

CONCLUSIONS

This is the first report that RIC effect may be attenuated with increasing age in patients with acute moderate ischemic stroke with respect to functional outcome.

New Perspectives in Neuroprotection for Ischemic Stroke

The constant failure of new neuroprotective therapies for ischemic stroke has partially halted the search for new therapies in recent years, mainly because of the high investment risk required to develop a new treatment for a complex pathology, such as stroke, with a narrow intervention window and associated comorbidities. However, owing to recent progress in understanding the stroke pathophysiology, improvement in patient care in stroke units, development of new imaging techniques, search for new biomarkers for early diagnosis, and increasingly widespread use of mechanical recanalization therapies, new opportunities have opened for the study of neuroprotection. This review summarizes the main protective agents currently in use, some of which are already in the clinical evaluation phase. It also includes an analysis of how recanalization therapies, new imaging techniques, and biomarkers have improved their efficacy.

Baseline neurologic deficit and efficacy of remote ischemic conditioning after acute ischemic stroke: A post hoc analysis of RICAMIS

RICAMIS (ClinicalTrials.gov Identifier: NCT03740971) trial has demonstrated efficacy of remote ischemic conditioning (RIC) in acute ischemic stroke, but whether baseline NIHSS score can affect outcomes in stroke remains unclear. We conducted a post hoc analysis of RICAMIS to investigate the issue. Patients included in RICAMIS were divided into three groups based on baseline NIHSS score. The primary outcome was excellent functional outcome at 90 days, defined as mRS score of 0-1. Compared with patients receiving usual care, we investigated association of RIC effect with outcomes in each group and interaction between RIC effect and stroke severity. Among 1776 patients, 1255 were assigned into NIHSS score 6-8 group, 402 into NIHSS score 9-12 group, and 119 into NIHSS score 13-16 group. A higher proportion of primary outcome was found associated with RIC in NIHSS score 9-12 group (adjusted risk difference [RD], 14.6 ​%; 95 ​% CI, 5.0 ​%-24.2 ​%; P ​= ​0.003), but no significant association was found in NIHSS score 6-8 group (adjusted RD, 2.3 ​%; 95 ​% CI, -2.5 ​%-7.2 ​%; P ​= ​0.34), or in NIHSS score 13-16 group (adjusted RD, 9.7 ​%; 95 ​% CI, -7.5 ​%-26.9 ​%; P ​= ​0.27). There was a significant interaction between RIC effect and stroke severity when analysis was performed between NIHSS score 6-8 and 9-12 groups (P ​= ​0.04), but not between NIHSS score 9-12 and 13-16 groups (P ​= ​0.57). Current study firstly reported patients with NIHSS score 9-12 may get more benefit from RIC after stroke with respect to excellent functional outcome at 90 days.

Effect and mechanisms of resveratrol in animal models of ischemic stroke: A systematic review and Bayesian meta-analysis

Resveratrol (RSV) holds promise as cerebroprotective treatment in cerebral ischemia. This systematic review aims to assess the effects and mechanisms of RSV in animal models of ischemic stroke. We searched Medline, Embase and Web of Science to identify 75 and 57 eligible rodent studies for qualitative and quantitative syntheses, respectively. Range of evidence met 10 of 13 STAIR criteria. Median (Q1, Q3) quality score was 7 (5, 8) on the CAMARADES 15-item checklist. Bayesian meta-analysis showed SMD estimates (95% CI) favoring RSV: infarct size (-1.72 [-2.03; -1.41]), edema size (-1.61 [-2.24; -0.98]), BBB impairment (-1.85 [-2.54; -1.19]), neurofunctional impairment (-1.60 [-1.92; -1.29]), and motor performance (1.39 [0.64; 2.08]); and less probably neuronal survival (0.63 [-1.40; 2.48]) and apoptosis (-0.96 [-2.87; 1.02]). Species (rat vs mouse) was associated to a larger benefit. Sensitivity analyses confirmed robustness of the estimates. Reduction of oxidative stress, inflammation, and apoptosis underlie these effects. Our results quantitatively state the beneficial effects of RSV on structural and functional outcomes in rodent stroke models, update the evidence on the mechanisms of action, and provide an exhaustive list of targeted signaling pathways. Current evidence highlights the need for conducting further high-quality preclinical research to better inform clinical research.

Inhibition of insulin-regulated aminopeptidase confers neuroprotection in a conscious model of ischemic stroke

Stroke is a leading cause of mortality and morbidity with a paucity of effective pharmacological treatments. We have previously identified insulin-regulated aminopeptidase (IRAP) as a potential target for the development of a new class of drugs for the treatment of stroke, as global deletion of this gene in mice significantly protected against ischemic damage. In the current study, we demonstrate that small molecular weight IRAP inhibitors reduce infarct volume and improve neurological outcome in a hypertensive animal model of ischemic stroke. The effects of two structurally distinct IRAP inhibitors (HFI419 or SJM164) were investigated in a model of stroke where the middle cerebral artery was transiently occluded with endothelin-1 in the conscious spontaneously hypertensive rat. IRAP inhibitor was administered into the lateral ventricle at 2 or 6 h after stroke, with subsequent doses delivered at 24, 48 and 70 h post-stroke. Functional outcomes were assessed prior to drug treatment, and on day 1 and 3 post-stroke. Histological analyses and neuroinflammatory cytokine profiling were conducted at 72 and 24 h post-stroke respectively. IRAP inhibitor treatment following stroke significantly reduced infarct volume and improved neurological and motor deficits. These protective effects were maintained even when the therapeutic window was extended to 6 h. Examination of the cellular architecture at 72 h post-stroke demonstrated that IRAP expression was upregulated in CD11b positive cells and activated astrocytes. Furthermore, IRAP inhibitor treatment significantly increased gene expression for interleukin 6 and C-C motif chemokine ligand 2 in the ischemic core. This study provides proof-of-principle that selective inhibition of IRAP activity with two structurally distinct IRAP inhibitors reduces infarct volume and improves functional outcome even when the first dose is administered 6 h post-stroke. This is the first direct evidence that IRAP inhibitors are a class of drug with potential use in the treatment of ischemic stroke.

Time from Onset to Remote Ischemic Conditioning and Clinical Outcome After Acute Moderate Ischemic Stroke

OBJECTIVE

We conducted a post hoc exploratory analysis of Remote Ischemic Conditioning for Acute Moderate Ischemic Stroke (RICAMIS) to determine whether early remote ischemic conditioning (RIC) initiation after stroke onset was associated with clinical outcome in patients with acute moderate ischemic stroke.

METHODS

In RICAMIS, patients receiving RIC treatment in the intention-to-treat analysis were divided into 2 groups based on onset-to-treatment time (OTT): early RIC group (OTT ≤ 24 hours) and late RIC group (OTT 24-48 hours). Patients receiving usual care without RIC treatment from intention-to-treat analysis were assigned as the control group. The primary outcome was excellent functional outcome at 90 days.

RESULTS

Among 1,776 patients from intention-to-treat analysis, 387 were in the early RIC group, 476 in the late RIC group, and 913 in the control group. In the post hoc exploratory analysis, a higher proportion of excellent functional outcome was found in the early RIC versus control group (adjusted absolute difference = 8.1%, 95% confidence interval [CI] = 2.5%-13.8%, p = 0.005), but no difference in outcomes was detected in the late RIC versus control group (adjusted absolute difference = 3.3%, 95% CI = -2.1% to 8.6%, p = 0.23), or in the early RIC versus late RIC group (adjusted absolute difference = 5.0%, 95% CI = -1.3% to 11.2%, p = 0.12). Similar results were found in the per-protocol analysis.

INTERPRETATION

Among patients with acute moderate ischemic stroke who are not candidates for intravenous thrombolysis or endovascular therapy, early RIC initiation within 24 hours of onset may be associated with higher likelihood of excellent clinical outcome. ANN NEUROL 2023;94:561-571.

Neuroprotection for Nonarteritic Central Retinal Artery Occlusion: Lessons from Acute Ischemic Stroke

Nonarteritic central retinal artery occlusion (NA-CRAO) is a variant of acute ischemic stroke (AIS) and is a cause of sudden severe loss of vision. There are guidelines by the American Heart Association and the American Stroke Association for the care of CRAO patients. This review explores the basis of retinal neuroprotection for CRAO and its potential for improving the outcome of NA-CRAO. Recently, there have been significant advances in research into the use of neuroprotection to treat retinal diseases, including retinal detachment, age-related macular degeneration, and inherited retinal diseases. Also, neuroprotective research in AIS has been extensive, and newer drugs tested, including Uric acid, Nerinetide, and Otaplimastat, with promising results. Progress in cerebral neuroprotection after AIS offers hope for retinal neuroprotection after CRAO; and a possibility of extrapolating research findings from AIS into CRAO. Combining neuroprotection and thrombolysis can extend the therapeutic window for NA-CRAO treatment and potentially improve outcomes. Experimented neuroprotection for CRAO includes Angiopoietin (Comp Ang1), KUS 121, Gene therapy (XIAP), and hypothermia. Efforts in the field of neuroprotection for NA-CRAO should focus on better imaging to delineate the penumbra after an acute episode of NA-CRAO (using a combination of high-definition optical coherence angiography and electrophysiology). Also, research should explore details of pathophysiologic mechanisms involved in NA-CRAO, allowing for further neuroprotective intervention, and closing the gap between preclinical and clinical neuroprotection.

Exploring the Therapeutic Effect of Neurotrophins and Neuropeptides in Neurodegenerative Diseases: at a Glance

Neurotrophins and neuropeptides are the essential regulators of peripheral nociceptive nerves that help to induce, sensitize, and maintain pain. Neuropeptide has a neuroprotective impact as it increases trophic support, regulates calcium homeostasis, and reduces excitotoxicity and neuroinflammation. In contrast, neurotrophins target neurons afflicted by ischemia, epilepsy, depression, and eating disorders, among other neuropsychiatric conditions. Neurotrophins are reported to inhibit neuronal death. Strategies maintained for "brain-derived neurotrophic factor (BDNF) therapies" are to upregulate BDNF levels using the delivery of protein and genes or compounds that target BDNF production and boosting BDNF signals by expanding with BDNF mimetics. This review discusses the mechanisms of neurotrophins and neuropeptides against acute neural damage as well as highlighting neuropeptides as a potential therapeutic agent against Parkinson's disease (PD), Huntington's disease (HD), Alzheimer's disease (AD), and Machado-Joseph disease (MJD), the signaling pathways affected by neurotrophins and their receptors in both standard and diseased CNS systems, and future perspectives that can lead to the potent application of neurotrophins and neuropeptides in neurodegenerative diseases (NDs).

Influence of sex, age and diabetes on brain transcriptome and proteome modifications following cerebral ischemia

Ischemic stroke is a major cause of death and disability worldwide. Translation into the clinical setting of neuroprotective agents showing promising results in pre-clinical studies has systematically failed. One possible explanation is that the animal models used to test neuroprotectants do not properly represent the population affected by stroke, as most of the pre-clinical studies are performed in healthy young male mice. Therefore, we aimed to determine if the response to cerebral ischemia differed depending on age, sex and the presence of comorbidities. Thus, we explored proteomic and transcriptomic changes triggered during the hyperacute phase of cerebral ischemia (by transient intraluminal middle cerebral artery occlusion) in the brain of: (1) young male mice, (2) young female mice, (3) aged male mice and (4) diabetic young male mice. Moreover, we compared each group's proteomic and transcriptomic changes using an integrative enrichment pathways analysis to disclose key common and exclusive altered proteins, genes and pathways in the first stages of the disease. We found 61 differentially expressed genes (DEG) in male mice, 77 in females, 699 in diabetics and 24 in aged mice. Of these, only 14 were commonly dysregulated in all groups. The enrichment pathways analysis revealed that the inflammatory response was the biological process with more DEG in all groups, followed by hemopoiesis. Our findings indicate that the response to cerebral ischemia regarding proteomic and transcriptomic changes differs depending on sex, age and comorbidities, highlighting the importance of incorporating animals with different phenotypes in future stroke research studies.

The Rescue on Reperfusion Damage in Cerebral Infarction by Nelonemdaz (RODIN) Trial: Protocol for a Double-Blinded Clinical Trial of Nelonemdaz in Patients with Hyperacute Ischemic Stroke and Endovascular Thrombectomy

BACKGROUND AND PURPOSE

Nelonemdaz (Neu2000) has both selective antagonism against 2B subunit of N-methyl-D-aspartate receptor and antioxidant activity. This drug provides sufficient evidence of neuroprotection in acute cerebral ischemia/reperfusion models. This phase III trial aims to determine this effect in patients.

DESIGN

The Rescue on Reperfusion Damage in Cerebral Infarction by Nelonemdaz is a multicenter, double-blinded clinical trial. A total of 496 patients will be randomly assigned into the nelonemdaz (a total of 5,250 mg divided by 10 times for 5 days) and placebo groups. Patients will be included if they have an acute ischemic stroke (National Institutes of Health Stroke Scale score ≥8) caused by intracranial large vessel occlusion in the anterior circulation (Alberta Stroke Program Early CT Score ≥4), and if they are expected to undergo endovascular thrombectomy within 12 hours after stroke onset.

ENDPOINTS

The primary endpoint is a favorable shift in the modified Rankin Scale (mRS) score at 90 days after the first dose of drug. The data will be analyzed by the Cochran-Mantel-Haenszel shift test. The secondary endpoints include functional independence (mRS 0-2) at 35 and 90 days, the favorable shift of mRS at 35 days, the proportion of mRS 0 at 35 and 90 days, and the occurrence rates of symptomatic intracranial hemorrhage within 7 days.

CONCLUSION

This trial will clarify the efficacy and safety of nelonemdaz in patients with acute ischemic stroke and endovascular thrombectomy. This study has been registered at ClinicalTrials. gov (NCT05041010).

Near infrared spectroscopy detection of hemispheric cerebral ischemia following middle cerebral artery occlusion in rats

Timely and sensitive in vivo estimation of ischemic stroke-induced brain infarction are necessary to guide diagnosis and evaluation of treatments' efficacy. The gold standard for estimation of the cerebral infarction volume is magnetic resonance imaging (MRI), which is expensive and not readily accessible. Measuring regional cerebral blood flow (rCBF) with Laser Doppler flowmetry (LDF) is the status quo for confirming reduced blood flow in experimental ischemic stroke models. However, rCBF reduction following cerebral artery occlusion often does not correlate with subsequent infarct volume. In the present study, we employed the continuous-wave near infrared spectroscopy (NIRS) technique to monitor cerebral oxygenation during 90 min of the intraluminal middle cerebral artery occlusion (MCAO) in Sprague-Dawley rats (n = 8, male). The NIRS device consisted of a controller module and an optical sensor with two LED light sources and two photodiodes making up two parallel channels for monitoring left and right cerebral hemispheres. Optical intensity measurements were converted to deoxyhemoglobin (Hb) and oxyhemoglobin (HbO2) changes relative to a 2-min window prior to MCAO. Area under the curve (auc) for Hb and HbO2 was calculated for the 90-min occlusion period for each hemisphere (ipsilateral and contralateral). To obtain a measure of total ischemia, auc of the contralateral side was subtracted from the ipsilateral side resulting in ΔHb and ΔHbO2 parameters. Infarct volume (IV) was calculated by triphenyl tetrazolium chloride (TTC) staining at 24h reperfusion. Results showed a significant negative correlation (r = -0.81, p = 0.03) between ΔHb and infarct volume. In conclusion, our results show feasibility of using a noninvasive optical imaging instrument, namely NIRS, in monitoring cerebral ischemia in a rodent stroke model. This cost-effective, non-invasive technique may improve the rigor of experimental models of ischemic stroke by enabling in vivo longitudinal assessment of cerebral oxygenation and ischemic injury.

Effect of admission serum glucose on the clinical prognosis of patients with acute ischemic stroke receiving alteplase intravenous thrombolysis

Objective: To investigate the effect of admission serum glucose on the clinical prognosis of patients with acute ischemic stroke receiving intravenous alteplase thrombolysis. Methods: Patients with acute ischemic stroke who received intravenous alteplase thrombolysis between January 2016 and December 2017 were enrolled. The clinical prognosis was assessed using the modified Rankin Scale (mRs) at 90 days after onset. Univariate and multivariate logistic regression analyses were conducted to investigate whether admission serum glucose was an independent factor in the 90-day prognosis. The predictive value of admission serum glucose for a 90-day poor prognosis was evaluated using receiver operating characteristic (ROC) curves. All patients were divided into two groups based on admission serum glucose levels: high admission serum glucose (above the cut-off value) and low admission serum glucose (below the cut-off value). The 90-day prognosis of patients with different admission serum glucose was analyzed. Results: A total of 138 patients were enrolled, including 79 males (57.24%), with a mean age of (68 ± 12) years and a median baseline National Institutes of Health Stroke Scale (NIHSS) score of 9 (6 to 13.75). There were 74 cases (53.62%) in the good prognosis group and 64 cases (46.37%) in the poor prognosis group. The results of the univariate analysis indicated that admission serum glucose in the good prognosis group was significantly lower than that in the poor prognosis group [(7.45 ± 2.31) versus (8.80 ± 3.65), p < .05]. Logistic regression analysis revealed that the admission serum glucose level was an independent risk factor for clinical prognosis at 90 days after onset (OR = 1.24, 95% CI:1.01-1.52). ROC curve analysis showed that the cutoff value of admission serum glucose for predicting poor prognosis 90 days after intravenous thrombolytic therapy with alteplase was 6.77 mmol/l AUC (area under curve) 0.623, 95%CI: 0.53-0.72, sensitivity 68.80%, specificity 52.70%. When compared with the admission serum glucose ≥6.77 mmol/l group (83 cases), the 90-day mRS scores in the admission serum glucose <6.77 mmol/l group (55 cases) were lower [3 (1 to 5) scores versus 1 (0 to 3) scores, Z = 2.89, p < .05]. Conclusions: In patients with acute ischemic stroke receiving intravenous alteplase thrombolytic therapy, a higher admission serum glucose level is an independent predictor of adverse neurological outcomes at 90 days postoperatively.

[Association of nutritional status with clinical outcomes of stroke patients with acute anterior circulation large vessel occlusion after emergency endovascular treatment]

OBJECTIVE

To explore the influence of nutritional status on 90-day functional outcomes of stroke patients with acute large vessel occlusion in the anterior circulation after endovascular treatment (EVT).

METHODS

We retrospectively analyzed the baseline, laboratory, surgical and 90-day follow-up data of patients with stroke resulting from acute large vessel occlusion in the anterior circulation, who underwent emergency endovascular treatment in our hospital from July, 2015 to December, 2020. A favorable outcome was defined as a modified Rankin scale score ≤2 at 90 days. Univariate and multivariate regression analyses were performed to explore the relationship between nutritional status and 90-day functional outcomes of the patients.

RESULTS

A total of 459 patients (mean age of 68.29±11.21 years, including 260 males) were enrolled in this study. According to their prognostic nutritional index (PNI), the patients were divided into normal nutrition group (392 cases, 85.4%), moderate malnutrition group (44 cases, 9.6%), and severe malnutrition group (23 cases, 5.0%). Univariate analysis showed that the patients with good clinical outcomes had a lower proportion of malnutrition with a younger age, a lower rate of diabetes, lower baseline blood pressure, lower baseline NIHSS score, higher baseline ASPECT score, and higher rates of good collateral circulation and complete vascular recanalization. Multivariate analysis showed that in addition to age, diabetes, baseline systolic blood pressure, successful recanalization, baseline ASPECT score, baseline NIHSS score and collateral circulation, a greater PNI was a protective factor for a good 90-day outcome of patients after EVT (moderate vs severe: OR=0.245, 95% CI: 0.066-0.908, P=0.035; normal vs severe: OR=0.185, 95% CI: 0.059-0.581, P=0.004).

CONCLUSION

Nutritional status an important factor affecting the 90-day outcomes after EVT of stroke patients with acute large vessel occlusion in the anterior circulation.

The transient intraluminal filament Middle Cerebral Artery Occlusion stroke model in rats. A step by step guide and technical considerations

OBJECTIVE

Stroke is a leading cause of disability and mortality worldwide. Related research, although already providing significant insights on the underlying pathophysiology and potential treatment strategies, is far from conclusive. In this respect, stroke models are proving of extreme significance for laboratories around the world. The scope of this article is to present in detail the most popular to date focal stroke model, the tifMCAO model in rats. This model mimics reliably stroke in humans and also approximates endovascular thrombectomy.

METHODS

The tifMCAO model was performed on Wistar rats with a weight of 300-400 gr. The surgical technique is described in a step-wise manner, while pictures and/or HD video accompany each step. Complete arteriotomy of the ECA stump is introduced during the procedure.

RESULTS

We performed the tifMCAO in 65 rats (male and female) involved in various experimental protocols. Although that initial mortality was 48%, practice reduced this number to10%. The mean procedural time was 53 min (range, 38 - 85 min). Stroke was confirmed in 87.5% of the cases.

CONCLUSIONS

The tifMCAO stroke model in rats is the most commonly utilized experimental model of focal ischemia because of its clinical relevance. We revisited the procedure and divided it, for instructional purposes, in 15 consecutive distinct steps.

Non-invasive brain stimulation as therapeutic approach for ischemic stroke: Insights into the (sub)cellular mechanisms

Although spontaneous recovery can occur following ischemic stroke due to endogenous neuronal reorganization and neuroplastic events, the degree of functional improvement is highly variable, causing many patients to remain permanently impaired. In the last decades, non-invasive brain stimulation (NIBS) techniques have emerged as potential add-on interventions to the standard neurorehabilitation programs to improve post-stroke recovery. Due to their ability to modulate cortical excitability and to induce neuroreparative processes in the brain, multiple studies have assessed the safety, efficacy and (sub)cellular mechanisms of NIBS following ischemic stroke. In this review, an overview will be provided of the different NIBS techniques that are currently being investigated in (pre)clinical stroke studies. The NIBS therapies that will be discussed include transcranial magnetic stimulation, transcranial direct current stimulation and extremely low frequency electromagnetic stimulation. First, an overview will be given of the cellular mechanisms induced by NIBS that are associated with enhanced stroke outcome in preclinical models. Furthermore, the current knowledge on safety and efficacy of these NIBS techniques in stroke patients will be reviewed.

Neuroprotection in Acute Ischemic Stroke: A Battle Against the Biology of Nature

Stroke is the second most common cause of global death following coronary artery disease. Time is crucial in managing stroke to reduce the rapidly progressing insult of the ischemic penumbra and the serious neurologic deficits that might follow it. Strokes are mainly either hemorrhagic or ischemic, with ischemic being the most common of all types of strokes. Thrombolytic therapy with recombinant tissue plasminogen activator and endovascular thrombectomy are the main types of management of acute ischemic stroke (AIS). In addition, there is a vital need for neuroprotection in the setting of AIS. Neuroprotective agents are important to investigate as they may reduce mortality, lessen disability, and improve quality of life after AIS. In our review, we will discuss the main types of management and the different modalities of neuroprotection, their mechanisms of action, and evidence of their effectiveness after ischemic stroke.

FUS aggregation following ischemic stroke favors brain astrocyte activation through inducing excessive autophagy

As is the case with neurodegenerative diseases, abnormal accumulation of aggregated proteins in neurons and glial are also known to implicate in the pathogenesis of ischemic stroke. However, the potential role of protein aggregates in brain ischemia remains largely unknown. Fused in Sarcoma (FUS) protein has a vital role in RNA metabolism and regulating cellular homeostasis. FUS pathology has been demonstrated in the formation of toxic aggregates and critically affecting cell viability in neurodegenerative diseases including amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), but whether this also applies to neurological injury following cerebral ischemia is unclear. Herein, we demonstrated a critical role of aggregated FUS in astrocyte activation caused by cerebral ischemia and a possible underlying molecular mechanism. Cerebral ischemic injury significantly induced the formation of cytoplasmic FUS aggregates in reactive astrocytes and injured neurons, thereby aggravating neurofunctional damages and worsening stroke outcomes. Further analysis revealed that extranuclear aggregation of FUS in astrocytes was involved in the induction of excessive autophagy, which contributes to autophagic cell injury or death. In conclusion, our results reveal the important contribution of FUS aggregates in promoting astrocyte activation in stroke pathology independent of its transcriptional regulation activity. We thus propose that aggregation of FUS is an important pathological process in ischemic stroke and targeting FUS aggregates might be of unique therapeutic value in the development of future treatment strategies for ischemic stroke.

Early amantadine treatment reduces the risk of death in patients with large hemisphere infarctions:a Chinese hospital-based study

Background

Amantadine hydrochloride is one of the most frequently prescribed drugs for patients with severe traumatic brain injury in restoring consciousness and accelerating the pace of functional recovery. However, there is a paucity of studies on the effectiveness of amantadine in patients with severe stroke especially large hemisphere infarction (LHI). The present study aimed to investigate whether amantadine treatment is associated with better clinical outcomes in conservatively treated LHI patients.

Methods

We retrospectively collected conservatively treated LHI patients according to inclusion/exclusion criteria. The patients were divided into two groups based on the treatment regimen, whether they did receive amantadine hydrochloride in addition to standard therapy (ST) or not. The primary outcomes were in-hospital death, 3-month mortality, and unfavorable outcome (defined as modified Rankin Scale score of 4 to 6). All outcomes were compared between the two groups before and after propensity score matching (PSM). Multivariate logistic regression was performed to identify the association between early amantadine hydrochloride treatment and clinical outcomes in LHI patients.

Results

Thirty-one LHI patients treated with amantadine combined with ST and 127 patients treated with ST were enrolled. Amantadine group had a shorter prehospital delay (median: 2 vs. 10 h), a higher baseline NIHSS score (21.71 ± 4.76 vs. 17.49 ± 5.84), and a higher rate of dominant hemisphere involvement (67.74% vs. 45.67%). After PSM, amantadine treatment significantly reduced the risk of in-hospital death (7.41% vs. 31.11%, p=0.019) and 3-month mortality (25.93% vs. 55.56%, p=0.008). Amantadine treatment yielded a significant decrease in death in-hospital (before PSM: OR 0.143, 95% CI 0.034 to 0.605; after PSM: OR 0.113, 95% CI 0.020 to 0.635) and 3-month mortality (before PSM: OR 0.214, 95% CI 0.077 to 0.598; after PSM: OR 0.176, 95% CI 0.053 to 0.586) in unmatched and matched multivariate analyses.

Conclusion

The results of our study provide initial evidence that early amantadine treatment was associated with a decrease in death in conservatively treated LHI patients. Considering the limitations of observational study, randomized controlled trials with a large sample size may help provide a clearer picture of the utility of amantadine in LHI patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-021-02444-w.

Rho/ROCK Pathway and Noncoding RNAs: Implications in Ischemic Stroke and Spinal Cord Injury

Ischemic strokes (IS) and spinal cord injuries (SCI) are major causes of disability. RhoA is a small GTPase protein that activates a downstream effector, ROCK. The up-regulation of the RhoA/ROCK pathway contributes to neuronal apoptosis, neuroinflammation, blood-brain barrier dysfunction, astrogliosis, and axon growth inhibition in IS and SCI. Noncoding RNAs (ncRNAs), such as microRNAs (miRNAs) and long noncoding RNAs (lncRNAs), were previously considered to be non-functional. However, they have attracted much attention because they play an essential role in regulating gene expression in physiological and pathological conditions. There is growing evidence that ROCK inhibitors, such as fasudil and VX-210, can reduce injury in IS and SCI in animal models and clinical trials. Recently, it has been reported that miRNAs are decreased in IS and SCI, while lncRNAs are increased. Inhibiting the Rho/ROCK pathway with miRNAs alleviates apoptosis, neuroinflammation, oxidative stress, and axon growth inhibition in IS and SCI. Further studies are required to explore the significance of ncRNAs in IS and SCI and to establish new strategies for preventing and treating these devastating diseases.

Hypoxia Tolerant Species: The Wisdom of Nature Translated into Targets for Stroke Therapy

Human neurons rapidly die after ischemia and current therapies for stroke management are limited to restoration of blood flow to prevent further brain damage. Thrombolytics and mechanical thrombectomy are the available reperfusion treatments, but most of the patients remain untreated. Neuroprotective therapies focused on treating the pathogenic cascade of the disease have widely failed. However, many animal species demonstrate that neurons can survive the lack of oxygen for extended periods of time. Here, we reviewed the physiological and molecular pathways inherent to tolerant species that have been described to contribute to hypoxia tolerance. Among them, Foxo3 and Eif5A were reported to mediate anoxic survival in Drosophila and Caenorhabditis elegans, respectively, and those results were confirmed in experimental models of stroke. In humans however, the multiple mechanisms involved in brain cell death after a stroke causes translation difficulties to arise making necessary a timely and coordinated control of the pathological changes. We propose here that, if we were able to plagiarize such natural hypoxia tolerance through drugs combined in a pharmacological cocktail it would open new therapeutic opportunities for stroke and likely, for other hypoxic conditions.

Successful management of spinal cord ischemia in a pediatric patient with fibrocartilaginous embolism: illustrative case

BACKGROUND

Fibrocartilaginous embolism (FCE) is a rare cause of ischemic myelopathy that occurs when the material of the nucleus pulposus migrates into vessels supplying the spinal cord. The authors presented a case of pediatric FCE that was successfully managed by adapting evidence-based recommendations used for spinal cord neuroprotection in aortic surgery.

OBSERVATIONS

A 7-year-old boy presented to the emergency department with acute quadriplegia and hemodynamic instability that quickly progressed to cardiac arrest. After stabilization, the patient regained consciousness but remained in a locked-in state with no spontaneous breathing. The patient presented a diagnostic challenge. Traumatic, inflammatory, infectious, and ischemic etiologies were considered. Eventually, the clinical and radiological findings led to the presumed diagnosis of FCE. Treatment with continuous cerebrospinal fluid drainage (CSFD), pulse steroids, and mean arterial pressure augmentation was applied, with subsequent considerable and consistent neurological improvement.

LESSONS

The authors proposed consideration of the adaptation of spinal cord neuroprotection principles used routinely in aortic surgery for the management of traumatic spinal cord ischemia (FCE-related in particular), namely, permissive arterial hypertension and CSFD. This is hypothesized to allow for the maintenance of sufficient spinal cord perfusion until adequate physiological blood perfusion is reestablished (remodeling of the collateral arterial network and/or clearing/absorption of the emboli).

Intra-arterial combination therapy for experimental acute ischemic stroke

Acute ischemic stroke continues to devastate millions of individuals worldwide. Current treatments work to restore blood flow but not rescue affected tissue. Our goal was to develop a combination of neuroprotective agents administered intra-arterially following recanalization to target ischemic tissue. Using C57Bl/6J male mice, we performed tandem transient ipsilateral middle cerebral/common carotid artery occlusion, followed by immediate intra-arterial pharmacotherapy administration through a standardized protocol. Two pharmacotherapy agents, verapamil and lubeluzole, were selected based on their potential to modulate different aspects of the ischemic cascade; verapamil, a calcium channel blocker, works in an acute fashion blocking L-type calcium channels, whereas lubeluzole, an N-methyl-D-aspartate modulator, works in a delayed fashion blocking intracellular glutamate trafficking. We hypothesized that combination therapy would provide complimentary and potentially synergistic benefit treating brain tissue undergoing various stages of injury. Physiological measurements for heart rate and pulse distention (blood pressure) demonstrated no detrimental effects between groups, suggesting that the combination drug administration is safe. Tissue analysis demonstrated a significant difference between combination and control (saline) groups in infarct volume, neuronal health, and astrogliosis. Although a significant difference in functional outcome was not observed, we did note that the combination treatment group had a greater percent change from baseline in forced motor movement as compared with controls. This study demonstrates the safety and feasibility of intra-arterial combination therapy following successful recanalization and warrants further study.

Cerebroprotective effect of pterostilbene against global cerebral ischemia in rats

Aim of the study

The role of pterostilbene against induced neurobehavioral alterations in global cerebral ischemia-reperfusion and oxidative damage was studied.

Materials and methods

Male SD rats (180–200 g) were exposed for 30 min to bilateral carotid artery occlusion accompanied by 60 min reperfusion to cause cerebral injury. Pretreatment with pterostilbene (200 and 400 mg/kg, orally) was given to the animals for ten days followed by ischemia-reperfusion injury. Various behavioral tests (locomotor activity, neurological score, transfer latency, hanging wire test) were studied. The brain tissues of animals were used for both the biochemical parameters (lipid peroxidation, reduced glutathione, superoxide dismutase, catalase activity) and histopathological study.

Result

The pterostilbene as given orally significantly improved neurobehavioral alterations compared to control ischemia-reperfusion. Treatment with pterostilbene (200, and 400 mg/kg, orally) also significantly attenuated oxidative damage as indicated by reduced lipid peroxidation, nitrite concentration, restored reduced glutathione, and catalase activity as compared to control (ischemia-reperfusion) animals. Overall, pterostilbene treated animals showed non significant histological alteration as compared to ischemia-reperfusion control.

Conclusion

This work suggests the beneficial effect of pterostilbene and its therapeutic potential against reperfusion-induced ischemia and associated behavioral changes in rats due to the stabilization of DNA damage with significant free radical scavenging properties.

Preclinical Stroke Research and Translational Failure: A Bird's Eye View on Preventable Variables

Despite achieving remarkable success in understanding the cellular, molecular and pathophysiological aspects of stroke, translation from preclinical research has always remained an area of debate. Although thousands of experimental compounds have been reported to be neuro-protective, their failures in clinical setting have left the researchers and stakeholders in doldrums. Though the failures described have been excruciating, they also give us a chance to refocus on the shortcomings. For better translational value, evidences from preclinical studies should be robust and reliable. Preclinical study design has a plethora of variables affecting the study outcome. Hence, this review focusses on the factors to be considered for a well-planned preclinical study while adhering to guidelines with emphasis on the study design, commonly used animal models, their limitations with special attention on various preventable attritions including comorbidities, aged animals, time of dosing, outcome measures and physiological variables along with the concept of multicentric preclinical randomized controlled trials. Here, we provide an overview of a panorama of practical aspects, which could be implemented, so that a well-defined preclinical study would result in a neuro-protectant with better translational value.

A review of experimental models of focal cerebral ischemia focusing on the middle cerebral artery occlusion model

Cerebral ischemic stroke is a leading cause of death and disability, but current pharmacological therapies are limited in their utility and effectiveness. In vitro and in vivo models of ischemic stroke have been developed which allow us to further elucidate the pathophysiological mechanisms of injury and investigate potential drug targets. In vitro models permit mechanistic investigation of the biochemical and molecular mechanisms of injury but are reductionist and do not mimic the complexity of clinical stroke. In vivo models of ischemic stroke directly replicate the reduction in blood flow and the resulting impact on nervous tissue. The most frequently used in vivo model of ischemic stroke is the intraluminal suture middle cerebral artery occlusion (iMCAO) model, which has been fundamental in revealing various aspects of stroke pathology. However, the iMCAO model produces lesion volumes with large standard deviations even though rigid surgical and data collection protocols are followed. There is a need to refine the MCAO model to reduce variability in the standard outcome measure of lesion volume. The typical approach to produce vessel occlusion is to induce an obstruction at the origin of the middle cerebral artery and reperfusion is reliant on the Circle of Willis (CoW). However, in rodents the CoW is anatomically highly variable which could account for variations in lesion volume. Thus, we developed a refined approach whereby reliance on the CoW for reperfusion was removed. This approach improved reperfusion to the ischemic hemisphere, reduced variability in lesion volume by 30%, and reduced group sizes required to determine an effective treatment response by almost 40%. This refinement involves a methodological adaptation of the original surgical approach which we have shared with the scientific community via publication of a visualised methods article and providing hands-on training to other experimental stroke researchers.

Investigation of brain damage mechanism in middle cerebral artery occlusion/reperfusion rats based on i-TRAQ quantitative proteomics

The objective of this study is to analyze the differential protein expression profile in cerebral cortex of rats with middle cerebral ischemia/reperfusion (MCAO/R), explore the brain damage mechanism of MCAO/R at protein level, and provide experimental foundation for searching specific marker proteins of MCAO/R. Rat model of MCAO/R was established by modified suture-occluded method, and the model was evaluated by the results of brain 2,3,5-triphenyltetrazolium chloride (TTC) and hematoxylin-eosin (HE) staining. Cerebral cortex of rats from sham-operated group (Sham) and MCAO/R groups was used for FASP enzymatic hydrolysis, i-TRAQ quantitative labeling, and reverse-phase liquid chromatography purification and separation. Orbitrap Q Exactive mass spectrometry was used for qualitative and quantitative analyses of total differential protein expression profiles. MCAO/R rats had obvious cerebral infarction lesions, and the relative surface area of cerebral infarction was significantly different compared with sham rats, suggesting that MCAO/R rat model was successfully prepared. There were 199 significant difference proteins (MCAO/R vs Sham, p < 0.05, |fold change|> 1.2), including 104 up-regulated proteins and 95 down-regulated proteins. Gene ontology (GO) enrichment analysis showed that the up-regulated proteins were mainly concentrated in the biological processes of positive regulation of NF-κB transcription and I-κB kinase-NF-κB, etc. Down-regulated proteins were mainly concentrated in long-term synaptic potentiation, cellular response to DNA damage stimulus, etc. KEGG pathway analysis showed that the pathway involved in differential proteins includes oxidative phosphorylation, metabolic pathway, and Ras signaling pathway. Network analysis of differential proteins showed that Alb, ndufb5, ndufs7, ApoB, Cdc42, Ndufa3, Igf1r, P4hb, Mbp, Gc, Nme1, Akt2, and other proteins may play an important role in regulating oxidative stress, apoptosis, and inflammatory response in MCAO/R. Quantitative proteomics based on i-TRAQ labeling reveals the effect of inflammation and apoptosis in brain damage mechanism of MCAO/R. Besides, this research provide some experimental foundation for search and determination of potential therapeutic targets of MCAO/R.

Neuroprotection by Remote Ischemic Conditioning in Rodent Models of Focal Ischemia: a Systematic Review and Meta-Analysis

Remote ischemic conditioning (RIC) is a promising neuroprotective therapy for ischemic stroke. Preclinical studies investigating RIC have shown RIC reduced infarct volume, but clinical trials have been equivocal. Therefore, the efficacy of RIC in reducing infarct volume and quality of current literature needs to be evaluated to identify knowledge gaps to support future clinical trials. We performed a systematic review and meta-analysis of preclinical literature involving RIC in rodent models of focal ischemia. This review was registered with PROSPERO (CRD42019145441). Eligibility criteria included rat or mice models of focal ischemia that received RIC to a limb either before, during, or after stroke. MEDLINE and Embase databases were searched from 1946 to August 2019. Risk of bias was assessed using the SYRCLE risk of bias tool along with construct validity. Seventy-two studies were included in the systematic review. RIC was shown to reduce infarct volume (SMD - 2.19; CI - 2.48 to - 1.91) when compared to stroke-only controls and no adverse events were reported with regard to RIC. Remote ischemic conditioning was shown to be most efficacious in males (SMD - 2.26; CI - 2.58 to - 1.94) and when delivered poststroke (SMD - 1.34; CI - 1.95 to - 0.73). A high risk of bias was present; thus, measures of efficacy may be exaggerated. A limitation is the poor methodological reporting of many studies, resulting in unclear construct validity. We identified several important, but under investigated topics including the efficacy of RIC in different stroke models, varied infarct sizes and location, and potential sex differences.

Serum Albumin Levels and Clinical Outcomes Among Ischemic Stroke Patients Treated with Endovascular Thrombectomy

BACKGROUND AND AIMS

Albumin levels have been reported to be associated with all-cause and cardiovascular mortality. The aim of this study was to investigate the association between serum albumin and prognosis of ischemic stroke patients after endovascular thrombectomy (EVT) treatment.

METHODS

Patients with EVT due to large artery occlusion in anterior circulation were selected from ACTUAL (endovascular treatment for acute anterior circulation) ischemic stroke multicenter registry in China. Serum albumin levels were measured within 24 h of admission. The primary outcome was poor functional outcome (modified Rankin scale score of 3-6) at three months. Secondary outcomes were symptomatic intracranial hemorrhage (sICH) and three-month mortality.

RESULTS

A total of 605 patients (mean age, 64.2 years; 59.3% male) were enrolled. Up to three months after stroke, 342 patients (56.5%) developed poor functional outcome. After multivariate adjustment for demographic characteristics, National Institutes of Health stroke score, and other potential confounders, the odds ratio for the lowest tertile of serum albumin levels was 2.43 (95%CI, 1.18-5.01; P=0.046) for poor functional outcome, compared with the highest category. Restricted cubic spline regression demonstrated a linear association between albumin levels and poor functional outcome (P for linearity=0.017). Subgroup analyses further confirmed these results. Similar significant findings were also found in the association of serum albumin with mortality, but not with sICH.

CONCLUSION

Decreased serum albumin levels were independently associated with poor prognosis at 90 days after acute large vessel occlusion stroke in anterior circulation treated with EVT.

Impact of aging and comorbidities on ischemic stroke outcomes in preclinical animal models: A translational perspective

Ischemic stroke is a highly complex and devastating neurological disease. The sudden loss of blood flow to a brain region due to an ischemic insult leads to severe damage to that area resulting in the formation of an infarcted tissue, also known as the ischemic core. This is surrounded by the peri-infarct region or penumbra that denotes the functionally impaired but potentially salvageable tissue. Thus, the penumbral tissue is the main target for the development of neuroprotective strategies to minimize the extent of ischemic brain damage by timely therapeutic intervention. Given the limitations of reperfusion therapies with recombinant tissue plasminogen activator or mechanical thrombectomy, there is high enthusiasm to combine reperfusion therapy with neuroprotective strategies to further reduce the progression of ischemic brain injury. Till date, a large number of candidate neuroprotective drugs have been identified as potential therapies based on highly promising results from studies in rodent ischemic stroke models. However, none of these interventions have shown therapeutic benefits in stroke patients in clinical trials. In this review article, we discussed the urgent need to utilize preclinical models of ischemic stroke that more accurately mimic the clinical conditions in stroke patients by incorporating aged animals and animal stroke models with comorbidities. We also outlined the recent findings that highlight the significant differences in stroke outcome between young and aged animals, and how major comorbid conditions such as hypertension, diabetes, obesity and hyperlipidemia dramatically increase the vulnerability of the brain to ischemic damage that eventually results in worse functional outcomes. It is evident from these earlier studies that including animal models of aging and comorbidities during the early stages of drug development could facilitate the identification of neuroprotective strategies with high likelihood of success in stroke clinical trials.

Glucagon-like peptide-1 receptor agonists as neuroprotective agents for ischemic stroke: a systematic scoping review

Stroke mortality and morbidity is expected to rise. Despite considerable recent advances within acute ischemic stroke treatment, scope remains for development of widely applicable neuroprotective agents. Glucagon-like peptide-1 receptor agonists (GLP-1RAs), originally licensed for the management of Type 2 Diabetes Mellitus, have demonstrated pre-clinical neuroprotective efficacy in a range of neurodegenerative conditions. This systematic scoping review reports the pre-clinical basis of GLP-1RAs as neuroprotective agents in acute ischemic stroke and their translation into clinical trials. We included 35 pre-clinical studies, 11 retrospective database studies, 7 cardiovascular outcome trials and 4 prospective clinical studies. Pre-clinical neuroprotection was demonstrated in normoglycemic models when administration was delayed by up to 24 h following stroke induction. Outcomes included reduced infarct volume, apoptosis, oxidative stress and inflammation alongside increased neurogenesis, angiogenesis and cerebral blood flow. Improved neurological function and a trend towards increased survival were also reported. Cardiovascular outcomes trials reported a significant reduction in stroke incidence with semaglutide and dulaglutide. Retrospective database studies show a trend towards neuroprotection. Prospective interventional clinical trials are on-going, but initial indicators of safety and tolerability are favourable. Ultimately, we propose that repurposing GLP-1RAs is potentially advantageous but appropriately designed trials are needed to determine clinical efficacy and cost-effectiveness.

Early Neurological Change After Ischemic Stroke Is Associated With 90-Day Outcome

BACKGROUND AND PURPOSE

Large-scale observational studies of acute ischemic stroke (AIS) promise to reveal mechanisms underlying cerebral ischemia. However, meaningful quantitative phenotypes attainable in large patient populations are needed. We characterize a dynamic metric of AIS instability, defined by change in National Institutes of Health Stroke Scale score (NIHSS) from baseline to 24 hours baseline to 24 hours (NIHSSbaseline - NIHSS24hours = ΔNIHSS6-24h), to examine its relevance to AIS mechanisms and long-term outcomes.

METHODS

Patients with NIHSS prospectively recorded within 6 hours after onset and then 24 hours later were enrolled in the GENISIS study (Genetics of Early Neurological Instability After Ischemic Stroke). Stepwise linear regression determined variables that independently influenced ΔNIHSS6-24h. In a subcohort of tPA (alteplase)-treated patients with large vessel occlusion, the influence of early sustained recanalization and hemorrhagic transformation on ΔNIHSS6-24h was examined. Finally, the association of ΔNIHSS6-24h with 90-day favorable outcomes (modified Rankin Scale score 0-2) was assessed. Independent analysis was performed using data from the 2 NINDS-tPA stroke trials (National Institute of Neurological Disorders and Stroke rt-PA).

RESULTS

For 2555 patients with AIS, median baseline NIHSS was 9 (interquartile range, 4-16), and median ΔNIHSS6-24h was 2 (interquartile range, 0-5). In a multivariable model, baseline NIHSS, tPA-treatment, age, glucose, site, and systolic blood pressure independently predicted ΔNIHSS6-24h (R2=0.15). In the large vessel occlusion subcohort, early sustained recanalization and hemorrhagic transformation increased the explained variance (R2=0.27), but much of the variance remained unexplained. ΔNIHSS6-24h had a significant and independent association with 90-day favorable outcome. For the subjects in the 2 NINDS-tPA trials, ΔNIHSS3-24h was similarly associated with 90-day outcomes.

CONCLUSIONS

The dynamic phenotype, ΔNIHSS6-24h, captures both explained and unexplained mechanisms involved in AIS and is significantly and independently associated with long-term outcomes. Thus, ΔNIHSS6-24h promises to be an easily obtainable and meaningful quantitative phenotype for large-scale genomic studies of AIS.

Excitotoxicity: Still Hammering the Ischemic Brain in 2020

Interest in excitotoxicity expanded following its implication in the pathogenesis of ischemic brain injury in the 1980s, but waned subsequent to the failure of N-methyl-D-aspartate (NMDA) antagonists in high profile clinical stroke trials. Nonetheless there has been steady progress in elucidating underlying mechanisms. This review will outline the historical path to current understandings of excitotoxicity in the ischemic brain, and suggest that this knowledge should be leveraged now to develop neuroprotective treatments for stroke.

Pathophysiology and Treatment of Stroke: Present Status and Future Perspectives

Stroke is the second leading cause of death and a major contributor to disability worldwide. The prevalence of stroke is highest in developing countries, with ischemic stroke being the most common type. Considerable progress has been made in our understanding of the pathophysiology of stroke and the underlying mechanisms leading to ischemic insult. Stroke therapy primarily focuses on restoring blood flow to the brain and treating stroke-induced neurological damage. Lack of success in recent clinical trials has led to significant refinement of animal models, focus-driven study design and use of new technologies in stroke research. Simultaneously, despite progress in stroke management, post-stroke care exerts a substantial impact on families, the healthcare system and the economy. Improvements in pre-clinical and clinical care are likely to underpin successful stroke treatment, recovery, rehabilitation and prevention. In this review, we focus on the pathophysiology of stroke, major advances in the identification of therapeutic targets and recent trends in stroke research.

Combination therapy of the granulocyte colony stimulating factor and intravenous lipid emulsion protect the hippocampus after global ischemia in rat: focusing on CA1 region

Brain stroke is one of the causes of human death and disability worldwide. Global ischemia results in the accumulation of free radicals in the neurons. It leads to histologically brain damage. The CA1 region of the hippocampus is a sensitive area for free radicals. This study investigated the combined therapy of the Granulocyte colony stimulating factor (G-CSF) and the Intravenous lipid emulsion (ILE). These neuroprotective agents play a role in the regeneration of neurons. They improve the learning ability and memory in rats induced global ischemia. We divided 35 rats into five groups. The groups were sham group, ischemia group, G-CSF group, ILE group, and G-CSF plus ILE group. Ischemia was induced by occlusion of the bilateral common carotid about 10 min. The drugs applied on days 1, 3 and 7. The treated groups received subcutaneous injection of 20 μg/kg G-CSF and intravenous injection of 5 ml/kg ILE. After two weeks, the memory and learning ability of the rats was evaluated by the shuttle box. Hematoxylin and Eosin and Nissl and TUNEL stainings were used to determine the necrosis, normal and apoptotic cells. The combined therapy increased normal cells compared to the ischemia group. They decreased the number of necrotic and apoptosis cells in other groups. The combined group improved the passive avoidance test compared to the other groups. The combination therapy of G-CSF plus ILE is more effective than each alone.

Serum IgG-induced microglial activation enhances neuronal cytolysis via the NO/sGC/PKG pathway in children with opsoclonus-myoclonus syndrome and neuroblastoma

Background

Opsoclonus-myoclonus syndrome (OMS) is a rare neurological disease. Some children with OMS also have neuroblastoma (NB). We and others have previously documented that serum IgG from children with OMS and NB induces neuronal cytolysis and activates several signaling pathways. However, the mechanisms underlying OMS remain unclear. Here, we investigated whether nitric oxide (NO) from activated microglias and its cascade contribute to neuronal cytolysis in pediatric OMS.

Methods

The activation of cultured cerebral cortical and cerebellar microglias incubated with sera or IgG isolated from sera of children with OMS and NB was measured by the expression of the activation marker, cytokines, and NO. Neuronal cytolysis was determined after exposing to IgG-treated microglia-conditioned media. Using inhibitors and activators, the effects of NO synthesis and its intracellular cascade, namely soluble guanylyl cyclase (sGC) and protein kinase G (PKG), on neuronal cytolysis were evaluated.

Results

Incubation with sera or IgG from children with OMS and NB increased the activation of cerebral cortical and cerebellar microglias, but not the activation of astrocytes or the cytolysis of glial cells. Moreover, the cytolysis of neurons was elevated by conditioned media from microglias incubated with IgG from children with OMS and NB. Furthermore, the expression of NO, sGC, and PKG was increased. Neuronal cytolysis was relieved by the inhibitors of NO signaling, while neuronal cytolysis was exacerbated by the activators of NO signaling but not proinflammatory cytokines. The cytolysis of neurons was suppressed by pretreatment with the microglial inhibitor minocycline, a clinically tested drug. Finally, increased microglial activation did not depend on the Fab fragment of serum IgG.

Conclusions

Serum IgG from children with OMS and NB potentiates microglial activation, which induces neuronal cytolysis through the NO/sGC/PKG pathway, suggesting an applicability of microglial inhibitor as a therapeutic candidate.

Protopanaxadiol ginsenoside Rd protects against NMDA receptor-mediated excitotoxicity by attenuating calcineurin-regulated DAPK1 activity

Neuroprotective strategies in the treatment of stroke have been attracting a great deal of attentions. Our previous clinical and basic studies have demonstrated that protopanaxadiol ginsenoside-Rd (Rd), a monomer compound extracted from Panax ginseng or Panax notoginseng, has neuroprotective effects against ischemic stroke, probably due to its ability to block Ca²⁺ overload, an usual consequence of the overactivation of NMDA receptor (NMDAR). As an extending study, we explored here whether Rd exerted its neuroprotection as a novel NMDAR blocker. Our whole-cell patch-clamp results showed that Rd reduced NMDAR currents of cultured rat cortical neurons (EC50 = 7.7 μM) dose-dependently by acting on extrasynaptic NMDAR NR2b subunit. However, unexpectedly, cell transfection and radioligand binding assays revealed that Rd did not bind to the NMDAR channel directly. Alternatively, it inhibited the phosphorylation of NR2b at Ser-1303, a target of death associated protein kinase 1 (DAPK1). Moreover, cell-based and cell-free enzymatic assays showed that Rd did not inhibit the activity of DAPK1 directly, but blocked the activity of calcineurin, a key phosphatase for activating DAPK1. Importantly, other protopanaxadiol ginsenosides were also found to have potential inhibitory effects on calcineurin activity. Furthermore, as expected, calcineurin inhibition by cyclosporin A could mimic Rd's effects and protect against NMDA-, oxygen glucose deprivation- or transient ischemic stroke-induced neuronal injury. Therefore, our present study provided the first evidence that Rd could exert an inhibitive effect on NMDAR-triggered currents and sequential excitotoxicity through mitigation of DAPK1-mediated NR2b phosphorylation by attenuating calcineurin activity.

Transcranial contrast-enhanced ultrasound in the rat brain reveals substantial hyperperfusion acutely post-stroke

Direct and real-time assessment of cerebral hemodynamics is key to improving our understanding of cerebral blood flow regulation in health and disease states such as stroke. While a number of sophisticated imaging platforms enable assessment of cerebral perfusion, most are limited either spatially or temporally. Here, we applied transcranial contrast-enhanced ultrasound (CEU) to measure cerebral perfusion in real-time through the intact rat skull before, during and after ischemic stroke, induced by intraluminal filament middle cerebral artery occlusion (MCAO). We demonstrate expected decreases in cortical and striatal blood volume, flow velocity and perfusion during MCAO. After filament retraction, blood volume and perfusion increased two-fold above baseline, indicative of acute hyperperfusion. Adjacent brain regions to the ischemic area and the contralateral hemisphere had increased blood volume during MCAO. We assessed our data using wavelet analysis to demonstrate striking vasomotion changes in the ischemic and contralateral cortices during MCAO and reperfusion. In conclusion, we demonstrate the application of CEU for real-time assessment of cerebral hemodynamics and show that the ischemic regions exhibit striking hyperemia post-MCAO. Whether this post-stoke hyperperfusion is sustained long-term and contributes to stroke severity is not known.

Applying univariate vs. multivariate statistics to investigate therapeutic efficacy in (pre)clinical trials: A Monte Carlo simulation study on the example of a controlled preclinical neurotrauma trial

BACKGROUND

Small sample sizes combined with multiple correlated endpoints pose a major challenge in the statistical analysis of preclinical neurotrauma studies. The standard approach of applying univariate tests on individual response variables has the advantage of simplicity of interpretation, but it fails to account for the covariance/correlation in the data. In contrast, multivariate statistical techniques might more adequately capture the multi-dimensional pathophysiological pattern of neurotrauma and therefore provide increased sensitivity to detect treatment effects.

RESULTS

We systematically evaluated the performance of univariate ANOVA, Welch's ANOVA and linear mixed effects models versus the multivariate techniques, ANOVA on principal component scores and MANOVA tests by manipulating factors such as sample and effect size, normality and homogeneity of variance in computer simulations. Linear mixed effects models demonstrated the highest power when variance between groups was equal or variance ratio was 1:2. In contrast, Welch's ANOVA outperformed the remaining methods with extreme variance heterogeneity. However, power only reached acceptable levels of 80% in the case of large simulated effect sizes and at least 20 measurements per group or moderate effects with at least 40 replicates per group. In addition, we evaluated the capacity of the ordination techniques, principal component analysis (PCA), redundancy analysis (RDA), linear discriminant analysis (LDA), and partial least squares discriminant analysis (PLS-DA) to capture patterns of treatment effects without formal hypothesis testing. While LDA suffered from a high false positive rate due to multicollinearity, PCA, RDA, and PLS-DA were robust and PLS-DA outperformed PCA and RDA in capturing a true treatment effect pattern.

CONCLUSIONS

Multivariate tests do not provide an appreciable increase in power compared to univariate techniques to detect group differences in preclinical studies. However, PLS-DA seems to be a useful ordination technique to explore treatment effect patterns without formal hypothesis testing.

LincRNA-EPS in biomimetic vesicles targeting cerebral infarction promotes inflammatory resolution and neurogenesis

BACKGROUND

Inflammatory damage following stroke aggravates brain damage, resulting in long-term neurological sequelae. The purpose of this study was to identify ways to reduce inflammatory reactions and to accelerate neuron regeneration after cerebral apoplexy.

METHODS

We formulated a biomimetic vesicle, the leukosome, constituted by liposome, artificial long intergenic noncoding RNA (lincRNA)-EPS, and membrane proteins derived from macrophages and their physical-chemical characteristics were evaluated. Migration distance and cytotoxic levels were measured to determine the effect of lncEPS-leukosomes on lipopolysaccharide-activated microglia. An in vivo transient middle cerebral artery occlusion/reperfusion (tMCAO) model was established in mice, which were treated with lncEPS-leukosomes. Vesicle seepage, infiltration of inflammatory cells, cytotoxic levels in the cerebrospinal fluid, and neural stem cell (NSC) density were measured.

RESULTS

Biomimetic vesicles with a homogeneous size increased lincRNA-EPS levels in activated microglia by 77.9%. In vitro studies showed that lincRNA-EPS inhibited the migration and cytotoxic levels of activated microglia by 63.2% and 43.6%, respectively, which promoted NSC proliferation and anti-apoptotic ability. In vivo data showed that leukosomes targeted to inflamed sites and lncEPS-leukosomes decreased the infiltration of inflammatory cells and cytotoxic levels by 81.3% and 48.7%, respectively. In addition, lncEPS-leukosomes improved neuron density in the ischemic core and boundary zone after tMCAO.

CONCLUSIONS

The biomimetic vesicles formulated in this study targeted inflammatory cells and accelerated neuron regeneration by promoting inflammation resolution. This study may provide a promising treatment approach for accelerated neuron regeneration after cerebral apoplexy.

Are researchers moving away from animal models as a result of poor clinical translation in the field of stroke? An analysis of opinion papers

Objectives

Despite decades of research using animals to develop pharmaceutical treatments for patients who have had a stroke, few therapeutic options exist. The vast majority of interventions successful in preclinical animal studies have turned out to have no efficacy in humans or to be harmful to humans. In view of this, we explore whether there is evidence of a move away from animal models in this field.

Methods

We used an innovative methodology, the analysis of opinion papers. Although we took a systematic approach to literature searching and data extraction, this is not a systematic review because the study involves the synthesis of opinions, not research evidence. Data were extracted from retrieved papers in chronological order and analysed qualitatively and descriptively.

Results

Eighty eligible papers, published between 1979 and 2018, were identified. Most authors were from academic departments of neurology, neuroscience or stroke research. Authors agreed that translational stroke research was in crisis. They held diverse views about the causes of this crisis, most of which did not fundamentally challenge the use of animal models. Some, however, attributed the translational crisis to animal–human species differences and one to a lack of human in vitro models. Most of the proposed solutions involved fine-tuning animal models, but authors disagreed about whether such modifications would improve translation. A minority suggested using human in vitro methods alongside animal models. One proposed focusing only on human in vitro methods.

Conclusion

Despite recognising that animal models have been unsuccessful in the field of stroke, most researchers exhibited a strong resistance to relinquishing them. Nevertheless, there is an emerging challenge to the use of animal models, in the form of human-focused in vitro approaches. For the sake of stroke patients there is an urgent need to revitalise translational stroke research and explore the evidence for these new approaches.

Brain-Derived Neurotrophic Factor and Its Potential Therapeutic Role in Stroke Comorbidities

With the rise in the aging global population, stroke comorbidities have become a serious health threat and a tremendous economic burden on human society. Current therapeutic strategies mainly focus on protecting neurons from cytotoxic damage at the acute phase upon stroke onset, which not only is a difficult way to ameliorate stroke symptoms but also presents a challenge for the patients to receive effective treatment in time. The brain-derived neurotrophic factor (BDNF) is the most abundant neurotrophin in the adult brain, which possesses a remarkable capability to repair brain damage. Recent promising preclinical outcomes have made BDNF a popular late-stage target in the development of novel stroke treatments. In this review, we aim to summarize the latest progress in the understanding of the cellular/molecular mechanisms underlying stroke pathogenesis, current strategies and difficulties in drug development, the mechanism of BDNF action in poststroke neurorehabilitation and neuroplasticity, and recent updates in novel therapeutic methods.

Novel approaches for the delivery of therapeutics in ischemic stroke

Here, we review novel approaches to deliver neuroprotective drugs to salvageable penumbral brain areas of stroke injury with the goals of offsetting ischemic brain injury and enhancing recovery.

Considering risk factors for the effectiveness of translational therapies in brain stroke

Multiple studies on cerebral ischemia have been performed in animal models to propose different strategies of neuroprotection that mitigate either the early or late consequences of the disease. These therapies have been successful in reducing the volume of infarction, the proinflammatory cascade, and the amount of free radicals, as well as reversing markers of neurodegeneration, among other events. However, when those strategies are translated to clinical studies, their effectiveness is not reproduced. This review will focus on highlighting some of the main limitations of the animal models of stroke that lead to unsuccessful translational therapies and the common risk factors in humans that should be carefully considered in the experimental design of future studies to generate a more realistic spatiotemporal physiopathology and improve therapeutic efficacy in cerebral ischemia.

Can prospective systematic reviews of animal studies improve clinical translation?

Systematic reviews are powerful tools with the potential to generate high quality evidence. Their application to animal studies has been instrumental in exposing the poor quality of these studies, as well as a catalyst for improvements in study design, conduct and reporting. It has been suggested that prospective systematic reviews of animal studies (i.e. systematic reviews conducted prior to clinical trials) would allow scrutiny of the preclinical evidence, providing valuable information on safety and efficacy, and helping to determine whether clinical trials should proceed. However, while prospective systematic reviews allow valuable scrutiny of the preclinical animal data, they are not necessarily able to reliably predict the safety and efficacy of an intervention when trialled in humans. Consequently, they may not reliably safeguard humans participating in clinical trials and might potentially result in lost opportunities for beneficial clinical treatments. Furthermore, animal and human studies are often conducted concurrently, which not only makes prospective systematic reviews of animal studies impossible, but suggests that animal studies do not inform human studies in the manner presumed. We suggest that this points to a confused attitude regarding animal studies, whereby tradition demands that they precede human studies but practice indicates that their findings are often ignored. We argue that it is time to assess the relative contributions of animal and human research in order to better understand how clinical knowledge is actually produced.