The future of neuroprotection in stroke

Neuroprotective potential for mitigating ischemia-reperfusion-induced damage

Reperfusion following cerebral ischemia causes both structural and functional damage to brain tissue and could aggravate a patient's condition; this phenomenon is known as cerebral ischemia-reperfusion injury. Current studies have elucidated the neuroprotective role of the sirtuin protein family (Sirtuins) in modulating cerebral ischemia-reperfusion injury. However, the potential of utilizing it as a novel intervention target to influence the prognosis of cerebral ischemia-reperfusion injury requires additional exploration. In this review, the origin and research progress of Sirtuins are summarized, suggesting the involvement of Sirtuins in diverse mechanisms that affect cerebral ischemia-reperfusion injury, including inflammation, oxidative stress, blood-brain barrier damage, apoptosis, pyroptosis, and autophagy. The therapeutic avenues related to Sirtuins that may improve the prognosis of cerebral ischemia-reperfusion injury were also investigated by modulating Sirtuins expression and affecting representative pathways, such as nuclear factor-kappa B signaling, oxidative stress mediated by adenosine monophosphate-activated protein kinase, and the forkhead box O. This review also summarizes the potential of endogenous substances, such as RNA and hormones, drugs, dietary supplements, and emerging therapies that regulate Sirtuins expression. This review also reveals that regulating Sirtuins mitigates cerebral ischemia-reperfusion injury when combined with other risk factors. While Sirtuins show promise as a potential target for the treatment of cerebral ischemia-reperfusion injury, most recent studies are based on rodent models with circadian rhythms that are distinct from those of humans, potentially influencing the efficacy of Sirtuins-targeting drug therapies. Overall, this review provides new insights into the role of Sirtuins in the pathology and treatment of cerebral ischemia-reperfusion injury.

Neuroprotective effects of Aframomum pruinosum seed extract against stroke in rat: Role of antioxidant and anti-inflammatory mechanisms

BACKGROUND

Stroke is a major cause of disability and neurological impairment worldwide. Effective prevention and management strategies are needed to reduce its burden. This study aimed to investigate the therapeutic effect of the seed ethanolic extract of Aframomum pruinosum (EEAP) on stroke and its related motor and cognitive deficits in rats.

MATERIALS AND METHODS

Stroke was induced by either middle cerebral artery occlusion (MCAO) or bilateral common carotid artery occlusion (BCCAO). In the MCAO model, rats received EEAP (75, 150, or 300 mg kg-1) or N-acetyl-L-cysteine (100 mg kg-1) orally for one week before 2 h of occlusion, followed by reperfusion. Twenty-four hours after ischemia, brain was collected for infarct size using 2, 3, 5 -TriphenylTetrazolium Chloride (TTC) staining, oxidative stress markers and inflammatory cytokines (TNF-α, IL-1β) measurements. In the BCCAO model, rats underwent occlusion for 30 min and received EEAP or quercetin (25 mg kg-1) for 7 days post-induction. Behavioral parameters were evaluated at the end of the treatment. Oxidative stress and inflammatory markers were measured in the cerebrum and cerebellum.

RESULTS

MCAO caused significant brain infarction, and increased lipid peroxidation, TNF-α and IL-1β contents. EEAP, rich in nerolidol, prevented these changes in a dose-dependent manner. BCCAO impaired the neurological function, mobility, and muscle strength of rats. It also increased lipid peroxidation and inflammatory cytokines in the cerebellum. EEAP significantly ameliorated these impairments.

CONCLUSION

EEAP exerts preventive and curative neuroprotective effects against ischemic stroke and its associated motor impairments at least partially through its antioxidant and anti-inflammatory properties, and its nerolidol content.

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

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

Astrocyte TrkB promotes brain injury and edema formation in ischemic stroke

Following ischemic stroke astrocytes undergo rapid molecular and functional changes that may accentuate tissue damage. In this study we identified the neurotrophin receptor TrkB in astrocytes as a key promoter of acute CNS injury in ischemic stroke. In fact, TrkB protein was strongly upregulated in astrocytes after human and experimental stroke, and transgenic mice lacking astrocyte TrkB displayed significantly smaller lesion volume, lower brain atrophy and better motor performance than control animals after transient middle cerebral artery occlusion. Neuropathological studies evidenced that edema directly correlated with astrogliosis and was limited in transgenic mice. Importantly, adaptive levels of the water channel AQP4 was astrocyte TrkB-dependent as AQP4 upregulation after stroke did not occur in mice lacking astrocyte TrkB. In vitro experiments with wild-type and/or TrkB-deficient astrocytes highlighted TrkB-dependent upregulation of AQP4 via activation of HIF1-alpha under hypoxia. Collectively, our observations indicate that TrkB signaling in astrocytes contributes to the development of edema and worsens cerebral ischemia.

Prevention and Treatment Strategies for Alzheimer's Disease: Focusing on Microglia and Astrocytes in Neuroinflammation

Alzheimer's disease (AD) is a fatal neurodegenerative disease characterized by its insidious onset and progressive development, making it the most common form of dementia. Despite its prevalence, the exact causes and mechanisms responsible for AD remain unclear. Recent studies have highlighted that inflammation in the central nervous system (CNS) plays a crucial role in both the initiation and progression of AD. Neuroinflammation, an immune response within the CNS triggered by glial cells in response to various stimuli, such as nerve injury, infection, toxins, or autoimmune reactions, has emerged as a significant factor alongside amyloid deposition and neurofibrillary tangles (NFTs) commonly associated with AD. This article aims to provide an overview of the most recent research regarding the involvement of neuroinflammation in AD, with a particular focus on elucidating the specific mechanisms involving microglia and astrocytes. By exploring these intricate processes, a new theoretical framework can be established to further probe the impact of neuroinflammation on the development and progression of AD. Through a deeper understanding of these underlying mechanisms, potential targets for therapeutic interventions and novel treatment strategies can be identified in the ongoing battle against AD.

Microglia-mediated endothelial protection: the role of SHPL-49 in ischemic stroke

It was previously shown that SHPL-49, a glycoside derivative of salidroside formed through structural modification, exhibited neuroprotective effects in a rat cerebral ischemia model of permanent middle cerebral artery occlusion (pMCAO). Additionally, SHPL-49 enhanced the mRNA expression of vascular endothelial growth factor-a (Vegf-a) in macrophages. Microglia, functioning as resident macrophages within the brain, promptly respond to cerebral ischemia and engage in interactions with the cells of the Glial-Vascular Unit to orchestrate nerve injury responses. We postulated that the neuroprotective effects of SHPL-49 were mediated through microglia-dependent amelioration of endothelial dysfunction following cerebral ischemia. The present study demonstrates that SHPL-49 effectively mitigated microglia-dependent endothelial dysfunction in the pMCAO model by upregulating the expression of VEGF and suppressing the release of MMP-9 from microglia. Further MRI analyses confirmed that SHPL-49 significantly reduced nerve and endothelial function when microglia were depleted in the brains of pMCAO rats. The above phenomenon was also confirmed in the in vitro experiment investigating microglia-mediated brain endothelial cell function. Furthermore, we discovered that SHPL-49 activates the VEGFR2/Akt/eNOS pathways in endothelial cells and suppresses the p38 MAPK/MMP-9 pathways in microglia cells, thereby facilitating brain endothelial cell protection. Altogether, we have demonstrated that SHPL-49 effectively ameliorates endothelial dysfunction induced by cerebral ischemia through a microglia-dependent mechanism, thereby providing more valuable insights and references for the clinical evaluation of SHPL-49 injection for ischemic stroke.

Neuronal Death: Now You See It, Now You Don't

Fatally injured neurons may necrose and rupture immediately, or they may initiate a programmed cell death pathway and then wait for microglial phagocytosis. Biochemical and histopathologic assays of neuronal death assess the numbers of neurons awaiting phagocytosis at a particular time point after injury. This number varies with the fraction of neurons that have necrosed vs initiated programmed cell death, the time elapsed since injury, the rate of phagocytosis, and the assay's ability to detect neurons at different stages of programmed cell death. Many of these variables can be altered by putatively neurotoxic and neuroprotective interventions independent of the effects on neuronal death. This complicates analyses of neurotoxicity and neuroprotection and has likely contributed to difficulties with clinical translation of neuroprotective strategies after brain injury. Time-resolved assays of neuronal health, such as ongoing expression of transgenic fluorescent proteins, are a useful means of avoiding these problems.

Safety and efficacy of GD-11 in patients with ischaemic stroke: a multicentre, double-blind, randomised, placebo-controlled, phase 2 trial

BACKGROUND

GD-11, a novel brain cytoprotective drug, was designed to be actively taken up and transported across the blood-brain barrier via the glucose transporter. This study aimed to evaluate the safety and efficacy of GD-11 for improving the recovery of patients with acute ischaemic stroke (AIS).

METHODS

A double-blind, randomised, placebo-controlled, phase 2 trial was conducted at 15 clinical sites in China. Patients aged 18-80 years with AIS within 48 hours were randomly assigned (1:1:1) to receive 160 mg GD-11, 80 mg GD-11 and placebo, two times a day for 10 days. The primary endpoint was a modified Rankin Scale (mRS) score of 0-1 at 90 days after treatment. The safety outcome was any adverse events within 90 days.

RESULTS

From 17 November 2022 to 22 March 2023, a total of 80 patients in the 160 mg GD-11 group, 79 patients in the 80 mg GD-11 group and 80 patients in the placebo group were included. The proportion of an mRS score of 0-1 at day 90 was 77.5% in the 160 mg GD-11 group, 72.2% in the 80 mg GD-11 group and 67.5% in the placebo group. Though no significant difference was found (p=0.3671), a numerically higher proportion was observed in the GD-11 group, especially in the 160 mg GD-11 group. The incidence of adverse events was similar across the three groups (p=0.1992).

CONCLUSION

GD-11 was safe and well-tolerated. A dosage of GD-11 160 mg two times a day was recommended for a large trial to investigate the efficacy.

Targeting post-stroke neuroinflammation with Salvianolic acid A: molecular mechanisms and preclinical evidence

Salvianolic acid A (SalA), a bioactive compound extracted from Salvia miltiorrhiza, has garnered considerable interest for its potential in ameliorating the post-stroke neuroinflammation. This review delineates the possible molecular underpinnings of anti-inflammatory and neuroprotective roles of SalA, offering a comprehensive analysis of its therapeutic efficacy in preclinical studies of ischemic stroke. We explore the intricate interplay between post-stroke neuroinflammation and the modulatory effects of SalA on pro-inflammatory cytokines, inflammatory signaling pathways, the peripheral immune cell infiltration through blood-brain barrier disruption, and endothelial cell function. The pharmacokinetic profiles of SalA in the context of stroke, characterized by enhanced cerebral penetration post-ischemia, makes it particularly suitable as a therapeutic agent. Preliminary clinical findings have demonstrated that salvianolic acids (SA) has a positive impact on cerebral perfusion and neurological deficits in stroke patients, warranting further investigation. This review emphasizes SalA as a potential anti-inflammatory agent for the advancement of innovative therapeutic approaches in the treatment of ischemic stroke.

Partners in health and disease: pineal gland and purinergic signalling

In mammal's pineal glands, ATP interacts with the high-affinity P2Y1 and the low-affinity P2X7 receptors. ATP released from sympathetic nerve terminals potentiates noradrenaline-induced serotonin N-acetyltransferase (Snat) transcription, N-acetylserotonin (NAS), and melatonin (MLT) synthesis. Circulating melatonin impairs the expression of adhesion molecules in endothelial cells, blocking the migration of leukocytes. Acute defence response induced by pathogen- and danger/damage-associated molecular patterns (PAMPs and DAMPs) triggers the NF-κB pathway in pinealocytes and blocks the transcription of Snat. Therefore, the darkness hormone is not released, and neutrophils and monocytes migrate to the lesion sites. ATP released in high amounts from apoptotic and death cells was considered a DAMP, and the blockage of P2X7 receptors was tested as a new class of drugs for treating brain damage. However, this is not a simple equation. High ATP injected in a lateral ventricle blocked MLT, but not NAS, synthesis as it impairs the transcription of acetyl serotonin N-methyltransferase. NAS is released in the plasma and the cerebral spinal fluid. NAS also blocks the rolling and adhesion of leukocytes to endothelial cells. Otherwise, it is metabolised specifically in each brain area to provide the requested concentration of MLT as a neuroprotector. As observed in physiological conditions, high extracellular ATP, different from the other DAMPs, reports the environmental light/dark cycle rhythm because NAS substitutes MLT as the nocturnal chemical indicator, the darkness hormone. Thus, blocking the P2X7R should not be considered a universal therapy for improving acute strokes, as MLT and ATP are partners in health and disease.

Mechanisms of Postischemic Stroke Angiogenesis: A Multifaceted Approach

Ischemic stroke constitutes a significant global health care challenge, and a comprehensive understanding of its recovery mechanisms is imperative for the development of innovative therapeutic strategies. Angiogenesis, a pivotal element of ischemic tissue repair, facilitates the restoration of blood flow to damaged regions, thereby promoting neuronal regeneration and functional recovery. Nevertheless, the mechanisms underlying postischemic stroke angiogenesis remain incompletely elucidated. This review meticulously examines the constituents of the neurovascular unit, ion channels, molecular mediators, and signaling pathways implicated in angiogenesis following stroke. Furthermore, it delves into prospective therapeutic strategies informed by these factors. Our objective is to provide detailed and exhaustive information on the intricate mechanisms governing postischemic stroke angiogenesis, thus providing a robust scientific foundation for the advancement of novel neurorepair therapies.

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.

Hypothermia protects the integrity of corticospinal tracts and alleviates mitochondria injury after intracerebral hemorrhage in mice

Disruption of corticospinal tracts (CST) is a leading factor for motor impairments following intracerebral hemorrhage (ICH) in the striatum. Previous studies have shown that therapeutic hypothermia (HT) improves outcomes of ICH patients. However, whether HT has a direct protection effect on the CST integrity and the underlying mechanisms remain largely unknown. In this study, we employed a chemogenetics approach to selectively activate bilateral warm-sensitive neurons in the preoptic areas to induce a hypothermia-like state. We then assessed effects of HT treatment on the integrity of CST and motor functional recovery after ICH. Our results showed that HT treatment significantly alleviated axonal degeneration around the hematoma and the CST axons at remote midbrain region, ultimately promoted skilled motor function recovery. Anterograde and retrograde tracing revealed that HT treatment protected the integrity of the CST over an extended period. Mechanistically, HT treatment prevented mitochondrial swelling in degenerated axons around the hematoma, alleviated mitochondrial impairment by reducing mitochondrial ROS accumulation and improving mitochondrial membrane potential in primarily cultured cortical neurons with oxyhemoglobin treatment. Serving as a proof of principle, our study provided novel insights into the application of HT to improve functional recovery after ICH.

Reducing the global burden of cerebral venous thrombosis: An international research agenda

BACKGROUND

Due to the rarity of cerebral venous thrombosis (CVT), performing high-quality scientific research in this field is challenging. Providing answers to unresolved research questions will improve prevention, diagnosis, and treatment, and ultimately translate to a better outcome of patients with CVT. We present an international research agenda, in which the most important research questions in the field of CVT are prioritized.

AIMS

This research agenda has three distinct goals: (1) to provide inspiration and focus to research on CVT for the coming years, (2) to reinforce international collaboration, and (3) to facilitate the acquisition of research funding.

SUMMARY OF REVIEW

This international research agenda is the result of a research summit organized by the International Cerebral Venous Thrombosis Consortium in Amsterdam, the Netherlands, in June 2023. The summit brought together 45 participants from 15 countries including clinical researchers from various disciplines, patients who previously suffered from CVT, and delegates from industry and non-profit funding organizations. The research agenda is categorized into six pre-specified themes: (1) epidemiology and clinical features, (2) life after CVT, (3) neuroimaging and diagnosis, (4) pathophysiology, (5) medical treatment, and (6) endovascular treatment. For each theme, we present two to four research questions, followed by a brief substantiation per question. The research questions were prioritized by the participants of the summit through consensus discussion.

CONCLUSIONS

This international research agenda provides an overview of the most burning research questions on CVT. Answering these questions will advance our understanding and management of CVT, which will ultimately lead to improved outcomes for CVT patients worldwide.

The Involvement of Immune Cells Between Ischemic Stroke and Gut Microbiota

Ischemic stroke, a disease with high mortality and disability rate worldwide, currently has no effective treatment. The systemic inflammation response to the ischemic stroke, followed by immunosuppression in focal neurologic deficits and other inflammatory damage, reduces the circulating immune cell counts and multiorgan infectious complications such as intestinal and gut dysfunction dysbiosis. Evidence showed that microbiota dysbiosis plays a role in neuroinflammation and peripheral immune response after stroke, changing the lymphocyte populations. Multiple immune cells, including lymphocytes, engage in complex and dynamic immune responses in all stages of stroke and may be a pivotal moderator in the bidirectional immunomodulation between ischemic stroke and gut microbiota. This review discusses the role of lymphocytes and other immune cells, the immunological processes in the bidirectional immunomodulation between gut microbiota and ischemic stroke, and its potential as a therapeutic strategy for ischemic stroke.

Neuroprotective effects of the salidroside derivative SHPL-49 via the BDNF/TrkB/Gap43 pathway in rats with cerebral ischemia

Ischemic stroke is a common intravascular disease and one of the leading causes of death and disability. The salidroside derivative SHPL-49, which we previously synthesized, significantly attenuates cerebral ischemic injury in a rat model of permanent middle cerebral artery occlusion. To explore the neuroprotective mechanism of SHPL-49, the effects of SHPL-49 on the expression levels of neurotrophic factors in neurons and microglia and the polarization of microglia were investigated in the present study. SHPL-49 activated the brain-derived neurotrophic factor (BDNF) pathway, decreased the number of degenerated neurons, and accelerated neurogenesis in rats with cerebral ischemia. In addition, SHPL-49 promoted the polarization of microglia toward the M2 phenotype to alleviate neuroinflammation. In BV2 cells, SHPL-49 upregulated CD206 mRNA and protein levels and inhibited CD86 mRNA and protein levels. SHPL-49 also increased neurotrophic factor secretion in BV2 cells, which indirectly promoted the survival of primary neurons after oxygen-glucose deprivation (OGD). Proteomics analysis revealed that SHPL-49 promoted growth-associated protein 43 (Gap43) expression. SHPL-49 enhanced synaptic plasticity and increased Gap43 protein levels via activation of the BDNF pathway in the OGD primary neuron model. These results indicate that SHPL-49 prevents cerebral ischemic injury by activating neurotrophic factor pathways and altering microglial polarization. Thus, SHPL-49 is a potential neuroprotective agent.

Current and further outlook on the protective potential of Antrodia camphorata against neurological disorders

Prevalent neurological disorders such as Alzheimer's disease, Parkinson's disease, and stroke are increasingly becoming a global burden as society ages. It is well-known that degeneration and loss of neurons are the fundamental underlying processes, but there are still no effective therapies for these neurological diseases. In recent years, plenty of studies have focused on the pharmacology and feasibility of natural products as new strategies for the development of drugs that target neurological disorders. Antrodia camphorata has become one of the most promising candidates, and the crude extracts and some active metabolites of it have been reported to play various pharmacological activities to alleviate neurological symptoms at cellular and molecular levels. This review highlights the current evidence of Antrodia camphorata against neurological disorders, including safety evaluation, metabolism, blood-brain barrier penetration, neuroprotective activities, and the potential on regulating the gut-microbiome-brain axis. Furthermore, potential strategies to resolve problematic issues identified in previous studies are also discussed. We aim to provide an overview for the ongoing development and utilization of Antrodia camphorata in cerebral neuropathology.

Impact of inflammatory preconditioning on murine microglial proteome response induced by focal ischemic brain injury

Preconditioning with lipopolysaccharide (LPS) induces neuroprotection against subsequent cerebral ischemic injury, mainly involving innate immune pathways. Microglia are resident immune cells of the central nervous system (CNS) that respond early to danger signals through memory-like differential reprogramming. However, the cell-specific molecular mechanisms underlying preconditioning are not fully understood. To elucidate the distinct molecular mechanisms of preconditioning on microglia, we compared these cell-specific proteomic profiles in response to LPS preconditioning and without preconditioning and subsequent transient focal brain ischemia and reperfusion, - using an established mouse model of transient focal brain ischemia and reperfusion. A proteomic workflow, based on isolated microglia obtained from mouse brains by cell sorting and coupled to mass spectrometry for identification and quantification, was applied. Our data confirm that LPS preconditioning induces marked neuroprotection, as indicated by a significant reduction in brain infarct volume. The established brain cell separation method was suitable for obtaining an enriched microglial cell fraction for valid proteomic analysis. The results show a significant impact of LPS preconditioning on microglial proteome patterns by type I interferons, presumably driven by the interferon cluster regulator proteins signal transducer and activator of transcription1/2 (STAT1/2).

Combination therapy of Epidermal Growth Factor and Growth Hormone-Releasing Hexapeptide in acute ischemic stroke: a phase I/II non-blinded, randomized clinical trial

Objective

This study tested the hypothesis that a neuroprotective combined therapy based on epidermal growth factor (EGF) and growth hormone-releasing hexapeptide (GHRP6) could be safe for acute ischemic stroke patients, admitting up to 30% of serious adverse events (SAE) with proven causality.

Methods

A multi-centric, randomized, open-label, controlled, phase I-II clinical trial with parallel groups was conducted (July 2017 to January 2018). Patients aged 18-80 years with a computed tomography-confirmed ischemic stroke and less than 12 h from the onset of symptoms were randomly assigned to the study groups I (75 μg rEGF + 3.5 mg GHRP6 i.v., n=10), II (75 μg rEGF + 5 mg GHRP6 i.v., n=10), or III (standard care control, n=16). Combined therapy was given BID for 7 days. The primary endpoint was safety over 6 months. Secondary endpoints included neurological (NIHSS) and functional [Barthel index and modified Rankin scale (mRS)] outcomes.

Results

The study population had a mean age of 66 ± 11 years, with 21 men (58.3%), a baseline median NIHSS score of 9 (95% CI: 8-11), and a mean time to treatment of 7.3 ± 2.8 h. Analyses were conducted on an intention-to-treat basis. SAEs were reported in 9 of 16 (56.2%) patients in the control group, 3 of 10 (30%) patients in Group I (odds ratio (OR): 0.33; 95% CI: 0.06-1.78), and 2 of 10 (20%) patients in Group II (OR: 0.19; 95% CI: 0.03-1.22); only two events in one patient in Group I were attributed to the intervention treatment. Compliance with the study hypothesis was greater than 0.90 in each group. Patients treated with EGF + GHRP6 had a favorable neurological and functional evolution at both 90 and 180 days, as evidenced by the inferential analysis of NIHSS, Barthel, and mRS and by their moderate to strong effect size. At 6 months, proportion analysis evidenced a higher survival rate for patients treated with the combined therapy. Ancillary analysis including merged treated groups and utility-weighted mRS also showed a benefit of this combined therapy.

Conclusion

EGF + GHRP6 therapy was safe. The functional benefits of treatment in this study supported a Phase III study.

Clinical Trial Registration

RPCEC00000214 of the Cuban Public Registry of Clinical Trials, Unique identifier: IG/CIGB-845I/IC/1601.

Advances in nanomedicines: a promising therapeutic strategy for ischemic cerebral stroke treatment

Ischemic stroke, prevalent among the elderly, necessitates attention to reperfusion injury post treatment. Limited drug access to the brain, owing to the blood-brain barrier, restricts clinical applications. Identifying efficient drug carriers capable of penetrating this barrier is crucial. Blood-brain barrier transporters play a vital role in nutrient transport to the brain. Recently, nanoparticles emerged as drug carriers, enhancing drug permeability via surface-modified ligands. This article introduces the blood-brain barrier structure, elucidates reperfusion injury pathogenesis, compiles ischemic stroke treatment drugs, explores nanomaterials for drug encapsulation and emphasizes their advantages over conventional drugs. Utilizing nanoparticles as drug-delivery systems offers targeting and efficiency benefits absent in traditional drugs. The prospects for nanomedicine in stroke treatment are promising.

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.

Post-ischemic ubiquitination at the postsynaptic density reversibly influences the activity of ischemia-relevant kinases

Ubiquitin modifications alter protein function and stability, thereby regulating cell homeostasis and viability, particularly under stress. Ischemic stroke induces protein ubiquitination at the ischemic periphery, wherein cells remain viable, however the identity of ubiquitinated proteins is unknown. Here, we employed a proteomics approach to identify these proteins in mice undergoing ischemic stroke. The data are available in a searchable web interface ( https://hochrainerlab.shinyapps.io/StrokeUbiOmics/ ). We detected increased ubiquitination of 198 proteins, many of which localize to the postsynaptic density (PSD) of glutamatergic neurons. Among these were proteins essential for maintaining PSD architecture, such as PSD95, as well as NMDA and AMPA receptor subunits. The largest enzymatic group at the PSD with elevated post-ischemic ubiquitination were kinases, such as CaMKII, PKC, Cdk5, and Pyk2, whose aberrant activities are well-known to contribute to post-ischemic neuronal death. Concurrent phospho-proteomics revealed altered PSD-associated phosphorylation patterns, indicative of modified kinase activities following stroke. PSD-located CaMKII, PKC, and Cdk5 activities were decreased while Pyk2 activity was increased after stroke. Removal of ubiquitin restored kinase activities to pre-stroke levels, identifying ubiquitination as the responsible molecular mechanism for post-ischemic kinase regulation. These findings unveil a previously unrecognized role of ubiquitination in the regulation of essential kinases involved in ischemic injury.

Efficacy and safety of hyperbaric oxygen therapy in acute ischaemic stroke: a systematic review and meta-analysis

OBJECTIVE

This study aims to evaluate the efficacy and safety of adjunctive hyperbaric oxygen therapy (HBOT) in acute ischaemic stroke (AIS) based on existing evidence.

METHODS

We conducted a comprehensive search through April 15, 2023, of seven major databases for randomized controlled trials (RCTs) comparing adjunctive hyperbaric HBOT with non-HBOT (no HBOT or sham HBOT) treatments for AIS. Data extraction and assessment were independently performed by two researchers. The quality of included studies was evaluated using the tool provided by the Cochrane Collaboration. Meta-analysis was conducted using Rev Man 5.3.

RESULTS

A total of 8 studies involving 493 patients were included. The meta-analysis showed no statistically significant differences between HBOT and the control group in terms of NIHSS score (MD = -1.41, 95%CI = -7.41 to 4.58), Barthel index (MD = 8.85, 95%CI = -5.84 to 23.54), TNF-α (MD = -5.78, 95%CI = -19.93 to 8.36), sICAM (MD = -308.47, 95%CI = -844.13 to 13227.19), sVCAM (MD = -122.84, 95%CI = -728.26 to 482.58), sE-selectin (MD = 0.11, 95%CI = -21.86 to 22.08), CRP (MD = -5.76, 95%CI = -15.02 to 3.51), adverse event incidence within ≤ 6 months of follow-up (OR = 0.98, 95%CI = 0.25 to 3.79). However, HBOT showed significant improvement in modified Rankin score (MD = 0.10, 95%CI = 0.03 to 0.17), and adverse event incidence at the end of treatment (OR = 0.42, 95%CI = 0.19 to 0.94) compared to the control group.

CONCLUSION

While our findings do not support the routine use of HBOT for improving clinical outcomes in AIS, further research is needed to explore its potential efficacy within specific therapeutic windows and for different cerebral occlusion scenarios. Therefore, the possibility of HBOT offering clinical benefits for AIS cannot be entirely ruled out.

WITHDRAWN: Advances in Neurovascular Research: Scientific Highlights from the 15th World Stroke Congress

The Publisher regrets that this article is an accidental duplication of an article that has already been published, http://dx.doi.org/10.1016/j.jstrokecerebrovasdis.2024.107614. The duplicate article has therefore been withdrawn. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/policies/article-withdrawal.

Transnasal cooling: New prospect of selective hypothermia in acute ischemic stroke

Rapid and selective therapeutic hypothermia is a promising neuroprotective method for acute ischemic stroke. A recent study developed a simple but efficient technique of transnasal cooling, in which air at ambient temperature was passed through standard nasal cannula to induce evaporative cooling of the brain. Selective brain temperature decrease was achieved within 25 minutes in piglets. It is a major step forward to initiate early brain cooling. However, it is still necessary to devise a more comprehensive strategy to enhance the benefits of selective brain cooling in the era of effective reperfusion.

A systematic-search-and-review of registered pharmacological therapies investigated to improve neuro-recovery after a stroke

Background

Stroke burden is largely due to long-term impairments requiring prolonged care with loss of productivity. We aimed to identify and assess studies of different registered pharmacological therapies as treatments to improve post-stroke impairments and/or disabilities.

Methods

We performed a systematic-search-and-review of treatments that have been investigated as recovery-enhancing or recovery-promoting therapies in adult patients with stroke. The treatment must have received registration or market authorization in any country regardless of primary indication. Outcomes included in the review were neurological impairments and functional/disability assessments. "The best available studies" based on study design, study size, and/or date of publication were selected and graded for level of evidence (LOE) by consensus.

Results

Our systematic search yielded 7,801 citations, and we reviewed 665 full-text papers. Fifty-eight publications were selected as "the best studies" across 25 pharmacological classes: 31 on ischemic stroke, 21 on ischemic or hemorrhagic stroke, 4 on intracerebral hemorrhage, and 2 on subarachnoid hemorrhage (SAH). Twenty-six were systematic reviews/meta-analyses, 29 were randomized clinical trials (RCTs), and three were cohort studies. Only nimodipine for SAH had LOE A of benefit (systematic review and network meta-analysis). Many studies, some of which showed treatment effects, were assessed as LOE C-LD, mainly due to small sample sizes or poor quality. Seven interventions had LOE B-R (systematic review/meta-analysis or RCT) of treatment effects.

Conclusion

Only one commercially available treatment has LOE A for routine use in stroke. Further studies of putative neuroprotective drugs as adjunctive treatment to revascularization procedures and more confirmatory trials on recovery-promoting therapies will enhance the certainty of their benefit. The decision on their use must be guided by the clinical profile, neurological impairments, and target outcomes based on the available evidence.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=376973, PROSPERO, CRD42022376973.

Neuroprotection during Thrombectomy for Acute Ischemic Stroke: A Review of Future Therapies

Stroke is a major cause of death and disability worldwide. Endovascular thrombectomy has been impactful in decreasing mortality. However, many clinical results continue to show suboptimal functional outcomes despite high recanalization rates. This gap in recanalization and symptomatic improvement suggests a need for adjunctive therapies in post-thrombectomy care. With greater insight into ischemia-reperfusion injury, recent preclinical testing of neuroprotective agents has shifted towards preventing oxidative stress through upregulation of antioxidants and downstream effectors, with positive results. Advances in multiple neuroprotective therapies, including uric acid, activated protein C, nerinetide, otaplimastat, imatinib, verapamil, butylphthalide, edaravone, nelonemdaz, ApTOLL, regional hypothermia, remote ischemic conditioning, normobaric oxygen, and especially nuclear factor erythroid 2-related factor 2, have promising evidence for improving stroke care. Sedation and blood pressure management in endovascular thrombectomy also play crucial roles in improved stroke outcomes. A hand-in-hand approach with both endovascular therapy and neuroprotection may be the key to targeting disability due to stroke.

Ginsenoside Rg1 treats ischemic stroke by regulating CKLF1/CCR5 axis-induced neuronal cell pyroptosis

BACKGROUND

Ischemic stroke, a severe and life-threatening neurodegenerative condition, currently relies on thrombolytic therapy with limited therapeutic window and potential risks of hemorrhagic transformation. Thus, there is a crucial need to explore novel therapeutic agents for ischemic stroke. Ginsenoside Rg1 (Rg1), a potential neuroprotective agent, exhibits anti-ischemic effects attributed to its anti-inflammatory, anti-oxidant, and anti-apoptotic properties. Nevertheless, the precise underlying mechanism of action remains to be fully elucidated.

PURPOSE

This study aimed to explore whether Rg1 exerts anti-ischemic stroke effects by inhibiting pyroptotic neuronal cell death through modulation of the chemokine like factor 1 (CKLF1)/ C-C chemokine receptor type 5 (CCR5) axis.

METHODS

In this study, the MCAO model was used as an ischemic stroke model, and experimental tests were performed after 6 hours of ischemia. The anti-ischemic effect of Rg1 was examined by TTC staining, nissl-staining and neurobehavioral tests. In the in vitro experiments, PC12 cells were subjected to stimulation with CKLF1's mimetic peptide C27 to assess the potential of CKLF1 to induce focal neuronal cell death. Additionally, the impact of CKLF1 mimetic peptide C27, antagonistic peptide C19, and CCR5 inhibitor MVC on PC12 cells subjected to oxygen-glucose deprivation (OGD) and subsequently treated with Rg1 was investigated. In vivo, Rg1 treatment was examined by quantitative real-time PCR (qPCR), ELISA, immunohistochemistry (IHC), immunofluorescence (IF), western blot (WB), and co-immunoprecipitate (Co-IP) assays to perspective whether Rg1 treatment reduces CKLF1/CCR5 axis-induced pyroptotic neuronal cell death. In addition, to further explore the biological significance of CKLF1 in ischemic stroke, CKLF1-/- rats were used as the observation subjects in this study.

RESULTS

The in vitro results suggested that CKLF1 was able to induce neuronal cells to undergo pyroptosis. In vivo pharmacodynamic results showed that Rg1 treatment was able to significantly improve symptoms in ischemic stroke rats. In addition, Rg1 treatment was able to inhibit the interaction between CKLF1 and CCR5 after ischemic stroke and inhibited CKLF1/CCR5 axis-induced pyroptosis. The results of related experiments in CKLF1-/- rats showed that Rg1 lost its therapeutic effect after CKLF1 knockdown.

CONCLUSION

Our findings indicate that the activation of the NLRP3 inflammasome is initiated by the CKLF1/CCR5 axis, facilitated through the activation of the NF-κB pathway, ultimately resulting in the pyroptosis of neuronal cells. Conversely, Rg1 demonstrates the capability to mitigate neuronal cell damage following CKLF1-induced effects by suppressing the expression of CKLF1. Thus, CKLF1 represents a crucial target for Rg1 in the context of cerebral ischemia treatment, and it also holds promise as a potential target for drug screening in the management of ischemic stroke.

Development of Pharmacological Strategies with Therapeutic Potential in Ischemic Stroke

Acute ischemic stroke constitutes a health challenge with great social impact due to its high incidence, with the social dependency that it generates being an important source of inequality. The lack of treatments serving as effective neuroprotective therapies beyond thrombolysis and thrombectomy is presented as a need. With this goal in mind, our research group's collaborative studies into cerebral ischemia and subsequent reperfusion concluded that there is a need to develop compounds with antioxidant and radical scavenger features. In this review, we summarize the path taken toward the identification of lead compounds as potential candidates for the treatment of acute ischemic stroke. Evaluations of the antioxidant capacity, neuroprotection of primary neuronal cultures and in vivo experimental models of cerebral ischemia, including neurological deficit score assessments, are conducted to characterize the biological efficacy of the various neuroprotective compounds developed. Moreover, the initial results in preclinical development, including dose-response studies, the therapeutic window, the long-term neuroprotective effect and in vivo antioxidant evaluation, are reported. The results prompt these compounds for clinical trials and are encouraging regarding new drug developments aimed at a successful therapy for ischemic stroke.

Gene therapy of adeno-associated virus (AAV) vectors in preclinical models of ischemic stroke

Stroke has been associated with devastating clinical outcomes, with current treatment strategies proving largely ineffective. Therefore, there is a need to explore alternative treatment options for addressing post-stroke functional deficits. Gene therapy utilizing adeno-associated viruses (AAVs) as a critical gene vector delivering genes to the central nervous system (CNS) gene delivery has emerged as a promising approach for treating various CNS diseases. This review aims to provide an overview of the biological characteristics of AAV vectors and the therapeutic advancements observed in preclinical models of ischemic stroke. The study further investigates the potential of manipulating AAV vectors in preclinical applications, emphasizing the challenges and prospects in the selection of viral vectors, drug delivery strategies, immune reactions, and clinical translation.

Signaling pathways in brain ischemia: Mechanisms and therapeutic implications

Ischemic stroke occurs when the arteries supplying blood to the brain are narrowed or blocked, inducing damage to brain tissue due to a lack of blood supply. One effective way to reduce brain damage and alleviate symptoms is to reopen blocked blood vessels in a timely manner and reduce neuronal damage. To achieve this, researchers have focused on identifying key cellular signaling pathways that can be targeted with drugs. These pathways include oxidative/nitrosative stress, excitatory amino acids and their receptors, inflammatory signaling molecules, metabolic pathways, ion channels, and other molecular events involved in stroke pathology. However, evidence suggests that solely focusing on protecting neurons may not yield satisfactory clinical results. Instead, researchers should consider the multifactorial and complex mechanisms underlying stroke pathology, including the interactions between different components of the neurovascular unit. Such an approach is more representative of the actual pathological process observed in clinical settings. This review summarizes recent research on the multiple molecular mechanisms and drug targets in ischemic stroke, as well as recent advances in novel therapeutic strategies. Finally, we discuss the challenges and future prospects of new strategies based on the biological characteristics of stroke.

Phenothiazines reduced autophagy in ischemic stroke through endoplasmic reticulum (ER) stress-associated PERK-eIF2α pathway

BACKGROUND

Neuroprotective effects have been the main focus of new treatment modalities for ischemic stroke. Phenothiazines, or chlorpromazine plus promethazine (C + P), are known to prevent the generation of free radicals and uptake of Ca2+ by plasma membrane; they have a potential as a treatment for acute ischemic stroke (AIS). This study aims to investigate the role of endoplasmic reticulum (ER) stress-associated PERK-eIF2α pathway underlying the phenothiazine-induced neuroprotective effects after cerebral ischemia/reperfusion (I/R) injury.

METHODS

A total of 49 male Sprague Dawley rats (280-320 g) were randomly divided into 4 groups (n = 7 per group): (1) sham, (2) I/R that received 2 h of middle cerebral artery occlusion (MCAO), followed by 6 or 24 h of reperfusion, (3) MCAO treated by C + P without temperature control and (4) MCAO treated by C + P with temperature control. Human neuroblastoma (SH-SY5Y) cells were used in 5 groups: (1) control, (2) oxygen-glucose deprivation (OGD) for 2 h followed by reoxygenation (OGD/R), (3) OGD/R with C + P; (4) OGD/R with PERK inhibitor, GSK2656157, and (5) OGD/R with C + P and GSK2656157. The molecules of ER stress, unfolded protein response (UPR) (Bip, PERK, p-PERK, p-PERK/PERK, eIF2α, p-eIF2α, p-eIF2α/eIF2α), autophagy (ATG12, LC3II/I), and apoptosis (BAX, Bcl-XL) were measured at mRNA levels by real time PCR and protein levels by Western blotting.

RESULTS

In ischemic rats followed by reperfusion, expression of Bip, p-PERK/PERK, p-eIF2α/eIF2α, ATG12, and LC3II/I, as well as BAX were all significantly increased. These markers were significantly reduced by C + P at both 6 and 24 h of reperfusion. Anti-apoptotic Bcl-XL expression was increased, while pro-apoptotic BAX expression was decreased by C + P. In SH-SY5Y cell lines, both C + P and GSK2656157 significantly reduced the level of autophagy and apoptosis after I/R, respectively. The combination of GSK2656157 and C + P did not promote the same effect, suggesting that C + P did not induce any neuroprotective effect by inhibiting autophagy and apoptosis through the PERK-eIF2α pathway when this pathway was already blocked by GSK2656157. In general, the reduction in body temperature by phenothiazines was associated with better neuroprotection but it did not reach significant levels.

CONCLUSION

The combined treatment of C + P plays a crucial role in stroke therapy by inhibiting ER stress-mediated autophagy, thereby leading to reduced apoptosis and increased neuroprotection. Our findings highlight the PERK-eIF2α pathway as a central mechanism through which C + P exerts its beneficial effects. The results from this study may pave the way for the development of more targeted and effective treatments for stroke patients.

The Value of Applying Machine Learning in Predicting the Time of Symptom Onset in Stroke Patients: Systematic Review and Meta-Analysis

BACKGROUND

Machine learning is a potentially effective method for identifying and predicting the time of the onset of stroke. However, the value of applying machine learning in this field remains controversial and debatable.

OBJECTIVE

We aimed to assess the value of applying machine learning in predicting the time of stroke onset.

METHODS

PubMed, Web of Science, Embase, and Cochrane were comprehensively searched. The C index and sensitivity with 95% CI were used as effect sizes. The risk of bias was evaluated using PROBAST (Prediction Model Risk of Bias Assessment Tool), and meta-analysis was conducted using R (version 4.2.0; R Core Team).

RESULTS

Thirteen eligible studies were included in the meta-analysis involving 55 machine learning models with 41 models in the training set and 14 in the validation set. The overall C index was 0.800 (95% CI 0.773-0.826) in the training set and 0.781 (95% CI 0.709-0.852) in the validation set. The sensitivity and specificity were 0.76 (95% CI 0.73-0.80) and 0.79 (95% CI 0.74-0.82) in the training set and 0.81 (95% CI 0.68-0.90) and 0.83 (95% CI 0.73-0.89) in the validation set, respectively. Subgroup analysis revealed that the accuracy of machine learning in predicting the time of stroke onset within 4.5 hours was optimal (training: 0.80, 95% CI 0.77-0.83; validation: 0.79, 95% CI 0.71-0.86).

CONCLUSIONS

Machine learning has ideal performance in identifying the time of stroke onset. More reasonable image segmentation and texture extraction methods in radiomics should be used to promote the value of applying machine learning in diverse ethnic backgrounds.

TRIAL REGISTRATION

PROSPERO CRD42022358898; https://www.crd.york.ac.uk/Prospero/display_record.php?RecordID=358898.

Visual bibliometric analysis of electroacupuncture research in stroke treatment: a 20-year overview

Background

Electroacupuncture has been used as a treatment; however, a visual bibliometric analysis has not yet been performed in this field. In this study, we aimed to suggest future research topics and directions related to the field by examining the last 20 years of research trends and hotspots of electroacupuncture in stroke.

Methods

We searched the Web of Science database on electroacupuncture as a treatment for stroke published from 2003 to 2022. We analyzed the papers by annual publication, research fields, nations, affiliations, authors, journals, and keywords. VOSviewer software was used to visualize the bibliometric analysis and results. A total of 440 papers were included in the analysis.

Results

The number of publications has gradually increased every year, and neuroscience has become the most actively studied field. Neural Regeneration Research journal and China had the most publications. Fujian University of Traditional Chinese Medicine, as an affiliated institute, published the most articles. Chen Lidian and Tao Jing presented the largest number of papers, making them the leading contributors in this field. Four clusters were created by analyzing keywords, such as "neuroprotection," "clinical rehabilitation," "neuroplasticity," and "pretreatment-induced tolerance".

Conclusion

This study is the first to analyze the research trends in electroacupuncture as a treatment for stroke using the VOSviewer. It shows the current state of research in the field by visualizing research trends and hotspots. This will help offer reference data for future studies.

A multi-laboratory preclinical trial in rodents to assess treatment candidates for acute ischemic stroke

Human diseases may be modeled in animals to allow preclinical assessment of putative new clinical interventions. Recent, highly publicized failures of large clinical trials called into question the rigor, design, and value of preclinical assessment. We established the Stroke Preclinical Assessment Network (SPAN) to design and implement a randomized, controlled, blinded, multi-laboratory trial for the rigorous assessment of candidate stroke treatments combined with intravascular thrombectomy. Efficacy and futility boundaries in a multi-arm multi-stage statistical design aimed to exclude from further study highly effective or futile interventions after each of four sequential stages. Six independent research laboratories performed a standard focal cerebral ischemic insult in five animal models that included equal numbers of males and females: young mice, young rats, aging mice, mice with diet-induced obesity, and spontaneously hypertensive rats. The laboratories adhered to a common protocol and efficiently enrolled 2615 animals with full data completion and comprehensive animal tracking. SPAN successfully implemented treatment masking, randomization, prerandomization inclusion and exclusion criteria, and blinded assessment of outcomes. The SPAN design and infrastructure provide an effective approach that could be used in similar preclinical, multi-laboratory studies in other disease areas and should help improve reproducibility in translational science.

Unfavorable cerebral venous outflow is associated with futile recanalization in acute ischemic stroke patients

BACKGROUND AND PURPOSE

Mechanical thrombectomy (MT) has proven to be the standard of care for patients with acute ischemic stroke due to large vessel occlusion (AIS-LVO). However, high revascularization rates do not necessarily result in favorable functional outcomes. We aimed to investigate imaging biomarkers associated with futile recanalization, defined as unfavorable functional outcome despite successful recanalization in AIS-LVO patients.

METHODS

A retrospective multicenter cohort study was made of AIS-LVO patients treated by MT. Successful recanalization was defined as modified Thrombolysis in Cerebral Infarction score of 2b-3. A modified Rankin Scale score of 3-6 at 90 days was defined as unfavorable functional outcome. Cortical Vein Opacification Score (COVES) was used to assess venous outflow (VO), and the Tan scale was utilized to determine pial arterial collaterals on admission computed tomography angiography (CTA). Unfavorable VO was defined as COVES ≤ 2. Multivariable regression analysis was performed to investigate vascular imaging factors associated with futile recanalization.

RESULTS

Among 539 patients in whom successful recanalization was achieved, unfavorable functional outcome was observed in 59% of patients. Fifty-eight percent of patients had unfavorable VO, and 31% exhibited poor pial arterial collaterals. In multivariable regression, unfavorable VO was a strong predictor (adjusted odds ratio = 4.79, 95% confidence interval = 2.48-9.23) of unfavorable functional outcome despite successful recanalization.

CONCLUSIONS

We observe that unfavorable VO on admission CTA is a strong predictor of unfavorable functional outcomes despite successful vessel recanalization in AIS-LVO patients. Assessment of VO profiles could help as a pretreatment imaging biomarker to determine patients at risk for futile recanalization.

Non-human primate models of focal cortical ischemia for neuronal replacement therapy

Despite the high prevalence, stroke remains incurable due to the limited regeneration capacity in the central nervous system. Neuronal replacement strategies are highly diverse biomedical fields that attempt to replace lost neurons by utilizing exogenous stem cell transplants, biomaterials, and direct neuronal reprogramming. Although these approaches have achieved encouraging outcomes mostly in the rodent stroke model, further preclinical validation in non-human primates (NHP) is still needed prior to clinical trials. In this paper, we briefly review the recent progress of promising neuronal replacement therapy in NHP stroke studies. Moreover, we summarize the key characteristics of the NHP as highly valuable translational tools and discuss (1) NHP species and their advantages in terms of genetics, physiology, neuroanatomy, immunology, and behavior; (2) various methods for establishing NHP focal ischemic models to study the regenerative and plastic changes associated with motor functional recovery; and (3) a comprehensive analysis of experimentally and clinically accessible outcomes and a potential adaptive mechanism. Our review specifically aims to facilitate the selection of the appropriate NHP cortical ischemic models and efficient prognostic evaluation methods in preclinical stroke research design of neuronal replacement strategies.

MicroRNA-323-5p Involved in Dexmedetomidine Preconditioning Impart Neuroprotection

Background and Objectives: Cerebral ischemia is one of the major preoperative complications. Dexmedetomidine is a well-known sedative-hypnotic agent that has potential organ-protective effects. We examine the miRNAs associated with preconditioning effects of dexmedetomidine in cerebral ischemia. Materials and Methods: Transient infarcts were induced in mice via reperfusion after temporary occlusion of one side of the middle cerebral artery. A subset of these mice was exposed to dexmedetomidine prior to cerebral infarction and miRNA profiling of the whole brain was performed. We administered dexmedetomidine and miRNA-323-5p mimic/inhibitor to oxygen-glucose deprivation/reoxygenation astrocytes. Additionally, we administered miR-323-5p mimic and inhibitor to mice via intracerebroventricular injection 2 h prior to induction of middle cerebral artery occlusion. Results: The infarct volume was significantly lower in the dexmedetomidine-preconditioned mice. Analysis of brain samples revealed an increased expression of five miRNAs and decreased expression of three miRNAs in the dexmedetomidine-pretreated group. The viability of cells significantly increased and expression of miR-323-5p was attenuated in the dexmedetomidine-treated oxygen-glucose deprivation/reoxygenation groups. Transfection with anti-miR-323-5p contributed to increased astrocyte viability. When miRNA-323-5p was injected intraventricularly, infarct volume was significantly reduced when preconditioned with the miR-323-5p inhibitor compared with mimic and negative control. Conclusions: Dexmedetomidine has a protective effect against transient neuronal ischemia-reperfusion injury and eight specific miRNAs were profiled. Also, miRNA-323-5p downregulation has a cell protective effect under ischemic conditions both in vivo and in vitro. Our findings suggest the potential of the miR-323-5p inhibitor as a therapeutic agent against cerebral infarction.

Post-ischemic ubiquitination at the postsynaptic density reversibly influences the activity of ischemia-relevant kinases

Ubiquitin modifications alter protein function and stability, thereby regulating cell homeostasis and viability, particularly under stress. Ischemic stroke induces protein ubiquitination at the ischemic periphery, wherein cells remain viable, however the identity of ubiquitinated proteins is unknown. Here, we employed a proteomics approach to identify these proteins in mice undergoing ischemic stroke. The data are available in a searchable web interface ( https://hochrainerlab.shinyapps.io/StrokeUbiOmics/ ). We detected increased ubiquitination of 198 proteins, many of which localize to the postsynaptic density (PSD) of glutamatergic neurons. Among these were proteins essential for maintaining PSD architecture, such as PSD95, as well as NMDA and AMPA receptor subunits. The largest enzymatic group at the PSD with elevated post-ischemic ubiquitination were kinases, such as CaMKII, PKC, Cdk5, and Pyk2, whose aberrant activities are well-known to contribute to post-ischemic neuronal death. Concurrent phospho-proteomics revealed altered PSD-associated phosphorylation patterns, indicative of modified kinase activities following stroke. PSD-located CaMKII, PKC, and Cdk5 activities were decreased while Pyk2 activity was increased after stroke. Removal of ubiquitin restored kinase activities to pre-stroke levels, identifying ubiquitination as the responsible molecular mechanism for post-ischemic kinase regulation. These findings unveil a previously unrecognized role of ubiquitination in the regulation of essential kinases involved in ischemic injury.

Neuroprotective Effects of Tryptanthrin-6-Oxime in a Rat Model of Transient Focal Cerebral Ischemia

The activation of c-Jun N-terminal kinase (JNK) plays an important role in stroke outcomes. Tryptanthrin-6-oxime (TRYP-Ox) is reported to have high affinity for JNK and anti-inflammatory activity and may be of interest as a promising neuroprotective agent. The aim of this study was to investigate the neuroprotective effects of TRYP-Ox in a rat model of transient focal cerebral ischemia (FCI), which involved intraluminal occlusion of the left middle cerebral artery (MCA) for 1 h. Animals in the experimental group were administered intraperitoneal injections of TRYP-Ox 30 min before reperfusion and 23 and 47 h after FCI. Neurological status was assessed 4, 24, and 48 h following FCI onset. Treatment with 5 and 10 mg/kg of TRYP-Ox decreased mean scores of neurological deficits by 35-49 and 46-67% at 24 and 48 h, respectively. At these doses, TRYP-Ox decreased the infarction size by 28-31% at 48 h after FCI. TRYP-Ox (10 mg/kg) reduced the content of interleukin (IL) 1β and tumor necrosis factor (TNF) in the ischemic core area of the MCA region by 33% and 38%, respectively, and attenuated cerebral edema by 11% in the left hemisphere, which was affected by infarction, and by 6% in the right, contralateral hemisphere 24 h after FCI. TRYP-Ox reduced c-Jun phosphorylation in the MCA pool at 1 h after reperfusion. TRYP-Ox was predicted to have high blood-brain barrier permeability using various calculated descriptors and binary classification trees. Indeed, reactive oxidant production was significantly lower in the brain homogenates from rats treated with TRYP-Ox versus that in control animals. Our data suggest that the neuroprotective activity of TRYP-Ox may be due to the ability of this compound to inhibit JNK and exhibit anti-inflammatory and antioxidant activity. Thus, TRYP-Ox may be considered a promising neuroprotective agent that potentially could be used for the development of new treatment strategies in cerebral ischemia.

Preserving and enhancing mitochondrial function after stroke to protect and repair the neurovascular unit: novel opportunities for nanoparticle-based drug delivery

The neurovascular unit (NVU) is composed of vascular cells, glia, and neurons that form the basic component of the blood brain barrier. This intricate structure rapidly adjusts cerebral blood flow to match the metabolic needs of brain activity. However, the NVU is exquisitely sensitive to damage and displays limited repair after a stroke. To effectively treat stroke, it is therefore considered crucial to both protect and repair the NVU. Mitochondrial calcium (Ca2+) uptake supports NVU function by buffering Ca2+ and stimulating energy production. However, excessive mitochondrial Ca2+ uptake causes toxic mitochondrial Ca2+ overloading that triggers numerous cell death pathways which destroy the NVU. Mitochondrial damage is one of the earliest pathological events in stroke. Drugs that preserve mitochondrial integrity and function should therefore confer profound NVU protection by blocking the initiation of numerous injury events. We have shown that mitochondrial Ca2+ uptake and efflux in the brain are mediated by the mitochondrial Ca2+ uniporter complex (MCUcx) and sodium/Ca2+/lithium exchanger (NCLX), respectively. Moreover, our recent pharmacological studies have demonstrated that MCUcx inhibition and NCLX activation suppress ischemic and excitotoxic neuronal cell death by blocking mitochondrial Ca2+ overloading. These findings suggest that combining MCUcx inhibition with NCLX activation should markedly protect the NVU. In terms of promoting NVU repair, nuclear hormone receptor activation is a promising approach. Retinoid X receptor (RXR) and thyroid hormone receptor (TR) agonists activate complementary transcriptional programs that stimulate mitochondrial biogenesis, suppress inflammation, and enhance the production of new vascular cells, glia, and neurons. RXR and TR agonism should thus further improve the clinical benefits of MCUcx inhibition and NCLX activation by increasing NVU repair. However, drugs that either inhibit the MCUcx, or stimulate the NCLX, or activate the RXR or TR, suffer from adverse effects caused by undesired actions on healthy tissues. To overcome this problem, we describe the use of nanoparticle drug formulations that preferentially target metabolically compromised and damaged NVUs after an ischemic or hemorrhagic stroke. These nanoparticle-based approaches have the potential to improve clinical safety and efficacy by maximizing drug delivery to diseased NVUs and minimizing drug exposure in healthy brain and peripheral tissues.

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.

Insights into Advanced Neurological Dysfunction Mechanisms Following DBS Surgery in Parkinson's Patients: Neuroinflammation and Pyroptosis

Parkinson's disease is a severe neurodegenerative disorder. Currently, deep brain electrical stimulation (DBS) is the first line of surgical treatment. However, serious neurological impairments such as speech disorders, disturbances of consciousness, and depression after surgery limit the efficacy of treatment. In this review, we summarize the recent experimental and clinical studies that have explored the possible causes of neurological deficits after DBS. Furthermore, we tried to identify clues from oxidative stress and pathological changes in patients that could lead to the activation of microglia and astrocytes in DBS surgical injury. Notably, reliable evidence supports the idea that neuroinflammation is caused by microglia and astrocytes, which may contribute to caspase-1 pathway-mediated neuronal pyroptosis. Finally, existing drugs and treatments may partially ameliorate the loss of neurological function in patients following DBS surgery by exerting neuroprotective effects.

Targeting pyroptosis as a preventive and therapeutic approach for stroke

Stroke has caused tremendous social stress worldwide, yet despite decades of research and development of new stroke drugs, most have failed and rt-PA (Recombinant tissue plasminogen activator) is still the accepted treatment for ischemic stroke. the complexity of the stroke mechanism has led to unsatisfactory efficacy of most drugs in clinical trials, indicating that there are still many gaps in our understanding of stroke. Pyroptosis is a programmed cell death (PCD) with inflammatory properties and are thought to be closely associated with stroke. Pyroptosis is regulated by the GSDMD of the gasdermin family, which when cleaved by Caspase-1/Caspase-11 into N-GSDMD with pore-forming activity can bind to the plasma membrane to form small 10-20 nm pores, which would allow the release of inflammatory factors IL-18 and IL-1β before cell rupture, greatly exacerbating the inflammatory response. The pyroptosis occurs mainly in the border zone of cerebral infarction, and glial cells, neuronal cells and brain microvascular endothelial cells (BMECs) all undergo pyroptosis after stroke, which largely exacerbates the breakdown of the blood-brain barrier (BBB) and thus aggravates brain injury. Therefore, pyroptosis may be a good direction for the treatment of stroke. In this review, we focus on the latest mechanisms of action of pyroptosis and the process by which pyroptosis regulates stroke development. We also suggest potential therapeutic stroke drugs that target the pyroptosis pathway, providing additional therapeutic strategies for the clinical management of stroke. The role of pyroptosis after stroke. After stroke, microglia first rush to the damaged area and polarize into M1 and M2 types. Under the influence of various stimuli, microglia undergo pyroptosis, release pro-inflammatory factors, and are converted to the M1 type; astrocytes and neuronal cells also undergo pyroptosis under the stimulation of various pro-inflammatory factors, leading to astrocyte death due to increased osmotic pressure in the membrane, resulting in water absorption and swelling until rupture. BMECs, the main structural component of the BBB, also undergo pyroptosis when stimulated by pro-inflammatory factors released from microglia and astrocytes, leading to the destruction of the structural integrity of the BBB, ultimately causing more severe brain damage. In addition, GSDMD in neutrophils mainly mediate the release of NETs rather than pyroptosis, which also aggravates brain injury. IL-10=interleukin-10; TGF-β = transforming growth factor-β; IL-18=interleukin-18; IL-1β = interleukin-1β; TNF-α = tumor necrosis factor-α; iNOS=induced nitrogen monoxide synthase; MMPs=Matrix metalloproteinases; GSDMD = gasdermin D; BMECs=brain microvascular endothelial cells; BBB = blood-brain barrier.

N-Terminomic Changes in Neurons During Excitotoxicity Reveal Proteolytic Events Associated With Synaptic Dysfunctions and Potential Targets for Neuroprotection

Excitotoxicity, a neuronal death process in neurological disorders such as stroke, is initiated by the overstimulation of ionotropic glutamate receptors. Although dysregulation of proteolytic signaling networks is critical for excitotoxicity, the identity of affected proteins and mechanisms by which they induce neuronal cell death remain unclear. To address this, we used quantitative N-terminomics to identify proteins modified by proteolysis in neurons undergoing excitotoxic cell death. We found that most proteolytically processed proteins in excitotoxic neurons are likely substrates of calpains, including key synaptic regulatory proteins such as CRMP2, doublecortin-like kinase I, Src tyrosine kinase and calmodulin-dependent protein kinase IIβ (CaMKIIβ). Critically, calpain-catalyzed proteolytic processing of these proteins generates stable truncated fragments with altered activities that potentially contribute to neuronal death by perturbing synaptic organization and function. Blocking calpain-mediated proteolysis of one of these proteins, Src, protected against neuronal loss in a rat model of neurotoxicity. Extrapolation of our N-terminomic results led to the discovery that CaMKIIα, an isoform of CaMKIIβ, undergoes differential processing in mouse brains under physiological conditions and during ischemic stroke. In summary, by identifying the neuronal proteins undergoing proteolysis during excitotoxicity, our findings offer new insights into excitotoxic neuronal death mechanisms and reveal potential neuroprotective targets for neurological disorders.

Cerebroprotection in the endovascular era: an update

Despite advances in clinical diagnosis and increasing numbers of patients eligible for revascularisation, ischaemic stroke remains a significant public health concern accounting for 3.3 million deaths annually. In addition to recanalisation therapy, patient outcomes could be improved through cerebroprotection, but all translational attempts have remained unsuccessful. In this narrative review, we discuss potential reasons for those failures. We then outline the diverse, multicellular effects of ischaemic stroke and the complex temporal sequences of the pathophysiological cascade during and following ischaemia, reperfusion, and recovery. This evidence is linked with findings from prior cerebroprotective trials and interpreted for the modern endovascular era. Future cerebroprotective agents that are multimodal and multicellular, promoting cellular and metabolic health to different targets at time points that are most responsive to treatment, might prove more successful.

Combined Therapeutics: Future Opportunities for Co-therapy with Thrombectomy

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

Evolving Stroke Systems of Care: Stroke Diagnosis and Treatment in the Post-Thrombectomy Era

Thrombectomy became the gold-standard treatment of acute ischemic stroke caused by large-vessel occlusions (LVO) in 2015 after five clinical trials published that year demonstrated significantly improved patient outcomes. In subsequent years, advances in stroke systems of care have centered around improving access to and expanding patient eligibility for thrombectomy. The prehospital and acute stroke treatment settings have had the greatest emphasis. Numerous prehospital stroke scales now provide emergency medical services with focused physical exams to identify LVOs, and many devices to non-invasively detect LVO are undergoing clinical testing. Mobile stroke units deployed throughout Western Europe and the USA also show promising results by bringing elements of acute stroke care directly to the patient. Numerous clinical trials since 2015 have aimed to increase candidates for thrombectomy by expanding indications and the eligibility time window. Further optimizations of thrombectomy treatment have focused on the role of thrombolytics and other adjunctive therapies that may promote neuroprotection and neurorecovery. While many of these approaches require further clinical investigation, the next decade shows significant potential for further advances in stroke care.

The Implications of Microglial Regulation in Neuroplasticity-Dependent Stroke Recovery

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