Intracerebral haemorrhage: mechanisms of injury and therapeutic targets

Pleiotropic role of PPARγ in intracerebral hemorrhage: an intricate system involving Nrf2, RXR, and NF-κB

Intracerebral hemorrhage (ICH) is a subtype of stroke involving formation of hematoma within brain parenchyma, which accounts for 8-15% of all strokes in Western societies and 20-30% among Asian populations, and has a 1-year mortality rate >50%. The high mortality and severe morbidity make ICH a major public health problem. Only a few evidence-based targeted treatments are used for ICH management, and interventions focus primarily on supportive care and comorbidity prevention. Even in patients who survive the ictus, extravasated blood (including plasma components) and subsequent intrahematoma hemolytic products trigger a series of adverse events within the brain parenchyma, leading to secondary brain injury, edema and severe neurological deficits or death. Although the hematoma in humans gradually resolves within months, full restoration of neurological function can be slow and often incomplete, leaving survivors with devastating neurological deficits. During past years, peroxisome proliferator-activated receptor gamma (PPARγ) transcription factor and its agonists received recognition as important players in regulating not only glucose and lipid metabolism (which underlies its therapeutic effect in type 2 diabetes mellitus), and more recently, as an instrumental pleiotropic regulator of antiinflammation, antioxidative regulation, and phagocyte-mediated cleanup processes. PPARγ agonists have emerged as potential therapeutic target for stroke. The use of PPARγ as a therapeutic target appears to have particularly strong compatibility toward pathogenic components of ICH. In addition to its direct genomic effect, PPARγ may interact with transcription factor, NF-κB, which may underlie many aspects of the antiinflammatory effect of PPARγ. Furthermore, PPARγ appears to regulate expression of Nrf2, another transcription factor and master regulator of detoxification and antioxidative regulation. Finally, the synergistic costimulation of PPARγ and retinoid X receptor, RXR, may play an additional role in the therapeutic modulation of PPARγ function. In this article, we outline the main components of the role of PPARγ in ICH pathogenesis.

Neuroinflammation after intracerebral hemorrhage

Spontaneous intracerebral hemorrhage (ICH) is a particularly severe type of stroke for which no specific treatment has been established yet. Although preclinical models of ICH have substantial methodological limitations, important insight into the pathophysiology has been gained. Mounting evidence suggests an important contribution of inflammatory mechanisms to brain damage and potential repair. Neuroinflammation evoked by intracerebral blood involves the activation of resident microglia, the infiltration of systemic immune cells and the production of cytokines, chemokines, extracellular proteases and reactive oxygen species (ROS). Previous studies focused on innate immunity including microglia, monocytes and granulocytes. More recently, the role of adaptive immune cells has received increasing attention. Little is currently known about the interactions among different immune cell populations in the setting of ICH. Nevertheless, immunomodulatory strategies are already being explored in ICH. To improve the chances of translation from preclinical models to patients, a better characterization of the neuroinflammation in patients is desirable.

Localized hypothermia aggravates bleeding in the collagenase model of intracerebral hemorrhage

Animal studies testing whether therapeutic hypothermia is neuroprotective after intracerebral hemorrhage (ICH) have been inconclusive. In rodents, ICH is often produced in the striatum by infusing collagenase, which causes prolonged hemorrhaging from multiple vessels. Our previous data shows that this bleeding (hematoma) is worsened by systemic hypothermia given soon after collagenase infusion. In this study we hypothesized that localized brain hypothermia would also aggravate bleeding in this model (0.2 U of collagenase in 1.2 μL of saline). We also evaluated cooling after intrastriatal thrombin infusion (1 U in 30 μL of saline)-a simplified model of ICH thought to cause bleeding. Focal hypothermia was achieved by flushing cold water through an implanted cooling device attached to the skull underneath the temporalis muscle of adult rats. Previous work and data at this time shows this method cools the striatum to ∼33°C, whereas the body remains normothermic. In comparison to normothermic groups, cooling significantly worsened bleeding when instituted at 6 hours (∼94 vs. 42 μL, p=0.018) and 12 hours (79 vs. 61 μL, p=0.042) post-ICH (24-hour survival), but not after a 24-hour delay (36-hour survival). Rats were cooled until euthanasia when hematoma size was determined by a hemoglobin-based spectrophotometry assay. Cooling did not influence cerebral blood volume after just saline or thrombin infusion. The latter is explained by the fact that thrombin did not cause bleeding beyond that caused by saline infusion. In summary, local hypothermia significantly aggravates bleeding many hours after collagenase infusion suggesting that bleeding may have confounded earlier studies with hypothermia. Furthermore, these findings serve as a cautionary note on using cooling even many hours after cerebral bleeding.

Thrombin Causes Neuronal Atrophy and Acute but not Chronic Cell Death

BACKGROUND

Brain injury after intracerebral hemorrhage (ICH) arises from numerous contributors, of which some also play essential roles. Notably, thrombin production, needed to stop bleeding, also causes acute cell death and edema. In some rodent models of ICH, peri-hematoma neurons die over weeks. Hence we evaluated whether thrombin is responsible for this chronic degeneration. Functional impairments after ICH also result from sub-lethal damage to neurons, especially the loss of dendrites. Thus, we evaluated whether thrombin infusion alone, a reductionist model of ICH, causes similar injury.

METHODS

Adult rats had a modest intra-striatal infusion of thrombin (1 U) or saline followed by a behavioral test, to verify impairment, 7 days later. After this they were euthanized and tissue stained with Golgi-Cox solution to allow the assessment of dendritic morphology in striatal neurons. In a second experiment, rats survived 7 or 60 days after thrombin infusion in order to histologically determine lesion volume.

RESULTS

Thrombin caused early cell death and considerable atrophy in surviving peri-lesion neurons, which had less than half of their usual numbers of branches. However, total tissue loss was comparable at 7 (24.1 mm3) and 60 days (25.6 mm3).

CONCLUSION

Thrombin infusion causes early cell death and neuronal atrophy in nearby surviving striatal neurons but thrombin does not cause chronic tissue loss. Thus, the chronic degeneration found after ICH in rats is not simply and solely due to acute thrombin production. Nonetheless, thrombin is an important contributor to behavioral dysfunction because it causes cell death and substantial dendritic injury.

Alteration in rectification of potassium channels in perinatal hypoxia ischemia brain damage

Oligodendrocyte progenitor cells (OPCs) are susceptible to perinatal hypoxia ischemia brain damage (HIBD), which results in infant cerebral palsy due to the effects on myelination. The origin of OPC vulnerability in HIBD, however, remains controversial. In this study, we defined the HIBD punctate lesions by MRI diffuse excessive high signal intensity (DEHSI) in postnatal 7-day-old rats. The electrophysiological functional properties of OPCs in HIBD were recorded by patch-clamp in acute cerebral cortex slices. The slices were intracellularly injected with Lucifer yellow and immunohistochemically labeled with NG2 antibody to identify local OPCs. Passive membrane properties and K(+) channel functions in OPCs were analyzed to estimate the onset of vulnerability in HIBD. The resting membrane potential, membrane resistance, and membrane capacitance of OPCs were increased in both the gray and white matter of the cerebral cortex. OPCs in both the gray and white matter exhibited voltage-dependent K(+) currents, which consisted of the initiated rectified potassium currents (IA) and the sustained rectified currents (IK). The significant alternation in membrane resistance was influenced by the diversity of potassium channel kinetics. These findings suggest that the rectification of IA and IK channels may play a significant role in OPC vulnerability in HIBD.

The relationship between the serum levels of ferritin and the radiological brain injury indices in patients with spontaneous intracerebral hemorrhage

OBJECTIVES

Preclinical studies show that iron plays a key role in mediating neuronal injury. This study was performed in order to identify the relationship between the serum level of ferritin and severity of the brain injury which occur after an Intracerebral hemorrhage (ICH).

MATERIALS AND METHODS

This was a cross sectional descriptive - analytic study, which was conducted on those patients who had suffered from an ICH and had attended Poursina Hospital. The Serum levels of ferritin were measured at admittance. A Cranial CT scan was performed at admission and also 72 hr afterward. Hematoma and edema surrounding the hematoma volumes were also measured at entrance and 72 hr afterward. Data analysis was carried out by a descriptive - analytic statistics approach and calculated later on by the Spss-20 software.

RESULTS

In this investigation, 63 patients were studied, from which 34 (54%) were male and 29 (46%) female. The average age of the patients was 69.7± 11.9 (Min 43 and Max 94 years old). A significant relationship was observed between the level of ferritin and the edema volume surrounding the hematoma at first and next 72 hr after the patients were admitted.

CONCLUSION

These results delineated the effective role of iron on the edema volume elevation. More studies are essentially urged to ascertain the clinical evaluation of the curing effect of iron chelators in those patients who suffer from ICH.

No exacerbation of perihematomal edema with intraclot urokinase in patients with spontaneous intracerebral hemorrhage

BACKGROUND

Perihematomal edema (PHE) can worsen patient outcomes after spontaneous intracerebral hemorrhage (ICH). Minimally invasive surgery (MIS) in combination with thrombolytic removal of hematoma has been proven to be a promising treatment strategy. However, preclinical studies have suggested that intraclot thrombolysis may exacerbate PHE after ICH. Herein, we investigated the effects of MIS and urokinase on PHE.

METHODS

ICH patients were retrospectively identified from our institutional ICH database. Computerized volumetric analysis was applied to assess changes in both ICH and PHE volumes using computed tomographic (CT) scans of T1 (pre-MIS) and T2 (post-MIS) time points. Relative PHE (rPHE) was calculated as a ratio of PHE and T1 ICH volume.

RESULTS

Data from 60 MIS plus urokinase (MIS + U), 20 MIS aspiration only (MO), and 30 control patients were analyzed. The ICH volume, PHE volume and rPHE on T2 CT in both MIS + U and MO groups significantly decreased as compared with the control group (ICH volume, 13.7 ± 5.7 ml, 17.0 ± 10.5 ml vs. 30.5 ± 10.3 ml, P < 0.01; PHE volume, 36.5 ± 18.9 ml, 32.2 ± 17.5 ml vs. 45.4 ± 16.0 ml, P < 0.01; rPHE, 0.9 ± 0.4, 0.8 ± 0.4 vs.1.4 ± 0.5, P < 0.01). Between the MIS + U and MO groups, the ICH volume, PHE volume and rPHE at T2 trended towards similarity, but was not significant (P = 0.09, P = 0.40, P = 0.43). Furthermore, we found a significant correlation between the percent of ICH removal and PHE reduction (r = 0.59, P < 0.01). There was no correlation between the cumulative dose of urokinase and either T2 PHE volume (r = 0.19; P = 0.16) or T2 rPHE (r = -0.12; P = 0.37).

CONCLUSIONS

Hematoma evacuation using MIS leads to a significant reduction in PHE. Furthermore, the use of urokinase does not exacerbate PHE, making its hypothesized proedematous effects unlikely when the thrombolytic is administered directly into the clot.

Chronic hydrocephalus and perihematomal tissue injury developed in a rat model of intracerebral hemorrhage with ventricular extension

Primary spontaneous intracerebral hemorrhage (ICH) with secondary intraventricular hemorrhage (IVH) is an important clinical problem of which little is known. IVH and hydrocephalus are independent predictors of poor outcome in ICH. The aims of this study were, therefore, to establish a rat model of ICH with ventricular extension and investigate the occurrence of post-hemorrhagic chronic hydrocephalus and perihematomal tissue injury. Based on our previous rat model of IVH, we adjusted the injection coordinates and 200 μl autologous blood was stereotaxically infused into the right striatum (coordinates: 0.2 mm posterior, 2.2 mm lateral, and 5.0 mm depth to the bregma). At 24 h post-infusion, the rats produced reproducible hematoma and ventricle expansion, which closely mimics the ICH with ventricular extension in humans. Hematoma consequences and perihematomal tissue injury were evaluated on the acute phase. At 4 weeks, ventricular dilatation, brain tissue loss, hippocampus volume, and cortical thickness were measured with magnetic resonance imaging and neurocognitive function was assessed using the Morris water maze test. With blood infusion, the animals demonstrated brain edema, blood-brain barrier breakdown, and marked perihematomal tissue injury on the acute phase. At 4 weeks, the T2 images showed remarkable hydrocephalus and tissue loss, and the Morris water maze test revealed neurocognitive deficits. The present ICH with the ventricular extension rat model features characteristics of both ICH and IVH rat models, which could be used for extending our pathophysiological understanding of post-hemorrhagic chronic hydrocephalus and perihematomal tissue damage.

Nrf2 to pre-condition the brain against injury caused by products of hemolysis after ICH

Brain damage caused by intracerebral hemorrhage (ICH) is mediated in part by the toxicity of extravascular blood deposited in brain parenchyma during the hematoma formation. In this paper we discuss the therapeutic benefits and potential mechanisms associated with the activation of transcription factor Nrf2 regarding its role in defending brain tissue against toxicity of blood, a component of secondary injury. We emphasize the pleiotropic capacity of Nrf2 as it recruits multiple pathways aiming at reducing deleterious effects of blood lysis products.

INTERACT2: a reason for optimism with spontaneous intracerebral hemorrhage?

The first Intensive Blood Pressure Reduction in Acute Intracerebral Hemorrhage Trial (INTERACT1) study found that early intensive BP lowering seemed to attenuate haematoma growth when compared with a more conservative guideline based policy. Clinicians were therefore waiting with anticipation for the results of INTERACT2, in which 2839 patients with spontaneous ICH and a systolic BP between 150 and 220 mmHg were randomly assigned to receive intensive anti-hypertensive therapy with a systolic target of <140 mmHg within one hour, or a standard guideline recommended treatment of <180 mmHg. INTERACT2 failed to show a significant reduction in the rate of the primary outcome of death or major disability [modified Rankin scale score (mRS) of 3-6], with early intensive BP lowering. However, in the key secondary endpoint of an ordinal analysis of the distribution of mRS scores, there was a significant favorable shift in those patients with aggressive therapy. There were also more patients who were normal or near normal (mRS of 0-1) at 90 days. Reassuringly, there were no differences in the rate of death or numbers of serious adverse events between the two groups. INTERACT2 has shown that a strategy of early and aggressive BP lowering is safe in a wide range of clinical settings, and is probably effective. The Antihypertensive Treatment of Acute Cerebral Haemorrhage (ATACH) II trial, which is using similar BP targets to INTERACT, should shed further light on the benefit of early aggressive BP lowering in patients with spontaneous ICH.

Vascular disruption and blood-brain barrier dysfunction in intracerebral hemorrhage

This article reviews current knowledge of the mechanisms underlying the initial hemorrhage and secondary blood-brain barrier (BBB) dysfunction in primary spontaneous intracerebral hemorrhage (ICH) in adults. Multiple etiologies are associated with ICH, for example, hypertension, Alzheimer's disease, vascular malformations and coagulopathies (genetic or drug-induced). After the initial bleed, there can be continued bleeding over the first 24 hours, so-called hematoma expansion, which is associated with adverse outcomes. A number of clinical trials are focused on trying to limit such expansion. Significant progress has been made on the causes of BBB dysfunction after ICH at the molecular and cell signaling level. Blood components (e.g. thrombin, hemoglobin, iron) and the inflammatory response to those components play a large role in ICH-induced BBB dysfunction. There are current clinical trials of minimally invasive hematoma removal and iron chelation which may limit such dysfunction. Understanding the mechanisms underlying the initial hemorrhage and secondary BBB dysfunction in ICH is vital for developing methods to prevent and treat this devastating form of stroke.

Minimally Invasive Subcortical Parafascicular Transsulcal Access for Clot Evacuation (Mi SPACE) for Intracerebral Hemorrhage

Background. Spontaneous intracerebral hemorrhage (ICH) is common and causes significant mortality and morbidity. To date, optimal medical and surgical intervention remains uncertain. A lack of definitive benefit for operative management may be attributable to adverse surgical effect, collateral tissue injury. This is particularly relevant for ICH in dominant, eloquent cortex. Minimally invasive surgery (MIS) offers the potential advantage of reduced collateral damage. MIS utilizing a parafascicular approach has demonstrated such benefit for intracranial tumor resection. Methods. We present a case of dominant hemisphere spontaneous ICH evacuated via the minimally invasive subcortical parafascicular transsulcal access clot evacuation (Mi SPACE) model. We use this report to introduce Mi SPACE and to examine the application of this novel MIS paradigm. Case Presentation. The featured patient presented with a left temporal ICH and severe global aphasia. The hematoma was evacuated via the Mi SPACE approach. Postoperative reassessments showed significant improvement. At two months, bedside language testing was normal. MRI tractography confirmed limited collateral injury. Conclusions. This case illustrates successful application of the Mi SPACE model to ICH in dominant, eloquent cortex and subcortical regions. MRI tractography illustrates collateral tissue preservation. Safety and feasibility studies are required to further assess this promising new therapeutic paradigm.

Deferoxamine reduces neuronal death and hematoma lysis after intracerebral hemorrhage in aged rats

Intracerebral hemorrhage (ICH) is primarily a disease of the elderly. Deferoxamine (DFX), an iron chelator, reduces long-term neurological deficits and brain atrophy after ICH in aged rats. In the present study, we investigated whether DFX can reduce acute ICH-induced neuronal death and whether it affects the endogenous response to ICH (ferritin upregulation and hematoma resolution) in aged rats. Male Fischer 344 rats (18 months old) had an intracaudate injection of 100 μL autologous whole blood into the right basal ganglia and were treated with DFX (100 mg/kg) or vehicle 2 hours post-ICH and then every 12 hours up to 7 days. Rats were euthanized 1, 3, or 7 days later for neuronal death, ferritin and hematoma size measurements. Plasma ferritin levels and behavioral outcome following ICH were also examined. DFX treatment significantly reduced ICH-induced neuronal death and neurological deficits. DFX also suppressed ferritin upregulation in the ipsilateral basal ganglia after ICH and hematoma lysis (hematoma volume at day 7: 13.2±4.9 vs. 3.8±1.2 mm3 in vehicle-treated group, p<0.01). However, effects of DFX on plasma ferritin levels after ICH did not reach significance. In conclusion, DFX reduces neuronal death and neurological deficits after ICH in aged rats. It also affects the endogenous response to ICH.

Brain CD47 expression in a swine model of intracerebral hemorrhage

CD47 contributes to neuronal death, inflammation and angiogenesis after brain ischemia. The role of CD47 in intracerebral hemorrhage (ICH) has not been investigated and the current study examined brain CD47 expression in a pig ICH model. Pigs received a blood injection or needle insertion into the right frontal lobe and were euthanized at different times to examine CD47 expression. Pigs were also treated with an iron chelator, deferoxamine, (50mg/kg, i.m.) or vehicle and killed at day-3 to examine the effects on CD47. ICH resulted in upregulation of brain CD47 in both white and gray matter by both immunohistochemistry and Western blot. A time-course showed ICH-induced CD47 upregulation from 4h to day-14, with a peak at day-3. CD47 positive cells were neurons, microglia/macrophage and oliogodendrocytes. Brain CD47 levels were lower in the ipsilateral white and gray matter in pigs which had deferoxamine treatment. In conclusion, CD47 expression was increased in the perihematomal white and gray matter after ICH. Deferoxamine and iron may modulate CD47 expression.

Leukocyte invasion of the brain after experimental intracerebral hemorrhage in mice

BACKGROUND AND PURPOSE

Neuroinflammatory processes contribute to secondary neuronal damage after intracerebral hemorrhage. We aimed to characterize the time course of brain immigration of different leukocyte subsets after striatal injection of either autologous blood or collagenase in mice.

METHODS

Intracerebral hemorrhage was induced by injection of either autologous blood (20 μL) or collagenase (0.03 U) in C57Bl/6J mice. Hematoma volumetry was performed on cryosections. Blood volume was measured by hemoglobin spectrophotometry. Leukocytes were isolated from hemorrhagic hemisphere 1, 3, 5, and 14 days after intracerebral hemorrhage, stained for leukocyte markers, and measured by flow cytometry. Heterologous blood injection from CD45.1 mice was used to investigate the origin of brain-invading leukocytes.

RESULTS

Collagenase injection induced a larger hematoma volume but a similar blood content compared with blood injection. Cerebral leukocyte infiltration in the hemorrhagic hemisphere was similar in both models. The majority of leukocytes isolated from the brain originated from the circulation. CD4+ T lymphocytes were the predominant brain leukocyte population in both models. However, cerebral granulocyte counts were higher after collagenase compared with blood injection.

CONCLUSIONS

Brain infiltration of systemic immune cells is similar in both murine intracerebral hemorrhage models. The pathophysiological impact of invading leukocytes and, in particular, of T cells requires further investigation.

Role of red blood cell lysis and iron in hydrocephalus after intraventricular hemorrhage

Thrombin and iron are two major players in intracerebral hemorrhage-induced brain injury and our recent study found that thrombin contributes to hydrocephalus development in a rat model of intraventricular hemorrhage (IVH). This study investigated the role of red blood cell (RBC) lysis and iron in hydrocephalus after IVH. There were three parts to this study. First, male Sprague-Dawley rats received an injection of saline, packed, or lysed RBCs into the right lateral ventricle. Second, rats had an intraventricular injection of iron or saline. Third, the rats received intraventricular injection of lysed RBCs mixed with deferoxamine (0.5 mg in 5 μL saline) or saline. All rats underwent magnetic resonance imaging at 24 hours and were then euthanized for brain edema measurement, western blot analysis, or brain histology. We found that intraventricular injection of lysed RBCs, but not packed RBCs, resulted in ventricular enlargement and marked increases in brain heme oxygenase-1 and ferritin at 24 hours. Intraventricular injection of iron also resulted in ventricular enlargement and ventricular wall damage 24 hours later. Coinjection of deferoxamine reduced lysed RBC-induced ventricular enlargement (P<0.01). These results suggest that iron, a degradation product of hemoglobin, has an important role in hydrocephalus development after IVH.

Toll-like receptor 2/4 heterodimer mediates inflammatory injury in intracerebral hemorrhage

OBJECTIVE

Inflammatory injury plays a critical role in intracerebral hemorrhage (ICH)-induced secondary brain injury. However, the upstream events that initiate inflammatory responses following ICH remain elusive. Our previous studies suggested that Toll-like receptor 4 (TLR4) may be the upstream signal that triggers inflammatory injury in ICH. In addition, recent clinical findings indicated that both TLR2 and TLR4 may participate in ICH-induced brain injury. However, it is unclear how TLR2 functions in ICH-induced inflammatory injury and how TLR2 interacts with TLR4.

METHODS

The role of TLR2 and TLR2/TLR4 heterodimerization in ICH-induced inflammatory injury was investigated in both in vivo and in vitro models of ICH.

RESULTS

TLR2 mediated ICH-induced inflammatory injury, which forms a heterodimer with TLR4 in both in vivo and in vitro models of ICH. Hemoglobin (Hb), but not other blood components, triggered inflammatory injury in ICH via assembly of TLR2/TLR4 heterodimers. MyD88 (myeloid differentiation primary response gene 88), but not TRIF (Toll/IR-1 domain-containing adaptor protein inducing interferon-beta), was required for ICH-induced TLR2/TLR4 heterodimerization. Mutation of MyD88 Arg196 abolished the TLR2/TLR4 heterodimerization.

INTERPRETATION

Our results suggest that a novel TLR2/TLR4 heterodimer induced by Hb initiates inflammatory injury in ICH. Interfering with the assembly of the TLR2/TLR4 heterodimer may be a novel target for developing effective treatment of ICH.

Genetic variations of MMP9 gene and intracerebral hemorrhage outcome: a cohort study in Chinese Han population

OBJECTIVE

To investigate the association between genetic variations of matrix metalloproteinase 9 (MMP9) gene and intracerebral hemorrhage (ICH) outcome in Chinese Han population.

METHODS

The clinical data and peripheral blood samples from the patients with ICH were collected. The patients were followed up for 3 months, and poor outcome was defined as death or dependency (modified Rankin scale score of 3-6). MassARRAY Analyser was used to genotype the tagger single nucleotide polymorphisms (SNPs) of MMP9 gene. Construction of haplotypes and genetic comparisons were performed by employing PLINK 1.0.7 software.

RESULTS

181 patients with ICH were recruited between September 2009 and October 2010. Information on genetic variations and follow-up assessments were available for 169 (93.4%) patients. Independent patients at 90 days were younger than those who died or dependent (57.82 ± 13.47 vs. 66.99 ± 11.49 years, p<0.01). In addition, independent patients had lower National Institutes of Health Stroke Scale (NIHSS) score (4[1-6] vs. 13[9-19], p<0.01). There were no significant associations (all p>0.05) between MMP9 genetic variations (alleles, genotypes and haplotypes) and ICH outcome after adjustment for conventional risk factors.

CONCLUSIONS

The genetic variations of MMP9 gene were not significantly associated with ICH outcome at 90 days in Chinese Han population.

Urokinase versus Alteplase for intraventricular hemorrhage fibrinolysis

Intraventricular hemorrhage (IVH) is the most severe form of stroke with intraventricular fibrinolysis (IVF) as a hopeful treatment. Urokinase (uPA) and tissue-type plasminogen activator (tPA) are used for IVF in Human. No clinical trial has evaluated the differential impact of these two fibrinolytics for IVF. Thus, we decided here to compare the use of these two fibrinolytics in a pre-clinical study. IVH was induced in rats by injection of collagenase type VII within the brain parenchyma followed by an IVF. Rats were randomized to receive uPA, tPA or saline within the ventricle, and cerebrospinal fluid was aspirated. Hematoma and ventricular volumes, brain water contents, inflammation and neurological deficits were measured at day three post-treatments. We also performed in vitro studies, in which neuronal cultures were subjected to an excitotoxic paradigm in the presence of either uPA or tPA. In the IVH model, we showed that although both uPA and tPA led to reduced ventricular volumes, only uPA significantly improved functional recovery. These results could be explained by the fact that uPA, in contrast of tPA, fails to promote inflammatory processes and neurotoxicity. Our study provides evidence supporting the use of uPA for fibrinolysis of IVH. A clinical trial could be warranted if tPA failed to improve outcomes in human IVH.

Mouse models of intracerebral hemorrhage in ventricle, cortex, and hippocampus by injections of autologous blood or collagenase

Intracerebral hemorrhage (ICH) is a devastating condition. Existing preclinical ICH models focus largely on striatum but neglect other brain areas such as ventricle, cortex, and hippocampus. Clinically, however, hemorrhagic strokes do occur in these other brain regions. In this study, we established mouse hemorrhagic models that utilize stereotactic injections of autologous whole blood or collagenase to produce ventricular, cortical, and hippocampal injury. We validated and characterized these models by histology, immunohistochemistry, and neurobehavioral tests. In the intraventricular hemorrhage (IVH) model, C57BL/6 mice that received unilateral ventricular injections of whole blood demonstrated bilateral ventricular hematomas, ventricular enlargement, and brain edema in the ipsilateral cortex and basal ganglia at 72 h. Unilateral injections of collagenase (150 U/ml) caused reproducible hematomas and brain edema in the frontal cortex in the cortical ICH (c-ICH) model and in the hippocampus in the hippocampal ICH (h-ICH) model. Immunostaining revealed cellular inflammation and neuronal death in the periventricular regions in the IVH brain and in the perihematomal regions in the c-ICH and h-ICH brains. Locomotor abnormalities measured with a 24-point scoring system were present in all three models, especially on days 1, 3, and 7 post-ICH. Locomotor deficits measured by the wire-hanging test were present in models of IVH and c-ICH, but not h-ICH. Interestingly, mice in the c-ICH model demonstrated emotional abnormality, as measured by the tail suspension test and forced swim test, whereas h-ICH mice exhibited memory abnormality, as measured by the novel object recognition test. All three ICH models generated reproducible brain damage, brain edema, inflammation, and consistent locomotor deficits. Additionally, the c-ICH model produced emotional deficits and the h-ICH model produced cognitive deficits. These three models closely mimic human ICH and should be useful for investigating the pathophysiology of ICH in ventricle, cortex, and hippocampus and for evaluating potential therapeutic strategies.

CD36-mediated hematoma absorption following intracerebral hemorrhage: negative regulation by TLR4 signaling

Promoting hematoma absorption is a novel therapeutic strategy for intracerebral hemorrhage (ICH); however, the mechanism of hematoma absorption is unclear. The present study explored the function and potential mechanism of CD36 in hematoma absorption using in vitro and in vivo ICH models. Hematoma absorption in CD36-deficient ICH patients was examined. Compared with patients with normal CD36 expression, CD36-deficient ICH patients had slower hematoma adsorption and aggravated neurologic deficits. CD36 expression in perihematomal tissues in wild-type mice following ICH was increased, whereas the hematoma absorption in CD36(-/-) mice was decreased. CD36(-/-) mice also showed aggravated neurologic deficits and increased TNF-α and IL-1β expression levels. The phagocytic capacity of CD36(-/-) microglia for RBCs was also decreased. Additionally, the CD36 expression in the perihematoma area after ICH in TLR4(-/-) and MyD88(-/-) mice was significantly increased, and hematoma absorption was significantly promoted, which was significantly inhibited by an anti-CD36 Ab. In vitro, TNF-α and IL-1β significantly inhibited the microglia expression of CD36 and reduced the microglia phagocytosis of RBCs. Finally, the TLR4 inhibitor TAK-242 upregulated CD36 expression in microglia, promoted hematoma absorption, increased catalase expression, and decreased the H2O2 content. These results suggested that CD36 mediated hematoma absorption after ICH, and TLR4 signaling inhibited CD36 expression to slow hematoma absorption. TLR4 inhibition could promote hematoma absorption and significantly improve neurologic deficits following ICH.

Use of statin during hospitalization improves the outcome after intracerebral hemorrhage

AIMS

To examine the relationship between statin use in Chinese patients with intracerebral hemorrhage (ICH) during their hospitalization and the outcomes.

METHODS

Data were collected from the China National Stroke Registry. Good functional outcome was defined by a modified Rankin Scale score between 0-2. Functional outcome and rate of mortality at 3 months and 1 year were compared between ICH patients on statin and those without it during their hospitalization. Odds ratios (ORs) with 95% confidence intervals (CI) were calculated using the multivariable logistic regression model adjusted for baseline risk factors.

RESULTS

Among 3218 consecutive ICH patients from 2007 to 2008, 220 (6.8%) were on statin during their hospitalization. Compared with those without statin, patients on statin were younger, had more stroke risk factors but lower stroke severity. ICH patients on statin had better functional outcome at 3 months (OR 2.24, 95% CI 1.49-3.36) and at 1 year (OR 2.04, 95% CI 1.37-3.06). They also had lower rate of mortality at 3 months (OR 0.44, 95% CI 0.22-0.87) and 1 year (OR 0.49, 95% CI 0.27-0.86).

CONCLUSIONS

In-hospital statin use in ICH patients is associated with better functional outcome and lower mortality at 3 months and 1 year.

Inhibition of SRC family kinases protects hippocampal neurons and improves cognitive function after traumatic brain injury

Traumatic brain injury (TBI) is often associated with intracerebral and intraventricular hemorrhage. Thrombin is a neurotoxin generated at bleeding sites fater TBI and can lead to cell death and subsequent cognitive dysfunction via activation of Src family kinases (SFKs). We hypothesize that inhibiting SFKs can protect hippocampal neurons and improve cognitive memory function after TBI. To test these hypotheses, we show that moderate lateral fluid percussion (LFP) TBI in adult rats produces bleeding into the cerebrospinal fluid (CSF) in both lateral ventricles, which elevates oxyhemoglobin and thrombin levels in the CSF, activates the SFK family member Fyn, and increases Rho-kinase 1(ROCK1) expression. Systemic administration of the SFK inhibitor, PP2, immediately after moderate TBI blocks ROCK1 expression, protects hippocampal CA2/3 neurons, and improves spatial memory function. These data suggest the possibility that inhibiting SFKs after TBI might improve clinical outcomes.

Intraclot recombinant tissue-type plasminogen activator reduces perihematomal edema and mortality in patients with spontaneous intracerebral hemorrhage

The study aimed to investigate the impact of intraclot recombinant tissue-type plasminogen activator (rt-PA) on perihematomal edema (PHE) development in patients with intracerebral hemorrhage (ICH) treated with minimally invasive surgery (MIS) and the effects of intraclot rt-PA on the 30-day survival. We reviewed the medical records of ICH patients undergoing MIS between October 2011 and July 2013. A volumetric analysis was done to assess the change in PHE and ICH volumes at pre-MIS (T1), post-MIS (T2) and day 10-16 (T3) following diagnostic computed tomographic scans (T0). Forty-three patients aged 52.8±11.1 years with (n=30) or without rt-PA (n=13) were enrolled from our institutional ICH database. The median rt-PA dose was 1.5 (1) mg, with a maximum dose of 4.0 mg. The ratio of clot evacuation was significantly increased by intraclot rt-PA as compared with controls (77.9%±20.4% vs. 64%±15%; P=0.046). From T1 to T2, reduction in PHE volume was strongly associated with the percentage of clot evacuation (ρ=0.34; P=0.027). In addition, PHE volume was positively correlated with residual ICH volume at the same day (ρ ranging from 0.39-0.56, P<0.01). There was no correlation between the cumulative dose of rt-PA and early (T2) PHE volume (ρ=0.24; P=0.12) or delayed (T3) PHE volume (ρ=0.19; P=0.16). The 30-day mortality was zero in this cohort. In the selected cohort of ICH patients treated with MIS, intraclot rt-PA accelerated clot removal and had no effects on PHE formation. MIS aspiration and low dose of rt-PA seemed to be feasible to reduce the 30-day mortality in patients with severe ICH. A large, randomized study addressing dose titration and long-term outcome is needed.

Polymorphonuclear neutrophil in brain parenchyma after experimental intracerebral hemorrhage

Polymorphonuclear neutrophils (PMNs) infiltration into brain parenchyma after cerebrovascular accidents is viewed as a key component of secondary brain injury. Interestingly, a recent study of ischemic stroke suggests that after ischemic stroke, PMNs do not enter brain parenchyma and as such may cause no harm to the brain. Thus, the present study was designed to determine PMNs' behavior after intracerebral hemorrhage (ICH). Using the autologous blood injection model of ICH in rats and immunohistochemistry for PMNs and vascular components, we evaluated the temporal and spatial PMNs distribution in the ICH-affected brain. We found that, similar to ischemia, there is a robust increase in presence of PMNs in the ICH-injured tissue that lasts for at least 1 to 2 weeks. However, in contrast to what was suggested for ischemia, besides PMNs that stay in association with the vasculature, after ICH, we found abundance of intraparenchymal PMNs (with no obvious association with vessels) in the ICH core and hematoma border, especially between 1 and 7 days after the ictus. Interestingly, the increased presence of intraparenchymal PMNs after ICH coincided with the massive loss of microvascular integrity, suggesting vascular disruption as a potential cause of PMNs presence in the brain parenchyma. Our study indicates that in contrast to ischemic stroke, after ICH, PMNs target not only vascular compartment but also brain parenchyma in the affected brain. As such, it is possible that the pathogenic role and therapeutic implications of targeting PMNs after ICH could be different from these after ischemic stroke. Our work suggests the needs for more studies addressing the role of PMNs in ICH.

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.

Hydrocephalus after intraventricular hemorrhage: the role of thrombin

Previous studies demonstrated that thrombin is an important factor in brain injury after intracerebral hemorrhage. This study investigated the effect of thrombin on hydrocephalus development in a rat intraventricular hemorrhage (IVH) model. There were three parts in this study. First, male Sprague-Dawley rats had an injection of 200 μL saline, autologous blood or heparinized blood, into the right lateral ventricle. Second, rats had an injection of 50 μL saline or 3U thrombin into the right lateral ventricle. Third, rats had an injection of thrombin (3U) with a protease-activated receptor-1 (PAR-1) antagonist, SCH79797 (0.15 nmol), or vehicle into the right lateral ventricle. Lateral ventricle volumes were measured by magnetic resonance imaging and the brains were used for immunohistochemistry and western blot analyses. Intraventricular injection of autologous blood induced hydrocephalus from day 1 to 28. Heparinized blood injection resulted in less hydrocephalus at all time points compared with blood injection alone (P<0.05). Intraventricular injection of thrombin caused significant hydrocephalus, ventricular wall damage, and periventricular blood-brain barrier disruption. Thrombin-induced hydrocephalus was reduced by co-injection of the PAR-1 antagonist SCH79797 (P<0.05). In conclusion, thrombin contributes to hydrocephalus development after IVH and thrombin-induced hydrocephalus is through PAR-1.

Fingolimod exerts neuroprotective effects in a mouse model of intracerebral hemorrhage

Recent studies have shown that fingolimod (FTY720) is neuroprotective in CNS injury models of cerebral ischemia and spinal cord injury. The purpose of the study was to examine the effect of fingolimod in a mouse model of intracerebral hemorrhage. ICH was produced in adult CD1 mice by injecting collagenase VII-S (0.5 µL, 0.06 U) into the basal ganglia. Fingolimod (or saline) was given 30 min after surgery and once daily for two days. Three days after intracerebral hemorrhage, brain edema, hematoma volume and the number of apoptotic cells were quantified. In another cohort of mice, brain atrophy was evaluated two weeks following intracerebral hemorrhage. Neurobehavioral tests were performed on the 3rd, the 7th and the 14th day. Fingolimod significantly decreased edema, apoptosis and brain atrophy. More importantly, fingolimod enhanced neurobehavioral recovery. Preliminary experiments showed no difference in the number of inflammatory (CD68-positive) cells between the two groups. In conclusion, fingolimod exerts protective effects in a mouse model of intracerebral hemorrhage; the mechanisms underlying these neuroprotective effects deserve further study.

Prognostic value of plasma β-amyloid levels in patients with acute intracerebral hemorrhage

BACKGROUND AND PURPOSE

It has been proposed that the deposition of the β-amyloid peptide (Aβ) in the brain parenchyma and brain blood vessels has deleterious effects. We tested the hypothesis that the levels of plasma Aβ are related to the outcome in patients with intracerebral hemorrhage.

METHODS

In a multicenter study, we prospectively included patients with spontaneous intracerebral hemorrhage within the first 24 hours after onset. At admission, we measured plasma Aβ40 and Aβ42 levels using ELISA techniques. Also, we recorded age, sex, vascular risk factors, National Institutes of Health Stroke Scale score, presence of intraventricular hemorrhage, localization, cause, and volume of the hematoma. We obtained the modified Rankin scale and defined a unfavorable outcome as modified Rankin scale >2 at 3 months. Bivariate and multivariate regression analyses were performed.

RESULTS

We studied 160 patients (mean age, 73.8±11.3 years; 59.4% of them were men). A favorable outcome was observed in 64 (40%) of the patients. In the bivariate analyses, unfavorable outcome was associated with high age, female sex, diabetes mellitus, presence of intraventricular hemorrhage, high blood glucose, high National Institutes of Health Stroke Scale score, high volume, and high plasma levels of Aβ42 and Aβ40. The multivariate analysis showed that increased age (odds ratio, 1.07; 95% confidence interval, 1.035-1.21; P<0.0001), high admission National Institutes of Health Stroke Scale score (odds ratio, 1.29, 95% confidence interval, 1.17-1.42; P<0.0001), presence of diabetes mellitus (odds ratio, 4.15; 95% confidence interval, 1.21-14.1; P=0.02), and Aβ42 levels >9.7 pg/mL (odds ratio, 4.11; 95% confidence interval, 1.65-10.1; P=0.02) were independently associated with an increased likelihood of an unfavorable outcome.

CONCLUSIONS

High levels of plasma Aβ42 in patients with acute intracerebral hemorrhage are associated with a poor functional prognosis.

Rehabilitation Improves Behavioral Recovery and Lessens Cell Death Without Affecting Iron, Ferritin, Transferrin, or Inflammation After Intracerebral Hemorrhage in Rats

Background. Rehabilitation aids recovery from stroke in animal models, including in intracerebral hemorrhage (ICH). Sometimes, rehabilitation lessens brain damage. Objective. We tested whether rehabilitation improves recovery and reduces perihematoma neuronal death. We also evaluated whether rehabilitation influences iron toxicity and inflammation, mediators of secondary degeneration after ICH. Methods. Rats were trained to retrieve food pellets in a staircase apparatus and later subjected to striatal ICH (via collagenase infusion). After 1 week, they were given either enriched rehabilitation (ER), including reach training with group housing and environmental enrichment, or control treatment (group housing). Rats in the first experiment were treated for 2 weeks, functionally assessed, and killed humanely at 1 month to determine brain levels of nonheme iron. A second experiment used a similar approach, except that animals were euthanized at 14 days to evaluate perihematoma neuronal death (FluoroJade), iron distribution (Perls), and astrocyte (GFAP) and microglia (Iba-1) activity. A third experiment measured levels of iron-binding proteins (ferritin and transferrin) at 14 days. Results. Striatal ICH caused functional impairments, which were significantly improved with ER. The ICH caused delayed perihematoma neuronal death, which ER significantly reduced. Hemispheric iron levels, the amount of iron-binding proteins, and perihematoma astrocytes and microglia numbers were significantly elevated after ICH (vs normal side) but were not affected by ER. Conclusions. Rehabilitation is an effective behavioral and neuroprotective strategy for ICH. Neither effect appears to stem from influencing iron toxicity or inflammation. Thus, additional work must identify underlying mechanisms to help further therapeutic gains.

Iron and intracerebral hemorrhage: from mechanism to translation

Intracerebral hemorrhage (ICH) is a leading cause of morbidity and mortality around the world. Currently, there is no effective medical treatment available to improve functional outcomes in patients with ICH due to its unknown mechanisms of damage. Increasing evidence has shown that the metabolic products of erythrocytes are the key contributor of ICH-induced secondary brain injury. Iron, an important metabolic product that accumulates in the brain parenchyma, has a detrimental effect on secondary injury following ICH. Because the damage mechanism of iron during ICH-induced secondary injury is clear, iron removal therapy research on animal models is effective. Although many animal and clinical studies have been conducted, the exact metabolic pathways of iron and the mechanisms of iron removal treatments are still not clear. This review summarizes recent progress concerning the iron metabolism mechanisms underlying ICH-induced injury. We focus on iron, brain iron metabolism, the role of iron in oxidative injury, and iron removal therapy following ICH, and we suggest that further studies focus on brain iron metabolism after ICH and the mechanism for iron removal therapy.

Alpha-7 nicotinic acetylcholine receptor agonists in intracerebral hemorrhage: an evaluation of the current evidence for a novel therapeutic agent

Intracerebral hemorrhage (ICH) is the most deadly and least treatable subtype of stroke, and at the present time there are no evidence-based therapeutic interventions for patients with this disease. Secondary injury mechanisms are known to cause substantial rates of morbidity and mortality following ICH, and the inflammatory cascade is a major contributor to this post-ICH secondary injury. The alpha-7 nicotinic acetylcholine receptor (α7-nAChR) agonists have a well-established antiinflammatory effect and have been shown to attenuate perihematomal edema volume and to improve functional outcome in experimental ICH. The authors evaluate the current evidence for the use of an α7-nAChR agonist as a novel therapeutic agent in patients with ICH.

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.

Predictors of hematoma volume in deep and lobar supratentorial intracerebral hemorrhage

IMPORTANCE

Hematoma volume is the strongest predictor of outcome in intracerebral hemorrhage (ICH). Despite known differences in the underlying biology between deep and lobar ICHs, limited data are available on location specificity of factors reported to affect hematoma volume.

OBJECTIVE

To evaluate whether determinants of ICH volume differ by topography, we sought to estimate location-specific effects for potential predictors of this radiological outcome.

DESIGN

Prospective cohort study.

SETTING

Academic medical center.

PARTICIPANTS

A total of 744 supratentorial primary ICH patients (388 deep and 356 lobar) aged older than 18 years admitted between January 1, 2000, and December 31, 2010.

MAIN OUTCOMES AND MEASURES

Intracerebral hemorrhage volume measured from the computed tomography scan obtained on presentation to the emergency department. Linear regression analysis, stratified by ICH location, was implemented to identify determinants of log-transformed ICH volume.

RESULTS

Median ICH volume was larger in lobar hemorrhages (39 mL; interquartile range, 16-75 mL) than in deep hemorrhages (13 mL; interquartile range, 5-40 mL; P < .001). In multivariable linear regression, independent predictors of deep ICH volume were intensity of anticoagulation (β = 0.32; standard error [SE] = 0.08; P < .001; test for trend across 4 categories of the international normalized ratio), history of coronary artery disease (β = 0.33; SE = 0.17; P = .05), male sex (β = 0.28; SE = 0.14; P = .05), and age (β = -0.02; SE = 0.01; P = .001). Independent predictors of lobar ICH volume were intensity of anticoagulation (β = 0.14; SE = 0.06; P = .02) and antiplatelet treatment (β = 0.27; SE = 0.13; P = .03).

CONCLUSIONS AND RELEVANCE

Predictors of hematoma volume only partially overlap between deep and lobar ICHs. These findings suggest that the mechanisms that determine the extent of bleeding differ for deep and lobar ICHs. Further studies are needed to characterize the specific biological pathways that underlie the observed associations.

Deferoxamine attenuates white matter injury in a piglet intracerebral hemorrhage model

BACKGROUND AND PURPOSE

Deferoxamine reduces neuronal death in a piglet model of intracerebral hemorrhage (ICH). This study examined the effect of deferoxamine on perihematomal white matter edema in piglets.

METHODS

ICH was induced by an injection of autologous blood into the right frontal lobe of piglets. In the first part of study, the time course of edema formation was determined. In the second part, the effects of deferoxamine on ICH-induced white matter edema, tumor necrosis factor α, and receptor-interacting protein kinase 1 were examined.

RESULTS

ICH resulted in marked brain edema and increased tumor necrosis factor α and receptor-interacting protein kinase 1 levels in white matter. Systemic treatment with deferoxamine markedly reduced white matter tumor necrosis factor α and receptor-interacting protein kinase 1 levels and attenuated white matter edema after ICH.

CONCLUSIONS

Deferoxamine reduces white matter edema, tumor necrosis factor α, and receptor-interacting protein kinase 1 levels after ICH in piglets, suggesting deferoxamine is a potential effective therapeutic agent for patients with ICH.

Functional recovery after transplantation of induced pluripotent stem cells in a rat hemorrhagic stroke model

Transplantation of induced pluripotent stem cells (iPSCs) has shown promising therapeutic effects for ischemic stroke. However, it is not clear if this treatment would promote recovery after intracerebral hemorrhage (ICH). In this study, we investigated the functional outcome of iPSCs transplantation in experimental ICH in rats. IPSCs were derived from an ICH patient's fibroblasts and were injected into the ipsilateral side of ICH in rats. IPSCs transplantation significantly improved the neurological functions after ICH as compared to vehicle and fibroblast injection. The grafted iPSCs migrated into brain tissue around the hematoma, survived after 4 weeks of transplantation, and exhibited the neural cell-specific biomarkers nestin, β-tubulin, and GFAP. Immunohistochemical staining showed that the densities of brain derived neurophic factors (BDNF)-positive cells and vascular endothelial growth factor (VEGF)-positive cells were significantly increased around the hemorrhagic brain tissues of iPSCs-treated rats. In addition, iPSCs treatment increased the protein expression of BDNF and VEGF in the surrounding region of hematoma. These findings demonstrate that the transplantation of ICH patient-derived iPSCs contributes toward the improved neurological function in experimental ICH rats. The mechanisms are possibly due to neuronal replacement and enhanced secretion of neurophic factors. Our data suggest that transplantation of ICH patient-derived iPSCs may be a therapeutic strategy for hemorrhagic stroke.

Microglial responses after ischemic stroke and intracerebral hemorrhage

Stroke is a leading cause of death worldwide. Ischemic stroke is caused by blockage of blood vessels in the brain leading to tissue death, while intracerebral hemorrhage (ICH) occurs when a blood vessel ruptures, exposing the brain to blood components. Both are associated with glial toxicity and neuroinflammation. Microglia, as the resident immune cells of the central nervous system (CNS), continually sample the environment for signs of injury and infection. Under homeostatic conditions, they have a ramified morphology and phagocytose debris. After stroke, microglia become activated, obtain an amoeboid morphology, and release inflammatory cytokines (the M1 phenotype). However, microglia can also be alternatively activated, performing crucial roles in limiting inflammation and phagocytosing tissue debris (the M2 phenotype). In rodent models, microglial activation occurs very early after stroke and ICH; however, their specific roles in injury and repair remain unclear. This review summarizes the literature on microglial responses after ischemic stroke and ICH, highlighting the mediators of microglial activation and potential therapeutic targets for each condition.

Transplantation of human neuro-epithelial-like stem cells derived from induced pluripotent stem cells improves neurological function in rats with experimental intracerebral hemorrhage

Specific targeted therapy for intracerebral hemorrhage (ICH), which has high disability and case-fatality rate, is currently not available. Induced pluripotent stem cells (iPSCs) generated from somatic cells of ICH patients have therapeutic potential for individualized cerebral protection. While, whether ICH patient-originated iPSCs could differentiate into neuro-epithelial-like stem (NES) cells and whether such NES cells could improve functional recovery in the hemorrhage-injured brain are unclear. Here, we showed that fibroblasts from an ICH patient can be efficiently reprogrammed to iPSCs by lentiviral vectors carrying defined transcription factors (OCT4, SOX2, KLF4, and c-MYC). These iPSCs have the typical morphology, surface antigens, capability of self-renewal and differentiating into cell types of all three embryonic germ layers that are similar to human embryonic stem cells (hESCs). Using defined serum-free neural differentiation medium, we induced the iPSCs differentiate into NES cells. Subsequently, the NES cells from ICH patient-originated iPSCs were transplanted into the perihematoma of rats with experimental ICH injury. Intriguingly, recovery of neurological dysfunction in experimental ICH rats was observed post-NES cells graftage. Transplanted NES cells migrated to the surrounding area of hematoma, survived and differentiated into neuron-like cells. Our study demonstrates that the transplantation of human iPS-originated NES cells is an effective approach of treating ICH injury and the improvement of neural function is partially due to neuronal replacement and regeneration.

The role of inflammation and interleukin-1 in acute cerebrovascular disease

Acute cerebrovascular disease can affect people at all stages of life, from neonates to the elderly, with devastating consequences. It is responsible for up to 10% of deaths worldwide, is a major cause of disability, and represents an area of real unmet clinical need. Acute cerebrovascular disease is multifactorial with many mechanisms contributing to a complex pathophysiology. One of the major processes worsening disease severity and outcome is inflammation. Pro-inflammatory cytokines of the interleukin (IL)-1 family are now known to drive damaging inflammatory processes in the brain. The aim of this review is to discuss the recent literature describing the role of IL-1 in acute cerebrovascular disease and to provide an update on our current understanding of the mechanisms of IL-1 production. We also discuss the recent literature where the effects of IL-1 have been targeted in animal models, thus reviewing potential future strategies that may limit the devastating effects of acute cerebrovascular disease.

Bipyridine, an iron chelator, does not lessen intracerebral iron-induced damage or improve outcome after intracerebral hemorrhagic stroke in rats

Iron chelators, such as the intracellular ferrous chelator 2,2'-bipyridine, are a potential means of ameliorating iron-induced injury after intracerebral hemorrhage (ICH). We evaluated bipyridine against the collagenase and whole-blood ICH models and a simplified model of iron-induced damage involving a striatal injection of FeCl2 in adult rats. First, we assessed whether bipyridine (25 mg/kg beginning 12 h post-ICH and every 12 h for 3 days) would attenuate non-heme iron levels in the brain and lessen behavioral impairments (neurological deficit scale, corner turn test, and horizontal ladder) 7 days after collagenase-induced ICH. Second, we evaluated bipyridine (20 mg/kg beginning 6 h post-ICH and then every 24 h) on edema 3 days after collagenase infusion. Body temperature was continually recorded in a subset of these rats beginning 24 h prior to ICH until euthanasia. Third, bipyridine was administered (as per experiment 2) after whole-blood infusion to examine tissue loss, neuronal degeneration, and behavioral impairments at 7 days post-stroke, as well as body temperature for 3 days post-stroke. Finally, we evaluated whether bipyridine (25 mg/kg given 2 h prior to surgery and then every 12 h for 3 days) lessens tissue loss, neuronal death, and behavioral deficits after striatal FeCl2 injection. Bipyridine caused a significant hypothermic effect (maximum drop to 34.6 °C for 2-5 h after each injection) in both ICH models; however, in all experiments bipyridine-treated rats were indistinguishable from vehicle controls on all other measures (e.g., tissue loss, behavioral impairments, etc.). These results do not support the use of bipyridine against ICH.

[Management of intracerebral hemorrhage: can we still learn something?]

Intracerebral hemorrhage (ICH) is the most devastating form of stroke. It affects approximately 2 million people worldwide every year and is a major cause of mortality and morbidity. Despite the focus of intensive scientific research on ICH for decades there is still no proven treatment strategy for this disease. Advances in knowledge on the underlying pathomechanisms of ICH and the clinical impact have contributed to the development of novel treatment approaches. Currently, surgical treatment, aggressive blood pressure management and intraventricular fibrinolysis in patients with additional severe intraventricular hemorrhage are being investigated in large scale phase III clinical trials.

Role of PGE₂ EP1 receptor in intracerebral hemorrhage-induced brain injury

Prostaglandin E₂ (PGE₂) has been described to exert beneficial and detrimental effects in various neurologic disorders. These conflicting roles of PGE₂ could be attributed to its diverse receptor subtypes, EP1-EP4. At present, the precise role of EP1 in intracerebral hemorrhage (ICH) is unknown. Therefore, to elucidate its possible role in ICH, intrastriatal injection of collagenase was given in randomized groups of adult male wildtype (WT) and EP1 receptor knockout (EP1⁻/⁻)C57BL/6 mice. Functional outcomes including neurologic deficits, rotarod performance, open field activity, and adhesive removal performance were evaluated at 24, 48, and 72 h post-ICH. Lesion volume, cell survival and death, were assessed using Cresyl Violet, and Fluoro-Jade staining, respectively. Microglial activation and phagocytosis were estimated using Iba1 immunoreactivity and fluorescently-labeled microspheres. Following 72 h post-ICH, EP1⁻/⁻ mice showed deteriorated outcomes compared to the WT control mice. These outcomes were demonstrated by elevated neurological deficits, exacerbated lesion volume, and significantly worsened sensorimotor functions. Fluoro-Jade staining showed significantly increased numbers of degenerating neurons and reduced neuronal survival in EP1⁻/⁻ compared to WT mice. To assess in vivo phagocytosis, the number of microspheres phagocytosed by Iba1-positive cells was 145.4 ± 15.4 % greater in WT compared to EP1⁻/⁻ mice. These data demonstrate that EP1 deletion exacerbates neuro-behavioral impairments following ICH, potentially by slowing down/impairing microglial phagocytosis. A better understanding of this EP1 mechanism could lead to improved intervention strategies for hemorrhagic stroke.

Ethyl pyruvate ameliorates intracerebral hemorrhage-induced brain injury through anti-cell death and anti-inflammatory mechanisms

Ethyl pyruvate (EP) is a pyruvate derivative and known to be cytoprotective in various pathological conditions through anti-cell death and anti-inflammatory mechanisms. The present study investigated the neuroprotective effect of ethyl pyruvate using a mouse model of collagenase-induced intracerebral hemorrhage (ICH). Our results showed that EP treatment to mice reduced brain edema and improved neurological function after ICH. Delayed treatment with EP until 6h after ICH to mice was still neuroprotective. We further demonstrated that EP protected neurons from hemoglobin-induced cell death in vitro and neuronal cell degeneration in ICH mice. Moreover, EP exerted anti-inflammatory effects by inhibiting microglia activation, nuclear factor-κB (NF-κB) DNA binding activity and subsequent downstream pro-inflammatory cytokines (tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β)) production. Taken together, these results suggest that EP exerts neuroprotective effect via anti-cell death and anti-inflammatory actions. EP is a potential novel treatment for ICH patients and deserves further investigation.

Role of iron in brain lipocalin 2 upregulation after intracerebral hemorrhage in rats

Brain iron overload has a detrimental role in brain injury after intracerebral hemorrhage (ICH). Lipocalin 2 (LCN2), a siderophore-binding protein, is involved in cellular iron transport. The present study investigated changes in LCN2 expression after ICH and the role of iron in those changes. Male Sprague-Dawley rats had an intracaudate injection of autologous blood (ICH) or iron. Control rats received a needle insertion or saline injection. Some ICH animals were treated with either vehicle or deferoxamine, an iron chelator. Brain LCN2 expression was determined by Western blot analysis and immunohistochemistry. Real-time PCR was also used to confirm brain LCN2 mRNA expression. The number of LCN2 positive cells was markedly increased in the ipsilateral basal ganglia and cortex after ICH and most LCN2 positive cells were astrocytes. Western blots showed that brain LCN2 levels were higher at days 1, 3 and 7 in the ipsilateral hemisphere after ICH (70 to 80 fold higher than contralateral hemisphere or sham-operated rats at 3 days), and declined to lower levels at day 14. Iron, but not saline injection also caused brain LCN2 upregulation (a more than 100-fold increase). In addition, systemic treatment of deferoxamine reduced ICH-induced LCN2 upregulation (p<0.05). These results suggest that iron has a role in brain LCN2 upregulation following ICH. LCN2 upregulation after ICH may be part of the response to clear iron released from the hematoma during clot resolution.