Deferoxamine-induced attenuation of brain edema and neurological deficits in a rat model of intracerebral hemorrhage

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.

T2* magnetic resonance imaging sequences reflect brain tissue iron deposition following intracerebral hemorrhage

BACKGROUND AND PURPOSE

To examine the utility of magnetic resonance imaging (MRI) T2* sequences as a measure of iron overload in the brain following intracerebral hemorrhage (ICH).

METHODS

We examined the time course of T2* changes in the brain around intracerebral hemorrhages in a series of patients. We also performed a series of experiments in an animal model of ICH, examining the time course of T2* changes along with correlation of these changes with histological markers of ferric iron deposition.

RESULTS

We found that T2* changes in the brain occur with increasing intensity and spatial distribution over a three month period. Experimental ICH in the rat model induces similar changes, and these changes correlate tightly with histological markers of ferric iron deposition.

CONCLUSIONS

MRI T2* changes after ICH can be used to measure the degree of iron overload in the brain. The T2* sequence may be useful as a measure of interventions aimed at reducing ICH-related brain injury by reducing iron deposition.

Is there a place for cerebral preconditioning in the clinic?

Preconditioning (PC) describes a phenomenon whereby a sub-injury inducing stress can protect against a later injurious stress. Great strides have been made in identifying the mechanisms of PC-induced protection in animal models of brain injury. While these may help elucidate potential therapeutic targets, there are questions over the clinical utility of cerebral PC, primarily because of questions over the need to give the PC stimulus prior to the injury, narrow therapeutic windows and safety. The object of this review is to address the question of whether there may indeed be a clinical use for cerebral PC and to discuss the deficiencies in our knowledge of PC that may hamper such clinical translation.

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.

Hemin uptake and release by neurons and glia

Hemin accumulates in intracerebral hematomas and may contribute to cell injury in adjacent tissue. Despite its relevance to hemorrhagic CNS insults, very little is known about hemin trafficking by neural cells. In the present study, hemin uptake and release were quantified in primary murine cortical cultures, and the effect of the hemin-binding compound deferoxamine (DFO) was assessed. Net uptake of (55)Fe-hemin was similar in mixed neuron-glia, neuron, and glia cultures, but was 2.6-3.6-fold greater in microglia cultures. After washout, 40-60% of the isotope signal was released by mixed neuron-glia cultures into albumin-containing medium within 24 h. Inhibiting hemin breakdown with tin protoporphyrin IX (SnPPIX) had minimal effect, while release of the fluorescent hemin analog zinc mesoporphyrin was quantitatively similar to that of (55)Fe-hemin. Isotope was released most rapidly by neurons (52.2 ± 7.2% at 2 h), compared with glia (15.6 ± 1.3%) and microglia (17.6 ± 0.54%). DFO did not alter (55)Fe-hemin uptake, but significantly increased its release. Mixed cultures treated with 10 μM hemin for 24 h sustained widespread neuronal loss that was attenuated by DFO. Concomitant treatment with SnPPIX had no effect on either enhancement of isotope release by DFO or neuroprotection. These results suggest that in the presence of a physiologic albumin concentration, hemin uptake by neural cells is followed by considerable extracellular release. Enhancement of this release by DFO may contribute to its protective effect against hemin toxicity.

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.

Quantitative gait analysis of long-term locomotion deficits in classical unilateral striatal intracerebral hemorrhage rat model

Gait analysis is a systematic collection of quantitative information on bodily movements during locomotion. Gait analysis has been employed clinically in stroke patients for their rehabilitation planning. In animal studies, gait analysis has been employed for the assessment of their locomotive disturbances in ischemic stroke, spinal cord injury and Parkinson's disease. The aims of the work reported here were to identify the gait parameters, collected from the computer-generated CatWalk System, that change after unilateral intracerebral hemorrhage (ICH) in the acute stage and long term up to 56 days post-ICH. The results showed that with the collagenase-induced unilateral striatal lesion, the rats displayed a significant contralateral decrease in print and maximum contact area and paw intensity, a diagonal increase in the stance duration of the left front and right hind paws, a significant decrease in the stride length of all four limbs, and foot pattern instability as reflected by the base of support, support on styles, and cadence. These deficits, including those in print area, stance and pressure, were demonstrated throughout the long-term period following ICH. The correlations between the gait parameters, lesion volume and asymmetrical forelimb use were also reported in this paper. This work has provided a systematic description on gait parameters in the classical striatal ICH model, which might become an essential assessment tool in future studies of pathophysiology and the development of novel treatments for experimental unilateral intracerebral hemorrhage with gait deficits.

Cerebral hemorrhage, brain edema, and heme oxygenase-1 expression after experimental traumatic brain injury

Intracranial bleeding is a common and serious consequence of traumatic brain injury (TBI). In the present study, we investigated cerebral hematoma occurrence, brain edema formation, blood-brain barrier (BBB) disruption, and heme oxygenase-1 (HO-1) expression after TBI. Moderate severity (1.8-2.2 atmospheres [ATM]) TBI was induced by lateral fluid percussion in male adult Sprague-Dawley rats. Sham rats underwent only a craniotomy. Rats were euthanized 24 h later for brain histology and immunoblotting analysis. We found TBI-induced cerebral hematomas and iron deposition in the ipsilateral hemisphere in all rats. TBI also caused marked BBB disruption (p < 0.05) and brain swelling (p < 0.05). HO-1, a key enzyme for heme degradation, was upregulated significantly after TBI (419 ± 89 vs 194 ± 59 pixels in the sham, p < 0.05). These results suggest that cerebral hematomas might play a role in brain injury after TBI. Future studies should determine the role of iron released from the cerebral hematoma in TBI.

Potential mechanisms of cerebellar hypoplasia in prematurity

INTRODUCTION

The cerebellum undergoes dramatic growth and maturation over the neonatal period after preterm birth and is thus particularly sensitive to impaired development due to various clinical factors.

METHODS

Impairments in growth can occur independent of cerebellar parenchymal damage, such as from local hemorrhage, resulting from reduced expression of sonic hedgehog signaling to trigger the appropriate expansion of the granule precursor cells.

RESULTS

The primary risk factors for impaired cerebellar development include postnatal glucocorticoid exposure, which has direct effects on the sonic hedgehog pathway, and supratentorial brain injury, including intraventricular hemorrhage and white matter injury, which may result in crossed cerebellar diaschisis and local toxic effects of blood products on the external granular layer. Other cardiorespiratory and nutritional factors may also exist. Impaired cerebellar development is associated with adverse outcomes in motor and cognitive development.

CONCLUSION

New approaches to care to counteract these risk factors may help improve long-term outcome after preterm birth.

A rapid fluorescent method to quantify neuronal loss after experimental intracerebral hemorrhage

Neuronal loss in tissue surrounding an intracerebral hemorrhage (ICH) is usually quantified by labor-intensive histological methods that are subject to bias. Fluorescent protein expression has been successfully used as a marker of cell viability in vitro and in retinal studies in vivo, but not in any ICH model to date. The potential of this approach was investigated using transgenic mice that constitutively express the red fluorescent protein variant dTomato in central neurons under the control of the Thy1 promoter. Breeding and growth of these mice were similar to their wild-type counterparts; behavioral phenotyping by digital analysis of home cage video recordings detected no differences. Bright fluorescence was evident in fresh brain samples with minimal background fluorescence, and was reduced in tissue surrounding the hematoma. In order to assess fluorescence loss as an injury marker in a planned study, these mice were crossed with heme oxygenase (HO)-2 knockouts and wild-type controls; striatal hemorrhage was induced by stereotactic injection of collagenase. Fluorescence in hemorrhagic striata was reduced to 86.4±3.9%, 62.2±5.1%, and 58.3±3.0% of contra-lateral on days 1, 4 and 8, respectively, and correlated closely with reduction in striatal cell viability as quantified by MTT assay. HO-2 knockout and wild-type values did not differ significantly. Similar results were observed with stereological cell counts of striatal neurons identified by NeuN immunoreactivity. These results suggest that loss of constitutive dTomato fluorescence is an accurate and efficient marker of neuronal loss in tissue surrounding a striatal hematoma.

Brain microbleeds: distribution and influence on hematoma and perihematomal edema in patients with primary intracerebral hemorrhage

Brain microbleed is a marker of small vessel microhemorrhagic or microaneurysmal lesions, which may induce intracerebral hemorrhage (ICH). This study to prospectively evaluated the association between microbleeds, hematoma and perihematomal edema volume, and various clinical data, as well as patient outcome. Thirty-one patients with ICH and 31 healthy age-matched subjects were enrolled in our study. They were divided into two groups according to the presence or absence of microbleeds detected by MRI. Serial clinical and laboratory data were recorded. Modified Rankin Scale and Barthel Index were estimated three months after hemorrhage. The major location of microbleeds among patients with ICH was the basal ganglia. The volume of perihematomal edema was correlated with the initial hematoma volume on the first, fifth and seventh days after hemorrhage in patients with microbleeds. For patients without microbleeds, this correlation was also significant on the seventh day. Cerebral microbleeds in patients with ICH, especially in the basal ganglia region, represent micro-angiopathy, and are associated with leakage of blood and formation of perihemorrhage edema. Brain microbleeds found in patients with ICH warrant further investigation for evaluation of stroke risk.

Spinal cavernous and capillary hemangiomas in adults

STUDY DESIGN

Retrospective cohort analysis.

OBJECTIVE

To evaluate the neurological outcomes after resection of intramedullary, intradural extramedullary, and extradural hemangiomas.

SUMMARY OF BACKGROUND DATA

Spinal hemangiomas most commonly arise in the vertebral bodies and are typically asymptomatic. Uncommonly, hemangiomas may cause significant neurological deficits via extraosseous extension. Intramedullary hemangiomas may also occur and account for approximately 5% of all spinal cord lesions, with those located intradural extramedullary occurring rarely. Although retrospective studies have primarily examined the neurological outcome of intramedullary and vertebral hemangiomas, there is little literature comparing outcomes after surgical treatment of hemangiomas of varying location.

METHODS

We performed a retrospective review of all patients treated for hemangiomas affecting the spinal cord at our institution between 1999 and 2012. Various patient, clinical, and tumor data were collected including patient demographics, neurological examinations, and procedure, clinic, and pathology notes. Imaging studies were evaluated to determine the extent of resection, presence of recurrence, and lesion volume. Functional status was defined using the Modified McCormick Scale (MMS).

RESULTS

A total of 19 patients were evaluated, with our cohort consisting of 8 intramedullary, 5 intradural extramedullary, and 6 vertebral hemangiomas with extraosseous extension. Cavernous hemangiomas were most common (47.4%), followed by those of the capillary type. At long-term follow-up, 73.7% of patients had improved neurological outcome and 15.8% had worsened. However, only 50% of patients with intramedullary hemangiomas improved, compared with 80% and 100% for intradural extramedullary and vertebral hemangiomas, respectively. Also, those with intramedullary lesions more frequently had worse outcomes after surgery (25%) than those with intradural extramedullary (20%) and vertebral hemangiomas (0%).

CONCLUSION

Although all patients typically present with a similar functional status, patients with intramedullary lesions are more unlikely to improve after surgical resection and derive less of a benefit compared with those with intradural extramedullary and vertebral hemangiomas.

The response of cerebral cortex to haemorrhagic damage: experimental evidence from a penetrating injury model

Understanding the response of the brain to haemorrhagic damage is important in haemorrhagic stroke and increasingly in the understanding the cerebral degeneration and dementia that follow head trauma and head-impact sports. In addition, there is growing evidence that haemorrhage from small cerebral vessels is important in the pathogenesis of age-related dementia (Alzheimer's disease). In a penetration injury model of rat cerebral cortex, we have examined the neuropathology induced by a needlestick injury, with emphasis on features prominent in the ageing and dementing human brain, particularly plaque-like depositions and the expression of related proteins. Needlestick lesions were made in neo- and hippocampal cortex in Sprague Dawley rats aged 3-5 months. Brains were examined after 1-30 d survival, for haemorrhage, for the expression of hyperphosphorylated tau, Aβ, amyloid precursor protein (APP), for gliosis and for neuronal death. Temporal cortex from humans diagnosed with Alzheimer's disease was examined with the same techniques. Needlestick injury induced long-lasting changes-haem deposition, cell death, plaque-like deposits and glial invasion-along the needle track. Around the track, the lesion induced more transient changes, particularly upregulation of Aβ, APP and hyperphosporylated tau in neurons and astrocytes. Reactions were similar in hippocampus and neocortex, except that neuronal death was more widespread in the hippocampus. In summary, experimental haemorrhagic injury to rat cerebral cortex induced both permanent and transient changes. The more permanent changes reproduced features of human senile plaques, including the formation of extracellular deposits in which haem and Aβ-related proteins co-localised, neuronal loss and gliosis. The transient changes, observed in tissue around the direct lesion, included the upregulation of Aβ, APP and hyperphosphorylated tau, not associated with cell death. The findings support the possibility that haemorrhagic damage to the brain can lead to plaque-like pathology.

Effects of sulfaphenazole after collagenase-induced experimental intracerebral hemorrhage in rats

Treatment of intracerebral hemorrhage is often pointless, although considerable effort has been devoted to developing treatments for ischemic stroke. The purpose of this study was to determine the influence of drugs in improving neurological outcomes with pharmaceutical therapy after intracerebral hemorrhage. The free-radical hypothesis for intracerebral hemorrhage is based on the cytotoxicity triggered by blood components and its degradation products, such as heme and iron as a potent pro-oxidant atom. Sulfaphenazole (SPZ) has a different mechanism such as reactive oxygen species scavenging, in addition to the inhibition of superoxide production by cytochrome P450. The present study investigated the properties of SPZ in collagenase-induced intracerebral hemorrhage rat brain damage. The results show that systemic SPZ treatment after intracerebral hemorrhage reduces striatal dysfunction, the elevation of lipid peroxidation, and brain edema in the rat. These results suggest that SPZ is a potentially effective therapeutic approach for intracerebral hemorrhage as the effect of SPZ was initiated for either 1 h or 3 d post-intracerebral hemorrhage.

Effect of quercetin and desferrioxamine on 6-hydroxydopamine (6-OHDA) induced neurotoxicity in striatum of rats

The catecholaminergic neurotoxin 6-hydroxydopamine is used to lesion dopaminergic pathways in the experimental animal models of Parkinson's disease. The present study was aimed to evaluate the combined treatment with bioflavonoid quercetin (QN) and desferrioxamine (DFO) on 6-hydroxydopamine (6-OHDA) - induced neurotoxicity in the striatum of rats. Adult, male Sprague - Dawley rats were divided into control, sham lesion, 6-OHDA treated (300 µg, intracisternal), 6-OHDA with QN (50 mg/kg) treated, 6-OHDA with DFO (50 mg/kg) treated and 6-OHDA with QN and DFO treated groups. Striatal dopamine, protein carbonyl content (PCC), glutathione (GSH) and superoxide dismutase (SOD) were estimated. There was a significant increase (p < 0.05) in PCC and decrease in dopamine, GSH and SOD level and striatal neuronal number with 6-OHDA treatment. QN and DFO treatment significantly (p < 0.05) reduced these changes showing a significant neuronal protection. Combined treatment has a more significant effect (p < 0.05) in protecting the neurons and increasing the antioxidant enzymes in the striatum. In conclusion, an antioxidant with iron chelator treatment showed a significant neuroprotective effect against 6-hydroxydopamine (6-OHDA) by preventing dopaminergic neuronal loss and maintaining the striatal dopamine level.

Dynamic increase in extracellular ATP accelerates photoreceptor cell apoptosis via ligation of P2RX7 in subretinal hemorrhage

Photoreceptor degeneration is the most critical cause of visual impairment in age-related macular degeneration (AMD). In neovascular form of AMD, severe photoreceptor loss develops with subretinal hemorrhage due to choroidal neovascularization (CNV), growth of abnormal blood vessels from choroidal circulation. However, the detailed mechanisms of this process remain elusive. Here we demonstrate that neovascular AMD with subretinal hemorrhage accompanies a significant increase in extracellular ATP, and that extracellular ATP initiates neurodegenerative processes through specific ligation of Purinergic receptor P2X, ligand-gated ion channel, 7 (P2RX7; P2X7 receptor). Increased extracellular ATP levels were found in the vitreous samples of AMD patients with subretinal hemorrhage compared to control vitreous samples. Extravascular blood induced a massive release of ATP and photoreceptor cell apoptosis in co-culture with primary retinal cells. Photoreceptor cell apoptosis accompanied mitochondrial apoptotic pathways, namely activation of caspase-9 and translocation of apoptosis-inducing factor (AIF) from mitochondria to nuclei, as well as TUNEL-detectable DNA fragmentation. These hallmarks of photoreceptor cell apoptosis were prevented by brilliant blue G (BBG), a selective P2RX7 antagonist, which is an approved adjuvant in ocular surgery. Finally, in a mouse model of subretinal hemorrhage, photoreceptor cells degenerated through BBG-inhibitable apoptosis, suggesting that ligation of P2RX7 by extracellular ATP may accelerate photoreceptor cell apoptosis in AMD with subretinal hemorrhage. Our results indicate a novel mechanism that could involve neuronal cell death not only in AMD but also in hemorrhagic disorders in the CNS and encourage the potential application of BBG as a neuroprotective therapy.

Neuroprotective effects of valproic acid against hemin toxicity: possible involvement of the down-regulation of heme oxygenase-1 by regulating ubiquitin-proteasomal pathway

During hemorrhagic stroke induced by intracerebral hemorrhage (ICH), brain injury occurs from the deleterious actions of hemoglobin byproducts; induction of heme oxygenase-1 (HO-1) also plays a critical role in the neurotoxicity in ICH. Valproic acid (VPA), which is a commonly used drug in the treatment of epilepsy, has been reported to have neuroprotective effects against various neuronal insults including ischemic stroke. We investigated the effect of VPA on HO-1-mediated neurotoxicity in an experimental model of ICH. We investigated the effects of VPA on HO-1 protein in primary cortical neurons: (1) the expression levels of HO-1 mRNA and protein measured by RT-PCR and Western blotting; (2) the cell viability and ROS generation by MTT reduction assay and ROS measurement; (3) the signal pathway regulated by VPA using IP-Western blotting; (4) the effects of VPA on hemin-induced cell death by hemin microinjection and immunohistochemistry in vivo. VPA treatment partially blocked cell death induced by hemin, which is released from hemoglobin during ICH, both in rat primary cortical neurons and rat brain. Treatment of VPA significantly decreased the expression of HO-1 protein both in vitro and in vivo. Hemin treatment induced HO-1 protein expression and this was partially blocked by pretreatment with VPA, which might be mediated by increased ubiquitination and degradation of HO-1 via ERK1/2 and JNK activation in primary cortical neurons. Our results indicate that VPA inhibits hemin toxicity by downregulating HO-1 protein expression, and provide a therapeutic strategy to attenuate intracerebral hemorrhagic injury.

Thrombin and hemin as central factors in the mechanisms of intracerebral hemorrhage-induced secondary brain injury and as potential targets for intervention

Intracerebral hemorrhage (ICH) is a subtype of stoke that may cause significant morbidity and mortality. Brain injury due to ICH initially occurs within the first few hours as a result of mass effect due to hematoma formation. However, there is increasing interest in the mechanisms of secondary brain injury as many patients continue to deteriorate clinically despite no signs of rehemorrhage or hematoma expansion. This continued insult after primary hemorrhage is believed to be mediated by the cytotoxic, excitotoxic, oxidative, and inflammatory effects of intraparenchymal blood. The main factors responsible for this injury are thrombin and erythrocyte contents such as hemoglobin. Therapies including thrombin inhibitors, N-methyl-D-aspartate antagonists, chelators to bind free iron, and antiinflammatory drugs are currently under investigation for reducing this secondary brain injury. This review will discuss the molecular mechanisms of brain injury as a result of intraparenchymal blood, potential targets for therapeutic intervention, and treatment strategies currently in development.

DARPP-32 to quantify intracerebral hemorrhage-induced neuronal death in basal ganglia

Quantification of acute brain injury in basal ganglia is essential for mechanistic and therapeutic studies in experimental intracerebral hemorrhage (ICH). Using conventional counting of degenerating cells based on morphological or immunohistochemical criteria, it is hard to define the boundary of the whole lesion area. Dopamine- and cAMP-regulated phosphoprotein, Mr 32 kDa (DARPP-32) is a cytosolic protein highly enriched in medium-sized spiny neurons of the striatum. We developed new methods for quantifying lesion area by detecting the difference of the DARPP-32 negative area and the hematoma clot, and by measuring DARPP-32 protein level for semi-qualification in rat model of ICH. We found that DARPP-32 negative area around hematoma was present at day-1, peaked at day-3, and decreased at day-14 after ICH, a time course paralleled by DARPP-32 Western blots. The DARPP-32 negative area matched well with the necrotic area determined using propidium iodide. Treatment with an iron chelator, deferoxamine, attenuated the ICH-induced reduction in DARPP-32 protein levels. These results suggest that DARPP-32 is a simple and quantifiable indicator of ICH-induced neuronal death in basal ganglia.

Iron chelators for acute stroke

BACKGROUND

Stroke is a serious public health problem that causes morbidity and mortality throughout the world. Iron chelators are potential neuroprotective drugs to treat patients with both hemorrhagic and ischemic stroke.

OBJECTIVES

To evaluate the effectiveness and safety of the administration of iron chelators in patients with acute stroke.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (May 2012), the Chinese Stroke Trials Register (May 2012), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 1), MEDLINE (1950 to May 2012), EMBASE (1980 to May 2012), Science Citation Index (1980 to May 2012) and three Chinese databases. In an effort to identify further published, unpublished and ongoing trials we searched ongoing trials registers, checked reference lists, and contacted authors and pharmaceutical companies.

SELECTION CRITERIA

We included published and unpublished randomized controlled trials (RCTs) of iron chelator versus no iron chelator or placebo for the treatment of acute stroke.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened search results to identify the full texts of potentially relevant studies for inclusion. From the results of the screened searches two review authors independently selected trials meeting the inclusion criteria, with no disagreement.

MAIN RESULTS

We found no completed RCTs eligible for inclusion in the review. We identified one ongoing RCT but no data were available.

AUTHORS' CONCLUSIONS

There is insufficient evidence to support or refute the use of iron chelators for the treatment of acute stroke. Further RCTs are required to assess the effect of iron chelators in people with acute stroke.

Susceptibility to intracerebral hemorrhage-induced brain injury segregates with low aerobic capacity in rats

Although low exercise capacity is a risk factor for stroke, the exact mechanisms that underlie this connection are not known. As a model system for exploring the association between aerobic capacity and disease risks we applied two-way artificial selection over numerous generations in rats to produce low capacity runners (LCR) and high capacity runners (HCR). Here we compared intracerebral hemorrhage (ICH)-induced brain injury in both genders of these rat lines. HCR and LCR rats had 100μl blood injected into the right caudate and were killed at days 1, 3, 7 and 28 for brain water content determination, immunohistochemistry, histology, Western blot, and behavioral tests. Compared to male HCRs, male LCRs had more severe ICH-induced brain injury including worse brain edema, necroptosis, brain atrophy, and neurological deficits, but not increased numbers of Fluoro-Jade C positive cells or elevated cleaved caspase-3 levels. This was associated with greater microglial activation, and heme oxygenase-1 and protease activated receptor (PAR)-1 upregulation. In females, edema was also greater in LCRs than in HCRs, although it was less severe in females than in males for both LCRs and HCRs. Thus, ICH-induced brain injury was more severe in LCRs, a model of low exercise capacity, than in HCRs. Increased activation of microglia and PAR-1 may participate mechanistically in increased ICH-susceptibility. Females were protected against ICH-induced brain edema formation in both HCRs and LCRs.

Hypoxia-inducible factor prolyl hydroxylase inhibition: robust new target or another big bust for stroke therapeutics?

A major challenge in developing stroke therapeutics that augment adaptive pathways to stress has been to identify targets that can activate compensatory programs without inducing or adding to the stress of injury. In this regard, hypoxia-inducible factor prolyl hydroxylases (HIF PHDs) are central gatekeepers of posttranscriptional and transcriptional adaptation to hypoxia, oxidative stress, and excitotoxicity. Indeed, some of the known salutary effects of putative 'antioxidant' iron chelators in ischemic and hemorrhagic stroke may derive from their abilities to inhibit this family of iron, 2-oxoglutarate, and oxygen-dependent enzymes. Evidence from a number of laboratories supports the notion that HIF PHD inhibition can improve histological and functional outcomes in ischemic and hemorrhagic stroke models. In this review, we discuss this evidence and highlight important gaps in our understanding that render HIF PHD inhibition a promising but not yet preclinically validated target for protection and repair after stroke.

Advances in spontaneous intracerebral haemorrhage

OBJECTIVES

  To assess the evidence and available literature on the clinical, pathogenetic, prognostic and therapeutic aspects of intracerebral haemorrhage.

METHODS

  The most important manuscripts and reviews on the subject were considered. Information was collected from Medline, Embase & National Library of Medicine over the last 40 years up to Oct 2011. The bibliographies of relevant articles were searched for additional references. The most up to date and randomised trials were given preference. Clinical guidelines including AHA/ASA, Royal college of Physicians, NICE, Scottish Intercollegiate guidelines and several others were taken into consideration.

FINDINGS

  There are numerous advances in the understanding of the pathogenesis and management, but hardly any change in the overall mortality in the last few decades. There is a poor understanding of the results of surgical trials that has resulted in a large drop in surgical intervention since 2007. INTERPRETATIONS AND IMPLICATIONS:  Advances in neuroimaging and neurophysiology have improved our understanding of the mechanisms of neuronal injury and existence of perihaematomal 'tissue at risk'. Numerous new therapeutic targets have been identified. There is a lot of misunderstanding of the results of the newer surgical trials which need to be clarified. The importance of cerebral amyloid angiopathy and microbleeds in older patients is increasingly recognised. Control of hypertension is the most important public health measure. Stroke units provide the best outcomes for the patients.

Intracerebral hemorrhage: clinical overview and pathophysiologic concepts

Intracerebral hemorrhage is by far the most destructive form of stroke. Apart from the management in a specialized stroke or neurological intensive care unit (NICU), no specific therapies have been shown to consistently improve outcomes after ICH. Current guidelines endorse early aggressive optimization of physiologic derangements with ventilatory support when indicated, blood pressure control, reversal of any preexisting coagulopathy, intracranial pressure monitoring for certain cases, osmotherapy, temperature modulation, seizure prophylaxis, treatment of hyerglycemia, and nutritional support in the stroke unit or NICU. Ventriculostomy is the cornerstone of therapy for control of intracranial pressure patients with intraventricular hemorrhage. Surgical hematoma evacuation does not improve outcome for more patients, but is a reasonable option for patients with early worsening due to mass effect due to large cerebellar or lobar hemorrhages. Promising experimental treatments currently include ultra-early hemostatic therapy, intraventricular clot lysis with thrombolytics, pioglitazone, temperature modulation, and deferoxamine to reduce iron-mediated perihematomal inflammation and tissue injury.

Ischemic preconditioning attenuates brain edema after experimental intracerebral hemorrhage

Ischemic preconditioning (IPC) provides protection against subsequent severe ischemic injury. A recent study found that cerebral IPC prolongs bleeding time. In this study, we examined whether IPC protects against intra-cerebral hemorrhage (ICH)-induced brain edema formation and whether IPC affects blood coagulation. There were three sets of experiments in this study. In the first set, male Sprague-Dawley rats were preconditioned with either 15 min of left middle cerebral artery occlusion, an IPC stimulus, or a sham operation. Three days later, rats received an infusion of autologous whole blood in the ipsilateral or contralateral caudate. Rats were killed 24 h later for brain water content measurement. In the second set, rats underwent 15 min of IPC or a sham operation. Three days later, rats were used for bleeding and thrombin clotting time tests. In the third set, the levels of p44/42 mitogen-activated protein kinases (MAPKs), heme oxygenase-1 (HO-1), transferrin (Tf), and transferrin receptor (TfR) in the brain 24 or 72 h after IPC were examined. We found that IPC reduced ICH-induced brain edema when blood was injected into the ipsilateral caudate but it did not when blood was injected into the contralateral caudate. IPC resulted in prolongation of bleeding time and thrombin clotting time. IPC also induced the activation of p44/42 MAPKs and upregulation of HO-1, Tf, and TfR levels in the ipsilateral caudate. These results suggest that IPC protects against ICH-induced brain edema formation and decreases blood coagulation. The protection of IPC against ICH is mainly due to local factors in the brain and may be related to activation of p44/42 MAPKs and upregulation of HO-1, Tf, and TfR.

Chemokines and their receptors in intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a devastating clinical event which results in a high rate of disability and death. At present, no effective treatment is available for ICH. Accumulating evidence suggests that inflammatory responses contribute significantly to the ICH-induced secondary brain outcomes. During ICH, inflammatory cells accumulate at the ICH site attracted by gradients of chemokines. This review summarizes recent progress in ICH studies and the chemoattractants that act during the injury and focuses on and introduces the basic biology of the chemokine monocyte chemoattractant protein-1 (MCP1) and its role in the progression of ICH. Better understanding of MCP1 signaling cascade and the compensation after its inhibition could shed light on the development of effective treatments for ICH.

A critical appraisal of experimental intracerebral hemorrhage research

The likelihood of translating therapeutic interventions for stroke rests on the quality of preclinical science. Given the limited success of putative treatments for ischemic stroke and the reasons put forth to explain it, we sought to determine whether such problems hamper progress for intracerebral hemorrhage (ICH). Approximately 10% to 20% of strokes result from an ICH, which results in considerable disability and high mortality. Several animal models reproduce ICH and its underlying pathophysiology, and these models have been widely used to evaluate treatments. As yet, however, none has successfully translated. In this review, we focus on rodent models of ICH, highlighting differences among them (e.g., pathophysiology), issues with experimental design and analysis, and choice of end points. A Pub Med search for experimental ICH (years: 2007 to 31 July 2011) found 121 papers. Of these, 84% tested neuroprotectants, 11% tested stem cell therapies, and 5% tested rehabilitation therapies. We reviewed these to examine study quality (e.g., use of blinding procedures) and choice of end points (e.g., behavioral testing). Not surprisingly, the problems that have plagued the ischemia field are also prevalent in ICH literature. Based on these data, several recommendations are put forth to facilitate progress in identifying effective treatments for ICH.

Hemopexin decreases hemin accumulation and catabolism by neural cells

Hemopexin is a serum, CSF, and neuronal protein that is protective after experimental stroke. Its efficacy in the latter has been linked to increased expression and activity of heme oxygenase (HO)-1, suggesting that it facilitates heme degradation and subsequent release of cytoprotective biliverdin and carbon monoxide. In this study, the effect of hemopexin on the rate of hemin breakdown by CNS cells was investigated in established in vitro models. Equimolar hemopexin decreased hemin breakdown, as assessed by gas chromatography, by 60-75% in primary cultures of murine neurons and glia. Extracellular hemopexin reduced cell accumulation of ⁵⁵Fe-hemin by over 90%, while increasing hemin export or extraction from membranes by fourfold. This was associated with significant reduction in HO-1 expression and neuroprotection. In a cell-free system, hemin breakdown by recombinant HO-1 was reduced over 80% by hemopexin; in contrast, albumin and two other heme-binding proteins had no effect. Although hemopexin was detected on immunoblots of cortical lysates from adult mice, hemopexin knockout per se did not alter HO activity in cortical cells treated with hemin. These results demonstrate that hemopexin decreases the accumulation and catabolism of exogenous hemin by neural cells. Its beneficial effect in stroke models is unlikely to be mediated by increased production of cytoprotective heme breakdown products.

Antioxidant strategies in neurocritical care

An increase in oxidative stress and overproduction of oxidizing reactive species plays an important role in the pathophysiology of several conditions encountered in the neurocritical care setting including: ischemic and hemorrhagic strokes, traumatic brain injury, acute respiratory distress syndrome, sepsis, and organ failure. The presence of oxidative stress in these conditions is supported by a large body of pre-clinical and clinical studies, and provides a rationale to support a potential therapeutic role for antioxidants. The purpose of this article is to briefly review the basic mechanisms and molecular biology of oxidative stress, summarize its role in critically ill neurological patients, and review available data regarding the potential role of antioxidant strategies in neurocritical care and future directions.

Iron accumulation and neurotoxicity in cortical cultures treated with holotransferrin

Nonheme iron accumulates in CNS tissue after ischemic and hemorrhagic insults and may contribute to cell loss. The source of this iron has not been precisely defined. After blood-brain barrier disruption, CNS cells may be exposed to plasma concentrations of transferrin-bound iron (TBI), which exceed that in the CSF by over 50-fold. In this study, the hypothesis that these concentrations of TBI produce cell iron accumulation and neurotoxicity was tested in primary cortical cultures. Treatment with 0.5-3mg/ml holotransferrin for 24h resulted in the loss of 20-40% of neurons, associated with increases in malondialdehyde, ferritin, heme oxygenase-1, and iron; transferrin receptor-1 expression was reduced by about 50%. Deferoxamine, 2,2'-bipyridyl, Trolox, and ascorbate prevented all injury, but apotransferrin was ineffective. Cell TBI accumulation was significantly reduced by deferoxamine, 2,2'-bipyridyl, and apotransferrin, but not by ascorbate or Trolox. After treatment with (55)Fe-transferrin, approximately 40% of cell iron was exported within 16h. Net export was increased by deferoxamine and 2,2'-bipyridyl, but not by apotransferrin. These results suggest that downregulation of transferrin receptor-1 expression is insufficient to prevent iron-mediated death when neurons are exposed to plasma concentrations of TBI. Chelator therapy may be beneficial for acute CNS injuries associated with loss of blood-brain barrier integrity.

Management of intracerebral hemorrhage in 2020

Intracerebral hemorrhage (ICH) remains a common and deadly form of stroke, with virtually no greatly effective treatments aside from supportive and stroke unit care. Several surgical and medical therapies have been studied, but nothing has yet been found that greatly changes the pathophysiology. To achieve this, there will need to be substantial changes in treatment strategies. This article will focus on refinements to existing strategies and consider new approaches to the management of ICH. It will draw parallels with ischemic stroke treatments, and define the idea of ‘interventional therapy’ for ICH. It is suggested that reducing hematoma expansion could be compared with salvage of the ischemic penumbra, as a potential target for interventional ICH treatments. The concept of different time windows for the application of therapies according to the pathophysiology will be discussed. Finally, some novel treatment strategies are proposed, including an endovascular approach and ‘external, stereotactic cautery’, as future possibilities.

Experimental intracerebral hemorrhage: avoiding pitfalls in translational research

Intracerebral hemorrhage (ICH) has the highest mortality of all stroke subtypes, yet treatments are mainly limited to supportive management, and surgery remains controversial. Despite significant advances in our understanding of ICH pathophysiology, we still lack preclinical models that accurately replicate the underlying mechanisms of injury. Current experimental ICH models (including autologous blood and collagenase injection) simulate different aspects of ICH-mediated injury but lack some features of the clinical condition. Newly developed models, notably hypertension- and oral anticoagulant therapy-associated ICH models, offer added benefits but further study is needed to fully validate them. Here, we describe and discuss current approaches to experimental ICH, with suggestions for changes in how this condition is studied in the laboratory. Although advances in imaging over the past few decades have allowed greater insight into clinical ICH, there remains an important role for experimental models in furthering our understanding of the basic pathophysiologic processes underlying ICH, provided limitations of animal models are borne in mind. Owing to differences in existing models and the failed translation of benefits in experimental ICH to clinical practice, putative neuroprotectants should be trialed in multiple models using both histological and functional outcomes until a more accurate model of ICH is developed.

Minocycline-induced attenuation of iron overload and brain injury after experimental intracerebral hemorrhage

BACKGROUND AND PURPOSE

Brain iron overload plays a detrimental role in brain injury after intracerebral hemorrhage (ICH). A recent study found that minocycline acts as an iron chelator and reduces iron-induced neuronal death in vitro. The present study investigated if minocycline reduces iron overload after ICH and iron-induced brain injury in vivo.

METHODS

This study was divided into 4 parts: (1) rats with different sizes of ICH were euthanized 3 days later for serum total iron and brain edema determination; (2) rats had an ICH treated with minocycline or vehicle. Serum iron, brain iron, and brain iron handling proteins were measured; (3) rats had an intracaudate injection of saline, iron, iron+minocycline, or iron+macrophage/microglia inhibitory factor and were used for brain edema and neuronal death measurements; and (4) rats had an intracaudate injection of iron and were treated with minocycline. The brains were used for edema measurement.

RESULTS

After ICH, serum total iron and brain nonheme iron increased and these changes were reduced by minocycline treatment. Minocycline also reduced ICH-induced upregulation of brain iron handling proteins and neuronal death. Intracaudate injection of iron caused brain edema, blood-brain barrier leakage, and brain cell death, all of which were significantly reduced by coinjection with minocycline.

CONCLUSIONS

The current study found that minocycline reduces iron overload after ICH and iron-induced brain injury. It is also well known minocycline is an inhibitor of microglial activation. Minocycline may be very useful for patients with ICH because both iron accumulation and microglia activation contribute to brain damage after ICH.

Safety and tolerability of deferoxamine mesylate in patients with acute intracerebral hemorrhage

BACKGROUND AND PURPOSE

Treatment with the iron chelator, deferoxamine mesylate (DFO), improves neurological recovery in animal models of intracerebral hemorrhage (ICH). We aimed to evaluate the feasibility, safety, and tolerability of varying dose-tiers of DFO in patients with spontaneous ICH, and to determine the maximum tolerated dose to be adopted in future efficacy studies.

METHODS

This was a multicenter, phase-I, dose-finding study using the Continual Reassessment Method. DFO was administered by intravenous infusion for 3 consecutive days, starting within 18 hours of ICH onset. Subjects underwent repeated clinical assessments through 90 days, and computed tomography neuroimaging pre- and post-drug-administration.

RESULTS

Twenty subjects were enrolled onto 5 dose tiers, starting with 7 mg/kg per day and ending with 62 mg/kg per day as the maximum tolerated dose. Median age was 68 years (range, 50-90); 60% were men; and median Glasgow Coma Scale and National Institutes of Health Stroke Scale scores on admission were 15 (5-15) and 9 (0-39), respectively. ICH location was lobar in 40%, deep in 50%, and brain stem in 10%; intraventricular hemorrhage was present in 15%. DFO was discontinued because of adverse events in 2 subjects (10%). Six subjects (30%) experienced 12 serious adverse events, none of which were drug-related. DFO infusions were associated with mild blood-pressure-lowering effects. Fifty percent of patients had modified Rankin scale scores ≤2, and 39% had modified Rankin scale scores of 4 to 6 on day 90; 15% died.

CONCLUSIONS

Consecutive daily infusions of DFO after ICH are feasible, well-tolerated, and not associated with excessive serious adverse events or mortality. Our findings lay the groundwork for future studies to evaluate the efficacy of DFO in ICH.

Effects of statin and deferoxamine administration on neurological outcomes in a rat model of intracerebral hemorrhage

Deferoxamine (DFX), a potent iron-chelating agent, reduces brain edema and neuronal cell injury that develop due to the hemolysis cascade. Statins have neuroprotective effects via anti-inflammatory action and increment of cerebral blood flow after intracerebral hemorrhage (ICH). The purpose of this study was to identify the effects of combined DFX and statins treatment in an experimental ICH rat model. The treatments were: intraperitoneal (i.p.) injection of DFX (group I), combined treatment of i.p. DFX and oral statins (group II), statins only (group III) and treatment with vehicle (group IV). Induction of ICH was performed with injection of bacterial collagenase type IV into the left striatum. After removal of the brain, hematoma volume, water content and brain atrophy were measured. Immunohistochemistry in the perihematomal region was performed for identification of microglial infiltration, astrocyte expression and apoptotic cell presence. Statistical analysis was performed using the non-parametric Kruskal-Wallis test and significance was evaluated when the p value was less than 0.05. According to behavioral tests, significant differences among treatment groups were noted 4 weeks after ICH induction (p < 0.05). However, there were no significant differences among treatment groups in hematoma volume, brain water content or brain atrophy. In the perihematomal area, the activated microglial cells were reduced in the combined treatment group. Among the four groups, a significant difference in immunohistochemical staining was identified (p < 0.05). These results suggest that combined treatment with DFX and statins improves neurologic outcomes after ICH through reduction of microglial infiltration, apoptosis, inflammation and brain edema.

Molecular pathophysiology of cerebral hemorrhage: secondary brain injury

Intracerebral hemorrhage (ICH) is an often fatal type of stroke that kills approximately 30,000 people annually in the United States. If the patient survives the ictus, then the resulting hematoma within brain parenchyma triggers a series of adverse events causing secondary insults and severe neurological deficits. This article discusses selected aspects of secondary brain injury after ICH and outlines key mechanisms associated with hematoma toxicity, oxidative stress, and inflammation. Finally, this review discusses the relevance of hematoma resolution processes as a target for ICH therapy and presents potential clinically relevant molecular targets that could be harnessed to treat secondary injury associated with ICH injury.

Differential effects of intraventricular hemorrhage and white matter injury on preterm cerebellar growth

OBJECTIVE

To hypothesize that detailed examination of early cerebellar volumes in time would distinguish differences in cerebellar growth associated with intraventricular hemorrhage (IVH) and white matter injury in preterm infants.

STUDY DESIGN

Preterm newborns at the University of California San Francisco (n = 57) and the University of British Columbia (n = 115) were studied with serial magnetic resonance imaging scans near birth and again at near term-equivalent age. Interactive semi-automated tools were used to determine volumes of the cerebellar hemispheres.

RESULTS

Adjusting for supratentorial brain injury, cerebellar hemorrhage, and study site, cerebellar volume increased 1.7 cm(3)/week postmenstrual age (95% CI, 1.6-1.7; P < .001). More severe supratentorial IVH was associated with slower growth of cerebellar volumes (P < .001). Volumes by 40 weeks were 1.4 cm(3) lower in premature infants with grade 1 to 2 IVH and 5.4 cm(3) lower in infants with grade 3 to 4 IVH. The same magnitude of decrease was found between ipsilateral and contralateral IVH. No association was found with severity of white matter injury (P = .3).

CONCLUSIONS

Early effects of decreased cerebellar volume associated with supratentorial IVH in either hemisphere may be a result of concurrent cerebellar injury or direct effects of subarachnoid blood on cerebellar development.

Novel approaches to the treatment of intracerebral haemorrhage

Intracerebral haemorrhage is the most devastating subtype of stroke. It affects approximately two million patients worldwide every year and is a major cause of morbidity and mortality. After decades of research, we still face the fact that there is no evidence-based treatment strategy for this disease. However, research has contributed to a better understanding of the pathophysiology of intracerebral haemorrhage and also to the identification of new treatment targets. Several novel aspects of treatment of spontaneous intracerebral haemorrhage are reviewed in the present article.

Thrombin preconditioning reduces iron-induced brain swelling and brain atrophy

Cerebral preconditioning with a low dose of thrombin attenuates brain edema induced by intracerebral hemorrhage (ICH), a large dose of thrombin or iron. This study examined whether or not thrombin preconditioning (TPC) reduces neuronal death and brain atrophy caused by iron. The right hippocampus of rats was pretreated with or without thrombin, and iron was then injected into the same location 3 days later. Rats were killed at 1 day or 7 days after iron injection, and the brains were used for histology. We found that TPC reduced neuronal death and brain swelling in the hippocampus 1 day after iron injection, and hippocampal atrophy 7 days later. Western blots showed that thrombin activates p44/42 mitogen-activated protein kinase (p44/42 MAPK) and 70-kDa ribosomal protein S6 kinase (p70 S6K). Our results indicate that TPC reduction of iron-induced neuronal death may be through the p44/42 MAPK /p70 S6K signal transduction pathway.

Vascular Dysfunction in Brain Hemorrhage: Translational Pathways to Developing New Treatments from Old Targets

Hemorrhagic stroke which is a form of stroke that affects 20% of all stroke patients is a devastating condition for which new treatments must be developed. Current treatment methods are quite insufficient to reduce long term morbidity and high mortality rate, up to 50%, associated with bleeding into critical brain structures, into ventricular spaces and within the subarachnoid space. During the last 10-15 years, significant advances in the understanding of important mechanisms that contribute to cell death and clinical deficits have been made. The most important observations revolve around a key set of basic mechanisms that are altered in brain bleeding models, including activation of membrane metalloproteinases, oxidative stress and both inflammatory and coagulation pathways. Moreover, it is now becoming apparent that brain hemorrhage can activate the ischemic stroke cascade in neurons, glial cells and the vascular compartment. The activation of multiple pathways allows comes the opportunity to intervene pharmacologically using monotherapy or combination therapy. Ultimately, combination therapy or pleiotropic compounds with multi-target activities should prove to be more efficacious than any single therapy alone. This article provides a comprehensive look at possible targets for small molecule intervention as well as some new approaches that result in metabolic down-regulation or inhibition of multiple pathways simultaneously.

Intracranial hemorrhage: mechanisms of secondary brain injury

ICH is a disease with high rates of mortality and morbidity, with a substantial public health impact. Spontaneous ICH (sICH) has been extensively studied, and a large body of data has been accumulated on its pathophysiology. However, the literature on traumatic ICH (tICH) is limited, and further investigations of this important topic are needed. This review will highlight some of the cellular pathways in ICH with an emphasis on the mechanisms of secondary injury due to heme toxicity and to events in the coagulation process that are common to both sICH and tICH.