Stroke neuroprotection revisited: Intra-arterial verapamil is profoundly neuroprotective in experimental acute ischemic stroke

Drugs/agents for the treatment of ischemic stroke: Advances and perspectives

Ischemic stroke (IS) poses a significant threat to global human health and life. In recent decades, we have witnessed unprecedented progresses against IS, including thrombolysis, thrombectomy, and a few medicines that can assist in reopening the blocked brain vessels or serve as standalone treatments for patients who are not eligible for thrombolysis/thrombectomy therapies. However, the narrow time windows of thrombolysis/thrombectomy, coupled with the risk of hemorrhagic transformation, as well as the lack of highly effective and safe medications, continue to present big challenges in the acute treatment and long-term recovery of IS. In the past 3 years, several excellent articles have reviewed pathophysiology of IS and therapeutic medicines for the treatment of IS based on the pathophysiology. Regretfully, there is no comprehensive overview to summarize all categories of anti-IS drugs/agents designed and synthesized based on molecular mechanisms of IS pathophysiology. From medicinal chemistry view of point, this article reviews a multitude of anti-IS drugs/agents, including small molecule compounds, natural products, peptides, and others, which have been developed based on the molecular mechanism of IS pathophysiology, such as excitotoxicity, oxidative/nitrosative stresses, cell death pathways, and neuroinflammation, and so forth. In addition, several emerging medicines and strategies, including nanomedicines, stem cell therapy and noncoding RNAs, which recently appeared for the treatment of IS, are shortly introduced. Finally, the perspectives on the associated challenges and future directions of anti-IS drugs/agents are briefly provided to move the field forward.

Now that the door is open: an update on ischemic stroke pharmacotherapeutics for the neurointerventionalist

The last 10 years have seen a major shift in management of large vessel ischemic stroke with changes towards ever-expanding use of reperfusion therapies (intravenous thrombolysis and mechanical thrombectomy). These strategies 'open the door' to acute therapeutics for ischemic tissue, and we should investigate novel therapeutic approaches to enhance survival of recently reperfused brain. Key insights into new approaches have been provided through translational research models and preclinical paradigms, and through detailed research on ischemic mechanisms. Additional recent clinical trials offer exciting salvos into this new strategy of pairing reperfusion with neuroprotective therapy. This pairing strategy can be employed using drugs that have shown neuroprotective efficacy; neurointerventionalists can administer these during or immediately after reperfusion therapy. This represents a crucial moment when we emphasize reperfusion, and have the technological capability along with the clinical trial experience to lead the way in multiprong approaches to stroke treatment.

Reverse Translation to Develop Post-stroke Therapeutic Interventions during Mechanical Thrombectomy: Lessons from the BACTRAC Trial

The majority of strokes, approximately 87%, are ischemic in etiology with the remaining hemorrhagic in origin. Emergent large vessel occlusions (ELVOs) are a subtype of ischemic stroke accounting for approximately 30-40% of acute large vessel blockages. Treatment for ELVOs focuses on recanalization of the occluded vessel by time-sensitive administration of tissue plasminogen activator (tPA) or thrombus removal using mechanical thrombectomy. Although a great deal of time and resources have focused on translational stroke research, little progress has been made in the area of identifying additional new treatments for stroke. Translational limitations include difficulty simulating human comorbid conditions in animal models, as well as the temporal nature of stroke pathology. The Blood And Clot Thrombectomy Registry And Collaboration represents an ongoing tissue registry for thrombectomy patients and includes collection of intracranial arterial blood, systemic arterial blood, thrombi, as well as a series of clinical and radiographic data points for analysis. This chapter will explore the methodologies employed and results obtained from studying BACTRAC-derived human biological specimens and how they can inform translational experimental design in animal studies.

Reperfusion injury in acute ischemic stroke: Tackling the irony of revascularization

Reperfusion injury is an unfortunate consequence of restoring blood flow to tissue after a period of ischemia. This phenomenon can occur in any organ, although it has been best studied in cardiac cells. Based on cardiovascular studies, neuroprotective strategies have been developed. The molecular biology of reperfusion injury remains to be fully elucidated involving several mechanisms, however these mechanisms all converge on a similar final common pathway: blood brain barrier disruption. This results in an inflammatory cascade that ultimately leads to a loss of cerebral autoregulation and clinical worsening. In this article, the authors present an overview of these mechanisms and the current strategies being employed to minimize injury after restoration of blood flow to compromised cerebral territories.

Intra-arterial verapamil improves functional outcomes of thrombectomy in a preclinical model of extended hyperglycemic stroke

The abrupt hyperglycemic reperfusion following thrombectomy has been shown to harm the efficacy of the intervention in stroke patients with large vessel occlusion. Studies of ours and others have shown thioredoxin-interacting protein (TXNIP) is critically involved in hyperglycemic stroke injury. We recently found verapamil ameliorates cerebrovascular toxicity of tissue plasminogen activators in hyperglycemic stroke. The present study aims to answer if verapamil exerts direct neuroprotective effects and alleviates glucose toxicity following thrombectomy in a preclinical model of hyperglycemic stroke. Primary cortical neural (PCN) cultures were exposed to hyperglycemic reperfusion following oxygen-glucose deprivation (OGD), with or without verapamil treatment. In a mouse model of intraluminal stroke, animals were subjected to 4 h middle cerebral artery occlusion (MCAO) and intravenous glucose infusion. Glucose infusion lasted one more hour at reperfusion, along with intra-arterial (i.a.) verapamil infusion. Animals were subjected to sensorimotor function tests and histological analysis of microglial phenotype at 72 h post-stroke. According to our findings, glucose concentrations (2.5-20 mM) directly correlated with TXNIP expression in OGD-exposed PCN cultures. Verapamil (100 nM) effectively improved PCN cell neurite growth and reduced TXNIP expression as well as interaction with NOD-like receptor pyrin domain-containing-3 (NLRP3) inflammasome, as determined by immunoblotting and immunoprecipitation. In our mouse model of extended hyperglycemic MCAO, i.a. verapamil (0.5 mg/kg) could attenuate neurological deficits induced by hyperglycemic stroke. This was associated with reduced microglial pro-inflammatory transition. This finding encourages pertinent studies in hyperglycemic patients undergoing thrombectomy where the robust reperfusion may exacerbate glucose toxicity.

Verapamil inhibits TXNIP-NLRP3 inflammasome activation and preserves functional recovery after intracerebral hemorrhage in mice

Intracerebral hemorrhage (ICH) is the second most common type of stroke with no satisfactory treatment. Recent studies from our group and others indicated a potential positive effect of verapamil, a commonly prescribed calcium channel blocker, with thioredoxin-interacting protein (TXNIP) inhibitor properties, in ischemic stroke and cognitive disorders. It is unclear whether there would be a beneficial effect of verapamil administration in ICH. Therefore, this study was designed to determine the neuroprotective effects of verapamil in a murine ICH model. ICH was induced by stereotactic injection of collagenase type VII (0.075 U) into the right striatum of adult male C57BL/6 mice. Verapamil (0.15 mg/kg) or saline was administered intravenously at 1 h post-ICH followed by oral (1 mg/kg/d) administration in drinking water for 28 days. Motor and cognitive function were assessed using established tests for motor coordination, spatial learning, short- and long-term memory. A subset of animals was sacrificed at 72 h after ICH for molecular analysis. Verapamil treatment reduced expression of TXNIP and NOD-like receptor pyrin domain-containing-3 inflammasome activation in the perihematomal area. These protective effects of verapamil were associated with decreased proinflammatory mediators, microglial activation, and blood-brain barrier permeability markers and paralleled less phosphorylated nuclear factor kappa B level. Our findings also demonstrate that long-term low-dose verapamil effectively attenuated motor and cognitive impairments. Taken together, these data indicate that verapamil has therapeutic potential in improving acute motor function after ICH. Further investigations are needed to confirm whether verapamil treatment could be a promising candidate for clinical trials.

Chronotherapeutic neuroprotective effect of verapamil against lipopolysaccharide-induced neuroinflammation in mice through modulation of calcium-dependent genes

Background

Neuroinflammation is a major mechanism in neurodegenerative diseases such as Alzheimer’s disease (AD), which is a major healthcare problem. Notwithstanding of ample researches figured out possible molecular mechanisms underlying the pathophysiology of AD, there is no definitive therapeutics that aid in neuroprotection. Therefore, searching for new agents and potential targets is a critical demand. We aimed to investigate the neuroprotective effect of verapamil (VRP) against lipopolysaccharide (LPS)-induced neuroinflammation in mice and whether the time of VRP administration could affect its efficacy.

Methods

Forty male albino mice were used and were divided into normal control, LPS only, morning VRP, and evening VRP. Y-maze and pole climbing test were performed as behavioral tests. Hematoxylin and eosin together with Bielschowsky silver staining were done to visualize neuroinflammation and phosphorylated tau protein (pTAU); respectively. Additionally, the state of mitochondria, the levels of microglia-activation markers, inflammatory cytokines, intracellular Ca2+, pTAU, and Ca2+-dependent genes involving Ca2+/ calmodulin dependent kinase II (CAMKII) isoforms, protein kinase A (PKA), cAMP response element-binding protein (CREB), and brain-derived neurotrophic factor (BDNF), with the level of VRP in the brain tissue were measured.

Results

LPS successfully induced neuroinflammation and hyperphosphorylation of tau protein, which was indicated by elevated levels of microglia markers, inflammatory cytokines, and intracellular Ca2+ with compromised mitochondria and downregulated CAMKII isoforms, PKA, CREB and BDNF. Pretreatment with VRP showed significant enhancement in the architecture of the brain and in the behavioral tests as indicated by the measured parameters. Moreover, morning VRP exhibited better neuroprotective profile compared to the evening therapy.

Conclusions

VRP highlighted a multilevel of neuroprotection through anti-inflammatory activity, Ca2+ blockage, and regulation of Ca2+-dependent genes. Furthermore, chronotherapy of VRP administration should be consider to achieve best therapeutic efficacy.

Graphical Abstract

Calcium Channel Antagonists for Mood Disorders

PURPOSE

Development of new thymoleptic medications has primarily centered on anticonvulsants and antipsychotic drugs. Based on our studies of intracellular calcium ion signaling in mood disorders, we were interested in the use of novel medications that act on this mechanism of neuronal activation as potential mood stabilizers.

METHOD

We reviewed the dynamics of the calcium second messenger system and the international body of data demonstrating increased baseline and stimulated intracellular calcium levels in peripheral cells of patients with bipolar mood disorders. We then examined studies of the effect of established mood stabilizers on intracellular calcium ion levels and on mechanisms of mobilization of this second messenger. After summarizing studies of calcium channel blocking agents, whose primary action is to attenuate hyperactive intracellular calcium signaling, we considered clinical experience with this class of medications and the potential for further research.

FINDINGS

Established mood stabilizers normalize increased intracellular calcium ion levels in bipolar disorder patients. Most case series and controlled studies suggest an antimanic and possibly mood stabilizing effect of the calcium channel blocking medications verapamil and nimodipine, with fewer data on isradipine. A relatively low risk of teratogenicity and lack of cognitive adverse effects or weight gain suggest possible applications in pregnancy and in patients for whom these are considerations.

IMPLICATIONS

Medications that antagonize hyperactive intracellular signaling warrant more interest than they have received in psychiatry. Further experience will clarify the applications of these medications alone and in combination with more established mood stabilizers.

Two Children with Early-Onset Strokes and Intractable Epilepsy, Both with CACNA1A Mutations

Background: Mutations in the CACNA1A gene have been associated phenotypically with Familial Hemiplegic Migraine Type 1, Episodic Ataxia Type 2, Idiopathic Generalized Epilepsy, and Developmental and Epileptic Encephalopathy 42. Only six cases have linked ischemic strokes to mutations in the CACNA1A gene. Summary of Cases: We describe two unrelated patients who were found to have different mutations of the CACNA1A gene, one being a novel mutation, as shown by whole exome sequencing. One presented with seizures at birth and the other with seizures at 17 months old, both eventually exhibiting intractable epilepsy, ischemic stroke, and developmental delays. Results: Whole exome sequencing demonstrated de novo pathogenic mutations in the CACNA1A gene, which both caused similar phenotypes in unrelated patients. Conclusion: Pediatric patients who present with ischemic stroke and a history of seizures should be evaluated for CACNA1A mutations, as prompt recognition can help providers facilitate appropriate medical management.

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.

Extended Middle Cerebral Artery Occlusion (MCAO) Model to Mirror Stroke Patients Undergoing Thrombectomy

Stroke remains a leading global cause of death and disability. In the last decade, the therapeutic window for mechanical thrombectomy has increased from a maximum of 6 to 24 h and beyond. While endovascular advancements have improved rates of recanalization, no post-stroke pharmacotherapeutics have been effective in enhancing neurorepair and recovery. New experimental models are needed to closer mimic the human patient. Our group has developed a model of transient 5-h occlusion in rats to mimic stroke patients undergoing thrombectomy. Our procedure was designed specifically in aged rats and was optimized based on sex in order to keep mortality and extent of injury consistent between aged male and female rats. This model uses a neurological assessment modeled after the NIH Stroke Scale. Finally, the potential for translation between our rat model of stroke and humans was assessed using comparative gene expression for key inflammatory genes. This model will be useful in the evaluation of therapeutic targets to develop adjuvant treatments for large vessel occlusion during the thrombectomy procedure.

Mechanisms of neuronal cell death in ischemic stroke and their therapeutic implications

Ischemic stroke caused by arterial occlusion is the most common type of stroke, which is among the most frequent causes of disability and death worldwide. Current treatment approaches involve achieving rapid reperfusion either pharmacologically or surgically, both of which are time-sensitive; moreover, blood flow recanalization often causes ischemia/reperfusion injury. However, even though neuroprotective intervention is urgently needed in the event of stroke, the exact mechanisms of neuronal death during ischemic stroke are still unclear, and consequently, the capacity for drug development has remained limited. Multiple cell death pathways are implicated in the pathogenesis of ischemic stroke. Here, we have reviewed these potential neuronal death pathways, including intrinsic and extrinsic apoptosis, necroptosis, autophagy, ferroptosis, parthanatos, phagoptosis, and pyroptosis. We have also reviewed the latest results of pharmacological studies on ischemic stroke and summarized emerging drug targets with a focus on clinical trials. These observations may help to further understand the pathological events in ischemic stroke and bridge the gap between basic and translational research to reveal novel neuroprotective interventions.

Verapamil as an Adjunct Therapy to Reduce tPA Toxicity in Hyperglycemic Stroke: Implication of TXNIP/NLRP3 Inflammasome

Thrombolytic therapy has remained quite challenging in hyperglycemic patients for its association with poor prognosis and increased hemorrhagic conversions. We recently showed that tissue plasminogen activator (tPA)-induced cerebrovascular damage is associated with thioredoxin-interacting protein (TXNIP) upregulation, which has an established role in the detrimental effects of hyperglycemia. In the present work, we investigated whether verapamil, an established TXNIP inhibitor, may provide protection against hyperglycemic stroke and tPA-induced blood-brain barrier (BBB) disruption. Acute hyperglycemia was induced by intraperitoneal administration of 20% glucose, 15 min prior to transient middle cerebral artery occlusion (tMCAO). Verapamil (0.15 mg/kg) or saline was intravenously infused with tPA at hyperglycemic reperfusion, 1 h post tMCAO. After 24 h of ischemia/reperfusion (I/R), mice were assessed for neurobehavioral deficits followed by sacrifice and evaluation of brain infarct volume, edema, and microbleeding. Alterations in TXNIP, inflammatory mediators, and BBB markers were further analyzed using immunoblotting or immunostaining techniques. As adjunctive therapy, verapamil significantly reduced tPA-induced BBB leakage, matrix metalloproteinase 9 (MMP-9) upregulation, and tight junction protein deregulation, which resulted in lesser hemorrhagic conversions. Importantly, verapamil strongly reversed tPA-induced TXNIP/NLRP3 (NOD-like receptor pyrin domain-containing-3) inflammasome activation and reduced infarct volume. This concurred with a remarkable decrease in high-mobility group box protein 1 (HMGB-1) and nuclear factor kappa B (NF-κB) stimulation, leading to less priming of NLRP3 inflammasome. This preclinical study supports verapamil as a safe adjuvant that may complement thrombolytic therapy by inhibiting TXNIP's detrimental role in hyperglycemic stroke.

Method of intra-arterial drug administration in a rat: Sex based optimization of infusion rate

BACKGROUND

Endovascular thrombectomy is the process of removing a blood clot and re-establishing blood flow in patients with emergent large vessel occlusion. The technique provides an opportunity to deliver therapeutics directly to the site of injury. The intra-arterial (IA) route of drug administration in the mouse was developed to bridge the gap between animal stroke treatments and clinical stroke therapy. Here, we adapted the IA method for use in rats, by investigating various flow rates to optimize the IA injection through the internal carotid artery (ICA).

METHODS

Male and female Sprague-Dawley rats (∼4 months of age) were subjected to placement of micro-angio tubing at the bifurcation of the common carotid artery for injection into the ICA. We evaluated a range of infusion rates of carbon black ink and its vascular distribution within the brain.

RESULTS

Optimal injection rates in males was 4-6 μl/min and 2-4 μl/min in females. The IA injection using these sex-specific rates resulted in appropriate limited dye delivery to only the ipsilateral region of the brain, without inducing a subarachnoid hemorrhage.

CONCLUSION

Upon adapting the IA administration model to rats, it was determined that the rate of infusion varied between males and females. This variability is an important consideration for studies utilizing both sexes, such as in ischemic stroke studies.

A target-agnostic screen identifies approved drugs to stabilize the endoplasmic reticulum-resident proteome

Endoplasmic reticulum (ER) dysregulation is associated with pathologies including neurodegenerative, muscular, and diabetic conditions. Depletion of ER calcium can lead to the loss of resident proteins in a process termed exodosis. To identify compounds that attenuate the redistribution of ER proteins under pathological conditions, we performed a quantitative high-throughput screen using the Gaussia luciferase (GLuc)-secreted ER calcium modulated protein (SERCaMP) assay, which monitors secretion of ER-resident proteins triggered by calcium depletion. We identify several clinically used drugs, including bromocriptine, and further characterize them using assays to measure effects on ER calcium, ER stress, and ER exodosis. Bromocriptine elicits protective effects in cell-based models of exodosis as well as in vivo models of stroke and diabetes. Bromocriptine analogs with reduced dopamine receptor activity retain similar efficacy in stabilizing the ER proteome, indicating a non-canonical mechanism of action. This study describes a strategic approach to identify small-molecule drugs capable of improving ER proteostasis in human disease conditions.

Roles of Microglial Ion Channel in Neurodegenerative Diseases

As the average age and life expectancy increases, the incidence of both acute and chronic central nervous system (CNS) pathologies will increase. Understanding mechanisms underlying neuroinflammation as the common feature of any neurodegenerative pathology, we can exploit the pharmacology of cell specific ion channels to improve the outcome of many CNS diseases. As the main cellular player of neuroinflammation, microglia play a central role in this process. Although microglia are considered non-excitable cells, they express a variety of ion channels under both physiological and pathological conditions that seem to be involved in a plethora of cellular processes. Here, we discuss the impact of modulating microglia voltage-gated, potential transient receptor, chloride and proton channels on microglial proliferation, migration, and phagocytosis in neurodegenerative diseases.

Emerging neuroprotective strategies for the treatment of ischemic stroke: An overview of clinical and preclinical studies

Stroke is the leading cause of disability and thesecond leading cause of death worldwide. With the global population aged 65 and over growing faster than all other age groups, the incidence of stroke is also increasing. In addition, there is a shift in the overall stroke burden towards younger age groups, particularly in low and middle-income countries. Stroke in most cases is caused due to an abrupt blockage of an artery (ischemic stroke), but in some instances stroke may be caused due to bleeding into brain tissue when a blood vessel ruptures (hemorrhagic stroke). Although treatment options for stroke are still limited, with the advancement in recanalization therapy using both pharmacological and mechanical thrombolysis some progress has been made in helping patients recover from ischemic stroke. However, there is still a substantial need for the development of therapeutic agents for neuroprotection in acute ischemic stroke to protect the brain from damage prior to and during recanalization, extend the therapeutic time window for intervention and further improve functional outcome. The current review has assessed the past challenges in developing neuroprotective strategies, evaluated the recent advances in clinical trials, discussed the recent initiative by the National Institute of Neurological Disorders and Stroke in USA for the search of novel neuroprotectants (Stroke Preclinical Assessment Network, SPAN) and identified emerging neuroprotectants being currently evaluated in preclinical studies. The underlying molecular mechanism of each of the neuroprotective strategies have also been summarized, which could assist in the development of future strategies for combinational therapy in stroke treatment.

Intra-arterial neuroprotective therapy as an adjunct to endovascular intervention in acute ischemic stroke: A review of the literature and future directions

Mechanical thrombectomy for acute ischemic stroke due to large vessel occlusion has been shown to significantly improve outcomes. However, despite efficient rates of recanalization (60-90%), the rates of functional independence remain suboptimal (14-58%), most likely due to pathways of cell death in the brain that have already committed despite successful reperfusion. Pharmacologic neuroprotection provides a potential means of preventing this inevitable damage through targeting excitotoxicity, reactive oxygen species, cellular apoptosis, and inflammation. Numerous clinical trials using various neuroprotective agents have failed, but the majority of these trials did not include endovascular reperfusion, and thus the drugs were not reaching the therapeutic target. Intra-arterial delivery of neuroprotective agents via the guide catheter already in place for mechanical thrombectomy could provide a way to deliver high doses directly to the affected territory while limiting systemic exposure. Agents that have shown promise via the intra-arterial route in preclinical as well as some clinical models include magnesium sulfate, verapamil, cold saline, stem cells, and various combined approaches. Targeted hypothermia, achieved with intra-carotid infusion of cold saline, may provide an effective means of achieving hypothermia of the ischemic tissue while avoiding the systemic effects that have limited its use previously. Combination therapy of targeted hypothermia and a cocktail of drugs that provide anti-excitotoxic, anti-oxidant, anti-apopototic, and anti-inflammatory effects may provide an ideal approach that deserves further study in clinical trials.

Effect of Conscious Sedation vs. General Anesthesia on Outcomes in Patients Undergoing Mechanical Thrombectomy for Acute Ischemic Stroke: A Prospective Randomized Clinical Trial

Background: Although several studies have compared conscious sedation (CS) with general anesthesia (GA) in patients undergoing mechanical thrombectomy (MT), there has been no affirmative conclusion. We conducted this trial to assess whether CS is superior to GA for patients undergoing MT for acute ischemic stroke (AIS).

Methods: Acute ischemic stroke patients with anterior circulation large vascular occlusion were randomized into two groups. The primary outcome was modified Rankin scale score (0–2) at 90 days after stroke. Secondary outcomes included intraprocedural hemodynamics, time metrics, successful recanalization, neurointerventionalist satisfaction score, National Institutes of Health Stroke Scale (NIHSS) score, and Alberta Stroke Program Early CT Score (ASPECTS) at 48 h post-intervention, mortality at discharge and 3 months after stroke, and complications.

Results: Compared with the CS group, heart rate was significantly lower at T1–T8 in the GA group except at T4 (P < 0.05). Mean arterial pressure (MAP) and systolic blood pressure were significantly lower in the GA group at T4–T6 and T9 (P < 0.05). Pulse oxygen saturation was significantly higher at T2–T9 in the GA group (P < 0.05). There were no significant differences in time metrics, vasoactive drug use, occurrence of >20% fall in MAP, pre-recanalization time spent with >20% fall in MAP, neurointerventionalist satisfaction, successful recanalization rate, NIHSS, and ASPECTS scores at 48 h post-intervention, and mortality rate at discharge and 3 months after stroke (P > 0.05). The cerebral infarction rate at 30 days was greater in the CS group, but not significantly (P > 0.05). There were no differences in complication rates except for pneumonia (P > 0.05). Conversion rate from CS to GA was 9.52%.

Conclusion: Anesthetic management with GA or CS during MT had no differential impact on the functional outcomes and mortality at discharge or 3 months after stroke in AIS patients, but CS led to more stable hemodynamics and lower incidence of pneumonia.

Verapamil attenuates scopolamine induced cognitive deficits by averting oxidative stress and mitochondrial injury - A potential therapeutic agent for Alzheimer's Disease

Alzheimer's disease (AD) is a multifactorial disorder where amyloid beta (Aβ) plaques, Ca2+ dysregulation, excessive oxidative stress, mitochondrial dysfunction and synaptic loss operate synergistically to bring about cholinergic deficits and dementia. New therapeutic interventions are gaining prominence as the morbidity and mortality of AD increases exponentially every year. Treating AD with antihypertensive drugs is thought to be a promising intervention; however, its mechanism of action of ameliorating AD needs further investigation. In this context, the present study explores the protective effect of verapamil, an antihypertensive agent of Ca2+ channel blocker (CCB) class against scopolamine-induced in vitro neurotoxicity and in vivo cognitive impairment. Supplementation of verapamil was found to attenuate oxidative stress by preventing mitochondrial injury, and augment the expression of genes involved in the cholinergic function (mACR1), synaptic plasticity (GAP43, SYP) and Ca2+-dependent memory-related genes (CREB1, CREBBP, BDNF). Further, verapamil treatment in mice attenuated the cognitive and behavioural deficits induced by scopolamine as measured by the elevated plus maze and passive avoidance test (P < 0.05). Thus, the present study demonstrates the neuroprotective effect of verapamil against the pathogenesis of AD such as oxidative stress, mitochondrial dysfunction and cognitive decline. These observations emphasize the importance of ‛Ca2+ dysregulation' and ‛mitochondrial dysfunction' theories in AD and recommends the supplementation of compounds that regulate Ca2+ homeostasis and mitochondrial function in susceptible AD individuals.

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.

Interleukin 1 alpha administration is neuroprotective and neuro-restorative following experimental ischemic stroke

Background

Stroke remains a leading cause of death and disability worldwide despite recent treatment breakthroughs. A primary event in stroke pathogenesis is the development of a potent and deleterious local and peripheral inflammatory response regulated by the pro-inflammatory cytokine interleukin-1 (IL-1). While the role of IL-1β (main released isoform) has been well studied in stroke, the role of the IL-1α isoform remains largely unknown. With increasing utilization of intravenous tissue plasminogen activator (t-PA) or thrombectomy to pharmacologically or mechanically remove ischemic stroke causing blood clots, respectively, there is interest in pairing successful cerebrovascular recanalization with neurotherapeutic pharmacological interventions (Fraser et al., J Cereb Blood Flow Metab 37:3531–3543, 2017; Hill et al., Lancet Neurol 11:942–950, 2012; Amaro et al., Stroke 47:2874–2876, 2016).

Methods

Transient stroke was induced in mice via one of two methods. One group of mice were subjected to tandem ipsilateral common carotid artery and middle cerebral artery occlusion, while another group underwent the filament-based middle cerebral artery occlusion. We have recently developed an animal model of intra-arterial (IA) drug administration after recanalization (Maniskas et al., J Neurosci Met 240:22–27, 2015). Sub groups of the mice were treated with either saline or Il-1α, wherein the drug was administered either acutely (immediately after surgery) or subacutely (on the third day after stroke). This was followed by behavioral and histological analyses.

Results

We now show in the above-mentioned mouse stroke models (transient tandem ipsilateral common carotid artery (CCA) and middle cerebral artery occlusion (MCA) occlusion, MCA suture occlusion) that IL-1α is neuroprotective when acutely given either intravenously (IV) or IA at low sub-pathologic doses. Furthermore, while IV administration induces transient hemodynamic side effects without affecting systemic markers of inflammation, IA delivery further improves overall outcomes while eliminating these side effects. Additionally, we show that delayed/subacute IV IL-1α administration ameliorates functional deficit and promotes neurorepair.

Conclusions

Taken together, our present study suggests for the first time that IL-1α could, unexpectedly, be an effective ischemic stroke therapy with a broad therapeutic window.

Central Noradrenergic Agonists in the Treatment of Ischemic Stroke-an Overview

Ischemic stroke is the leading cause of morbidity and mortality with a significant health burden worldwide and few treatment options. Among the short- and long-term effects of ischemic stroke is the cardiovascular sympathetic autonomic dysfunction, presented in part as the by-product of the ischemic damage to the noradrenergic centers of the brain. Unlike high levels in the plasma, the brain may face suboptimal levels of norepinephrine (NE), with adverse effects on the clinical and functional outcomes of ischemic stroke. The intravenous administration of NE and other sympathomimetic agents, in an attempt to increase cerebral perfusion pressure, often aggravates the ischemia-induced rise in blood pressure (BP) with life-threatening consequences for stroke patients, the majority of whom present with hypertension at the time of admission. Unlike the systemic administration, the central administration of NE reduces BP while exerting anti-inflammatory and neuroprotective effects. These characteristics of centrally administered NE, combined with the short latency of response, make it an ideal candidate for use in the acute phase of stroke, followed by the use of centrally acting noradrenergic agonists, such as NE reuptake inhibitors and B2-adrenergic receptor agonists for stroke rehabilitation. In addition, a number of nonpharmacological strategies, such as transcutaneous vagus nerve stimulation (tVNS) and trigeminal nerve stimulation (TNS), have the potential to enhance the central noradrenergic functional activities and improve stroke clinical outcomes. Many factors could influence the efficacy of the noradrenergic treatment in stroke patients. These factors include the type of the noradrenergic agent; the dose, frequency, and duration of administration; the timing of administration in relation to the acute event; and the site and characteristics of the ischemic lesions. Having this knowledge, combined with the better understanding of the regulation of noradrenergic receptors in different parts of the brain, would pave the path for the successful use of the centrally acting noradrenergic agents in the management of ischemic stroke.

[Intracisternal administration of verapamil for the prevention and treatment of vasospasm in patients after microsurgical treatment of cerebral aneurysms in the acute period of hemorrhage]

The first results of intracisternal administration of verapamil for the prevention and treatment of cerebral vasospasm (CVS) in patients in the acute period of subarachnoid hemorrhage (SAH) after microsurgical clipping of cerebral aneurysms are presented.

OBJECTIVE

Safety assessment of the method of prolonged intracisternal infusion (PII) of verapamil.

MATERIAL AND METHODS

Over the period from May 2017 to December 2018, 42 patients were included in the study, who underwent clipping of aneurysm of the anterior segments of the Willis circle. Most patients (78.6%) were operated during the first 6 days after SAH. For each patient, a thin silicone catheter was installed, through which verapamil was infused. A prerequisite was the installation of external ventricular drainage and opening of the lamina terminalis. The daily dosage of verapamil varied from 25 to 50 mg of the drug diluted in 200-400 ml of isotonic sodium chloride solution. The indication for the use of the PII method was the presence of one of the following factors: a score on the Hunt-Hess scale from III to V, 3 or 4 points on the Fisher scale, confirmed angiographically by the CVS before the operation.

RESULTS

The PII procedure was performed from 2 to 5 days. The average dose of verapamil was 143.5±41.2 mg additionally, in the presence of an angiographically confirmed CVS accompanied by clinical manifestations, 14 (33.4%) patients received intra-arterial injection of verapamil in several stages, with individual selection of the drug dose. The formation of new cerebral ischemic foci of vasospastic genesis was observed in only 1 (2.4%) patient. No infectious intracranial complications were noted. The average follow-up period was 297.6±156.1 days. Long-term treatment outcomes, assessed by a modified Rankin scale from 0 to 2 points, were observed in 83.3% of patients. There were no outcomes such as vegetative status and no deaths. The frequency of liquorodynamic disorders, as well as epileptic syndrome did not exceed that among patients with SAH according to the literature.

CONCLUSION

The study has confirmed the safety of prolonged PII. The efficacy of the method, compared with other methods for CVS treatment requires further investigation. The first results look quite promising: the observation shows a low percentage of new foci of cerebral ischemia and the absence of deaths associated with it. In patients with severe CVS, the efficacy of the PII method is increased when combined with intra-arterial administration of verapamil.

Prevention of Severe Hypoglycemia-Induced Brain Damage and Cognitive Impairment With Verapamil

People with insulin-treated diabetes are uniquely at risk for severe hypoglycemia-induced brain damage. Because calcium influx may mediate brain damage, we tested the hypothesis that the calcium-channel blocker, verapamil, would significantly reduce brain damage and cognitive impairment caused by severe hypoglycemia. Sprague-Dawley rats (10 weeks old) were randomly assigned to one of three treatments: 1) control hyperinsulinemic (200 mU ⋅ kg^-1 ⋅ min^-1)-euglycemic (80-100 mg/dL) clamps (n = 14), 2) hyperinsulinemic-hypoglycemic (10-15 mg/dL) clamps (n = 16), or 3) hyperinsulinemic-hypoglycemic clamps, followed by a single treatment with verapamil (20 mg/kg) (n = 11). Compared with euglycemic controls, hypoglycemia markedly increased dead/dying neurons in the hippocampus by 16-fold and cortex by 14-fold. Verapamil treatment strikingly decreased hypoglycemia-induced hippocampal and cortical damage, by 87% and 94%, respectively. Morris Water Maze probe trial results demonstrated that hypoglycemia induced a retention, but not encoding, memory deficit (noted by both abolished target quadrant preference and reduced target quadrant time). Verapamil treatment significantly rescued spatial memory as noted by restoration of target quadrant preference and target quadrant time. In summary, a one-time treatment with verapamil after severe hypoglycemia prevented neural damage and memory impairment caused by severe hypoglycemia. For people with insulin-treated diabetes, verapamil may be a useful drug to prevent hypoglycemia-induced brain damage.

Advances in stroke pharmacology

Stroke occurs when a cerebral blood vessel is blocked or ruptured, and it is the major cause of death and adult disability worldwide. Various pharmacological agents have been developed for the treatment of stroke either through interrupting the molecular pathways leading to neuronal death or enhancing neuronal survival and regeneration. Except for rtPA, few of these agents have succeeded in clinical trials. Recently, with the understanding of the pathophysiological process of stroke, there is a resurrection of research on developing neuroprotective agents for stroke treatment, and novel molecular targets for neuroprotection and neurorestoration have been discovered to predict or offer clinical benefits. Here we review the latest major progress of pharmacological studies in stroke, especially in ischemic stroke; summarize emerging potential therapeutic mechanisms; and highlight recent clinical trials. The aim of this review is to provide a panorama of pharmacological interventions for stroke and bridge basic and translational research to guide the clinical management of stroke therapy.

Recent progress in translational research on neurovascular and neurodegenerative disorders

The already established and widely used intravenous application of recombinant tissue plasminogen activator as a re-opening strategy for acute vessel occlusion in ischemic stroke was recently added by mechanical thrombectomy, representing a fundamental progress in evidence-based medicine to improve the patient’s outcome. This has been paralleled by a swift increase in our understanding of pathomechanisms underlying many neurovascular diseases and most prevalent forms of dementia. Taken together, these current advances offer the potential to overcome almost two decades of marginally successful translational research on stroke and dementia, thereby spurring the entire field of translational neuroscience. Moreover, they may also pave the way for the renaissance of classical neuroprotective paradigms.

This review reports and summarizes some of the most interesting and promising recent achievements in neurovascular and dementia research. It highlights sessions from the 9th International Symposium on Neuroprotection and Neurorepair that have been discussed from April 19th to 22nd in Leipzig, Germany. To acknowledge the emerging culture of interdisciplinary collaboration and research, special emphasis is given on translational stories ranging from fundamental research on neurode- and -regeneration to late stage translational or early stage clinical investigations.

Intra-arterial verapamil post-thrombectomy is feasible, safe, and neuroprotective in stroke

Large vessel ischemic stroke represents the most disabling subtype. While t-PA and endovascular thrombectomy can recanalize the occluded vessel, good clinical outcomes are not uniformly achieved. We propose that supplementing endovascular thrombectomy with superselective intra-arterial (IA) verapamil immediately following recanalization could be safe and effective. Verapamil, a calcium channel blocker, has been shown to be an effective IA adjunct in a pre-clinical mouse focal ischemia model. To demonstrate translational efficacy, mechanism, feasibility, and safety, we conducted a group of translational experiments. We performed in vivo IA dose-response evaluation in our animal stroke model with C57/Bl6 mice. We evaluated neuroprotective mechanism through in vitro primary cortical neuron (PCN) cultures. Finally, we performed a Phase I trial, SAVER-I, to evaluate feasibility and safety of administration in the human condition. IA verapamil has a likely plateau or inverted-U dose-response with a defined toxicity level in mice (LD₅₀ 16-17.5 mg/kg). Verapamil significantly prevented PCN death and deleterious ischemic effects. Finally, the SAVER-I clinical trial showed no evidence that IA verapamil increased the risk of intracranial hemorrhage or other adverse effect/procedural complication in human subjects. We conclude that superselective IA verapamil administration immediately following thrombectomy is safe and feasible, and has direct, dose-response-related benefits in ischemia.

PEGylated insulin-like growth factor-I affords protection and facilitates recovery of lost functions post-focal ischemia

Insulin-like growth factor-I (IGF-I) is involved in the maturation and maintenance of neurons, and impaired IGF-I signaling has been shown to play a role in various neurological diseases including stroke. The aim of the present study was to investigate the efficacy of an optimized IGF-I variant by adding a 40 kDa polyethylene glycol (PEG) chain to IGF-I to form PEG-IGF-I. We show that PEG-IGF-I has a slower clearance which allows for twice-weekly dosing to maintain steady-state serum levels in mice. Using a photothrombotic model of focal stroke, dosing from 3 hrs post-stroke dose-dependently (0.3–1 mg/kg) decreases the volume of infarction and improves motor behavioural function in both young 3-month and aged 22–24 month old mice. Further, PEG-IGF-I treatment increases GFAP expression when given early (3 hrs post-stroke), increases Synaptophysin expression and increases neurogenesis in young and aged. Finally, neurons (P5–6) cultured in vitro on reactive astrocytes in the presence of PEG-IGF-I showed an increase in neurite length, indicating that PEG-IGF-I can aid in sprouting of new connections. This data suggests a modulatory role of IGF-I in both protective and regenerative processes, and indicates that therapeutic approaches using PEG-IGF-I should be given early and where the endogenous regenerative potential is still high.

Neuroprotective effects of a novel peptide, FK18, under oxygen-glucose deprivation in SH-SY5Y cells and retinal ischemia in rats via the Akt pathway

Ischemic neuronal injury is associated with several life- and vision-threatening diseases. Neuroprotection is essential in the treatment of these diseases. Here, we identified and characterized a novel peptide, FK18, from basic fibroblast growth factor (bFGF). We further assessed the neuroprotective effects of this peptide and its potential mechanisms using the in vitro oxygen-glucose deprivation (OGD) model in SH-SY5Y cells and the in vivo retinal ischemia-reperfusion (I/R) injury model to mimic ischemic neuronal injury. Our results suggested that FK18 significantly increased the viability of and attenuated the apoptosis of SH-SY5Y cells. It also markedly alleviated I/R-induced retinal neuronal apoptosis, damage to retinal ganglion cells (RGCs), and morphological and functional damage to the retina. Moreover, FK18 increased Akt phosphorylation under both normoxic and OGD conditions, attenuated mitochondrial translocation of the proapoptotic protein Bad, up-regulated the expression of Bcl-2/Bax, and inhibited the release of cytochrome c from the mitochondria into the cytoplasm. These results suggested that FK18 is a novel neuroprotective agent that may serve as a prototype for neuroprotective drug development.

Aerobic exercise combined with huwentoxin-I mitigates chronic cerebral ischemia injury

Ca²⁺ channel blockers have been shown to protect neurons from ischemia, and aerobic exercise has significant protective effects on a variety of chronic diseases. The present study injected huwentoxin-I (HWTX-I), a spider peptide toxin that blocks Ca²⁺ channels, into the caudal vein of a chronic cerebral ischemia mouse model, once every 2 days, for a total of 15 injections. During this time, a subgroup of mice was subjected to treadmill exercise for 5 weeks. Results showed amelioration of cortical injury and improved neurological function in mice with chronic cerebral ischemia in the HWTX-I + aerobic exercise group. The combined effects of HWTX-I and exercise were superior to HWTX-I or aerobic exercise alone. HWTX-I effectively activated the Notch signal transduction pathway in brain tissue. Aerobic exercise up-regulated synaptophysin mRNA expression. These results demonstrated that aerobic exercise, in combination with HWTX-I, effectively relieved neuronal injury induced by chronic cerebral ischemia via the Notch signaling pathway and promoting synaptic regeneration.

Intra-arterial nitroglycerin as directed acute treatment in experimental ischemic stroke

BACKGROUND

Nitroglycerin (also known as glyceryl trinitrate (GTN)), a vasodilator best known for treatment of ischemic heart disease, has also been investigated for its potential therapeutic benefit in ischemic stroke. The completed Efficacy of Nitric Oxide in Stroke trial suggested that GTN has therapeutic benefit with acute (within 6 hours) transdermal systemic sustained release therapy.

OBJECTIVE

To examine an alternative use of GTN as an acute therapy for ischemic stroke following successful recanalization.

METHODS

We administered GTN IA following transient middle cerebral artery occlusion in mice. Because no standard dose of GTN is available following emergent large vessel occlusion, we performed a dose-response (3.12, 6.25, 12.5, and 25 µg/µL) analysis. Next, we looked at blood perfusion (flow) through the middle cerebral artery using laser Doppler flowmetry. Functional outcomes, including forced motor movement rotor rod, were assessed in the 3.12, 6.25, and 12.5 µg/µL groups. Histological analysis was performed using cresyl violet for infarct volume, and glial fibrillary activating protein (GFAP) and NeuN immunohistochemistry for astrocyte activation and mature neuron survival, respectively.

RESULTS

Overall, we found that acute post-stroke IA GTN had little effect on vessel dilatation after 15 min. Functional analysis showed a significant difference between GTN (3.12 and 6.25 µg/µL) and control at post-stroke day 1. Histological measures showed a significant reduction in infarct volume and GFAP immunoreactivity and a significant increase in NeuN.

CONCLUSIONS

These results demonstrate that acute IA GTN is neuroprotective in experimental ischemic stroke and warrants further study as a potentially new stroke therapy.

A population-based incidence of acute large vessel occlusions and thrombectomy eligible patients indicates significant potential for growth of endovascular stroke therapy in the USA

BACKGROUND

Data on large vessel strokes are important for resource allocation and infrastructure development.

OBJECTIVE

To determine an annual incidence of large vessel occlusions (LVOs) and a thrombectomy eligible patient population.

METHODS

All patients with acute ischemic stroke discharged over 3 years from a tertiary-level hospital serving a large geographic area were evaluated for an LVO (M1, internal carotid artery terminus, basilar artery). The incidence of LVO was determined for the hospital's 4-county primary service area (PSA, population 210 000) based on each county's discharges and extrapolated to the US population. 'Thrombectomy eligibility' for anterior circulation LVOs was based on time (onset <6 hours) and imaging (Alberta Stroke Program Early CT Score (ASPECTS) ≥6). The number of annual thrombectomy procedures was calculated for Medicare and private payer patients using federally available databases.

RESULTS

1157 patients were discharged from the hospital's PSA, of whom 129 (11.1%, 95% CI 9.5% to 13.1%) had an LVO. This translated into an LVO incidence of 24 per 100 000 people per year (95% CI 20 to 28). 20 per 100 000 people per year had anterior circulation LVOs (95% CI 19 to 22), of whom 10/100 000/year (95% CI 8 to 11) were 'thrombectomy eligible'. An additional 5/100 000/year (95% CI 3 to 6) presented with favorable ASPECTS after 6 hours of symptom onset. Basilar occlusion incidence was estimated at 4/100 000/year (95% CI 2 to 5). These rates yield 77 569 (95% CI 65 835 to 91 091) new LVOs per year in the USA. An estimated 10 284 mechanical thrombectomy procedures were performed in 2015.

CONCLUSIONS

This study estimates an LVO incidence of 24 per 100 000 person-years (95% CI 20 to 28). A current estimated annual thrombectomy rate of three procedures per 100 000 people indicates significant potential increase in the volume of endovascular procedures and the need to develop systems of care.