Intracerebral hemorrhage: effects of aging on brain edema and neurological deficits

The cerebroprotection and prospects of FNDC5/irisin in stroke

Stroke, the leading cause of disability and cognitive impairment, is also the second leading cause of death worldwide. The drugs with multi-targeted brain cytoprotective effects are increasingly being advocated for the treatment of stroke. Irisin, a newly discovered myokine produced by cleavage of fibronectin type III domain 5, has been shown to regulate glucose metabolism, mitochondrial energy, and fat browning. A large amount of evidence indicated that irisin could exert anti-inflammatory, anti-apoptotic, and antioxidant properties in a variety of diseases such as myocardial infarction, inflammatory bowel disease, lung injury, and kidney or liver disease. Studies have found that irisin is widely distributed in multiple brain regions and also plays an important regulatory role in the central nervous system. The most common cause of a stroke is a sudden blockage of an artery (ischemic stroke), and in some circumstances, a blood vessel rupture can also result in a stroke (hemorrhagic stroke). After a stroke, complicated pathophysiological processes lead to serious brain injury and neurological dysfunction. According to recent investigations, irisin may protect elements of the neurovascular unit by acting on multiple pathological processes in stroke. This review aims to outline the currently recognized effects of irisin on stroke and propose possible directions for future research.

CSF1R blockade slows progression of cerebral hemorrhage by reducing microglial proliferation and increasing infiltration of CD8 + CD122+ T cells into the brain

Microglia play a pivotal role in the neuroinflammatory response after brain injury, and their proliferation is dependent on colony-stimulating factors. In the present study, we investigated the effect of inhibiting microglia proliferation on neurological damage post intracerebral hemorrhage (ICH) in a mouse model, an aspect that has never been studied before. Using a colony-stimulating factor-1 receptor antagonist (GW2580), we observed that inhibition of microglia proliferation significantly ameliorated neurobehavioral deficits, attenuated cerebral edema, and reduced hematoma volume after ICH. This intervention was associated with a decrease in pro-inflammatory factors in microglia and an increased infiltration of peripheral regulatory CD8 + CD122+ T cells into the injured brain tissue. The CXCR3/CXCL10 axis is the mechanism of brain homing of regulatory CD8 + CD122+ T cells, and the high expression of IL-10 is the hallmark of their synergistic anti-inflammatory effect with microglia. And activated astrocytes around the insult site are a prominent source of CXCL10. Thus, inhibition of microglial proliferation offers a new perspective for clinical translation. The cross-talk between multiple cells involved in the regulation of the inflammatory response highlights the comprehensive nature of neuroimmunomodulation.

Hypothermia and temperature modulation for intracerebral hemorrhage (ICH): pathophysiology and translational applications

Background

Intracerebral hemorrhage (ICH) still poses a substantial challenge in clinical medicine because of the high morbidity and mortality rate that characterizes it. This review article expands into the complex pathophysiological processes underlying primary and secondary neuronal death following ICH. It explores the potential of therapeutic hypothermia as an intervention to mitigate these devastating effects.

Methods

A comprehensive literature review to gather relevant studies published between 2000 and 2023.

Discussion

Primary brain injury results from mechanical damage caused by the hematoma, leading to increased intracranial pressure and subsequent structural disruption. Secondary brain injury encompasses a cascade of events, including inflammation, oxidative stress, blood-brain barrier breakdown, cytotoxicity, and neuronal death. Initial surgical trials failed to demonstrate significant benefits, prompting a shift toward molecular mechanisms driving secondary brain injury as potential therapeutic targets. With promising preclinical outcomes, hypothermia has garnered attention, but clinical trials have yet to establish its definitive effectiveness. Localized hypothermia strategies are gaining interest due to their potential to minimize systemic complications and improve outcomes. Ongoing and forthcoming clinical trials seek to clarify the role of hypothermia in ICH management.

Conclusion

Therapeutic hypothermia offers a potential avenue for intervention by targeting the secondary injury mechanisms. The ongoing pursuit of optimized cooling protocols, localized cooling strategies, and rigorous clinical trials is crucial to unlocking the potential of hypothermia as a therapeutic tool for managing ICH and improving patient outcomes.

Intracranial Pressure Dysfunction Following Severe Intracerebral Hemorrhage in Middle-Aged Rats

Rising intracranial pressure (ICP) aggravates secondary injury and heightens risk of death following intracerebral hemorrhage (ICH). Long-recognized compensatory mechanisms that lower ICP include reduced cerebrospinal fluid and venous blood volumes. Recently, we identified another compensatory mechanism in severe stroke, a decrease in cerebral parenchymal volume via widespread reductions in cell volume and extracellular space (tissue compliance). Here, we examined how age affects tissue compliance and ICP dynamics after severe ICH in rats (collagenase model). A planned comparison to historical young animal data revealed that aged SHAMs (no stroke) had significant cerebral atrophy (9% reduction, p ≤ 0.05), ventricular enlargement (9% increase, p ≤ 0.05), and smaller CA1 neuron volumes (21%, p ≤ 0.05). After ICH in aged animals, contralateral striatal neuron density and CA1 astrocyte density significantly increased (12% for neurons, 7% for astrocytes, p ≤ 0.05 vs. aged SHAMs). Unlike young animals, other regions in aged animals did not display significantly reduced cell soma volume despite a few trends. Nonetheless, overall contralateral hemisphere volume was 10% smaller in aged ICH animals compared to aged SHAMs (p ≤ 0.05). This age-dependent pattern of tissue compliance is not due to absent ICH-associated mass effect (83.2 mm3 avg. bleed volume) as aged ICH animals had significantly elevated mean and peak ICP (p ≤ 0.01), occurrence of ICP spiking events, as well as bilateral evidence of edema (e.g., 3% in injured brain, p ≤ 0.05 vs. aged SHAMs). Therefore, intracranial compliance reserve changes with age; after ICH, these and other age-related changes may cause greater fluctuation from baseline, increasing the chance of adverse outcomes like mortality.

Spatiotemporal Cofilin Signaling, Microglial Activation, Neuroinflammation, and Cognitive Impairment Following Hemorrhagic Brain Injury

Intracerebral hemorrhage (ICH) is a significant health concern associated with high mortality. Cofilin plays a crucial role in stress conditions, but its signaling following ICH in a longitudinal study is yet to be ascertained. In the present study, we examined the cofilin expression in human ICH autopsy brains. Then, the spatiotemporal cofilin signaling, microglia activation, and neurobehavioral outcomes were investigated in a mouse model of ICH. Human autopsy brain sections from ICH patients showed increased intracellular cofilin localization within microglia in the perihematomal area, possibly associated with microglial activation and morphological changes. Various cohorts of mice were subjected to intrastriatal collagenase injection and sacrificed at time points of 1, 3, 7, 14, 21, and 28 days. Mice suffered from severe neurobehavioral deficits after ICH, lasting for 7 days, followed by a gradual improvement. Mice suffered post-stroke cognitive impairment (PSCI) both acutely and in the chronic phase. Hematoma volume increased from day 1 to 3, whereas ventricle size increased from day 21 to 28. Cofilin protein expression increased in the ipsilateral striatum on days 1 and 3 and then decreased from days 7 to 28. An increase in activated microglia was observed around the hematoma on days 1 to 7, followed by a gradual reduction up to day 28. Around the hematoma, activated microglia showed morphological changes from ramified to amoeboid. mRNA levels of inflammatory [tumor necrosis factor-α (TNF-α), interleukin 1β (IL-1β), and interleukin-6 (IL-6) and anti-inflammatory markers [interleukin-10 (IL-10), transforming growth factor-β TGF-β, and arginase I (Arg1)] increased during the acute phase and decreased in the chronic phase. Blood cofilin levels increased on day 3 and matched the increase in chemokine levels. slingshot protein phosphatase 1 (SSH1) protein, which activates cofilin, was increased from day 1 to 7. These results suggest that microglial activation might be the sequel of cofilin overactivation following ICH, leading to widespread neuroinflammation and consequent PSCI.

Brain edema formation and therapy after intracerebral hemorrhage

Intracerebral hemorrhage (ICH) accounts for about 10% of all strokes in the United States of America causing a high degree of disability and mortality. There is initial (primary) brain injury due to the mechanical disruption caused by the hematoma. There is then secondary injury, triggered by the initial injury but also the release of various clot-derived factors (e.g., thrombin and hemoglobin). ICH alters brain fluid homeostasis. Apart from the initial hematoma mass, ICH causes blood-brain barrier disruption and parenchymal cell swelling, which result in brain edema and intracranial hypertension affecting patient prognosis. Reducing brain edema is a critical part of post-ICH care. However, there are limited effective treatment methods for reducing perihematomal cerebral edema and intracranial pressure in ICH. This review discusses the mechanisms underlying perihematomal brain edema formation, the effects of sex and age, as well as how edema is resolved. It examines progress in pharmacotherapy, particularly focusing on drugs which have been or are currently being investigated in clinical trials.

Remodeling of the Neurovascular Unit Following Cerebral Ischemia and Hemorrhage

Formulated as a group effort of the stroke community, the transforming concept of the neurovascular unit (NVU) depicts the structural and functional relationship between brain cells and the vascular structure. Composed of both neural and vascular elements, the NVU forms the blood-brain barrier that regulates cerebral blood flow to meet the oxygen demand of the brain in normal physiology and maintain brain homeostasis. Conversely, the dysregulation and dysfunction of the NVU is an essential pathological feature that underlies neurological disorders spanning from chronic neurodegeneration to acute cerebrovascular events such as ischemic stroke and cerebral hemorrhage, which were the focus of this review. We also discussed how common vascular risk factors of stroke predispose the NVU to pathological changes. We synthesized existing literature and first provided an overview of the basic structure and function of NVU, followed by knowledge of how these components remodel in response to ischemic stroke and brain hemorrhage. A greater understanding of the NVU dysfunction and remodeling will enable the design of targeted therapies and provide a valuable foundation for relevant research in this area.

Analysis of Age-Dependent Transcriptomic Changes in Response to Intracerebral Hemorrhage in Mice

Age is a well-known risk factor that is independently associated with poor outcomes after intracerebral hemorrhage (ICH). However, the interrelationship between age and poor outcomes after ICH is not well defined. In this study, we aimed to investigate this relationship based on collagenase-induced ICH mice models. After being assessed neurological deficit 24 h after ICH, mice were euthanized and brain perihematomal tissues were used for RNA-sequencing (RNA-seq). And then the functions of differentially expressed genes (DEGs) identified by RNA-seq were analyzed using Gene Ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, Ingenuity Pathway Analysis (IPA) and protein-protein interaction (PPI) analysis. In addition, we performed real-time quantitative polymerase chain reaction (RT-qPCR) for validation of candidate DEGs. In the behavioral tests, aged mice presented significantly worse neurological function than young mice and greater weight loss than aged sham controls 24 h after ICH. In DEGs analysis, ICH affected the expression of more genes in young mice (2,337 DEGs) compared with aged mice (2,005 DEGs). We found aged mice exhibited increased brain inflammatory responses compared with young animals and ICH induced significant activation of the interferon-β (IFN-β) and IFN signaling pathways exclusively in aged mice. Moreover, further analysis demonstrated that ICH resulted in the activation of cytosolic DNA-sensing pathway with the production of downstream molecule type I IFN, and the response to type I IFN was more significant in aged mice than in young mice. In agreement with the results of RNA-seq, RT-qPCR indicated that the expression of candidate genes of cyclic GMP-AMP synthase (cGAS), Z-DNA-binding protein 1 (ZBP1), and IFN-β was significantly altered in aged mice after ICH. Taken together, our study indicated that compared to young animals, aged mice exhibit increased vulnerability to ICH and that the differences in transcriptional response patterns to ICH between young and aged mice. We believe that these findings will facilitate our understanding of ICH pathology and help to translate the results of preclinical studies into a clinical setting.

Vitamin D Enhances Hematoma Clearance and Neurologic Recovery in Intracerebral Hemorrhage

BACKGROUND

Erythrophagocytosis by reparative monocyte-derived macrophage contributes to hematoma clearance and neurological recovery after intracerebral hemorrhage (ICH). Vitamin D (VitD) is a neuroprotective hormone and regulates the differentiation of monocyte-derived macrophage from monocytes. In this study, we examined the effects of VitD supplementation on monocyte-derived macrophage and hematoma clearance in rodent with ICH.

METHODS

Neurobehavioral functions and hematoma volume were assessed using a collagenase injection model in both young- and middle-aged mice with or without VitD treatment given 2 hours post-ICH induction. We used flow cytometry to analyze CD36 expression and macrophage and undifferentiated monocyte cell numbers during in vivo erythrophagocytosis in collagenase and autologous blood injection models. Western blot analysis and immunofluorescence were used to assess the expression levels of the PPAR-γ (peroxisome proliferator-activated receptor γ)-CD36 axis and CD206. A macrophage differentiation study was conducted on murine bone marrow-derived monocytes.

RESULTS

VitD promoted neurological recovery and facilitated hematoma clearance in both young- and middle-aged mice after ICH. Within the perihematomal region, mature macrophages, rather than undifferentiated monocytes, expressed higher levels of CD36 in driving erythrocyte clearance. VitD increased the macrophage number but decreased the monocyte number and elevated the levels of CD36 and PPAR-γ in the brain. In vitro, VitD accelerated the differentiation of reparative macrophages from bone marrow-derived monocytes.

CONCLUSIONS

VitD promotes reparative macrophage differentiation, facilitates hematoma clearance, and improves neurobehavioral performance in mice with ICH, suggesting that VitD should be further examined as a potentially promising treatment for ICH.

Intracerebral Hemorrhage: The Effects of Aging on Brain Injury

Intracerebral hemorrhage (ICH) is a devastating subtype of stroke with high rates of mortality and morbidity. ICH patients often suffer devastating and debilitating neurological impairments, from which the majority of victims are unable to fully recover to functional independence. Unfortunately, there is no established medical therapy for ICH, which is partly attributed to the lack of understanding of the complex pathology of the disorder. Despite advanced age being a major risk factor of ICH, most preclinical studies on ICH employed young animal subjects. Due to this discrepancy, the molecular level changes in the aging brain after ICH are largely unknown, limiting the translation of preclinical studies into potential human treatments. The purpose of this review is to highlight the effects of advanced age on ICH- induced brain injury and recovery and to draw attention to current knowledge gaps, which warrant further investigation.

Redistribution of Histone Marks on Inflammatory Genes Associated With Intracerebral Hemorrhage-Induced Acute Brain Injury in Aging Rats

The contribution of histone mark redistribution to the age-induced decline of endogenous neuroprotection remains unclear. In this study, we used an intracerebral hemorrhage (ICH)-induced acute brain injury rat model to study the transcriptional and chromatin responses in 13- and 22-month-old rats. Transcriptome analysis (RNA-seq) revealed that the expression of neuroinflammation-associated genes was systematically upregulated in ICH rat brains, irrespective of age. Further, we found that interferon-γ (IFN-γ) response genes were activated in both 13- and 22-month-old rats. Anti-IFN-γ treatment markedly reduced ICH-induced acute brain injury in 22-month-old rats. At the chromatin level, ICH induced the redistribution of histone modifications in the promoter regions, especially H3K4me3 and H3K27me3, in neuroinflammation-associated genes in 13- and 22-month-old rats, respectively. Moreover, ICH-induced histone mark redistribution and gene expression were found to be correlated. Collectively, these findings demonstrate that histone modifications related to gene expression are extensively regulated in 13- and 22-month-old rats and that anti-IFN-γ is effective for ICH treatment, highlighting the potential of developing therapies targeting histone modifications to cure age-related diseases, including brain injury and neuroinflammation.

Irisin ameliorates neuroinflammation and neuronal apoptosis through integrin αVβ5/AMPK signaling pathway after intracerebral hemorrhage in mice

Background

Neuroinflammation is a crucial factor in the development of secondary brain injury after intracerebral hemorrhage (ICH). Irisin is a newly identified myokine that confers strong neuroprotective effects in experimental ischemic stroke. However, whether this myokine can exert neuroprotection effects after ICH remains unknown. This study aimed to investigate the impact of irisin treatment on neuroinflammation and neuronal apoptosis and the underlying mechanism involving integrin αVβ5/AMPK pathway after ICH.

Methods

Two hundred and eighty-five adult (8-week-old) male C57BL/6 mice were randomly assigned to sham and ICH surgery groups. ICH was induced via intrastriatal injection of autologous blood. Irisin was administered intranasally at 30 min after ICH. To elucidate the underlying mechanism, cilengitide (a selective integrin αVβ5 inhibitor) and dorsomorphin (a selective phosphorylated AMPK inhibitor) were administered before irisin treatment. The short- and long-term neurobehavior tests, brain edema, quantitative-PCR, western blotting, Fluoro-Jade C, TUNEL, and immunofluorescence staining were performed to assess the neurofunctional outcome at the level of molecular, cell, histology, and function.

Results

Endogenous irisin and its receptor, integrin αVβ5, were increased, peaked at 24 h after ICH. irisin post-treatment improved both short- and long-term neurological functions, reduced brain edema after ICH. Interestingly, integrin αVβ5 was mainly located in the microglia after ICH, and irisin post-treatment inhibited microglia/macrophage pro-inflammatory polarization and promoted anti-inflammatory polarization. Moreover, irisin treatment inhibited neutrophil infiltration and suppressed neuronal apoptotic cell death in perihematomal areas after ICH. Mechanistically, irisin post-treatment significantly increased the expression of integrin αVβ5, p-AMPK and Bcl-2, and decreased the expression of IL-1β, TNF-α, MPO, and Bax following ICH. The neuroprotective effects of irisin were abolished by both integrin αVβ5 inhibitor cilengitide and AMPK inhibitor dorsomorphin.

Conclusions

This study demonstrated that irisin post-treatment ameliorated neurological deficits, reduced brain edema, and ameliorated neuroinflammation and neuronal apoptosis, at least in part, through the integrin αVβ5/AMPK signaling pathway after ICH. Thus, irisin post-treatment may provide a promising therapeutic approach for the early management of ICH.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-022-02438-6.

Glibenclamide Attenuates Neuroinflammation and Promotes Neurological Recovery After Intracerebral Hemorrhage in Aged Rats

Intracerebral hemorrhage (ICH) is a common disease in the elderly population. Inflammation following ICH plays a detrimental role in secondary brain injury, which is associated with a poor prognosis of patients with ICH, and no efficient pharmacological preventions are available. Here, we investigated the effects of glibenclamide (GLC) on neuroinflammation in an autoblood-induced aged rat (18 months old) model of ICH. Rats were randomized into the sham, vehicle, and GLC groups. First, we investigated the expression level of sulfonylurea receptor 1 (Sur1) surrounding the hematoma after ICH. Then, neurological scores were calculated, and water maze tests, brain water content analysis, western blotting, and immunofluorescence assays were implemented to detect the neuroprotective effect of GLC. The expression of the Sur1-Trpm4 channel was significantly increased in the perihematomal tissue following ICH in aged rats. The GLC administration effectively reduced brain edema and improved neurofunction deficits following ICH. In addition, GLC increased the expression of brain-derived neurotrophic factors and decreased the expression of proinflammatory factors [tumor necrosis factor (TNF)-α,interleukin (IL)-1, and IL-6]. Moreover, GLC markedly reduced Ikappa-B (IκB) kinase (IKK) expression in microglia and nuclear factor (NF)-κB-P65 levels in perihematomal tissue. GLC ameliorated ICH-induced neuroinflammation and improved neurological outcomes in aged rats. In part, GLC may exert these effects by regulating the NF-κB signaling pathway through the Sur1-Trpm4 channel.

Recombinant CCL17-dependent CCR4 activation alleviates neuroinflammation and neuronal apoptosis through the PI3K/AKT/Foxo1 signaling pathway after ICH in mice

Background

Intracerebral hemorrhage (ICH), a devastating subtype of stroke, is associated with high mortality and morbidity. Neuroinflammation is an important factor leading to ICH-induced neurological injuries. C-C Chemokine Receptor 4 (CCR4) plays an important role in enhancing hematoma clearance after ICH. However, it is unclear whether CCR4 activation can ameliorate neuroinflammation and apoptosis of neurons following ICH. The aim of the present study was to examine the effects of recombinant CCL17 (rCCL17)-dependent CCR4 activation on neuroinflammation and neuronal apoptosis in an intrastriatal autologous blood injection ICH model, and to determine whether the PI3K/AKT/Foxo1 signaling pathway was involved.

Methods

Two hundred twenty-six adult (8-week-old) male CD1 mice were randomly assigned to sham and ICH surgery groups. An intrastriatal autologous blood injection ICH model was used. rCCL17, a CCR4 ligand, was delivered by intranasal administration at 1 h, 3 h, and 6 h post-ICH. CCL17 antibody was administrated by intraventricular injection at 1 h post-ICH. C021, a specific inhibitor of CCR4 and GDC0068, an AKT inhibitor were delivered intraperitoneally 1 h prior to ICH induction. Brain edema, neurobehavioral assessments, western blotting, Fluoro-Jade C staining, terminal deoxynucleotidyl transferase dUTP nick end labeling, and immunofluorescence staining were conducted.

Results

Endogenous expression of CCL17 and CCR4 were increased following ICH, peaking at 5 days post-induction. CCR4 was found to co-localize with microglia, neurons, and astrocytes. rCCL17 treatment decreased brain water content, attenuated short- and long-term neurological deficits, deceased activation of microglia/macrophages and infiltration of neutrophils, and inhibited neuronal apoptosis in the perihematomal region post-ICH. Moreover, rCCL17 treatment post-ICH significantly increased the expression of CCR4, PI3K, phosphorylated AKT, and Bcl-2, while Foxo1, IL-1β, TNF-α, and Bax expression were decreased. The neuroprotective effects of rCCL17 were reversed with the administration of C021 or GDC0068.

Conclusions

rCCL17-dependent CCR4 activation ameliorated neurological deficits, reduced brain edema, and ameliorated neuroinflammation and neuronal apoptosis, at least in part, through the PI3K/AKT/Foxo1 signaling pathway after ICH. Thus, activation of CCR4 may provide a promising therapeutic approach for the early management of ICH.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-021-02112-3.

TRPV4 channels mediate the mechanoresponse in retinal microglia

The physiological and neurological correlates of plummeting brain osmolality during edema, traumatic CNS injury, and severe ischemia are compounded by neuroinflammation. Using multiple approaches, we investigated how retinal microglia respond to challenges mediated by increases in strain, osmotic gradients, and agonists of the stretch-activated cation channel TRPV4. Dissociated and intact microglia were TRPV4-immunoreactive and responded to the selective agonist GSK1016790A and substrate stretch with altered motility and elevations in intracellular calcium ([Ca²⁺ ]_i ). Agonist- and hypotonicity-induced swelling was associated with a nonselective outwardly rectifying cation current, increased [Ca²⁺ ]_i , and retraction of higher-order processes. The antagonist HC067047 reduced the extent of hypotonicity-induced microglial swelling and inhibited the suppressive effects of GSK1016790A and hypotonicity on microglial branching. Microglial TRPV4 signaling required intermediary activation of phospholipase A2 (PLA2), cytochrome P450, and epoxyeicosatrienoic acid production (EETs). The expression pattern of vanilloid thermoTrp genes in retinal microglia was markedly different from retinal neurons, astrocytes, and cortical microglia. These results suggest that TRPV4 represents a primary retinal microglial sensor of osmochallenges under physiological and pathological conditions. Its activation, associated with PLA2, modulates calcium signaling and cell architecture. TRPV4 inhibition might be a useful strategy to suppress microglial overactivation in the swollen and edematous CNS.

Optimized lactoferrin as a highly promising treatment for intracerebral hemorrhage: Pre-clinical experience

Intracerebral hemorrhage (ICH) is the deadliest form of stroke for which there is no effective treatment, despite an endless number of pre-clinical studies and clinical trials. The obvious therapeutic target is the neutralization of toxic products of red blood cell (RBC) lysis that lead to cytotoxicity, inflammation, and oxidative damage. We used rigorous approaches and translationally relevant experimental ICH models to show that lactoferrin-(LTF)-based monotherapy is uniquely robust in reducing brain damage after ICH. Specifically, we designed, produced, and pharmacokinetically/toxicologically characterized an optimized LTF, a fusion of human LTF and the Fc domain of human IgG (FcLTF) that has a 5.8-fold longer half-life in the circulation than native LTF. Following dose-optimization studies, we showed that FcLTF reduces neurological injury caused by ICH in aged male/female mice, and in young male Sprague Dawley (SD) and spontaneously hypertensive rats (SHR). FcLTF showed a remarkably long 24-h therapeutic window. In tissue culture systems, FcLTF protected neurons from the toxic effects of RBCs and promoted microglia toward phagocytosis of RBCs and dead neurons, documenting its pleotropic effect. Our findings indicate that FcLTF is safe and effective in reducing ICH-induced damage in animal models used in this study.

Potential therapeutic targets for intracerebral hemorrhage-associated inflammation: An update

Intracerebral hemorrhage (ICH) is a subtype of stroke with high mortality and disability but no specific or effective treatment. In the last two decades, much has been learned about the pathologic mechanisms of ICH. It is now known that after ICH onset, immune and inflammatory responses contribute to blood-brain barrier disruption, edema development, and cell death processes, jointly resulting in secondary brain injury. However, the translation of potential therapies from preclinical to clinical success has been disappointing. With the development of new laboratory technology, recent progress has been made in the understanding of ICH pathomechanisms, and promising therapeutic targets have been identified. This review provides an update of recent progress on ICH and describes the prospects for further preclinical studies in this field. Our goal is to discuss new therapeutic targets and directions for the treatment of ICH and promote the effective transformation from preclinical to clinical trials.

Autophagy and Hemorrhagic Stroke

Hemorrhagic stroke includes cerebral hemorrhage and subarachnoid hemorrhage. An increasing number of studies have found that autophagy also occurs in brain tissues after cerebral hemorrhage and subarachnoid hemorrhage. The potential role of selective autophagy in the clinical treatment of hemorrhagic stroke has been recognized, but a consensus on the exact effect and function of autophagy has not been reached, and the mechanism needs to be further studied. In this chapter, the mechanism of brain injury after cerebral hemorrhage and subarachnoid hemorrhage is briefly introduced, and changes in the autophagy pathway and the role of autophagy in the process of brain injury are discussed.

Different responses after intracerebral hemorrhage between young and early middle-aged mice

Although aging is a major risk factor for intracerebral hemorrhage (ICH), there are very few studies comparing ICH pathology between young and early middle-aged mice. In this study, 8-month old mice (early middle-aged mice) were compared against 2-month old mice (young mice) in neurological and histological changes after ICH induction, such as body weight, lesion volume, astrocytic responses, and motor and cognitive functions. At day 8 after ICH, there was no significant difference in lesion volume between the two groups, and both groups did not exhibit significant cognitive decline, as assessed by spontaneous alternative Y-maze test. On the other hand, 8-month old mice showed delayed recovery from body weight loss, along with reduced astrocytic activation. Interestingly, in the two motor function tests (beam-walking test and corner turn test), 8-month old mice exhibited lower scores only in the beam-walking test, suggesting a partial disturbance in motor recovery after ICH. These results suggest that age-related differences in ICH pathology may already start to appear in early middle-aged brains.

Effects of aging on hydrocephalus after intraventricular hemorrhage

BACKGROUND

Hydrocephalus is a common and major complication that affects outcome after intraventricular hemorrhage (IVH). While aging impacts the occurrence of hydrocephalus in patients with IVH this and the underlying mechanisms have received little attention. The present investigation, therefore, studied the impact of aging on hydrocephalus after IVH in a rat model.

METHODS

Young and aged (3 and 18 months old, respectively) male Fischer 344 rats had an intraventricular injection of 200 μl autologous blood or saline. Ventricular volume was estimated using magnetic resonance imaging (MRI), while ventricular wall damage, heme oxygenase-1 (HO-1) and epiplexus cell activation were quantified by histological staining and Western blot. Additionally, the impact of intraventricular iron injection was examined in young and aged rats.

RESULTS

Intraventricular injection of autologous blood induced hydrocephalus in both young and aged rats but ventricular volumes were larger in aged rats compared to young rats from day 3 to day 14 followed IVH. In addition, ventricular wall damage and periventricular HO-1 upregulation were greater in aged versus young rats on day 1 after IVH. Aged rats also had more choroid plexus epiplexus cells on day 14 after IVH. Additionally, organized hematomas were observed in 23% (3/13) of aged rats but not in young rats after IVH. Organized hematomas in aged rats showed larger T2* lesions on MRI compared to rats with non-organized hematomas. Similar to the effects of IVH, intraventricular injection of iron resulted in more epiplexus cells activation and more severe hydrocephalus in aged compared to young rats.

CONCLUSIONS

IVH causes more severe hydrocephalus in aged compared to young rats. Enhanced ventricular wall damage, epiplexus cell activation and iron overload may contribute to this aggravated hydrocephalus development in aged animals.

CD47 Blocking Antibody Accelerates Hematoma Clearance After Intracerebral Hemorrhage in Aged Rats

Both experimental studies and surgical clinical trials suggest that hematoma clearance is a therapeutic target in intracerebral hemorrhage (ICH). We have investigated effects of CD47, a "don't eat me" signal expressed on erythrocytes, on hematoma resolution after ICH in young mice. This study expands those findings by examining the effects on a CD47 blocking antibody in aged rats. First, male Fischer 344 rats (18 months old) received an intracaudate injection of 50 μL autologous whole blood or saline. Hematoma features of magnetic resonance imaging (MRI) and neurological deficits were evaluated within 3 days. Second, rats had an intracaudate co-injection of 50 μL autologous blood with either CD47 blocking antibody or IgG. MRI was used to quantify hematoma/iron volume, hemolysis, brain swelling, and atrophy at different time points, behavioral tests to assess neurological deficits, and immunohistochemistry to assess brain injury and neuroinflammation. The CD47 blocking antibody significantly promoted hematoma clearance, attenuated brain swelling, hemolysis, and neuronal loss and increased the number of phagocytic macrophages in and around hematoma 3 days after ICH. Moreover, CD47 blockade reduced neuronal loss, brain atrophy, and neurobehavioral deficits at day 28. These results indicate that a CD47 blocking antibody can accelerate hematoma clearance and alleviate short- and long-term brain injury after ICH in aged rats and that it might be a therapeutic strategy for ICH.

Oedema extension distance in intracerebral haemorrhage: Association with baseline characteristics and long-term outcome

Introduction

Oedema extension distance is a derived parameter that may reduce sample size requirements to demonstrate reduction in perihaematomal oedema in early phase acute intracerebral haemorrhage trials. We aimed to identify baseline predictors of oedema extension distance and its association with clinical outcomes.

Patients and methods

Using Virtual International Stroke Trials Archive-Intracerebral Haemorrhage, first Intensive Blood Pressure Reduction in Acute Cerebral Hemorrhage Trial, and Minimally Invasive Surgery and rtPA for Intracerebral Hemorrhage Evacuation II datasets, we calculated oedema extension distance at baseline and at 72 h measured using computed tomography. Using linear regression, we tested for associations between baseline characteristics and oedema extension distance at 72 h. Ordinal regression (underlying assumptions validated) was used to test for associations between oedema extension distance at baseline and 72 h and oedema extension distance change between baseline and 72 h, and modified Rankin scale scores at 90 days, adjusted for baseline and 72 h prognostic factors.

Results

There were 1028 intracerebral haemorrhage cases with outcome data for analyses. Mean (standard deviation, SD) oedema extension distance at 72 h was 0.54 (0.26) cm, and mean oedema extension distance difference from baseline (EED_72-0) was 0.24 (0.18) cm. Oedema extension distance at 72 h was greater with increasing baseline haematoma volume and baseline oedema extension distance. Increasing age, lobar haemorrhage, and intraventricular haemorrhage were independently associated with EED_72-0. In multifactorial ordinal regression analysis, EED_72-0 was associated with worse modified Rankin scale scores at 90 days (odds ratio 1.96, 95% confidence interval 1.00-3.82).

Discussion

Increase in oedema extension distance over 72 h is independently associated with decreasing functional outcome at 90 days. Oedema extension distance may be a useful surrogate outcome measure in early phase trials of anti-oedema or anti-inflammatory treatments in intracerebral haemorrhage.

miR-27a-3p protects against blood-brain barrier disruption and brain injury after intracerebral hemorrhage by targeting endothelial aquaporin-11

Previous studies have reported that miR-27a-3p is down-regulated in the serum of patients with intracerebral hemorrhage (ICH), but the implication of miR-27a-3p down-regulation in post-ICH complications remains elusive. Here we verified miR-27a-3p levels in the serum of ICH patients by real-time PCR and observed that miR-27a-3p is also significantly reduced in the serum of these patients. We then further investigated the effect of miR-27a-3p on post-ICH complications by intraventricular administration of a miR-27a-3p mimic in rats with collagenase-induced ICH. We found that the hemorrhage markedly reduced miR-27a-3p levels in the hematoma, perihematomal tissue, and serum and that intracerebroventricular administration of the miR-27a-3p mimic alleviated behavioral deficits 24 h after ICH. Moreover, ICH-induced brain edema, vascular leakage, and leukocyte infiltration were also attenuated by this mimic. Of note, miR-27a-3p mimic treatment also inhibited neuronal apoptosis and microglia activation in the perihematomal zone. We further observed that the miR-27a-3p mimic suppressed the up-regulation of aquaporin-11 (AQP11) in the perihematomal area and in rat brain microvascular endothelial cells (BMECs). Moreover, miR-27a-3p down-regulation increased BMEC monolayer permeability and impaired BMEC proliferation and migration. In conclusion, miR-27a-3p down-regulation contributes to brain edema, blood-brain barrier disruption, neuron loss, and neurological deficits following ICH. We conclude that application of exogenous miR-27a-3p may protect against post-ICH complications by targeting AQP11 in the capillary endothelial cells of the brain.

Modulators of microglial activation and polarization after intracerebral haemorrhage

Intracerebral haemorrhage (ICH) is the most lethal subtype of stroke but currently lacks effective treatment. Microglia are among the first non-neuronal cells on the scene during the innate immune response to ICH. Microglia respond to acute brain injury by becoming activated and developing classic M1-like (proinflammatory) or alternative M2-like (anti-inflammatory) phenotypes. This polarization implies as yet unrecognized actions of microglia in ICH pathology and recovery, perhaps involving microglial production of proinflammatory or anti-inflammatory cytokines and chemokines. Furthermore, alternatively activated M2-like microglia might promote phagocytosis of red blood cells and tissue debris, a major contribution to haematoma clearance. Interactions between microglia and other cells modulate microglial activation and function, and are also important in ICH pathology. This Review summarizes key studies on modulators of microglial activation and polarization after ICH, including M1-like and M2-like microglial phenotype markers, transcription factors and key signalling pathways. Microglial phagocytosis, haematoma resolution, and the potential crosstalk between microglia and T lymphocytes, neurons, astrocytes, and oligodendrocytes in the ICH brain are described. Finally, the clinical and translational implications of microglial polarization in ICH are presented, including the evidence that therapeutic approaches aimed at modulating microglial function might mitigate ICH injury and improve brain repair.

Upregulation and phosphorylation of HspB1/Hsp25 and HspB5/αB-crystallin after transient middle cerebral artery occlusion in rats

Ischemic stroke leads to cellular dysfunction, cell death, and devastating clinical outcomes. The cells of the brain react to such a cellular stress by a stress response with an upregulation of heat shock proteins resulting in activation of endogenous neuroprotective capacities. Several members of the family of small heat shock proteins (HspBs) have been shown to be neuroprotective. However, yet no systematic study examined all HspBs during cerebral ischemia. Here, we performed a comprehensive comparative study comprising all HspBs in an animal model of stroke, i.e., 1 h transient middle cerebral artery occlusion followed by 23 h of reperfusion. On the mRNA level out of the 11 HspBs investigated, HspB1/Hsp25, HspB3, HspB4/αA-crystallin, HspB5/αB-crystallin, HspB7/cvHsp, and HspB8/Hsp22 were significantly upregulated in the peri-infarct region of the cerebral cortex of infarcted hemispheres. HspB1 and HspB5 reached the highest mRNA levels and were also upregulated at the protein level, suggesting that these HspBs might be functionally most relevant. Interestingly, in the infarcted cortex, both HspB1 and HspB5 were mainly allocated to neurons and to a lesser extent to glial cells. Additionally, both proteins were found to be phosphorylated in response to ischemia. Our data suggest that among all HspBs, HspB1 and HspB5 might be most important in the neuronal stress response to ischemia/reperfusion injury in the brain and might be involved in neuroprotection.

T lymphocytes infiltration promotes blood-brain barrier injury after experimental intracerebral hemorrhage

T lymphocytes migrate into the brain after intracerebral hemorrhage (ICH) and promote cerebral inflammation, thus exacerbating neuronal injury. However, the relationship between of T lymphocytes infiltration and blood-brain barrier (BBB) injury after ICH has not been clarified. In this study, we investigated the spatial-temporal distribution of infiltrating T lymphocytes after ICH in C57BL/6 mice by immunofluorescence and flow cytometry, and the accompanying change rules of BBB permeability were detected by Evans blue dye leakage and tight junction protein expression. Furthermore, T lymphocyte-deficient nude mice and T lymphocyte-decreased C57BL/6 mice treated with fingolimod were used to verify the relationship between T lymphocytes infiltration and BBB leakage after ICH. Here, we reported that brain-infiltrating T lymphocytes in the hemorrhagic hemisphere began to accumulate on the first day and peaked on the fifth day after ICH; BBB leakage also at peaked on the fifth day. Moreover, T lymphocyte-deficient nude mice showed minor BBB leakage after ICH compared with C57BL/6 control mice. Similarly, fingolimod treatment can significantly decrease T lymphocyte infiltration and promote BBB integrity compared with a vehicle control. Overall, our results suggested that suppression of T lymphocyte infiltration may be a novel way to improve BBB integrity after ICH.

Aging of cerebral white matter

White matter (WM) occupies a large volume of the human cerebrum and is mainly composed of myelinated axons and myelin-producing glial cells. The myelinated axons within WM are the structural foundation for efficient neurotransmission between cortical and subcortical areas. Similar to neuron-enriched gray matter areas, WM undergoes a series of changes during the process of aging. WM malfunction can induce serious neurobehavioral and cognitive impairments. Thus, age-related changes in WM may contribute to the functional decline observed in the elderly. In addition, aged WM becomes more susceptible to neurological disorders, such as stroke, traumatic brain injury (TBI), and neurodegeneration. In this review, we summarize the structural and functional alterations of WM in natural aging and speculate on the underlying mechanisms. We also discuss how age-related WM changes influence the progression of various brain disorders, including ischemic and hemorrhagic stroke, TBI, Alzheimer's disease, and Parkinson's disease. Although the physiology of WM is still poorly understood relative to gray matter, WM is a rational therapeutic target for a number of neurological and psychiatric conditions.

Mitochondrial function in hypoxic ischemic injury and influence of aging

Mitochondria are a major target in hypoxic/ischemic injury. Mitochondrial impairment increases with age leading to dysregulation of molecular pathways linked to mitochondria. The perturbation of mitochondrial homeostasis and cellular energetics worsens outcome following hypoxic-ischemic insults in elderly individuals. In response to acute injury conditions, cellular machinery relies on rapid adaptations by modulating posttranslational modifications. Therefore, post-translational regulation of molecular mediators such as hypoxia-inducible factor 1α (HIF-1α), peroxisome proliferator-activated receptor γ coactivator α (PGC-1α), c-MYC, SIRT1 and AMPK play a critical role in the control of the glycolytic-mitochondrial energy axis in response to hypoxic-ischemic conditions. The deficiency of oxygen and nutrients leads to decreased energetic reliance on mitochondria, promoting glycolysis. The combination of pseudohypoxia, declining autophagy, and dysregulation of stress responses with aging adds to impaired host response to hypoxic-ischemic injury. Furthermore, intermitochondrial signal propagation and tissue wide oscillations in mitochondrial metabolism in response to oxidative stress are emerging as vital to cellular energetics. Recently reported intercellular transport of mitochondria through tunneling nanotubes also play a role in the response to and treatments for ischemic injury. In this review we attempt to provide an overview of some of the molecular mechanisms and potential therapies involved in the alteration of cellular energetics with aging and injury with a neurobiological perspective.

Role of Erythrocyte CD47 in Intracerebral Hematoma Clearance

BACKGROUND AND PURPOSE

Enhancing hematoma clearance through phagocytosis may reduce brain injury after intracerebral hemorrhage. In the current study, we investigated the role of cluster of differentiation 47 (CD47) in regulating erythrophagocytosis and brain injury after intracerebral hemorrhage in nude mice.

METHODS

This study was in 2 parts. First, male adult nude mice had an intracaudate injection of 30 μL saline, blood from male adult wild-type (WT) mice, or blood from CD47 knockout mice. Second, mice had an intracaudate injection of 30 μL CD47 knockout blood with clodronate or control liposomes. Clodronate liposomes were also tested in saline-injected mice. All mice then had magnetic resonance imaging to measure hematoma size and brain swelling. Brains were used for immunohistochemistry and Western blot.

RESULTS

Erythrophagocytosis occurred in and around the hematoma. Injection of CD47 knockout blood resulted in quicker clot resolution, less brain swelling, and less neurological deficits compared with wild-type blood. Higher brain heme oxygenase-1 levels and more microglial activation (mostly M2 polarized microglia) at day 3 were found after CD47 knockout blood injection. Co-injection of clodronate liposomes, to deplete phagocytes, caused more severe brain swelling and less clot resolution.

CONCLUSIONS

These results indicated that CD47 has a key role in hematoma clearance after intracerebral hemorrhage.

Minimally invasive endoscopic surgery for treatment of spontaneous intracerebral hematomas: a single-center analysis

BACKGROUND

Endoscopic minimally invasive surgery to evacuate ICH has been reported to be more effective than conservative treatment or standard surgical craniotomy. However, most of these reports are based on Asian populations, while European reports do not exist. Here, we, therefore, report our experience from a European neurosurgical stroke center.

METHODS

The variables assessed were patient characteristics, technical aspects of surgery, surgical complications, the outcomes grade of hematoma evacuation, 30-day mortality, and functional outcome (defined by modified Rankin Scale, mRS). The mRS was dichotomized into favorable (0-3) and unfavorable outcome (4-6). Mortality was compared to external evidence on conservatively and surgically treated patients by Poisson regression analysis with adjustment for ICH score.

RESULTS

Thirty-four patients with ICH were analyzed. The mean age was 62 (standard deviation [SD] 12) years, mean hematoma volume (SD) was 84 (35) ml, and mean time from onset to surgery (SD) was 17 (10) h. Operative times did not exceed 1.5 h. A significant mean hematoma reduction (SD) from 84 (35) ml to 21 (30) ml (p < 0.0001) could be achieved, resulting in a median evacuation rate of 87 %. Early complications related to surgery did not occur. A favorable outcome was observed in 44 % of the patients. Overall, 30-day mortality was 18 %. The relative risk of mortality compared to conventional treatment from other studies was 32 % (95 % confidence interval 23-43 %, p = 0.02).

CONCLUSIONS

This European surgical stroke center series of an endoscopic operative technique demonstrates safety and efficacy with regard to reduction of hematoma size in patients with large and space-occupying spontaneous ICH. The study suggests that low mortality and acceptable outcomes may be achievable by minimally invasive hematoma surgery. Whether this technique reduces long-term morbidity compared to standard treatment needs to be further investigated in larger prospective randomized controlled trials.

Efficacy of deferoxamine in animal models of intracerebral hemorrhage: a systematic review and stratified meta-analysis

Intracerebral hemorrhage (ICH) is a subtype of stroke associated with high morbidity and mortality rates. No proven treatments are available for this condition. Iron-mediated free radical injury is associated with secondary damage following ICH. Deferoxamine (DFX), a ferric-iron chelator, is a candidate drug for the treatment of ICH. We performed a systematic review of studies involving the administration of DFX following ICH. In total, 20 studies were identified that described the efficacy of DFX in animal models of ICH and assessed changes in the brain water content, neurobehavioral score, or both. DFX reduced the brain water content by 85.7% in animal models of ICH (-0.86, 95% CI: -.48- -0.23; P < 0.01; 23 comparisons), and improved the neurobehavioral score by -1.08 (95% CI: -1.23- -0.92; P < 0.01; 62 comparisons). DFX was most efficacious when administered 2–4 h after ICH at a dose of 10–50 mg/kg depending on species, and this beneficial effect remained for up to 24 h postinjury. The efficacy was higher with phenobarbital anesthesia, intramuscular injection, and lysed erythrocyte infusion, and in Fischer 344 rats or aged animals. Overall, although DFX was found to be effective in experimental ICH, additional confirmation is needed due to possible publication bias, poor study quality, and the limited number of studies conducting clinical trials.

Cerebroprotective effects of RAS inhibitors: Beyond their cardio-renal actions

Work on the brain renin-angiotensin system has been explored by various researchers and has led to elucidation of its basic physiologies and behavior, including its role in reabsorption and uptake of body fluid, blood pressure maintenance with angiotensin II being its prominent effector. Currently, this system has been implicated for its newly established effects, which are far beyond its cardio-renal effects accounting for maintenance of cerebral blood flow and cerebroprotection, seizure, in the etiology of Alzheimer's disease, Parkinson's disease, multiple sclerosis, and bipolar disorder. In this review, we have discussed the distribution of angiotensin receptor subtypes in the central nervous system (CNS) together with enzymatic pathways leading to active angiotensin ligands and its interaction with angiotensin receptor 2 (AT2) and Mas receptors. Secondly, the use of angiotensin analogues (angiotensin converting enzyme inhibitors and AT1 and/or AT2 receptor blockers) in the treatment and management of the CNS disorders mentioned above has been discussed.

Stem cell therapy in intracerebral hemorrhage rat model

Intracerebral hemorrhage (ICH) is a very complex pathology, with many different not fully elucidated etiologies and prognostics. It is the most severe subtype of stroke, with high mortality and morbidity rates. Unfortunately, despite the numerous promising preclinical assays including neuroprotective, anti-hypertensive, and anti-inflammatory drugs, to this moment only symptomatic treatments are available, motivating the search for new alternatives. In this context, stem cell therapy emerged as a promising tool. However, more than a decade has passed, and there is still much to be learned not only about stem cells, but also about ICH itself, and how these two pieces come together. To date, rats have been the most widely used animal model in this research field, and there is much more to be learned from and about them. In this review, we first summarize ICH epidemiology, risk factors, and pathophysiology. We then present different methods utilized to induce ICH in rats, and examine how accurately they represent the human disease. Next, we discuss the different types of stem cells used in previous ICH studies, also taking into account the tested transplantation sites. Finally, we summarize what has been achieved in assays with stem cells in rat models of ICH, and point out some relevant issues where attention must be given in future efforts.

Intercellular cross-talk in intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a devastating cerebrovascular disorder with high mortality and morbidity. Currently, there are few treatment strategies for ICH-induced brain injury. A recent increase in interest in the pathophysiology of ICH has led to elucidation of the pathways underlying ICH-induced brain injury, pathways where intercellular and hematoma to cell signaling play important roles. In this review, we summarize recent advances in ICH research focusing on intercellular and hematoma:cell cross-talk related to brain injury and recovery after ICH. This article is part of a Special Issue entitled SI: Cell Interactions In Stroke.

The role of necroptosis in neurosurgical diseases

Programmed necrosis or necroptosis is an alternative form of cell death that is executed through a caspase-independent pathway. Necroptosis has been implicated in many pathological conditions. Genetic or pharmacological inhibition of necroptotic signaling has been shown to confer neuroprotection after traumatic and ischemic brain injury. Therefore, the necroptotic pathway represents a potential target for neurological diseases that are managed by neurosurgeons. In this review, we summarize recent advances in the understanding of necroptotic signaling pathways and explore the role of necroptotic cell death in craniocerebral trauma, brain tumors, and cerebrovascular diseases.

Prognostic factors of clinical outcome after neuronavigation-assisted hematoma drainage in patients with spontaneous intracerebral hemorrhage

OBJECTIVE

The prognostic factors that contribute to outcome after navigation-assisted drainage in patients with spontaneous intracerebral hemorrhage (ICH) have not been defined. We compared the characteristics and clinical outcomes of patients with spontaneous ICHs who underwent neuronavigation-assisted hematoma drainage.

METHODS

Forty-seven patients were enrolled from January 2004 to August 2013. The patients were divided into two groups according to Glasgow Outcome Scale (GOS) scores: the good- (GOS 4-5) and poor-outcome (GOS 1-3) groups. A variety of factors, characteristics, and clinical outcomes were analyzed.

RESULTS

Among the 47 patients, 16 and 31 showed good and poor outcomes, respectively. The mortality rate was 4.3%. Patients' ages, horizontal and vertical diameters and volume of the hematoma on the initial brain computed tomography scan, and the initial Glasgow Coma Scale (GCS) scores were significantly different between the two groups (P<0.05). Ages less than 60 years, smaller horizontal and vertical diameters of the hematoma, less initial hematoma volume, higher initial GCS scores, and the absence of intraventricular hemorrhages were significantly associated with good outcome (P<0.05). Among these factors, initial hematoma volume was a borderline prognostic factor (odds ratio [OR], 0.951; 95% confidence interval [CI], 0.904-1.001; P=0.054), whereas initial GCS score was a significant prognostic factor (OR, 2.737; 95% CI, 1.371-5.465; P=0.004), in the multivariate analysis.

CONCLUSION

Initial GCS score and hematoma volume were important prognostic factors of clinical outcome in patients with spontaneous ICHs who underwent navigation-assisted drainage. Such factors should be carefully considered before patients are treated with navigation-assisted hematoma drainage.

Progress in translational research on intracerebral hemorrhage: is there an end in sight?

Intracerebral hemorrhage (ICH) is a common and often fatal stroke subtype for which specific therapies and treatments remain elusive. To address this, many recent experimental and translational studies of ICH have been conducted, and these have led to several ongoing clinical trials. This review focuses on the progress of translational studies of ICH including those of the underlying causes and natural history of ICH, animal models of the condition, and effects of ICH on the immune and cardiac systems, among others. Current and potential clinical trials also are discussed for both ICH alone and with intraventricular extension.

Aging and injury: alterations in cellular energetics and organ function

Aging is characterized by increased oxidative stress, heightened inflammatory response, accelerated cellular senescence and progressive organ dysfunction. The homeostatic imbalance with aging significantly alters cellular responses to injury. Though it is unclear whether cellular energetic imbalance is a cause or effect of the aging process, preservation of mitochondrial function has been reported to be important in organ function restoration following severe injury. Unintentional injuries are ranked among the top 10 causes of death in adults of both sexes, 65 years and older. Aging associated decline in mitochondrial function has been shown to enhance the vulnerability of heart, lung, liver and kidney to ischemia/reperfusion injury. Studies have identified alterations in the level or activity of factors such as SIRT1, PGC-1α, HIF-1α and c-MYC involved in key regulatory processes in the maintenance of mitochondrial structural integrity, biogenesis and function. Studies using experimental models of hemorrhagic injury and burn have demonstrated significant influence of aging in metabolic regulation and organ function. Understanding the age-associated molecular mechanisms regulating mitochondrial dysfunction following injury is important towards identifying novel targets and therapeutic strategies to improve the outcome after injury in the elderly.

Intracranial pressure measured in freely moving rats for days after intracerebral hemorrhage

In some patients, intracerebral hemorrhage (ICH) causes life-threatening elevations in intracranial pressure (ICP) arising from mass effect of the hematoma and edema. Accordingly, edema is a common endpoint to gauge treatment efficacy in rodent ICH models. Despite widespread reliance on edema, its relationship with ICP and cerebral perfusion pressure (CPP) is unknown. Blood pressure (BP) and ICP were measured by telemetry devices in rats after collagenase ("severe" - 0.3U, and "moderate" - 0.15U doses) or blood infusion (100μL) into striatum (vs. saline infused shams). We compared epidural and intraparenchymal ICP readings (collagenase), evaluated CPP (collagenase), and compared models. Moderate (9.46mmHg±4.72 SD, 3day average) and severe collagenase ICHs (10.79±3.50) significantly increased ICP versus shams (4.02±2.09), whereas blood infusion did not (5.37±0.55). The two monitoring locations gave similar readings after severe collagenase ICH. Increased ICP reduced CPP by ~7.5mmHg for days after the larger collagenase infusion. CPP averaged from 103-112mmHg in shams. Edema occurred in all ICH models and predicted ICP. However, ICP and CPP were only modestly changed even after severe ICH and edema. Thus, small changes in edema typically reported in the literature, which often use smaller bleeds than presently used, likely minimally affects ICP and CPP. Further research into the face validity of these models, endpoints, and their ability to evaluate therapeutics is needed.

Cerebroprotective action of angiotensin peptides in stroke

The goal of the present review is to examine the evidence for beneficial actions of manipulation of the RAS (renin-angiotensin system) in stroke, with particular focus on Ang-(1-7) [angiotensin-(1-7)] and its receptor Mas. The RAS appears to be highly involved in the multifactorial pathophysiology of stroke. Blocking the effects of AngII (angiotensin II) at AT1R (AngII type 1 receptor), through the use of commonly prescribed ACE (angiotensin-converting enzyme) inhibitors or AT1R blockers, has been shown to have therapeutic effects in both ischaemic and haemorrhagic stroke. In contrast with the deleterious actions of over activation of AT1R by AngII, stimulation of AT2Rs (AngII type 2 receptors) in the brain has been demonstrated to elicit beneficial effects in stroke. Likewise, the ACE2/Ang-(1-7)/Mas axis of the RAS has been shown to have therapeutic effects in stroke when activated, countering the effects of the ACE/AngII/AT1R axis. Studies have demonstrated that activating this axis in the brain elicits beneficial cerebral effects in rat models of ischaemic stroke, and we have also demonstrated the cerebroprotective potential of this axis in haemorrhagic stroke using stroke-prone spontaneously hypertensive rats and collagenase-induced striatal haemorrhage. The mechanism of cerebroprotection elicited by ACE2/Ang-(1-7)/Mas activation includes anti-inflammatory effects within the brain parenchyma. The major hurdle to overcome in translating these results to humans is devising strategies to activate the ACE2/Ang-(1-7)/Mas cerebroprotective axis using post-stroke treatments that can be administered non-invasively.

Age-dependent effect of treadmill exercise on hemorrhage-induced neuronal cell death in rats

Intracerebral hemorrhage (ICH) is a major cause of death and disability in the elderly. In the present study, we examined the age-dependence of the effect of treadmill exercise on the intrastriatal hemorrhage-induced neuronal cell death in rats. Young (8 weeks old) and old (64 weeks old) Sprague-Dawley male rats were used in the present study. Intrastriatal hemorrhage was induced by injection of 0.2 U collagenase (1 μL volume) into the striatum using a stereotaxic instrument. The rats in the exercise groups were forced to run on a treadmill for 30 min daily for 7 days. Lesion size was determined by Nissl staining. Apoptosis was assessed by the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay. In the present results, induction of hemorrhage increased lesion size and enhanced apoptosis. Treadmill exercise decreased the lesion size with suppressing apoptosis. However, the size of lesion induced by hemorrhage and the number of apoptotic cells were not different between young and old rats. Treadmill exercise significantly reduced the ICH-induced lesion size and the number of apoptotic cells irrespective of age. The data suggest that treadmill exercise may provide therapeutic value against ICH by suppressing neuronal apoptosis regardless of age.

Emerging experimental therapies for intracerebral hemorrhage: targeting mechanisms of secondary brain injury

Intracerebral hemorrhage (ICH) is associated with a higher degree of morbidity and mortality than other stroke subtypes. Despite this burden, currently approved treatments have demonstrated limited efficacy. To date, therapeutic strategies have principally targeted hematoma expansion and resultant mass effect. However, secondary mechanisms of brain injury are believed to be critical effectors of cell death and neurological outcome following ICH. This article reviews the pathophysiology of secondary brain injury relevant to ICH, examines pertinent experimental models, and highlights emerging therapeutic strategies. Treatment paradigms discussed include thrombin inhibitors, deferoxamine, minocycline, statins, granulocyte-colony stimulating factors, and therapeutic hypothermia. Despite promising experimental and preliminary human data, further studies are warranted prior to effective clinical translation.

Inflammation in intracerebral hemorrhage: from mechanisms to clinical translation

Intracerebral hemorrhage (ICH) accounts for 10-15% of all strokes and is associated with high mortality and morbidity. Currently, no effective medical treatment is available to improve functional outcomes in patients with ICH. Potential therapies targeting secondary brain injury are arousing a great deal of interest in translational studies. Increasing evidence has shown that inflammation is the key contributor of ICH-induced secondary brain injury. Inflammation progresses in response to various stimuli produced after ICH. Hematoma components initiate inflammatory signaling via activation of microglia, subsequently releasing proinflammatory cytokines and chemokines to attract peripheral inflammatory infiltration. Hemoglobin (Hb), heme, and iron released after red blood cell lysis aggravate ICH-induced inflammatory injury. Danger associated molecular patterns such as high mobility group box 1 protein, released from damaged or dead cells, trigger inflammation in the late stage of ICH. Preclinical studies have identified inflammatory signaling pathways that are involved in microglial activation, leukocyte infiltration, toll-like receptor (TLR) activation, and danger associated molecular pattern regulation in ICH. Recent advances in understanding the pathogenesis of ICH-induced inflammatory injury have facilitated the identification of several novel therapeutic targets for the treatment of ICH. This review summarizes recent progress concerning the mechanisms underlying ICH-induced inflammation. We focus on the inflammatory signaling pathways involved in microglial activation and TLR signaling, and explore potential therapeutic interventions by targeting the removal of hematoma components and inhibition of TLR signaling.