Clinical pharmacological issues in the development of acute stroke therapies

Integrative Approaches in Acute Ischemic Stroke: From Symptom Recognition to Future Innovations

Among the high prevalence of cerebrovascular diseases nowadays, acute ischemic stroke stands out, representing a significant worldwide health issue with important socio-economic implications. Prompt diagnosis and intervention are important milestones for the management of this multifaceted pathology, making understanding the various stroke-onset symptoms crucial. A key role in acute ischemic stroke management is emphasizing the essential role of a multi-disciplinary team, therefore, increasing the efficiency of recognition and treatment. Neuroimaging and neuroradiology have evolved dramatically over the years, with multiple approaches that provide a higher understanding of the morphological aspects as well as timely recognition of cerebral artery occlusions for effective therapy planning. Regarding the treatment matter, the pharmacological approach, particularly fibrinolytic therapy, has its merits and challenges. Endovascular thrombectomy, a game-changer in stroke management, has witnessed significant advances, with technologies like stent retrievers and aspiration catheters playing pivotal roles. For select patients, combining pharmacological and endovascular strategies offers evidence-backed benefits. The aim of our comprehensive study on acute ischemic stroke is to efficiently compare the current therapies, recognize novel possibilities from the literature, and describe the state of the art in the interdisciplinary approach to acute ischemic stroke. As we aspire for holistic patient management, the emphasis is not just on medical intervention but also on physical therapy, mental health, and community engagement. The future holds promising innovations, with artificial intelligence poised to reshape stroke diagnostics and treatments. Bridging the gap between groundbreaking research and clinical practice remains a challenge, urging continuous collaboration and research.

Transcriptome analysis reveals the neuroprotective effect of Dlg4 against fastigial nucleus stimulation-induced ischemia/reperfusion injury in rats

BACKGROUND

Previous studies have demonstrated that electrical stimulation of the cerebellar fastigial nucleus (FNS) can considerably decrease infarction volume and improve neurofunction restoration following cerebral ischemia. Nevertheless, the molecular mechanism of the neuroprotective effect of FNS is still vague.

METHODS

In this study, we developed a rat model of ischemia/reperfusion that included 1 h FNS followed by reperfusion for 3, 6, 12, 24, and 72 h. The expression profile of molecular alterations in brain tissues was obtained by transcriptome sequencing at five different time points. The function and pathway of miRNA expression pattern and core genes were annotated by Allen Brain Atlas, STRING database and Cytoscape software, so as to explore the mechanism of FNS-mediated neuroprotection.

RESULTS

The results indicated that FNS is associated with the neurotransmitter cycle pathway. FNS may regulate the release of monoamine neurotransmitters in synaptic vesicles by targeting the corresponding miRNAs through core Dlg4 gene, stimulate the Alternative polyadenylation (APA) incident's anti -apoptosis effect on the brain, and stimulate the interaction activation of neurons in cerebellum, cortex/thalamus and other brain regions, regulate neurovascular coupling, and reduce cerebral damage.

CONCLUSION

FNS may activate neuronal and neurovascular coupling by regulating the release of neurotransmitters in synaptic vesicles through the methylation of core Dlg4 gene and the corresponding transcription factors and protein kinases, inducing the anti-apoptotic mechanism of APA events. The findings from our investigation offer a new perspective on the way brain tissue responds to FNS-driven neuroprotection.

Neuroprotective Effects of Chlorogenic Acid in a Mouse Model of Intracerebral Hemorrhage Associated with Reduced Extracellular Matrix Metalloproteinase Inducer

Chlorogenic acid (CGA) has been reported to have various biological activities, such as anti-inflammatory, anti-oxidant and anti-apoptosis effects. However, the role of CGA in intracerebral hemorrhage (ICH) and the underlying mechanisms remain undiscovered. The current study aims to investigate the effect of CGA on neuroinflammation and neuronal apoptosis after inhibition of EMMPRIN in a collagenase-induced ICH mouse model. Dose optimization data showed that intraperitoneal administration of CGA (30 mg/kg) significantly attenuated neurological impairments and reduced brain water content at 24 h and 72 h compared with ICH mice given vehicle. Western blot and immunofluorescence analyses revealed that CGA remarkably decreased the expression of extracellular matrix metalloproteinase inducer (EMMPRIN) in perihematomal areas at 72 h after ICH. CGA also reduced the expression of matrix metalloproteinases-2/9 (MMP-2/9) at 72 h after ICH. CGA diminished Evans blue dye extravasation and reduced the loss of zonula occludens-1 (ZO-1) and occludin. CGA-treated mice had fewer activated Iba-1-positive microglia and MPO-positive neutrophils. Finally, CGA suppressed cell death around the hematoma and reduced overall brain injury. These outcomes highlight that CGA treatment confers neuroprotection in ICH likely by inhibiting expression of EMMPRIN and MMP-2/9, and alleviating neuroinflammation, blood–brain barrier (BBB) disruption, cell death and brain injury.

The neuroprotective effects of icariin on ageing, various neurological, neuropsychiatric disorders, and brain injury induced by radiation exposure

Epimedium brevicornum Maxim, a Traditional Chinese Medicine, has been used for the treatment of impotence, sinew and bone disorders, “painful impediment caused by wind-dampness,” numbness, spasms, hypertension, coronary heart disease, menopausal syndrome, bronchitis, and neurasthenia for many years in China. Recent animal experimental studies indicate that icariin, a major bioactive component of epimedium may effectively treat Alzheimer’s disease, cerebral ischemia, depression, Parkinson’s disease, multiple sclerosis, as well as delay ageing. Our recent study also suggested that epimedium extract could exhibit radio-neuro-protective effects and prevent ionizing radiation-induced impairment of neurogenesis. This paper reviewed the pharmacodynamics of icariin in treating different neurodegenerative and neuropsychiatric diseases, ageing, and radiation-induced brain damage. The relevant molecular mechanisms and its anti-neuroinflammatory, anti-apoptotic, anti-oxidant, as well as pro-neurogenesis roles were also discussed.

PRIMED2 Preclinical Evidence Scoring Tool to Assess Readiness for Translation of Neuroprotection Therapies

Many neuroprotective and other therapies for treatment of acute ischemic stroke have failed in translation to human studies, indicating a need for more rigorous, multidimensional quality assessment of the totality of preclinical evidence supporting a therapy prior to conducting human trials. A consensus panel of stroke preclinical model and human clinical trial experts assessed candidate items for the translational readiness scale, compiled from prior instruments (STAIR, ARRIVE, CAMARADES, RoB 2) based on importance, reliability, and feasibility. Once constructed, the tool was applied by two independent raters to four current candidate acute stroke therapies, including two pharmacologic agents [nerinetide and trans-sodium crocetinate] and two device interventions [cathodal transcranial direct current stimulation and fastigial nucleus stimulation]. The Preclinical evidence of Readiness In stroke Models Evaluating Drugs and Devices (PRIMED²) assessment tool rates the totality of evidence available from all reported preclinical animal stroke model studies in 11 domains related to diversity of tested animals, time windows, feasibility of agent route of delivery, and robustness of effect magnitude. Within each content domain, clearly operationalized rules assign strength of evidence ratings of 0–2. When applied to the four assessed candidate agents, inter-rater reliability was high (kappa = 0.88), and each agent showed a unique profile of evidentiary strengths and weaknesses. The PRIMED² assessment tool provides a multidimensional assessment of the cumulative preclinical evidence for a candidate acute stroke therapy on factors judged important for successful basic-to-clinical translation. Further evaluation and refinement of this tool is desirable to improve successful translation of therapies for acute stroke.

Necroptotic-Apoptotic Regulation in an Endothelin-1 Model of Cerebral Ischemia

The primary forms of cell death seen in ischemic stroke are of two major types: a necrotic/necroptotic form, and an apoptotic form that is frequently seen in penumbral regions of injury. Typically apoptotic versus necroptotic programmed cell death is described as competitive in nature, where necroptosis is often described as playing a backup role to apoptosis. In the present study, we examined the relationship between these two forms of cell death in a murine endothelin-1 model of ischemia-reperfusion injury in wildtype and caspase-3 null mice with and without addition of the pharmacologic RIPK1 phosphorylation inhibitor necrostatin-1. Analyses of ischemic brain injury were performed via both cellular and volumetric assessments, electron microscopy, TUNEL staining, activated caspase-3 and caspase-7 staining, as well as CD11b and F4/80 staining. Inhibition of caspase-3 or RIPK1 phosphorylation demonstrates significant neural protective effects which are non-additive and exhibit significant overlap in protected regions. Interestingly, morphologic analysis of the cortex demonstrates reduced apoptosis following RIPK1 inhibition. Consistent with this, RIPK1 inhibition reduces the levels of both caspase-3 and caspase-7 activation. Additionally, this protection appears independent of secondary inflammatory mediators. Together, these observations demonstrate that the necroptotic protein RIPK1 modifies caspase-3/-7 activity, ultimately resulting in decreased neuronal apoptosis. These findings thus modify the traditional exclusionary view of apoptotic/necroptotic signaling, revealing a new form of interaction between these dominant forms of cell death.

Central Nervous System Electrical Stimulation for Neuroprotection in Acute Cerebral Ischemia: Meta-Analysis of Preclinical Studies

Background and Purpose- Brain electrical stimulation, widely studied to facilitate recovery from stroke, has also been reported to confer direct neuroprotection in preclinical models of acute cerebral ischemia. Systematic review of controlled preclinical acute cerebral ischemia studies would aid in planning for initial human clinical trials. Methods- A systematic Medline search identified controlled, preclinical studies of central nervous system electrical stimulation in acute cerebral ischemia. Studies were categorized among 6 stimulation strategies. Three strategies applied different stimulation types to tissues within the ischemic zone (cathodal hemispheric stimulation [CHS], anodal hemispheric stimulation, and pulsed hemispheric stimulation), and 3 strategies applied deep brain stimulation to different neuronal targets remote from the ischemic zone (fastigial nucleus stimulation, subthalamic vasodilator area stimulation, and dorsal periaqueductal gray stimulation). Random-effects meta-analysis assessed electrical stimulation modification of final infarct volume. Study-level risk of bias and intervention-level readiness-for-translation were assessed using formal rating scales. Results- Systematic search identified 28 experiments in 21 studies, including a total of 350 animals, of electrical stimulation in preclinical acute cerebral ischemia. Overall, in animals undergoing electrical stimulation, final infarct volumes were reduced by 37% (95% CI, 34%-40%; P<0.001), compared with control. There was evidence of heterogeneity of efficacy among stimulation strategies (I²=93.1%, P_{heterogeneity}<0.001). Among the within-ischemic zone stimulation strategies, only CHS significantly reduced the infarct volume (27 %; 95% CI, 22%-33%; P<0.001); among the remote-from ischemic zone approaches, all (fastigial nucleus stimulation, subthalamic vasodilator area stimulation, and dorsal periaqueductal gray stimulation) reduced infarct volumes by approximately half. On formal rating scales, CHS studies had the lowest risk of bias, and CHS had the highest overall quality of intervention-level evidence supporting readiness to proceed to clinical testing. Conclusions- Electrical stimulation reduces final infarct volume across preclinical studies. CHS shows the most robust evidence and is potentially appropriate for progression to early-stage human clinical trial testing as a promising neuroprotective intervention.

Paradigm Shift to Neuroimmunomodulation for Translational Neuroprotection in Stroke

The treatment of acute ischemic stroke is still an unresolved clinical problem since the only approved therapeutic intervention relies on early blood flow restoration through pharmacological thrombolysis, mechanical thrombus removal, or a combination of both strategies. Due to their numerous complications and to the narrow time-window for the intervention, only a minority of stroke patients can actually benefit from revascularization procedures, highlighting the urgent need of identifying novel strategies to prevent the progression of an irreversible damage in the ischemic penumbra. During the past three decades, the attempts to target the pathways implicated in the ischemic cascade (e.g., excitotoxicity, calcium channels overactivation, reactive oxygen species (ROS) production) have failed in the clinical setting. Based on a better understanding of the pathobiological mechanisms and on a critical reappraisal of most failed trials, numerous findings from animal studies have demonstrated that targeting the immune system may represent a promising approach to achieve neuroprotection in stroke. In particular, given the dualistic role of distinct components of both the innate and adaptive arms of the immune system, a strategic intervention should be aimed at establishing the right equilibrium between inflammatory and reparative mechanisms, taking into consideration their spatio-temporal recruitment after the ischemic insult. Thus, the application of immunomodulatory drugs and their ability to ameliorate outcomes deserve validation in patients with acute ischemic stroke.

A single injection of liposomal asialo-erythropoietin improves motor function deficit caused by cerebral ischemia/reperfusion

Modification of the liposomal surface with a targeting molecule is a promising approach for the targeted delivery of therapeutics. Asialo-erythropoietin (AEPO) is a potent tool for targeting an ischemic region by binding to the EPO receptors on neuronal cells. Additionally, it shows a strong cytoprotective effect against programed cell death. Hence, AEPO-modified liposomes appear likely to have both a neuronal-targeting character and a neuroprotective effect on cerebral ischemic injury. In this study, we assessed the targeting ability of AEPO-modified PEGylated liposomes (AEPO-liposomes) to ischemic region and their improvement effect on neurological deficits induced by ischemia/reperfusion (I/R) in transient middle cerebral artery occlusion (t-MCAO) rats. Immunohistological analysis showed that the AEPO-liposomes given immediately after reperfusion extravasated into the ischemic region and attached strongly to neuronal cells. Also, neuronal nuclei (NeuN) staining was clearly visible only in the AEPO-liposome-treated group, suggesting that AEPO-liposomes protected neuronal cells from ischemia/reperfusion-induced damage. Moreover, a single administration of low-dose AEPO-liposomes significantly improved the neurological deficit compared to vehicle and free-AEPO treatment at 7 days after injection. In conclusion, AEPO-liposomes have clear potential as a neuroprotectant after stroke and as a DDS device targeting ischemic regions.

Chlorogenic acid ameliorates brain damage and edema by inhibiting matrix metalloproteinase-2 and 9 in a rat model of focal cerebral ischemia

Chlorogenic acid (CGA) has been reported to have various beneficial effects on the cardiovascular and central nervous systems. The purpose of the current study was to investigate whether CGA has protective effects against cerebral ischemia and whether these effects are due to modification of brain edema-related vascular factors. In a rat model of transient middle cerebral artery occlusion (MCAo, 2h of occlusion followed by 22 h of reperfusion), we measured infarct volume and performed behavioral test to evaluate the effects of CGA on brain damage and sensory-motor functional deficits. Brain water content and Evans blue extravasation were measured to evaluate brain edema and blood brain barrier (BBB) damage. Lipid peroxidation (LPO) and the expressions and activities of matrix metalloproteinase (MMP)-2 and MMP-9 were measured to investigate the mechanisms of action. Intraperitoneal injection of CGA (3, 10, and 30 mg/kg) at 0 h and 2h after MCAo dose-dependently reduced infarct volume and sensory-motor functional deficits. It also reduced brain water content and Evans blue extravasation. Mechanistically, CGA reduced LPO and MMPs expressions and activities. These results suggest that CGA reduces brain damage, BBB damage and brain edema by radical scavenging activity and the inhibitory effects on MMP-2 and MMP-9.

Neuroinflammation and cerebrovascular disease in old age: a translational medicine perspective

The incidence of cerebrovascular disease is highest in the elderly population. However, the pathophysiological mechanisms of brain response to cerebral ischemia in old age are currently poorly understood. Ischemic changes in the commonly used young animal stroke models do not reflect the molecular changes associated with the aged brain. Neuroinflammation and oxidative stress are important pathogenic processes occurring during the acute phase of cerebral ischemia. Free radical generation is also implicated in the aging process, and the combination of these effects in elderly stroke patients could explain the higher risk of morbidity and mortality. A better understanding of stroke pathophysiology in the elderly patient would assist in the development of new therapeutic strategies for this vulnerable age group. With the increasing use of reperfusion therapies, inflammatory pathways and oxidative stress remain attractive therapeutic targets for the development of adjuvant neuroprotective agents. This paper will discuss these molecular aspects of acute stroke and senescence from a bench-to-bedside research perspective.

Mucosal tolerance to E-selectin promotes the survival of newly generated neuroblasts via regulatory T-cell induction after stroke in spontaneously hypertensive rats

Neuroblasts in the subventricular zone (SVZ) proliferate markedly after brain ischemia, and migrate to the site of injury along with blood vessels. However, a large fraction of stroke-generated neuroblasts die shortly after being born, in part, because of local inflammation. In spontaneously hypertensive rats (SHRs) subjected to permanent middle cerebral artery occlusion, we primed E-selectin-specific regulatory T cells (Tregs) by repetitive intranasal administration of recombinant E-selectin to target local secretion of immunomodulating, antiinflammatory cytokines to activating blood vessel segments. E-selectin-tolerized SHRs had decreased infarction volumes, and increased numbers of Tregs in the cervical lymph nodes and ischemic brain. The brain Tregs were distributed primarily in periinfarct regions. E-selectin tolerization did not alter cellular proliferation in the ipsilateral SVZ after stroke, but the expression of tumor necrosis factor on vascular niche blood vessels was suppressed and both doublecortin protein levels and the number of newly generated neuroblasts or neurons were increased in the brain. This enhanced survival of neural progenitor cells and neurons was paralleled by improved functional performance. These studies suggest that E-selectin-specific Tregs can modulate the efficacy of neurogenesis after ischemia and promote repair after brain injury.

Nitrones as therapeutics

Nitrones have the general chemical formula X-CH=NO-Y. They were first used to trap free radicals in chemical systems and then subsequently in biochemical systems. More recently several nitrones, including alpha-phenyl-tert-butylnitrone (PBN), have been shown to have potent biological activity in many experimental animal models. Many diseases of aging, including stroke, cancer development, Parkinson disease, and Alzheimer disease, are known to have enhanced levels of free radicals and oxidative stress. Some derivatives of PBN are significantly more potent than PBN and have undergone extensive commercial development for stroke. Recent research has shown that PBN-related nitrones also have anti-cancer activity in several experimental cancer models and have potential as therapeutics in some cancers. Also, in recent observations nitrones have been shown to act synergistically in combination with antioxidants in the prevention of acute acoustic-noise-induced hearing loss. The mechanistic basis of the potent biological activity of PBN-related nitrones is not known. Even though PBN-related nitrones do decrease oxidative stress and oxidative damage, their potent biological anti-inflammatory activity and their ability to alter cellular signaling processes cannot readily be explained by conventional notions of free radical trapping biochemistry. This review is focused on our studies and others in which the use of selected nitrones as novel therapeutics has been evaluated in experimental models in the context of free radical biochemical and cellular processes considered important in pathologic conditions and age-related diseases.

The development of stroke therapeutics: promising mechanisms and translational challenges

Ischemic stroke is the second most common cause of death worldwide and a major cause of disability. Intravenous thrombolysis with rt-PA remains the only available acute therapy in patients who present within 3h of stroke onset other than the recently approved mechanical MERCI device, substantiating the high unmet need in available stroke therapeutics. The development of successful therapeutic strategies remains challenging, as evidenced by the continued failures of new therapies in clinical trials. However, significant lessons have been learned and this knowledge is currently being incorporated into improved pre-clinical and clinical design. Furthermore, advancements in imaging technologies and continued progress in understanding biological pathways have established a prolonged presence of salvageable penumbral brain tissue and have begun to elucidate the natural repair response initiated by ischemic insult. We review important past and current approaches to drug development with an emphasis on implementing principles of translational research to achieve a rigorous conversion of knowledge from bench to bedside. We highlight current strategies to protect and repair brain tissue with the promise to provide longer therapeutic windows, preservation of multiple tissue compartments and improved clinical success.

Pathways to ischemic neuronal cell death: are sex differences relevant?

We have known for some time that the epidemiology of human stroke is sexually dimorphic until late in life, well beyond the years of reproductive senescence and menopause. Now, a new concept is emerging: the mechanisms and outcome of cerebral ischemic injury are influenced strongly by biological sex as well as the availability of sex steroids to the brain. The principal mammalian estrogen (17 β estradiol or E2) is neuroprotective in many types of brain injury and has been the major focus of investigation over the past several decades. However, it is becoming increasingly clear that although hormones are a major contributor to sex-specific outcomes, they do not fully account for sex-specific responses to cerebral ischemia. The purpose of this review is to highlight recent studies in cell culture and animal models that suggest that genetic sex determines experimental stroke outcome and that divergent cell death pathways are activated after an ischemic insult. These sex differences need to be identified if we are to develop efficacious neuroprotective agents for use in stroke patients.