The choroid plexus maintains adult brain ventricles and subventricular zone neuroblast pool, which facilitates poststroke neurogenesis.

The brain's neuroreparative capacity after injuries such as ischemic stroke is partly contained in the brain's neurogenic niches, primarily the subventricular zone (SVZ), which lies in close contact with the cerebrospinal fluid (CSF) produced by the choroid plexus (ChP). Despite the wide range of their proposed functions, the ChP/CSF remain among the most understudied compartments of the central nervous system (CNS). Here, we report a mouse genetic tool (the ROSA26iDTR mouse line) for noninvasive, specific, and temporally controllable ablation of CSF-producing ChP epithelial cells to assess the roles of the ChP and CSF in brain homeostasis and injury. Using this model, we demonstrate that ChP ablation causes rapid and permanent CSF volume loss in both aged and young adult brains, accompanied by disruption of ependymal cilia bundles. Surprisingly, ChP ablation did not result in overt neurological deficits at 1 mo postablation. However, we observed a pronounced decrease in the pool of SVZ neuroblasts (NBs) following ChP ablation, which occurs due to their enhanced migration into the olfactory bulb. In the middle cerebral artery occlusion model of ischemic stroke, NB migration into the lesion site was also reduced in the CSF-depleted mice. Thus, our study establishes an important role of ChP/CSF in regulating the regenerative capacity of the adult brain under normal conditions and after ischemic stroke.

Aquaporin-4 deletion leads to reduced infarct volume and increased peri-infarct astrocyte reactivity in a mouse model of cortical stroke.

Aquaporin-4 (AQP4) is the main water channel in brain and is enriched in perivascular astrocyte processes abutting brain microvessels. There is a rich literature on the role of AQP4 in experimental stroke. While its role in oedema formation following middle cerebral artery occlusion (MCAO) has been studied extensively, its specific impact on infarct volume remains unclear. This study investigated the effects of total and partial AQP4 deletion on infarct volume in mice subjected to distal medial cerebral artery (dMCAO) occlusion. Compared to MCAO, this model induces smaller infarcts confined to neocortex, and less oedema. We show that AQP4 deletion significantly reduced infarct volume as assessed 1 week after dMCAO, suggesting that the role of AQP4 in stroke goes beyond its effect on oedema formation and dissolution. The reduction in infarct volume was associated with increased astrocyte reactivity in the peri-infarct areas. No significant differences were observed in the number of microglia among the genotypes. These findings provide new insights in the role of AQP4 in ischaemic injury indicating that AQP4 affects both infarct volume and astrocyte reactivity in the peri-infarct zone. KEY POINTS: Aquaporin-4 (AQP4) is the main water channel in brain and is enriched in perivascular astrocyte processes abutting microvessels. A rich literature exists on the role of AQP4 in oedema formation following middle cerebral artery occlusion (MCAO). We investigated the effects of total and partial AQP4 deletion on infarct volume in mice subjected to distal medial cerebral artery occlusion (dMCAO), a model inducing smaller infarcts confined to neocortex and less oedema compared to MCAO. AQP4 deletion significantly reduced infarct volume 1 week after dMCAO, suggesting a broader role for AQP4 in stroke beyond oedema formation. The reduction in infarct volume was associated with increased astrocyte reactivity in the peri-infarct areas, while no significant differences were observed in the number of microglia among the genotypes. These findings provide new insights into the role of AQP4 in stroke, indicating that AQP4 affects both infarct volume and astrocyte reactivity in the peri-infarct zone.

Emerging Roles of Exosomes in Stroke Therapy.

Stroke is the number one cause of morbidity in the United States and number two cause of death worldwide. There is a critical unmet medical need for more effective treatments of ischemic stroke, and this need is increasing with the shift in demographics to an older population. Recently, several studies have reported the therapeutic potential of stem cell-derived exosomes as new candidates for cell-free treatment in stoke. This review focuses on the use of stem cell-derived exosomes as a potential treatment tool for stroke patients. Therapy using exosomes can have a clear clinical advantage over stem cell transplantation in terms of safety, cost, and convenience, as well as reducing bench-to-bed latency due to fewer regulatory milestones. In this review article, we focus on (1) the therapeutic potential of exosomes in stroke treatment, (2) the optimization process of upstream and downstream production, and (3) preclinical application in a stroke animal model. Finally, we discuss the limitations and challenges faced by exosome therapy in future clinical applications.

Nuclear magnetic resonance spectroscopy reveals biomarkers of stroke recovery in a mouse model of obesity-associated type 2 diabetes.

Obesity and Type 2 diabetes (T2D) are known to exacerbate cerebral injury caused by stroke. Metabolomics can provide signatures of metabolic disease, and now we explored whether the analysis of plasma metabolites carries biomarkers of how obesity and T2D impact post-stroke recovery. Male mice were fed a high-fat diet (HFD) for 10 months leading to development of obesity with T2D or a standard diet (non-diabetic mice). Then, mice were subjected to either transient middle cerebral artery occlusion (tMCAO) or sham surgery and allowed to recover on standard diet for 2 months before serum samples were collected. Nuclear magnetic resonance (NMR) spectroscopy of serum samples was used to investigate metabolite signals and metabolic pathways that were associated with tMCAO recovery in either T2D or non-diabetic mice. Overall, after post-stroke recovery there were different serum metabolite profiles in T2D and non-diabetic mice. In non-diabetic mice, which show full neurological recovery after stroke, we observed a reduction of isovalerate, and an increase of kynurenate, uridine monophosphate, gluconate and N6-acetyllysine in tMCAO relative to sham mice. In contrast, in mice with T2D, which show impaired stroke recovery, there was a reduction of N,N-dimethylglycine, succinate and proline, and an increase of 2-oxocaproate in serum of tMCAO versus sham mice. Given the inability of T2D mice to recover from stroke, in contrast with non-diabetic mice, we propose that these specific metabolite changes following tMCAO might be used as biomarkers of neurophysiological recovery after stroke in T2D.

Stem cell grafts enhance endogenous extracellular vesicle expression in the stroke brain.

Endogenous brain repair occurs following an ischemic stroke but is transient, thus unable to fully mount a neuroprotective response against the evolving secondary cell death. Finding a treatment strategy that may render robust and long-lasting therapeutic effects stands as a clinically relevant therapy for stroke. Extracellular vesicles appear to be upregulated after stroke, which may represent a candidate target for neuroprotection. In this study, we probed whether transplanted stem cells could enhance the expression of extracellular vesicles to afford stable tissue remodeling in the ischemic stroke brain. Aged rats were initially exposed to the established ischemic stroke model of middle cerebral artery occlusion then received intravenous delivery of either bone marrow-derived mesenchymal stem cell transplantation or vehicle. A year later, the animals were assayed for brain damage, inflammation, and extracellular vesicle expression. Our findings revealed that while core infarction was not reduced, the stroke animals transplanted with stem cells displayed a significant reduction in peri-infarct cell loss that coincided with downregulated Iba1-labeled inflammatory cells and upregulated CD63-positive extracellular vesicles that appeared to be co-localized with GFAP-positive astrocytes. Interestingly, grafted stem cells were not detected at one year post-transplantation period, suggesting that the extracellular vesicles likely originated within the host brain. That long-lasting functional benefits persisted in the absence of surviving transplanted stem cells, but with upregulation of endogenous extracellular vesicles, advances the concept that transplantation of stem cells acutely after stroke propels host extracellular vesicles to the ischemic brain, altogether promoting chronic brain remodeling.

Exploring the Role of MMP-9 and MMP-9/TIMP-1 Ratio in Subacute Stroke Recovery: A Prospective Observational Study.

Despite the significant changes that unfold during the subacute phase of stroke, few studies have examined recovery abilities during this critical period. As neuroinflammation subsides and tissue degradation diminishes, the processes of neuroplasticity and angiogenesis intensify. An important factor in brain physiology and pathology, particularly neuroplasticity, is matrix metalloproteinase 9 (MMP-9). Its activity is modulated by tissue inhibitors of metalloproteinases (TIMPs), which impede substrate binding and activity by binding to its active sites. Notably, TIMP-1 specifically targets MMP-9 among other matrix metalloproteinases (MMPs). Our present study examines whether MMP-9 may play a beneficial role in psychological functions, particularly in alleviating depressive symptoms and enhancing specific cognitive domains, such as calculation. It appears that improvements in depressive symptoms during rehabilitation were notably linked with baseline MMP-9 plasma levels (r = -0.36, p = 0.025), and particularly so with the ratio of MMP-9 to TIMP-1, indicative of active MMP-9 (r = -0.42, p = 0.008). Furthermore, our findings support previous research demonstrating an inverse relationship between pre-rehabilitation MMP-9 serum levels and post-rehabilitation motor function. Crucially, our study emphasizes a positive correlation between cognition and motor function, highlighting the necessity of integrating both aspects into rehabilitation planning. These findings demonstrate the potential utility of MMP-9 as a prognostic biomarker for delineating recovery trajectories and guiding personalized treatment strategies for stroke patients during the subacute phase.

Protection of blood-brain barrier by endothelial DAPK1 deletion after stroke.

Death-associated protein kinase (DAPK) 1 is a critical mediator for neuronal cell death in cerebral ischemia, but its role in blood-brain barrier (BBB) disruption is incompletely understood. Here, we found that endothelial-specific deletion of Dapk1 using Tie2 Cre protected the brain of Dapk1fl/fl mice against middle cerebral artery occlusion (MCAO), characterized by mitigated Evans blue dye (EBD) extravasation, reduced infarct size and improved behavior. In vitro experiments also indicated that DAPK1 deletion inhibited oxygen-glucose deprivation (OGD)-induced tight junction alteration between cerebral endothelial cells (CECs). Mechanistically, we revealed that DAPK1-DAPK3 interaction activated cytosolic phospholipase A2 (cPLA2) in OGD-stimulated CECs. Our results thus suggest that inhibition of endothelial DAPK1 specifically prevents BBB damage after stroke.

CRHR1 antagonist alleviated depression-like behavior by downregulating p62 in a rat model of post-stroke depression.

Post-stroke depression (PSD) is a complication of cerebrovascular disease, which can increase mortality after stroke. CRH is one of the main signaling peptides released after activation of the hypothalamic-pituitary-adrenal (HPA) axis in response to stress. It affects synaptic plasticity by regulating inflammation, oxidative stress and autophagy in the central nervous system. And the loss of spines exacerbates depression-like behavior. Therefore, synaptic deficits induced by CRH may be related to post-stroke depression. However, the underlying mechanism remains unclear. The Keap1-Nrf2 complex is one of the core components of the antioxidant response. As an autophagy associated protein, p62 participates in the Keap1-NrF2 pathway through its Keap1 interaction domain. Oxidative stress is involved in the feedback regulation between Keap1-Nrf2 pathway and p62.However, whether the relationship between CRH and the Keap1-Nrf2-p62 pathway is involved in PSD remains unknown. This study found that serum levels of CRH in 22 patients with PSD were higher than those in healthy subjects. We used MCAO combined with CUMS single-cage SD rats to establish an animal model of PSD. Animal experiments showed that CRHR1 antagonist prevented synaptic loss in the hippocampus of PSD rats and alleviated depression-like behavior. CRH induced p62 accumulation in the prefrontal cortex of PSD rats through CRHR1. CRHR1 antagonist inhibited Keap1-Nrf2-p62 pathway by attenuating oxidative stress. In addition, we found that abnormal accumulation of p62 induces PSD. It alleviates depression-like behavior by inhibiting the expression of p62 and promoting the clearance of p62 in PSD rats. These findings can help explore the pathogenesis of PSD and design targeted treatments for PSD.

[123I]CLINDE SPECT as a neuroinflammation imaging approach in a rat model of stroke.

Poststroke neuroinflammation exacerbates disease progression. [11C]PK11195-positron emission tomography (PET) imaging has been used to visualize neuroinflammation; however, its short half-life of 20 min limits its clinical use. [123I]CLINDE has a longer half-life (13h); therefore, [123I]CLINDE-single-photon emission computed tomography (SPECT) imaging is potentially more practical than [11C]PK11195-PET imaging in clinical settings. The objectives of this study were to 1) validate neuroinflammation imaging using [123I]CLINDE and 2) investigate the mechanisms underlying stroke in association with neuroinflammation using multimodal techniques, including magnetic resonance imaging (MRI), gas-PET, and histological analysis, in a rat model of ischemic stroke, that is, permanent middle cerebral artery occlusion (pMCAo). At 6 days post-pMCAo, [123I]CLINDE-SPECT considerably corresponded to the immunohistochemical images stained with the CD68 antibody (a marker for microglia/microphages), comparable to the level observed in [11C]PK11195-PET images. In addition, the [123I]CLINDE-SPECT images corresponded well with autoradiography images. Rats with severe infarcts, as defined by MRI, exhibited marked neuroinflammation in the peri-infarct area and less neuroinflammation in the ischemic core, accompanied by a substantial reduction in the cerebral metabolic rate of oxygen (CMRO2) in 15O-gas-PET. Rats with moderate-to-mild infarcts exhibited neuroinflammation in the ischemic core, where CMRO2 levels were mildly reduced. This study demonstrates that [123I]CLINDE-SPECT imaging is suitable for neuroinflammation imaging and that the distribution of neuroinflammation varies depending on the severity of infarction.

Serum protein profiling reveals mechanism of activated thrombus formation in patients with stroke and atrial fibrillation.

Stroke is an acute cerebrovascular disease in which blood flow to the brain is suddenly disrupted, causing damage to nerve cells. It involves complex and diverse pathophysiological processes and the treatment strategies are also diverse. The treatment for patients with stroke and atrial fibrillation (AF) is aimed at suppressing thrombus formation and migration. However, information regarding the protein networking involved in different thrombus formation pathways in patients with AF and stroke is insufficient. We performed protein profiling of patients with ischemic stroke with and without AF to investigate the mechanisms of thrombus formation and its pathophysiological association while providing helpful information for treating and managing patients with AF. These two groups were compared to identify the protein networks related to thrombus formation in AF. We observed that patients with ischemic stroke and AF had activated inflammatory responses induced by C-reactive protein, lipopolysaccharide-binding protein, and alpha-1-acid glycoprotein 1. In contrast, thyroid hormones were increased due to a decrease in transthyretin and retinol-binding protein 4 levels. The mechanism underlying enhanced cardiac activity, vasodilation, and the resulting thrombosis pathway were confirmed in AF. These findings will play an essential role in improving the prevention and treatment of AF-related stroke.

The P2X7 Hypothesis of Central Post-Stroke Pain.

The present study examined how P2X7 receptor knockout (KO) modulates central post-stroke pain (CPSP) induced by lesions of the ventrobasal complex (VBC) of the thalamus in behaviors, molecular levels, and electrical recording tests. Following the experimental procedure, the wild-type and P2X7 receptor KO mice were injected with 10 mU/0.2 µL type IV collagenase in the VBC of the thalamus to induce an animal model of stroke-like thalamic hemorrhage. Behavioral data showed that the CPSP group induced thermal and mechanical pain. The P2X7 receptor KO group showed reduced thermal and mechanical pain responses compared to the CPSP group. Molecular assessments revealed that the CPSP group had lower expression of NeuN and KCC2 and higher expression of GFAP, IBA1, and BDNF. The P2X7 KO group showed lower expression of GFAP, IBA1, and BDNF but nonsignificant differences in KCC2 expression than the CPSP group. The expression of NKCC1, GABAa receptor, and TrkB did not differ significantly between the control, CPSP, and P2X7 receptor KO groups. Muscimol, a GABAa agonist, application increased multiunit numbers for monitoring many neurons and [Cl-] outflux in the cytosol in the CPSP group, while P2X7 receptor KO reduced multiunit activity and increased [Cl-] influx compared to the CPSP group. P2X4 receptor expression was significantly decreased in the 100 kDa but not the 50 kDa site in the P2X7 receptor KO group. Altogether, the P2X7 hypothesis of CPSP was proposed, wherein P2X7 receptor KO altered the CPSP pain responses, numbers of astrocytes and microglia, CSD amplitude of the anterior cingulate cortex and the medial dorsal thalamus, BDNF expression, [Cl-] influx, and P2X4 expression in 100 kDa with P2X7 receptors. The present findings have implications for the clinical treatment of CPSP symptoms.

Toxin-derived peptides: An unconventional approach to alleviating cerebral stroke burden and neurobehavioral impairments.

Cerebral stroke is a pressing global health concern, ranking as the second leading cause of mortality and resulting in persistent neurobehavioral impairments. Cerebral strokes, triggered by various embolic events, initiate complex signaling pathways involving neuroexcitotoxicity, ionic imbalances, inflammation, oxidative stress, acidosis, and mitochondrial dysfunction, leading to programmed cell death. Currently, the FDA has approved tissue plasminogen activator as a relatively benign intervention for cerebral stroke, leaving a significant treatment gap. However, a promising avenue has emerged from Earth's toxic creatures. Animal venoms harbor bioactive molecules, particularly neuropeptides, with potential in innovative healthcare applications. These venomous components, affecting ion channels, receptors, and transporters, encompass neurochemicals, amino acids, and peptides, making them prime candidates for treating cerebral ischemia and neurological disorders. This review explores the composition, applications, and significance of toxin-derived peptides as viable therapeutic agents. It also investigates diverse toxins from select venomous creatures, with the primary objective of shedding light on current stroke treatments and paving the way for pioneering therapeutic strategies capable of addressing neurobehavioral deficits.

Astrocytic Slc4a4 regulates blood-brain barrier integrity in healthy and stroke brains via a CCL2-CCR2 pathway and NO dysregulation.

Astrocytes play vital roles in blood-brain barrier (BBB) maintenance, yet how they support BBB integrity under normal or pathological conditions remains poorly defined. Recent evidence suggests that ion homeostasis is a cellular mechanism important for BBB integrity. In the current study, we investigated the function of an astrocyte-specific pH regulator, Slc4a4, in BBB maintenance and repair. We show that astrocytic Slc4a4 is required for normal astrocyte morphological complexity and BBB function. Multi-omics analyses identified increased astrocytic secretion of CCL2 coupled with dysregulated arginine-NO metabolism after Slc4a4 deletion. Using a model of ischemic stroke, we found that loss of Slc4a4 exacerbates BBB disruption, which was rescued by pharmacological or genetic inhibition of the CCL2-CCR2 pathway in vivo. Together, our study identifies the astrocytic Slc4a4-CCL2 and endothelial CCR2 axis as a mechanism controlling BBB integrity and repair, while providing insights for a therapeutic approach against BBB-related CNS disorders.

Gastrodin combined with electroacupuncture prevents the development of cerebral ischemia via rebalance of brain-derived neurotrophic factor and interleukin-6 in stroke model rats.

Traditional Chinese medicine (TCM) has long been used to treat various diseases, including cerebral ischemia. The specific molecular mechanism of TCM in the treatment of cerebral ischemia, however, is still unclear. This study investigated the effects of gastrodin, electroacupuncture and their combination on cerebral ischemic rats. We used Nissl staining, immunohistochemical staining and immunoblotting to detect the expression changes of brain-derived neurotrophic factor (BDNF) and interleukin-6 (IL-6) in the frontal cortex. The results showed that the combination therapy of gastrodin and electroacupuncture significantly increased the number of Nissl-positive neurons and improved cell morphology compared with other groups. Mechanistically, we found that the combination of gastrodin and electroacupuncture treatment group can restore the abnormal morphology of neuronal cells caused by cerebral ischemia by rebalancing the expression levels of BDNF and IL-6. Our research indicates that gastrodin combined with electroacupuncture has a significant protective effect on cerebral ischemic injury in rats, possibly by regulating the expression of BDNF and IL-6. This combination therapy is superior to single-drug or electroacupuncture therapy.

Recent advances in potential therapeutic targets of ferroptosis­associated pathways for the treatment of stroke (Review).

Stroke is a severe neurological disease that is associated with high rates of morbidity and mortality, and the underlying pathological processes are complex. Ferroptosis fulfills a significant role in the progression and treatment of stroke. It is well established that ferroptosis is a type of programmed cell death that is distinct from other forms or types of cell death. The process of ferroptosis involves multiple signaling pathways and regulatory mechanisms that interact with mechanisms inherent to stroke development. Inducers and inhibitors of ferroptosis have been shown to exert a role in the onset of this cell death process. Furthermore, it has been shown that interfering with ferroptosis affects the occurrence of stroke, indicating that targeting ferroptosis may offer a promising therapeutic approach for treating patients of stroke. Hence, the present review aimed to summarize the latest progress that has been made in terms of using therapeutic interventions for ferroptosis as treatment targets in cases of stroke. It provides an overview of the relevant pathways and molecular mechanisms that have been investigated in recent years, highlighting the roles of inducers and inhibitors of ferroptosis in stroke. Additionally, the intervention potential of various types of Traditional Chinese Medicine is also summarized. In conclusion, the present review provides a comprehensive overview of the potential therapeutic targets afforded by ferroptosis­associated pathways in stroke, offering new insights into how ferroptosis may be exploited in the treatment of stroke.

Insight into the pathophysiological advances and molecular mechanisms underlying cerebral stroke: current status.

Molecular pathways involved in cerebral stroke are diverse. The major pathophysiological events that are observed in stroke comprises of excitotoxicity, oxidative stress, mitochondrial damage, endoplasmic reticulum stress, cellular acidosis, blood-brain barrier disruption, neuronal swelling and neuronal network mutilation. Various biomolecules are involved in these pathways and several major proteins are upregulated and/or suppressed following stroke. Different types of receptors, ion channels and transporters are activated. Fluctuations in levels of various ions and neurotransmitters have been observed. Cells involved in immune responses and various mediators involved in neuro-inflammation get upregulated progressing the pathogenesis of the disease. Despite of enormity of the problem, there is not a single therapy that can limit infarction and neurological disability due to stroke. This is because of poor understanding of the complex interplay between these pathophysiological processes. This review focuses upon the past to present research on pathophysiological events that are involved in stroke and various factors that are leading to neuronal death following cerebral stroke. This will pave a way to researchers for developing new potent therapeutics that can aid in the treatment of cerebral stroke.

Spinal lipocalin 2 as a factor in the development of central post-stroke pain.

Central poststroke pain (CPSP) is a type of central neuropathic pain whose mechanisms remain unknown. Recently, we showed that activated astrocytes and microglial cells are present in the spinal cord of CPSP model mice. Activated glial cells exacerbate cerebral ischemic pathology by increasing the expression of inflammatory factors. However, the involvement of spinal glial cells in CPSP remains unknown. We hypothesized that spinal glial cell-derived molecules cause hyperexcitability or promoted the development of CPSP. In this study, we identified glial cell-derived factors involved in the development of CPSP using a bilateral common carotid occlusion (BCAO)-induced CPSP mouse model. Male ddY mice were subjected to BCAO for 30 min. The von Frey test assessed mechanical hypersensitivity in the right hind paw of mice. BCAO mice showed hypersensitivity to mechanical stimuli and astrocyte activation in the spinal cord 3 days after treatment. DNA microarray analysis revealed a significant increase in lipocalin 2 (LCN2), is known as neutrophil gelatinase-associated lipocalin, in the superficial dorsal horns of BCAO-induced CPSP model mice. LCN2 colocalized with GFAP, an astrocyte marker. Spinal GFAP-positive cells in BCAO mice co-expressed signal transducer and activator of transcription 3 (STAT3). The increase in the fluorescence intensity of LCN2 and GFAP in BCAO mice was suppressed by intrathecal injection of AG490, an inhibitor of JAK2 and downstream STAT3 activation, or anti-LCN2 antibody. Our findings indicated that LCN2 in spinal astrocytes may be a key molecule and may be partly involved in the development of CPSP.

Increased TMEM166 Level in Patients with Postoperative Stroke after Carotid Endarterectomy.

Postoperative stroke is a challenging and potentially devastating complication after elective carotid endarterectomy (CEA). We previously demonstrated that transmembrane protein 166 (TMEM166) levels were directly related to neuronal damage after cerebral ischemia-reperfusion injury in rats. In this subsequent clinical study, we aimed to evaluate the prognostic value of TMEM166 in patients suffering from post-CEA strokes. Thirty-five patients undergoing uncomplicated elective CEA and 8 patients who suffered ischemic strokes after CEA were recruited. We evaluated the protein level and expression of TMEM166 in patients diagnosed with postoperative strokes and compared it to those in patients who underwent uncomplicated elective CEA. Blood samples and carotid artery plaques were collected and analyzed. High expressions of TMEM166 were detected by immunofluorescence staining and Western Blot in carotid artery plaques of all patients who underwent CEA. Furthermore, circulating TMEM166 concentrations were statistically higher in post-CEA stroke patients than in patients allocated to the control group. Mean plasma concentrations of inflammatory markers, including interleukin 6 (IL-6) and C-reactive protein (CRP), were also elevated in patients with postoperative strokes. Therefore, based on these findings, we hypothesize that elevated TMEM166 levels, accompanied by a strong inflammatory response, serve as a useful biomarker for risk assessment of postoperative stroke following CEA.

How Clot Composition Influences Fibrinolysis in the Acute Phase of Stroke: A Proteomic Study of Cerebral Thrombi.

BACKGROUND: The dramatic clinical improvement offered by mechanical thrombectomy raised questions about the relevance of prior intravenous thrombolysis in large-vessel occlusion strokes. Hence, studying intravenous thrombolysis susceptibility and its dependence on thrombus composition is crucial. We used an observational proteomic study of whole thrombi retrieved by mechanical thrombectomy to identify factors associated with fibrin content and fibrinolytic activity (FA). METHODS: In 104 stroke patients, the thrombi proteome was established by mass spectrometry coupled to liquid chromatography. FA was estimated in clots both outside (FAout) by measuring D-dimer levels at the blood-thrombus interface and inside (FAin) by evaluating the ratio of fibrinogen α to its plasmin-cleaved forms using proteomics coupled with protein electrophoresis. The factors associated with fibrin content, FAin, and FAout were determined by intravenous thrombolysis-adjusted linear regression. RESULTS: FAout (P<0.0001) and FAin (P=0.0147) were driven by recombinant tissue-type plasminogen activator (r-tPA) administration (47/104) and thrombus composition. Indeed, FAout was greater with fibrin-rich than erythrocyte-rich thrombi, presumably because of more (r)tPA substrates. Thus, FAout was increased with cardioembolic thrombi (72/104), which are rich in fibrin (P=0.0300). Opposite results were found inside the thrombus, suggesting that (r)tPA penetrability was hampered by the density of the fibrinous cap. Moreover, blood cells had a strong impact on thrombus structure and susceptibility to (r)tPA. Indeed, fibrin content was negatively associated with erythrocyte-specific proteins in the thrombus, admission hematocrit (P=0.0139), and hemoglobin level (P=0.0080), which underlines the key role of erythrocytes in thrombus composition. Also, an increased number of neutrophils impaired FAout (P=0.0225), which suggests that their aggregation around the thrombus prevented the (r)tPA attack. Only FAout was significantly associated with reduced thrombus weight (P=0.0310), increased recanalization rate (P=0.0150), good clinical outcome (P=0.0480), and reduced mortality (P=0.0080). CONCLUSIONS: Proteomics can offer new insights into the close relationship between thrombus composition and susceptibility to fibrinolysis, paving the way for new adjuvant therapies.

Thyroid hormones and stroke, the gap between clinical and experimental studies.

Despite plenty of human studies on changes in thyroid hormones after stroke and some animal studies that assessed the effects of thyroid hormone administration on stroke, conclusive evidence for clinical application is lacking. This review aimed to determine the consistency of the results between clinical and preclinical studies. This article reviewed the PubMed, Embase, web of Knowledge, and Google Scholar databases up to June 2023 using the MeSH terms "stroke, cerebral ischemia, cerebral infarction, brain ischemia, brain infarction, triiodothyronine (T3), tetraiodothyronine (T4), thyroxine (T4), and thyroid hormone". The results of clinical and preclinical studies related to T3 substantially confirm each other. That is, in most human studies lower T3 was associated with poor outcomes, and in experimental studies, T3 administration also had therapeutic effects. However, the results of experimental studies related to T4 could not support those of clinical studies. There seem to be some conflicts between experimental and human studies, especially regarding changes and effects of T4 after stroke. The gap between experimental and clinical studies may lead to non-applicable results, wasting time and money, and unnecessary killing of animals.