Endothelial Cell Dysfunction and Injury in Subarachnoid Hemorrhage

Advanced Diffusion Tensor Imaging in White Matter Injury After Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is recognized as an especially severe stroke variant, notorious for its high mortality and long-term disability rates, in addition to a range of both immediate and enduring neurologic impacts. Over half of the SAH survivors experience varying degrees of neurologic disorders, with many enduring chronic neuropsychiatric conditions. Due to the limitations of traditional imaging techniques in depicting subtle changes within brain tissues posthemorrhage, the accurate detection and diagnosis of white matter (WM) injuries are complicated. Against this backdrop, diffusion tensor imaging (DTI) has emerged as a promising biomarker for structural imaging, renowned for its enhanced sensitivity in identifying axonal damage. This capability positions DTI as an invaluable tool for forming precise and expedient prognoses for SAH survivors. This study synthesizes an assessment of DTI for the diagnosis and prognosis of neurologic dysfunctions in patients with SAH, emphasizing the notable changes observed in DTI metrics and their association with potential pathophysiological processes. Despite challenges associated with scanning technology differences and data processing, DTI demonstrates significant clinical potential for early diagnosis of cognitive impairments following SAH and monitoring therapeutic effects. Future research requires the development of highly standardized imaging paradigms to enhance diagnostic accuracy and devise targeted therapeutic strategies for SAH patients. In sum, DTI technology not only augments our understanding of the impact of SAH but also may offer new avenues for improving patient prognoses.

Intimal Hemorrhage of Basilar Artery Induced by Severe Vasospasm Following Subarachnoid Hemorrhage: The Experimental Analysis

BACKGROUND

 Cerebral vasospasm, a serious complication of subarachnoid hemorrhage (SAH), has been extensively studied for its neurochemical and pathophysiologic mechanisms. However, the contribution of inner elastic membrane dissection and subintimal hemorrhage to basilar artery occlusion remains underexplored. This study investigates inner elastic membrane-related changes in the basilar artery after SAH.

METHODS

 Twenty-four hybrid rabbits were divided into control, sham, and SAH groups, with SAH induced by autologous blood injection. After 2 weeks, basilar artery changes, vasospasm indexes (VSIs), and dissections were evaluated.

RESULTS

 The SAH group showed significantly higher VSI, with vascular wall thickening, luminal narrowing, convoluted smooth muscle cells, intimal elastic membrane disruption, endothelial cell desquamation, and apoptosis. Some SAH animals exhibited subintimal hemorrhage, inner elastic membrane dissection, and ruptures. Basilar arteries with subintimal hemorrhage had notably higher VSI.

CONCLUSIONS

 These findings highlight the role of subintimal hemorrhage and inner elastic membrane dissection in basilar artery occlusion post-SAH, offering valuable insights into vasospasm pathophysiology.

Targeting brain-peripheral immune responses for secondary brain injury after ischemic and hemorrhagic stroke

The notion that the central nervous system is an immunologically immune-exempt organ has changed over the past two decades, with increasing evidence of strong links and interactions between the central nervous system and the peripheral immune system, both in the healthy state and after ischemic and hemorrhagic stroke. Although primary injury after stroke is certainly important, the limited therapeutic efficacy, poor neurological prognosis and high mortality have led researchers to realize that secondary injury and damage may also play important roles in influencing long-term neurological prognosis and mortality and that the neuroinflammatory process in secondary injury is one of the most important influences on disease progression. Here, we summarize the interactions of the central nervous system with the peripheral immune system after ischemic and hemorrhagic stroke, in particular, how the central nervous system activates and recruits peripheral immune components, and we review recent advances in corresponding therapeutic approaches and clinical studies, emphasizing the importance of the role of the peripheral immune system in ischemic and hemorrhagic stroke.

The Impact of Enteral Nimodipine on Endothelial Cell Apoptosis in an Animal Subarachnoid Hemorrhage Model

BACKGROUND

Enteral nimodipine is the most evidence-based and widely used drug for the treatment of delayed cerebral ischemia and is known to have various neuroprotective functions. However, the neuroprotective mechanism of nimodipine still remains unclear, and the effects of nimodipine remain ambiguous. Herein, we studied the effect of enteral nimodipine on endothelial apoptosis after subarachnoid hemorrhage (SAH).

METHODS

SAH was experimentally introduced in white rabbits (n = 42) that were grouped as follows: enteral nimodipine (SAH-nimodipine group, n = 14), a control that received normal saline (SAH-saline group, n = 13), and a control without hemorrhage (control group, n = 15). On the third day after SAH induction, the brain stem, including the vertebrobasilar vascular system, was extracted. The effects of enteral nimodipine were analyzed by group using histopathologic analysis, including immunohistochemical staining of apoptosis-related proteins (Bcl2 [anti-apoptotic] and Bax [pro-apoptotic]).

RESULTS

Cytoplasmic vacuolation of smooth muscle cells was observed in two SAH hemorrhagic groups and was more prominent in the SAH-saline group. Endothelial desquamation was observed only in the SAH-saline group. For the basilar artery, expression of Bcl2 and Bax in the SAH-nimodipine group was lower than that in the SAH-saline group, but significant differences were not observed (pBcl2 = 0.311 and pBax = 0.720, respectively). In penetrated arterioles, the expression of Bax in the SAH-nimodipine group was significantly lower than that of the SAH-saline group (p < 0.001). The thickness of the tunica media in the basilar artery was thinner in the SAH-nimodipine group than in the SAH-saline group (p < 0.001).

CONCLUSIONS

This study suggests that enteral nimodipine may have a neuroprotective function by inhibiting endothelial apoptosis in small arterioles and preventing smooth muscle cell proliferation in large arteries.

Temporal Alterations in Cerebrovascular Glycocalyx and Cerebral Blood Flow after Exposure to a High-Intensity Blast in Rats

The glycocalyx is a proteoglycan-glycoprotein structure lining the luminal surface of the vascular endothelium and is susceptible to damage due to blast overpressure (BOP) exposure. The glycocalyx is essential in maintaining the structural and functional integrity of the vasculature and regulation of cerebral blood flow (CBF). Assessment of alterations in the density of the glycocalyx; its components (heparan sulphate proteoglycan (HSPG/syndecan-2), heparan sulphate (HS), and chondroitin sulphate (CS)); CBF; and the effect of hypercapnia on CBF was conducted at 2-3 h, 1, 3, 14, and 28 days after a high-intensity (18.9 PSI/131 kPa peak pressure, 10.95 ms duration, and 70.26 PSI·ms/484.42 kPa·ms impulse) BOP exposure in rats. A significant reduction in the density of the glycocalyx was observed 2-3 h, 1-, and 3 days after the blast exposure. The glycocalyx recovered by 28 days after exposure and was associated with an increase in HS (14 and 28 days) and in HSPG/syndecan-2 and CS (28 days) in the frontal cortex. In separate experiments, we observed significant decreases in CBF and a diminished response to hypercapnia at all time points with some recovery at 3 days. Given the role of the glycocalyx in regulating physiological function of the cerebral vasculature, damage to the glycocalyx after BOP exposure may result in the onset of pathogenesis and progression of cerebrovascular dysfunction leading to neuropathology.

Comparison of efficacy between clazosentan and fasudil hydrochloride-based management of vasospasm after subarachnoid hemorrhage focusing on older and WFNS grade V patients: a single-center experience in Japan

Subarachnoid hemorrhage often leads to poor outcomes owing to vasospasm, even after successful aneurysm treatment. Clazosentan, an endothelin receptor inhibitor, has been proven to be an effective treatment for vasospasms in a Japanese randomized controlled trial. However, its efficacy in older patients (≥ 75 years old) and those with World Federation of Neurosurgical Societies (WFNS) grade V has not been demonstrated. We retrospectively evaluated the efficacy of clazosentan in older patients and those with WFNS grade V, using real-world data. Patients with subarachnoid hemorrhage treated before and after the introduction of clazosentan were retrospectively evaluated. The patients were categorized into two groups (clazosentan era versus pre-clazosentan era), in which vasospasm management and outcomes were compared. Vasospasms were managed with fasudil hydrochloride-based (pre-clazosentan era) or clazosentan-based treatment (clazosentan era). Seventy-eight patients were included in this study: the clazosentan era (n = 32) and pre-clazosentan era (n = 46). Overall, clazosentan significantly reduced clinical vasospasms (clazosentan era: 31.3% versus pre-clazosentan era: 60.9%, p = 0.01), delayed cerebral ischemia (DCI) (9.4% versus 39.1%, p = 0.004), and vasospasm-related morbidity and mortality (M/M) (3.1% versus 19.6%, p = 0.03). In subgroup analysis of older patients or those with WFNS grade V, no significant difference was observed in clinical outcomes, although both DCI and vasospasm-related M/M were lower in the clazosentan era. Clazosentan was more effective than fasudil-based management in preventing DCI and reducing vasospasm-related M/M. Clazosentan could be used safely in older patients and those with WFNS grade V, although clinical outcomes in these patients were comparable to those of conventional treatment.

Circular RNAs in intracranial aneurysms: Emerging roles in pathogenesis, diagnosis and therapeutic intervention

Intracranial aneurysms (IAs) present a substantial health threat, given the potential for catastrophic ruptures and subarachnoid hemorrhages (SAH). Swift and effective measures for diagnosis and treatment are paramount to enhance patient outcomes and alleviate the associated healthcare burden. In this context, circular RNAs (circRNAs) have emerged as an intriguing area of investigation, offering promise as both diagnostic biomarkers and therapeutic targets for IAs. CircRNAs have demonstrated their influence on critical molecular and cellular processes underpinning IAs pathogenesis, revealing their pivotal role in understanding this complex ailment. Beyond their diagnostic potential, circRNAs hold great potential as prognostic markers, providing crucial insights into IAs rupture risk. The unique circular structure and their regulatory functions make circRNAs an enticing avenue for innovative therapeutic approaches. The ongoing study of circRNAs in the context of IAs is an exciting and rapidly evolving field that has the potential to revolutionize approaches to diagnosis, treatment, and prevention of this life-threatening condition. As research continues to unravel the intricate roles of circRNAs, they are poised to become invaluable tools in clinical practice, enhancing patient care and ultimately reducing the impact of cerebral aneurysms on both individuals and healthcare systems. This comprehensive review delves deeply into the world of circRNAs in the realm of IAs, elucidating their multifaceted roles in the onset and progression of this condition. Moreover, this review ventures into the diagnosis and therapeutic potential of circRNAs, exploring their possible applications in gene therapy and as targets for novel treatment modalities.

Sirtuins as Potential Targets for Neuroprotection: Mechanisms of Early Brain Injury Induced by Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is a prevalent cerebrovascular disease with significant global mortality and morbidity rates. Despite advancements in pharmacological and surgical approaches, the quality of life for SAH survivors has not shown substantial improvement. Traditionally, vasospasm has been considered a primary contributor to death and disability following SAH, but anti-vasospastic therapies have not demonstrated significant benefits for SAH patients' prognosis. Emerging studies suggest that early brain injury (EBI) may play a crucial role in influencing SAH prognosis. Sirtuins (SIRTs), a group of NAD + -dependent deacylases comprising seven mammalian family members (SIRT1 to SIRT7), have been found to be involved in neural tissue development, plasticity, and aging. They also exhibit vital functions in various central nervous system (CNS) processes, including cognition, pain perception, mood, behavior, sleep, and circadian rhythms. Extensive research has uncovered the multifaceted roles of SIRTs in CNS disorders, offering insights into potential markers for pathological processes and promising therapeutic targets (such as SIRT1 activators and SIRT2 inhibitors). In this article, we provide an overview of recent research progress on the application of SIRTs in subarachnoid hemorrhage and explore their underlying mechanisms of action.

Clinical Potential of Immunotherapies in Subarachnoid Hemorrhage Treatment: Mechanistic Dissection of Innate and Adaptive Immune Responses

Subarachnoid hemorrhage (SAH), classified as a medical emergency, is a devastating and severe subtype of stroke. SAH induces an immune response, which further triggers brain injury; however, the underlying mechanisms need to be further elucidated. The current research is predominantly focused on the production of specific subtypes of immune cells, especially innate immune cells, post-SAH onset. Increasing evidence suggests the critical role of immune responses in SAH pathophysiology; however, studies on the role and clinical significance of adaptive immunity post-SAH are limited. In this present study, we briefly review the mechanistic dissection of innate and adaptive immune responses post-SAH. Additionally, we summarized the experimental studies and clinical trials of immunotherapies for SAH treatment, which may form the basis for the development of improved therapeutic approaches for the clinical management of SAH in the future.

Contrast Injection from an Intermediate Catheter Placed in an Intradural Artery is Associated with Contrast-Induced Encephalopathy following Neurointervention

BACKGROUND AND PURPOSE

Contrast-induced encephalopathy can result from neurotoxicity of contrast medium in the affected area. The development of intermediate catheters has allowed guidance of catheters to more distal arteries. This study focused on the association between contrast-induced encephalopathy and contrast injection from an intermediate catheter guided into a distal intradural artery during neurointervention for cerebral aneurysms.

MATERIALS AND METHODS

We retrospectively reviewed 420 consecutive aneurysms in 396 patients who underwent neurointervention for extracranial aneurysms and unruptured intracranial aneurysms at our institution from February 2012 to January 2023. Patients were divided into a group with contrast-induced encephalopathy and a group without. To identify risk factors for contrast-induced encephalopathy, we compared clinical, anatomic, and procedural factors between groups by multivariate logistic regression analysis and stepwise selection.

RESULTS

Among the 396 patients who underwent neurointervention for cerebral aneurysms, 14 (3.5%) developed contrast-induced encephalopathy. Compared with the group without contrast-induced encephalopathy, the group with contrast-induced encephalopathy showed significantly higher rates of patients on hemodialysis, previously treated aneurysms, intradural placement of a catheter for angiography, nonionic contrast medium, and flow-diversion procedures in univariate analyses. Stepwise multivariate logistic regression analysis revealed intradural placement of a catheter for angiography (OR = 40.4; 95% CI, 8.63-189) and previously treated aneurysms (OR = 8.20; 95% CI, 2.26-29.6) as independent predictors of contrast-induced encephalopathy.

CONCLUSIONS

Contrast injection from an intradural artery and retreatment of recurrent aneurysms were major risk factors for contrast-induced encephalopathy. Attention should be paid to the location of the intermediate catheter for angiography to avoid developing contrast-induced encephalopathy.

Systemic innate myeloid responses to acute ischaemic and haemorrhagic stroke

Acute ischaemic and haemorrhagic stroke account for significant disability and morbidity burdens worldwide. The myeloid arm of the peripheral innate immune system is critical in the immunological response to acute ischaemic and haemorrhagic stroke. Neutrophils, monocytes, and dendritic cells (DC) contribute to the evolution of pathogenic local and systemic inflammation, whilst maintaining a critical role in ongoing immunity protecting against secondary infections. This review aims to summarise the key alterations to myeloid immunity in acute ischaemic stroke, intracerebral haemorrhage (ICH), and subarachnoid haemorrhage (SAH). By integrating clinical and preclinical research, we discover how myeloid immunity is affected across multiple organ systems including the brain, blood, bone marrow, spleen, and lung, and evaluate how these perturbations associate with real-world outcomes including infection. These findings are placed in the context of the rapidly developing field of human immunology, which offers a wealth of opportunity for further research.

Compartmental Cerebrospinal Fluid Events Occurring after Subarachnoid Hemorrhage: An "Heparin Oriented" Systematic Review

Subarachnoid hemorrhage (SAH) represents a severe acute event with high morbidity and mortality due to the development of early brain injury (EBI), secondary delayed cerebral ischemia (DCI), and shunt-related hydrocephalus. Secondary events (SSE) such as neuroinflammation, vasospasm, excitotoxicity, blood-brain barrier disruption, oxidative cascade, and neuronal apoptosis are related to DCI. Despite improvement in management strategies and therapeutic protocols, surviving patients frequently present neurological deficits with neurocognitive impairment. The aim of this paper is to offer to clinicians a practical review of the actually documented pathophysiological events following subarachnoid hemorrhage. To reach our goal we performed a literature review analyzing reported studies regarding the mediators involved in the pathophysiological events following SAH occurring in the cerebrospinal fluid (CSF) (hemoglobin degradation products, platelets, complement, cytokines, chemokines, leucocytes, endothelin-1, NO-synthase, osteopontin, matricellular proteins, blood-brain barrier disruption, microglia polarization). The cascade of pathophysiological events secondary to SAH is very complex and involves several interconnected, but also distinct pathways. The identification of single therapeutical targets or specific pharmacological agents may be a limited strategy able to block only selective pathophysiological paths, but not the global evolution of SAH-related events. We report furthermore on the role of heparin in SAH management and discuss the rationale for use of intrathecal heparin as a pleiotropic therapeutical agent. The combination of the anticoagulant effect and the ability to interfere with SSE theoretically make heparin a very interesting molecule for SAH management.

Unpacking the Role of Extracellular Vesicles in Ischemic and Hemorrhagic Stroke: Pathophysiology and Therapeutic Implications

Stroke is a leading cause of death and disability worldwide. Inflammation and microvascular dysfunction have been associated with brain injury and long-term disability after both ischemic and hemorrhagic stroke. Recent studies have suggested a potential role of extracellular vesicles (EVs) as a link underlying these pathogenic processes. EVs are cell-derived particles enveloped by a lipid bilayer, containing proteins, lipids, and nucleic acids. From a functional standpoint, EVs can facilitate intercellular communication, including across the blood-brain barrier (BBB). Recent advances in EV research have shown a preferential release of EVs from specific cell types in the context of stroke, some of which were associated with increased neuroinflammation, microvascular dysfunction, and neuronal cytotoxicity while others offered a degree of neuroprotection. However, one historic challenge in the studies of EVs in stroke is the lack of consistent definitions and methods to analyze EVs, only recently updated in the MISEV2018 guidelines. Given limitations and complexity in the treatment of stroke, particularly delivery of therapeutics across the BBB, increasing attention has been paid towards manipulating EVs as one vehicle that can permit targeted therapeutic delivery to the central nervous system. These discoveries point towards a future where a better understanding of EVs will advance our knowledge of stroke-associated mechanisms of cerebral and systemic injury and contribute to the development of novel treatments. Here, we review the role that EVs play in ischemic and hemorrhagic stroke.

CNS-peripheral immune interactions in hemorrhagic stroke

Stroke is a sudden and rapidly progressing ischemic or hemorrhagic cerebrovascular disease. When stroke damages the brain, the immune system becomes hyperactive, leading to systemic inflammatory response and immunomodulatory disorders, which could significantly impact brain damage, recovery, and prognosis of stroke. Emerging researches suggest that ischemic stroke-induced spleen contraction could activate a peripheral immune response, which may further aggravate brain injury. This review focuses on hemorrhagic strokes including intracerebral hemorrhage (ICH) and subarachnoid hemorrhage (SAH) and discusses the central nervous system-peripheral immune interactions after hemorrhagic stroke induction. First, inflammatory progression after ICH and SAH is investigated. As a part of this review, we summarize the various kinds of inflammatory cell infiltration to aggravate brain injury after blood-brain barrier interruption induced by hemorrhagic stroke. Then, we explore hemorrhagic stroke-induced systemic inflammatory response syndrome (SIRS) and discuss the interactions of CNS and peripheral inflammatory response. In addition, potential targets related to inflammatory response for ICH and SAH are discussed in this review, which may lead to novel therapeutic strategies for hemorrhagic stroke.

The protective effect of low-dose minocycline on brain microvascular ultrastructure in a rodent model of subarachnoid hemorrhage

The multifaceted nature of subarachnoid hemorrhage (SAH) pathogenesis is poorly understood. To date, no pharmacological agent has been found to be efficacious for the prevention of brain injury when used for acute SAH intervention. This study was undertaken to evaluate the beneficial effects of low-dose neuroprotective agent minocycline on brain microvascular ultrastructures that have not been studied in detail. We studied SAH brain injury using an in vivo prechiasmatic subarachnoid hemorrhage rodent model. We analyzed the qualitative and quantitative ultrastructural morphology of capillaries and surrounding neuropil in the rodent brains with SAH and/or minocycline administration. Here, we report that low-dose minocycline (1 mg/kg) displayed protective effects on capillaries and surrounding cells from significant SAH-induced changes. Ultrastructural morphology analysis revealed also that minocycline stopped endothelial cells from abnormal production of vacuoles and vesicles that compromise blood-brain barrier (BBB) transcellular transport. The reported ultrastructural abnormalities as well as neuroprotective effects of minocycline during SAH were not directly mediated by inhibition of MMP-2, MMP-9, or EMMPRIN. However, SAH brain tissue treated with minocycline was protected from development of other morphological features associated with oxidative stress and the presence of immune cells in the perivascular space. These data advance the knowledge on the effect of SAH on brain tissue ultrastructure in an SAH rodent model and the neuroprotective effect of minocycline when administered in low doses.

The mechanism and relevant mediators associated with neuronal apoptosis and potential therapeutic targets in subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) is a dominant cause of death and disability worldwide. A sharp increase in intracranial pressure after SAH leads to a reduction in cerebral perfusion and insufficient blood supply for neurons, which subsequently promotes a series of pathophysiological responses leading to neuronal death. Many previous experimental studies have reported that excitotoxicity, mitochondrial death pathways, the release of free radicals, protein misfolding, apoptosis, necrosis, autophagy, and inflammation are involved solely or in combination in this disorder. Among them, irreversible neuronal apoptosis plays a key role in both short- and long-term prognoses after SAH. Neuronal apoptosis occurs through multiple pathways including extrinsic, mitochondrial, endoplasmic reticulum, p53 and oxidative stress. Meanwhile, a large number of blood contents enter the subarachnoid space after SAH, and the secondary metabolites, including oxygenated hemoglobin and heme, further aggravate the destruction of the blood-brain barrier and vasogenic and cytotoxic brain edema, causing early brain injury and delayed cerebral ischemia, and ultimately increasing neuronal apoptosis. Even there is no clear and effective therapeutic strategy for SAH thus far, but by understanding apoptosis, we might excavate new ideas and approaches, as targeting the upstream and downstream molecules of apoptosis-related pathways shows promise in the treatment of SAH. In this review, we summarize the existing evidence on molecules and related drugs or molecules involved in the apoptotic pathway after SAH, which provides a possible target or new strategy for the treatment of SAH.

Mechanisms of cerebral vasospasm and cerebral ischaemia in subarachnoid haemorrhage

Subarachnoid haemorrhage (SAH) is a cerebrovascular emergency associated with significant morbidity and mortality. SAH is characterized by heterogeneity, interindividual variation and complexity of pathophysiological responses following extravasation of blood from cerebral circulation. The purpose of this review is to integrate previously established pre-existing factors, pathophysiological pathways and to develop a concept map of mechanisms of SAH-induced cerebral vasospasm and delayed cerebral ischaemia using a systematic approach. We conducted an extensive mapping of a hypothesized sequence of pathophysiological events. Documentation of supporting evidence was done alongside a concept map building. After finalizing the model, we conducted an analysis of the consequences and connections of pathophysiological events. We included the findings of experimental research, focusing on pathophysiological processes. We focused on SAH-induced cerebral vasospasm and delayed cerebral ischaemia as a component of cerebral injury and potential systemic consequences. SAH-induced brain injury occurs within 72 h following haemorrhage. Pathophysiology of cerebral vasospasm may include reduction in NO production, direct activation of calcium channels, upregulating genes involved with inflammation and extracellular matrix remodelling, triggering oxidative stress and free radical damage to smooth muscle and lipid peroxidation of cell membranes, cortical spreading depolarizations, sympathetic activation, finally resulting in the failure of cerebral autoregulation, microthrombosis and cerebral ischaemic injury. This cascade of events might explain why medical therapy often fails to reverse resistant cerebral vasospasm and to prevent cerebral ischaemia.

Inflammatory Response and Immune Regulation in Brain-Heart Interaction after Stroke

Cerebrocardiac syndrome (CCS) is one of the secondary myocardial injuries after stroke. Cerebrocardiac syndrome may result in a poor prognosis with high mortality. Understanding the mechanism of the brain-heart interaction may be crucial for clinical treatment of pathological changes in CCS. Accumulating evidence suggests that the inflammatory response is involved in the brain-heart interaction after stroke. Systemic inflammatory response syndrome (SIRS) evoked by stroke may injure myocardial cells directly, in which the interplay between inflammatory response, oxidative stress, cardiac sympathetic/parasympathetic dysfunction, and splenic immunoregulation may be also the key pathophysiology factor. This review article summarizes the current understanding of inflammatory response and immune regulation in brain-heart interaction after stroke.

Exploration of cerebral vasospasm from the perspective of microparticles

Cerebral vasospasm is a frequently encountered clinical problem, especially in patients with traumatic brain injury and subarachnoid hemorrhage. Continued cerebral vasospasm can cause cerebral ischemia, even infarction and delayed ischemic neurologic deficits. It significantly affects the course of the disease and the outcome of the patient. However, the underlying mechanism of cerebral vasospasm is still unclear. Recently, increasing studies focus on the pathogenic mechanism of microparticles. It has been found that microparticles have a non-negligible role in promoting vasospasm. This research aims to summarize the dynamics of microparticles in vivo and identify a causal role of microparticles in the occurrence and development of cerebral vasospasm. We found that these various microparticles showed dynamic characteristics in body fluids and directly or indirectly affect the cerebral vasospasm or prompt it. Due to the different materials carried by microparticles from different cells, there are also differences in the mechanisms that lead to abnormal vasomotor. We suggest that microparticle scavengers might be a promising therapeutic target against microparticles associated complications.

Targeting Hemoglobin to Reduce Delayed Cerebral Ischemia After Subarachnoid Hemorrhage

Delayed cerebral ischemia (DCI) continues to be a sequela of aneurysmal subarachnoid hemorrhage (aSAH) that carries significant morbidity and mortality. Aside from nimodipine, no therapeutic agents are available to reduce the incidence of DCI. Pathophysiologic mechanisms contributing to DCI are poorly understood, but accumulating evidence over the years implicates several factors. Those have included microvessel vasoconstriction, microthrombosis, oxidative tissue damage, and cortical spreading depolarization as well as large vessel vasospasm. Common to these processes is red blood cell leakage into the cerebrospinal fluids (CSF) and subsequent lysis which releases hemoglobin, a central instigator in these events. This has led to the hypothesis that early blood removal may improve clinical outcome and reduce DCI. This paper will provide a narrative review of the evidence of hemoglobin as an instigator of DCI. It will also elaborate on available human data that discuss blood clearance and CSF drainage as a treatment of DCI. Finally, we will address a recent novel device that is currently being tested, the Neurapheresis CSF Management System™. This is an automated dual-lumen lumbar drainage system that has an option to filter CSF and return it to the patient.

New Mechanisms and Targets of Subarachnoid Hemorrhage: A Focus on Mitochondria

Spontaneous subarachnoid hemorrhage (SAH) accounts for 5-10% of all strokes and is a subtype of hemorrhagic stroke that places a heavy burden on health care. Despite great progress in surgical clipping and endovascular treatment for ruptured aneurysms, cerebral vasospasm (CVS) and delayed cerebral ischemia (DCI) threaten the long-term outcomes of patients with SAH. Moreover, there are limited drugs available to reduce the risk of DCI and adverse outcomes in SAH patients. New insight suggests that early brain injury (EBI), which occurs within 72 h after the onset of SAH, may lay the foundation for further DCI development and poor outcomes. The mechanisms of EBI mainly include excitotoxicity, oxidative stress, neuroinflammation, blood-brain barrier (BBB) destruction, and cellular death. Mitochondria are a double-membrane organelle, and they play an important role in energy production, cell growth, differentiation, apoptosis, and survival. Mitochondrial dysfunction, which can lead to mitochondrial membrane potential (Δψm) collapse, overproduction of reactive oxygen species (ROS), release of apoptogenic proteins, disorders of mitochondrial dynamics, and activation of mitochondria-related inflammation, is considered a novel mechanism of EBI related to DCI as well as post-SAH outcomes. In addition, mitophagy is activated after SAH. In this review, we discuss the latest perspectives on the role of mitochondria in EBI and DCI after SAH. We emphasize the potential of mitochondria as therapeutic targets and summarize the promising therapeutic strategies targeting mitochondria for SAH.

Glyoxal Fixation Is Optimal for Immunostaining of Brain Vessels, Pericytes and Blood-Brain Barrier Proteins

Brain vascular staining is very important for understanding cerebrovascular pathologies. 4% paraformaldehyde is considered the gold standard fixation technique for immunohistochemistry and it revolutionized the examination of proteins in fixed tissues. However, this fixation technique produces inconsistent immunohistochemical staining results due to antigen masking. Here, we test a new fixation protocol using 3% glyoxal and demonstrate that this method improves the staining of the brain vasculature, pericytes, and tight junction proteins compared to 4% paraformaldehyde. Use of this new fixation technique will provide more detailed information about vascular protein expressions, their distributions, and colocalizations with other proteins at the molecular level in the brain vasculature.

Extracellular vesicles derived from bone marrow mesenchymal stem cells alleviate neurological deficit and endothelial cell dysfunction after subarachnoid hemorrhage via the KLF3-AS1/miR-83-5p/TCF7L2 axis

BACKGROUND

New data are accumulating on the effects of mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) in cerebrovascular diseases. We explored the potential role of KLF3-AS1-containing bone marrow MSC-EVs (BMSC-EVs) in a rat model of subarachnoid hemorrhage (SAH).

METHODS

A rat model of SAH was established by endovascular perforation method, into which KLF3-AS1-containing EVs from BMSCs or miR-183-5p mimic were injected. Further, brain microvascular endothelial cells (BMECs) were induced by oxyhemoglobin (OxyHb) to simulate in vitro setting, which were co-cultured with KLF3-AS1-containing EVs from BMSCs. Effects of KLF3-AS1 on neurological deficits in vivo and endothelial cell dysfunction in vitro were investigated. We also performed bioinformatics analysis to predict downstream factors miR-183-5p and TCF7L2, which were verified by RIP, RNA pull-down and luciferase activity assays.

RESULTS

BMSC-EVs was demonstrated to alleviate neurological deficits in SAH rats and endothelial cell dysfunction in OxyHb-induced BMECs. In addition, BMSC-EVs were shown to deliver KLF3-AS1 to BMECs, where KLF3-AS1 bound to miR-183-5p and miR-183-5p targeted TCF7L2. In vivo results confirmed that BMSC-EVs regulated the KLF3-AS1/miR-183-5p/TCF7L2 signaling axis to attenuate neurological deficit and endothelial dysfunction after SAH.

CONCLUSION

Overall, KLF3-AS1 delivered by BMSC-EVs upregulate TCF7L2 expression by binding to miR-138-5p, thus attenuating neurological deficits and endothelial dysfunction after SAH.

The blood-brain barrier and the neurovascular unit in subarachnoid hemorrhage: molecular events and potential treatments

The response of the blood-brain barrier (BBB) following a stroke, including subarachnoid hemorrhage (SAH), has been studied extensively. The main components of this reaction are endothelial cells, pericytes, and astrocytes that affect microglia, neurons, and vascular smooth muscle cells. SAH induces alterations in individual BBB cells, leading to brain homeostasis disruption. Recent experiments have uncovered many pathophysiological cascades affecting the BBB following SAH. Targeting some of these pathways is important for restoring brain function following SAH. BBB injury occurs immediately after SAH and has long-lasting consequences, but most changes in the pathophysiological cascades occur in the first few days following SAH. These changes determine the development of early brain injury as well as delayed cerebral ischemia. SAH-induced neuroprotection also plays an important role and weakens the negative impact of SAH. Supporting some of these beneficial cascades while attenuating the major pathophysiological pathways might be decisive in inhibiting the negative impact of bleeding in the subarachnoid space. In this review, we attempt a comprehensive overview of the current knowledge on the molecular and cellular changes in the BBB following SAH and their possible modulation by various drugs and substances.

Treatment effect of DNA framework nucleic acids on diffuse microvascular endothelial cell injury after subarachnoid hemorrhage

Objectives

The purpose of this study was to investigate the treatment effect and molecular mechanism of tetrahedral framework nucleic acids (tFNAs), novel self‐assembled nucleic acid nanomaterials, in diffuse BMEC injury after SAH.

Materials and Methods

tFNAs were synthesized from four ssDNAs. The effects of tFNAs on SAH‐induced diffuse BMEC injury were explored by a cytotoxicity model induced by hemin, a breakdown product of hemoglobin, in vitro and a mouse model of SAH via internal carotid artery puncture in vivo. Cell viability assays, wound healing assays, transwell assays, and tube formation assays were performed to explore cellular function like angiogenesis.

Results

In vitro cellular function assays demonstrated that tFNAs could alleviate hemin‐induced injury, promote angiogenesis, and inhibit apoptosis in hemin cytotoxicity model. In vivo study using H&E and TEM results jointly indicated that the tFNAs attenuate the damage caused by SAH in situ, showing restored number of BMECs in the endothelium layer and more tight intercellular connectivity. Histological examination of SAH model animals confirmed the results of the in vitro study, as tFNAs exhibited treatment effects against diffuse BMEC injury in the cerebral microvascular bed.

Conclusions

Our study suggests the potential of tFNAs in ameliorating diffuse injury to BMECs after SAH, which laid theoretical foundation for the further study and use of these nucleic acid nanomaterials for tissue engineering vascularization.

Admission Homocysteine as a Potential Predictor for Delayed Cerebral Ischemia After Aneurysmal Subarachnoid Hemorrhage

Background

Delayed cerebral ischemia (DCI) is a primary cause of poor prognosis after aneurysmal subarachnoid hemorrhage (aSAH) and needs close medical attention in clinical practice. Homocysteine (Hcy) has been implicated in cerebrovascular diseases. This study aimed to investigate whether serum Hcy could help to predict the occurrence of DCI in aSAH patients, and compare its diagnostic value with traditional methods.

Methods

We enrolled 241 aSAH patients in this study. Serum Hcy levels were collected from each patient. The baseline information was reviewed and analyzed. The binary logistic regression was used to explore the relation of serum Hcy levels with occurrence of DCI, and diagnostic performance of serum Hcy for predicting DCI was evaluated using a receiver operating characteristic (ROC) curve.

Results

The admission serum Hcy levels were found significantly higher in aSAH patients with DCI than those without (P < 0.001). The serum Hcy levels were positively correlated with the World Federation of Neurosurgical Societies (WFNS) scores, modified Fisher scores as well as Hunt and Hess scores at admission. Multivariate analysis revealed that occurrence of DCI was associated with serum Hcy levels (Odds Ratio [OR] = 1.257; 95% Confidence Interval [CI], 1.133–1.396, P < 0.001), modified Fisher scores (OR = 1.871; 95%CI, 1.111–3.150, P = 0.018) and Hunt and Hess scores (OR = 2.581; 95%CI, 1.222–5.452, P = 0.013) after adjusting for the significant variables in univariate analysis. Meanwhile, serum Hcy levels achieved good performance for DCI prediction (area under the curve [AUC], 0.781; 95%CI, 0.723–0.831, P < 0.001).

Conclusion

Serum homocysteine might have the potential to be a useful and cost-effective biomarker for predicting the occurrence of DCI in aSAH patients.

p-Cresyl Sulfate Predicts Ischemic Stroke among Patients on Hemodialysis: A Prospective Cohort Study

Background and Purpose. Hemodialysis patients face a higher risk of ischemic stroke. p-Cresyl sulfate is a typical protein-bound uremic toxin that contributes to chronic kidney disease and cardiovascular disease progression, as well as mortality in hemodialysis patients. The present study was aimed at elucidating the association between p-cresyl sulfate and the risk of ischemic stroke in hemodialysis patients. Method. Patients on hemodialysis over 6 months were enrolled in this prospective cohort study and were divided into 2 groups based on plasma p-cresyl sulfate level. The primary end point was the first episode of ischemic stroke during follow-up. The association between p-cresyl sulfate and ischemic stroke incidence was analyzed by Kaplan-Meier method and Cox proportional hazard model. Results. 220 patients were enrolled in this study. 44 patients experienced episodes of first ischemic stroke during follow-up for 87.8 (47.6-119.5) months. Kaplan-Meier analysis demonstrated that the incidence of ischemic stroke in the high p-cresyl sulfate group was significantly higher than that in the low p-cresyl sulfate group (Log-Rank $P=0.007$ ). Cox regression analysis as well proved that p-cresyl sulfate level was significantly associated with the first incidence of ischemic stroke (HR (hazard ratio) 2.332, 95% CI (95% confidence interval) 1.236-4.399, $P=0.009$ ). After being adjusted for other confounding risk factors, the results persisted significant (model 11: HR 2.061, 95% CI 1.030-4.125, $P=0.041$ ). Conclusion. Plasma p-cresyl sulfate predicts the first incidence of ischemic stroke in hemodialysis patients.

Inflammation and Oxidative Stress: Potential Targets for Improving Prognosis After Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) has a high mortality rate and causes long-term disability in many patients, often associated with cognitive impairment. However, the pathogenesis of delayed brain dysfunction after SAH is not fully understood. A growing body of evidence suggests that neuroinflammation and oxidative stress play a negative role in neurofunctional deficits. Red blood cells and hemoglobin, immune cells, proinflammatory cytokines, and peroxidases are directly or indirectly involved in the regulation of neuroinflammation and oxidative stress in the central nervous system after SAH. This review explores the role of various cellular and acellular components in secondary inflammation and oxidative stress after SAH, and aims to provide new ideas for clinical treatment to improve the prognosis of SAH.

The Role of the Glycocalyx in the Pathophysiology of Subarachnoid Hemorrhage-Induced Delayed Cerebral Ischemia

The glycocalyx is an important constituent of blood vessels located between the bloodstream and the endothelium. It plays a pivotal role in intercellular interactions in neuroinflammation, reduction of vascular oxidative stress, and provides a barrier regulating vascular permeability. In the brain, the glycocalyx is closely related to functions of the blood-brain barrier and neurovascular unit, both responsible for adequate neurovascular responses to potential threats to cerebral homeostasis. An aneurysmal subarachnoid hemorrhage (aSAH) occurs following rupture of an intracranial aneurysm and leads to immediate brain damage (early brain injury). In some cases, this can result in secondary brain damage, also known as delayed cerebral ischemia (DCI). DCI is a life-threatening condition that affects up to 30% of all aSAH patients. As such, it is associated with substantial societal and healthcare-related costs. Causes of DCI are multifactorial and thought to involve neuroinflammation, oxidative stress, neuroinflammation, thrombosis, and neurovascular uncoupling. To date, prediction of DCI is limited, and preventive and effective treatment strategies of DCI are scarce. There is increasing evidence that the glycocalyx is disrupted following an aSAH, and that glycocalyx disruption could precipitate or aggravate DCI. This review explores the potential role of the glycocalyx in the pathophysiological mechanisms contributing to DCI following aSAH. Understanding the role of the glycocalyx in DCI could advance the development of improved methods to predict DCI or identify patients at risk for DCI. This knowledge may also alter the methods and timing of preventive and treatment strategies of DCI. To this end, we review the potential and limitations of methods currently used to evaluate the glycocalyx, and strategies to restore or prevent glycocalyx shedding.

Pathophysiology of Delayed Cerebral Ischemia After Subarachnoid Hemorrhage: A Review

Delayed cerebral ischemia is a major predictor of poor outcomes in patients who suffer subarachnoid hemorrhage. Treatment options are limited and often ineffective despite many years of investigation and clinical trials. Modern advances in basic science have produced a much more complex, multifactorial framework in which delayed cerebral ischemia is better understood and novel treatments can be developed. Leveraging this knowledge to improve outcomes, however, depends on a holistic understanding of the disease process. We conducted a review of the literature to analyze the current state of investigation into delayed cerebral ischemia with emphasis on the major themes that have emerged over the past decades. Specifically, we discuss microcirculatory dysfunction, glymphatic impairment, inflammation, and neuroelectric disruption as pathological factors in addition to the canonical focus on cerebral vasospasm. This review intends to give clinicians and researchers a summary of the foundations of delayed cerebral ischemia pathophysiology while also underscoring the interactions and interdependencies between pathological factors. Through this overview, we also highlight the advances in translational studies and potential future therapeutic opportunities.

Circ_0003423 Alleviates ox-LDL-Induced Human Brain Microvascular Endothelial Cell Injury via the miR-589-5p/TET2 Network

Brain microvascular endothelial cells (BMECs) injury is one of the main causes of cerebrovascular diseases. Circular RNA (circRNA) has been found to be involved in the regulation of cerebrovascular diseases progression. However, the role and mechanism of circ_0003423 in cerebrovascular diseases is still unclear. In our study, oxidized low density lipoprotein (ox-LDL)-induced HBMEC-IM cells were used to construct cerebrovascular cell injury model in vitro. Quantitative real-time PCR was used to determine the expression levels of circ_0003423, miR-589-5p and Ten-eleven translocation 2 (TET2). The interactions between miR-589-5p and circ_0003423 or TET2 were confirmed by dual-luciferase reporter assay, RIP assay and RNA pull-down assay. Cell viability, angiogenesis and apoptosis were measured using cell counting kit 8 assay, tube formation assay and flow cytometry. Cell oxidative stress was evaluated by detecting the levels of reactive oxygen species and lactate dehydrogenase. The protein levels were examined by western blot analysis. Our results showed that circ_0003423 was a downregulated circRNA in ox-LDL-induced HBMEC-IM cells. In the terms of mechanism, circ_0003423 was found to be a sponge of miR-589-5p. Function analysis showed that circ_0003423 overexpression could relieve ox-LDL-induced HBMEC-IM cell injury, and this effect could be reversed by miR-589-5p mimic. In addition, TET2 was confirmed to be a target of miR-589-5p, and its overexpression could alleviate ox-LDL-induced HBMEC-IM cell injury. Moreover, the rescue experiments also confirmed that TET2 silencing could abolish the inhibition effect of anti-miR-589-5p on ox-LDL-induced HBMEC-IM cell injury. In summary, our data showed that circ_0003423 alleviated ox-LDL-induced HBMEC-IM cells injury through regulating the miR-589-5p/TET2 axis.

Atmospheric variables and subarachnoid hemorrhage: narrative review

Background

Stroke is a neurological emergency that tends to be the first cause of death in many countries. Atmospheric variables are strongly associated with stroke, in which subarachnoid hemorrhage (SAH) has been associated in many studies to meteorological risk factors such as air pollution, air pressure, weather changes, and ambient temperature. These characteristics may influence the brain circulation and cause SAH, being diagnosed as idiopathic SAH or SAH with unknown cause.

Objective

The main objective of this review is to present the most relevant meteorological risk factors that may develop subarachnoid hemorrhage according to the current evidence that supports the strong association.

Conclusion

Brain vessel circulation may be influenced by atmospheric variables such as air pollution and weather changes, generating intrinsic changes in the intima of the vessels which leads to vasospasm and with comorbidities associated may develop SAH.

Clarithromycin Ameliorates Early Brain Injury After Subarachnoid Hemorrhage via Suppressing Periostin-Related Pathways in Mice

Subarachnoid hemorrhage (SAH) remains a life-threatening disease, and early brain injury (EBI) is an important cause of poor outcomes. The authors have reported that periostin, a matricellular protein, is one of key factors of post-SAH EBI. Clarithromycin (CAM) is a worldwide antibiotic that can inhibit periostin expression. This study aimed to investigate whether CAM suppressed EBI after experimental SAH, focusing on blood-brain barrier (BBB) disruption, an important pathology of EBI. C57BL/6 male adult mice underwent endovascular perforation SAH modeling (n = 139) or sham operation (n = 30). Different dosages (25, 50, or 100 mg/kg) of CAM or the vehicle (n = 16, 52, 13, and 58, respectively) were randomly administered by an intramuscular injection 5 min after SAH induction. Post-SAH 50 mg/kg CAM treatment most effectively improved neurological scores and brain water content at 24 and 48 h and reduced immunoglobulin G extravasation at 24 h compared with vehicle-treated SAH mice (p < 0.01). Western blotting showed that post-SAH BBB disruption was associated with increased expressions of periostin, phosphorylated signal transducer and activator of transcription 1 and 3, matrix metalloproteinase-9, and the consequent degradation of zonula occludens-1, which were suppressed by 50 mg/kg CAM treatment (p < 0.05, respectively, versus vehicle-treated SAH mice). Periostin and its related molecules were upregulated in capillary endothelial cells and neurons after SAH. An intracerebroventricular injection of recombinant periostin blocked the neuroprotective effects of CAM in SAH mice (n = 6, respectively; p < 0.05). In conclusion, this study first demonstrated that CAM improved post-SAH EBI in terms of BBB disruption at least partly via the suppression of periostin-related pathways.

Non-invasive Assessment of Neurovascular Coupling After Aneurysmal Subarachnoid Hemorrhage: A Prospective Observational Trial Using Retinal Vessel Analysis

Objective: Delayed cerebral ischemia (DCI) is a common complication after aneurysmal subarachnoid hemorrhage (aSAH) and can lead to infarction and poor clinical outcome. The underlying mechanisms are still incompletely understood, but animal models indicate that vasoactive metabolites and inflammatory cytokines produced within the subarachnoid space may progressively impair and partially invert neurovascular coupling (NVC) in the brain. Because cerebral and retinal microvasculature are governed by comparable regulatory mechanisms and may be connected by perivascular pathways, retinal vascular changes are increasingly recognized as a potential surrogate for altered NVC in the brain. Here, we used non-invasive retinal vessel analysis (RVA) to assess microvascular function in aSAH patients at different times after the ictus. Methods: Static and dynamic RVA were performed using a Retinal Vessel Analyzer (IMEDOS Systems GmbH, Jena) in 70 aSAH patients during the early (d_0-4), critical (d_5-15), late (d_16-23) phase, and at follow-up (f/u > 6 weeks) after the ictus. For comparison, an age-matched cohort of 42 healthy subjects was also included in the study. Vessel diameters were quantified in terms of the central retinal arterial and venous equivalent (CRAE, CRVE) and the retinal arterio-venous-ratio (AVR). Vessel responses to flicker light excitation (FLE) were quantified by recording the maximum arterial and venous dilation (MAD, MVD), the time to 30% and 100% of maximum dilation (tMAD₃₀, tMVD₃₀; tMAD, tMVD, resp.), and the arterial and venous area under the curve (AUC_art, AUC_ven) during the FLE. For subgroup analyses, patients were stratified according to the development of DCI and clinical outcomes after 12 months. Results: Vessel diameter (CRAE, CRVE) was significantly smaller in aSAH patients and showed little change throughout the whole observation period (p < 0.0001 vs. control for all time periods examined). In addition, aSAH patients exhibited impaired arterial but not venous responses to FLE, as reflected in a significantly lower MAD [2.2 (1.0-3.2)% vs. 3.6 (2.6-5.6)% in control subjects, p = 0.0016] and AUC_art [21.5 (9.4-35.8)%^*s vs. 51.4 (32.5-69.7)%^*s in control subjects, p = 0.0001] on d_0-4. However, gradual recovery was observed during the first 3 weeks, with close to normal levels at follow-up, when MAD and AUC_art amounted to 3.0 [2.0-5.0]% (p = 0.141 vs. control, p = 0.0321 vs. d_5-15) and 44.5 [23.2-61.1]%^*s (p = 0.138 vs. control, p < 0.01 vs. d_0-4 & d_5-15). Finally, patients with clinical deterioration (DCI) showed opposite changes in the kinetics of arterial responses during early and late phase, as reflected in a significantly lower tMAD₃₀ on d_0-4 [4.0 (3.0-6.8) s vs. 7.0 (5.0-8.0) s in patients without DCI, p = 0.022) and a significantly higher tMAD on d_16-23 (24.0 (21.0-29.3) s vs. 18.0 (14.0-21.0) s in patients without DCI, p = 0.017]. Conclusion: Our findings confirm and extend previous observations that aSAH results in sustained impairments of NVC in the retina. DCI may be associated with characteristic changes in the kinetics of retinal arterial responses. However, further studies will be required to determine their clinical implications and to assess if they can be used to identify patients at risk of developing DCI. Trial Registration: ClinicalTrials.gov Identifier: NCT04094155.

MFGE8 mitigates brain injury in a rat model of SAH by maintaining vascular endothelial integrity via TIGβ5/PI3K/CXCL12 signaling

Leaked blood components, injured endothelial cells, local inflammatory response and vasospasm may converge to promote microthrombosis following subarachnoid hemorrhage (SAH). Previously, we showed that the milk fat globule-epidermal growth factor 8 (MFGE8) can mitigate SAH-induced microthrombosis. This present study was aimed to explore the molecular pathway participated in MFGE8-dependent protection on vascular endothelium. Immunofluorescence, immunoblot and behavioral tests were used to determine the molecular partner and signaling pathway mediating the effect of MFGE8 in vascular endothelium in rats with experimental SAH and controls, together with the applications of RNA silencing and pharmacological intervention methods. Relative to control, recombinant human MFGE8 (rhMFGE8) treatment increased 5-bromo-2'-deoxyuridine (BrdU) labeled new endothelial cells, reduced TUNUL-positive endothelial cells and elevated the expression of phosphatidylinositol 3-kinase (PI3K) and chemokine (C-X-C motif) ligand 12 (CXCL12), in the brains of SAH rats. These effects were reversed by MFGE8 RNA silencing, as well as following cilengitide and wortmannin intervention. These results suggest that MFGE8 promotes endothelial regeneration and mitigates endothelial DNA damage through the activation of the TIGβ5/PI3K/CXCL12 signaling pathway.

The calcimimetic R-568 attenuates subarachnoid hemorrhage-induced vasospasm through PI3K/Akt/eNOS signaling pathway in the rat model

Cerebral vasospasm (CVS) causes mortality and morbidity in patients after subarachnoid hemorrhage (SAH). The mechanism and adequate treatment of CVS are still elusive. R-568 is a calcimimetic agent known to exert a vasodilating effect. However, there is no report on its vasodilator effect against SAH-induced vasospasm. In the present study, we investigated the therapeutic effect of R-568 on the SAH-induced CVS model in rats. Seventy-two adult male Sprague-Dawley rats were divided into 8 groups: sham surgery; SAH only; SAH + Vehicle, SAH + R-568; SAH + R-568 + Wortmannin (the PI3K inhibitor); SAH + Wortmannin; SAH + R-568 + Calhex-231 (a calcilytic agent); SAH + Calhex-231. SAH was induced by blood (0.3 mL) given by intracisternal injection. R-568 (20 µM) was administered intracisternal immediately prior to experimental SAH. Basilar arteries (BAs) were obtained to evaluate PI3K/Akt/eNOS pathway (immunoblotting) and morphological changes 48 h after SAH. Perimeters of BAs were decreased by 24.1% in the SAH group compared to the control group and the wall thickness was increased by 75.3%. With R-568 treatment, those percentages were 9.6% and 29.6%, respectively, indicating that vasospasm was considerably improved when compared with the SAH group (P < 0.001 in both). While p-PI3K/PI3K and p-Akt/Akt ratio and eNOS protein expression were markedly decreased in the SAH rats, treatment with R-568 resulted in a significant increase in these levels. The beneficial effects of R-568 were partially blocked in the presence of Calhex-231 and completely blocked in the presence of Wortmannin. Herein, we found that treatment with R-568 would attenuate SAH-induced CVS through the PI3K/Akt/eNOS pathway and demonstrate therapeutic promise in CVS treatment following SAH.

An overview of pharmacotherapy for cerebral vasospasm and delayed cerebral ischemia after subarachnoid hemorrhage

Introduction: Survival from aneurysmal subarachnoid hemorrhage has increased in the past few decades. However, functional outcome after subarachnoid hemorrhage is still suboptimal. Delayed cerebral ischemia (DCI) is one of the major causes of morbidity.Areas covered: Mechanisms underlying vasospasm and DCI after aneurysmal subarachnoid hemorrhage and pharmacological treatment are summarized in this review.Expert opinion: Oral nimodine, an L-type dihydropyridine calcium channel blocker, is the only FDA-approved drug for the prevention and treatment of neurological deficits after aneurysmal subarachnoid hemorrhage. Fasudil, a potent Rho-kinase inhibitor, has also been shown to improve the clinical outcome and has been approved in some countries for use in patients with aneurysmal subarachnoid hemorrhage. Although other drugs, including nicardipine, cilostazol, statins, clazosentan, magnesium and heparin, have been expected to have beneficial effects on DCI, there has been no convincing evidence supporting the routine use of those drugs in patients with aneurysmal subarachnoid hemorrhage in clinical practice. Further elucidation of the mechanisms underlying DCI and the development of effective therapeutic strategies for DCI, including combination therapy, are necessary to further improve the functional outcome and mortality after subarachnoid hemorrhage.

The Role of Tenascin-C in Tissue Injury and Repair After Stroke

Stroke is still one of the most common causes for mortality and morbidity worldwide. Following acute stroke onset, biochemical and cellular changes induce further brain injury such as neuroinflammation, cell death, and blood-brain barrier disruption. Matricellular proteins are non-structural proteins induced by many stimuli and tissue damage including stroke induction, while its levels are generally low in a normal physiological condition in adult tissues. Currently, a matricellular protein tenascin-C (TNC) is considered to be an important inducer to promote neuroinflammatory cascades and the resultant pathology in stroke. TNC is upregulated in cerebral arteries and brain tissues including astrocytes, neurons, and brain capillary endothelial cells following subarachnoid hemorrhage (SAH). TNC may be involved in blood-brain barrier disruption, neuronal apoptosis, and cerebral vasospasm via the activation of mitogen-activated protein kinases and nuclear factor-kappa B following SAH. In addition, post-SAH TNC levels in cerebrospinal fluid predicted the development of delayed cerebral ischemia and angiographic vasospasm in clinical settings. On the other hand, TNC is reported to promote fibrosis and exert repair effects for an experimental aneurysm via macrophages-induced migration and proliferation of smooth muscle cells. The authors review TNC-induced inflammatory signal cascades and the relationships with other matricellular proteins in stroke-related pathology.

The Stroke-Induced Blood-Brain Barrier Disruption: Current Progress of Inspection Technique, Mechanism, and Therapeutic Target

Stroke is one of the leading causes of mortality and morbidity worldwide. The blood-brain barrier (BBB) is a characteristic structure of microvessel within the brain. Under normal physiological conditions, the BBB plays a role in the prevention of harmful substances entering into the brain parenchyma within the central nervous system. However, stroke stimuli induce the breakdown of BBB leading to the influx of cytotoxic substances, vasogenic brain edema, and hemorrhagic transformation. Therefore, BBB disruption is a major complication, which needs to be addressed in order to improve clinical outcomes in stroke. In this review, we first discuss the structure and function of the BBB. Next, we discuss the progress of the techniques utilized to study BBB breakdown in in-vitro and in-vivo studies, along with biomarkers and imaging techniques in clinical settings. Lastly, we highlight the mechanisms of stroke-induced neuroinflammation and apoptotic process of endothelial cells causing BBB breakdown, and the potential therapeutic targets to protect BBB integrity after stroke. Secondary products arising from stroke-induced tissue damage provide transformation of myeloid cells such as microglia and macrophages to pro-inflammatory phenotype followed by further BBB disruption via neuroinflammation and apoptosis of endothelial cells. In contrast, these myeloid cells are also polarized to anti-inflammatory phenotype, repairing compromised BBB. Therefore, therapeutic strategies to induce anti-inflammatory phenotypes of the myeloid cells may protect BBB in order to improve clinical outcomes of stroke patients.

The Updated Role of the Blood Brain Barrier in Subarachnoid Hemorrhage: From Basic and Clinical Studies

Subarachnoid hemorrhage (SAH) is a type of hemorrhagic stroke associated with high mortality and morbidity. The blood-brain-barrier (BBB) is a structure consisting primarily of cerebral microvascular endothelial cells, end feet of astrocytes, extracellular matrix, and pericytes. Post-SAH pathophysiology included early brain injury and delayed cerebral ischemia. BBB disruption was a critical mechanism of early brain injury and was associated with other pathophysiological events. These pathophysiological events may propel the development of secondary brain injury, known as delayed cerebral ischemia. Imaging advancements to measure BBB after SAH primarily focused on exploring innovative methods to predict clinical outcome, delayed cerebral ischemia, and delayed infarction related to delayed cerebral ischemia in acute periods. These predictions are based on detecting abnormal changes in BBB permeability. The parameters of BBB permeability are described by changes in computed tomography (CT) perfusion and magnetic resonance imaging (MRI). K_ep seems to be a stable and sensitive indicator in CT perfusion, whereas K^trans is a reliable parameter for dynamic contrast-enhanced MRI. Future prediction models that utilize both the volume of BBB disruption and stable parameters of BBB may be a promising direction to develop practical clinical tools. These tools could provide greater accuracy in predicting clinical outcome and risk of deterioration. Therapeutic interventional exploration targeting BBB disruption is also promising, considering the extended duration of post-SAH BBB disruption.

Understanding Cognitive Deficit After Subarachnoid Hemorrhage: A Memory Focused Approach

Aneurysmal subarachnoid hemorrhage (aSAH) is a prevalent condition affecting a large portion of the population, many of them still in productive ages. Memory impairment is a common factor amongst those patients. Memory exerts a pivotal role in productivity. That is why it is important to understand how it can be affected in post-aSAH patients. There are certain areas most affected in cases of memory disturbances, as well as its functional connections with crucial cerebral regions. Active research on functional magnetic resonance and diffusion tension imaging is used to identify compromised areas within the brain. There are suggested factors regarding poor performance, such as cerebrospinal fluid drainage and new infarction areas, which should be addressed properly to benefit these patients and simultaneously help them return to a productive and functional life.

Contrast-induced encephalopathy mimicking total anterior circulation stroke: a case report and review of the literature

INTRODUCTION

Contrast-induced encephalopathy is a rare and usually reversible entity due to the administration of iodinated contrast. Clinical manifestations include cortical blindness, encephalopathy, seizures and focal neurological deficits.

METHODS

We report the case of a 56-year-old woman who developed global aphasia and right hemiplegia after a cerebral angiography performed for a subarachnoid haemorrhage. A prompt brain MRI resulted negative, while CT scan revealed left cerebral oedema with the cerebral sulci effacement. Complete recovery was observed in 10 days.

DISCUSSION

Diagnosis of contrast-induced encephalopathy requires a temporal correlation between neurological dysfunction and administration of iodinated contrast. Usually, the symptomatology is transient with a full recovery within 48-72 h. The most common symptom is cortical blindness, while other symptoms have been rarely reported. Only 20 cases previously reported global aphasia and/or hemiplegia or mimed anterior circulation strokes. Prompt brain neuroimaging is essential in order to exclude an alternative diagnosis that requires a distinct therapeutic approach.

Cerebrovascular pathophysiology of delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (SAH) remains a serious cerebrovascular disease. Even if SAH patients survive the initial insults, delayed cerebral ischemia (DCI) may occur at 4 days or later post-SAH. DCI is characteristics of SAH, and is considered to develop by blood breakdown products and inflammatory reactions, or secondary to early brain injury, acute pathophysiological events that occur in the brain within the first 72 hours of aneurysmal SAH. The pathology underlying DCI may involve large artery vasospasm and/or microcirculatory disturbances by microvasospasm, microthrombosis, dysfunction of venous outflow and compression of microvasculature by vasogenic or cytotoxic tissue edema. Recent clinical evidence has shown that large artery vasospasm is not the only cause of DCI, and that both large artery vasospasm-dependent and -independent cerebral infarction causes poor outcome. Animal studies suggest that mechanisms of vasospasm may differ between large artery and arterioles or capillaries, and that many kinds of cells in the vascular wall and brain parenchyma may be involved in the pathogenesis of microcirculatory disturbances. The impairment of the paravascular and glymphatic systems also may play important roles in the development of DCI. As pathological mediators for DCI, glutamate and several matricellular proteins have been investigated in addition to inflammatory molecules. Glutamate is involved in excitotoxicity contributing to cortical spreading ischemia and epileptic activity-related events. Microvascular dysfunction is an attractive mechanism to explain the cause of poor outcomes independently of large cerebral artery vasospasm, but needs more studies to clarify the pathophysiologies or mechanisms and to develop a novel therapeutic strategy.

Clinical and Imaging Characteristics in Patients with SARS-CoV-2 Infection and Acute Intracranial Hemorrhage

BACKGROUND AND PURPOSE

Intracranial hemorrhage has been observed in patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection (COVID-19), but the clinical, imaging, and pathophysiological features of intracranial bleeding during COVID-19 infection remain poorly characterized. This study describes clinical and imaging characteristics of patients with COVID-19 infection who presented with intracranial bleeding in a European multicenter cohort.

METHODS

This is a multicenter retrospective, observational case series including 18 consecutive patients with COVID-19 infection and intracranial hemorrhage. Data were collected from February to May 2020 at five designated European special care centers for COVID-19. The diagnosis of COVID-19 was based on laboratory-confirmed diagnosis of SARS-CoV-2. Intracranial bleeding was diagnosed on computed tomography (CT) of the brain within one month of the date of COVID-19 diagnosis. The clinical, laboratory, radiologic, and pathologic findings, therapy and outcomes in COVID-19 patients presenting with intracranial bleeding were analyzed.

RESULTS

Eighteen patients had evidence of acute intracranial bleeding within 11 days (IQR 9-29) of admission. Six patients had parenchymal hemorrhage (33.3%), 11 had subarachnoid hemorrhage (SAH) (61.1%), and one patient had subdural hemorrhage (5.6%). Three patients presented with intraventricular hemorrhage (IVH) (16.7%).

CONCLUSION

This study represents the largest case series of patients with intracranial hemorrhage diagnosed with COVID-19 based on key European countries with geospatial hotspots of SARS-CoV-2. Isolated SAH along the convexity may be a predominant bleeding manifestation and may occur in a late temporal course of severe COVID-19.

Posterior reversible encephalopathy syndrome and reversible cerebral vasoconstriction syndrome associated spinal subdural hematoma: A case report

RATIONALE

Posterior reversible encephalopathy syndrome (PRES) and reversible cerebral vasoconstriction syndrome (RCVS) are separate clinical entities with distinct pathophysiological features. But in some special conditions PRES and RCVS can occur simultaneously.

PATIENT CONCERNS

We report the unique case of a 40-year-old female presented with crescendo headache, blurred vision, and recurrent generalized tonic-clonic seizure. She had a minor neck injury 1 week before but attracted no more attention. Neurological tests on admission yielded a Glasgow Coma Scale score of 13. No obvious focal neurological deficit apart from positive signs of meningeal irritation was presented.

DIAGNOSES

Xanthochromia and hemorrhagic cerebrospinal fluid with pleocytosis was found on lumbar puncture. Cranial computed tomography was negative but magnetic resonance imaging demonstrated bilateral areas of vasogenic edema in the parieto-occipital lobes and cerebellum consistent with PRES. An incidental subacute spinal subdural hematoma extending from the level of C6 to T1 was depicted by spinal magnetic resonance imaging, presumably as a complication of negligible neck trauma. Spinal digital subtraction angiography showed no evidence of spinal aneurysm, arteriovenous malformation, or dural arteriovenous fistula. Cerebral digital subtraction angiography showed segmental narrowing and dilatation of vessels, a potential feature of RCVS, involving the circle of Willis and their branches.

INTERVENTIONS

The patient was treated with nimodipine for vasodilation and other symptomatic therapies. The spinal subdural hematoma was not warranted for surgical intervention and managed with simple analgesics.

OUTCOMES

The patient experienced a dramatic improvement in neurological symptoms and was discharged without sequelae. Follow-up imaging showed complete resolution of all radiological changes.

LESSONS

Clinician should be aware of spinal subdural hematoma as the potential trigger in development of PRES and RCVS. We speculate that endothelial dysfunction and vascular tone dysregulation may be implicated to play the major pathophysiologic role.

Loss of consciousness at ictus and/or poor World Federation of Neurosurgical Societies grade on admission reflects the impact of EBI and predicts poor outcome in patients with SAH

Background:

There are many scores and markers that predict poor outcome in patients with subarachnoid hemorrhage (SAH). However, parameters that can predict outcomes in patients with SAH with high specificity and sensitivity, which can be identified in the early postictal state and utilized as a clinical marker of early brain injury (EBI) have not been identified so far.

Methods:

Thirty-nine patients with SAH due to a saccular intracranial aneurysm rupture were reviewed. We retrospectively analyzed the relationships between patients’ baseline characteristics and patients’ outcomes to identify parameters that could predict patient outcomes in the early postictal state.

Results:

In the univariate analysis, older age (>65), loss of consciousness (LOC) at ictus, poor initial World Federation of Neurosurgical Societies (WFNS) grade (3–5), and delayed cerebral ischemia (DCI) were associated with poor outcome (GOS 1–3). Statistical analyses revealed that combined LOC at ictus and/or poor initial WFNS grade (3–5) was a more powerful surrogate marker of outcome (OR 15.2 [95% CI 3.1–75.5]) than either LOC at ictus or the poor initial WFNS grade (3–5) alone. Multivariate logistic regression analyses revealed that older age, combined LOC at ictus and/or poor initial WFNS grade, and DCI were independently associated with poor outcome.

Conclusion:

Combined LOC at ictus and/or poor initial WFNS grade (3–5) reflects the impact of EBI and was a useful surrogate marker of poor prognosis in SAH patients, independent of patients’ age and state of DCI.

Non-steroidal anti-inflammatory drugs in the pathophysiology of vasospasms and delayed cerebral ischemia following subarachnoid hemorrhage: a critical review

Aneurysmal subarachnoid hemorrhage (aSAH) is a life-threatening condition associated with the development of early brain injury (EBI) and delayed cerebral ischemia (DCI). Pharmacological treatment of vasospasm following aSAH currently mainly comprises nimodipine administration. In the past few years, many drugs that can potentially benefit cases of subarachnoid hemorrhage have become available. The objective of this review is to critically assess the effects of non-steroidal anti-inflammatory drugs (NSAIDs) following aSAH. A systematic literature review was conducted following PRISMA guidelines. The search was aimed at studies addressing aSAH and NSAIDs during the 2010 to 2019 period, and it yielded 13 articles. Following the application of search criteria, they were divided into two groups, one containing 6 clinical articles and the other containing 7 experimental articles on animal models of aSAH. Inflammatory cerebral changes after aneurysm rupture contribute to the development of EBI, DCI and cerebral vasospasm. It appears that NSAIDs (especially coxibs) are even more effective in reducing vasospasm than nimodipine. Other beneficial effects of NSAIDs include reduction in mortality, improved functional outcome and increased hypoaggregability. However, despite these positive effects, there is only one randomized, double-blind, placebo-controlled trial showing a tendency towards a better outcome with lower incidence of vasospasm or mortality in patients following aSAH.