Experimental intracerebral hemorrhage in the mouse: histological, behavioral, and hemodynamic characterization of a double-injection model

Mapping the pain pathway: the VPL-S1HL-ACC circuit's role in central post-stroke pain

Central post-stroke pain (CPSP) is a chronic neuropathic condition driven by central sensitization, often resulting in poor clinical outcomes. Neural circuits play a critical role in modulating chronic pain. To elucidate the mechanisms underlying CPSP, we established a mouse model via intracranial injection of type IV collagenase. cFos immunofluorescence and in vivo calcium imaging identified pain-associated activated nuclei. Using viral tracing, optogenetics, chemogenetics, and behavioral assays, we mapped a neural circuit comprising the ventral posterolateral thalamic nucleus (VPL), the hindlimb primary somatosensory cortex (S1HL), and the anterior cingulate cortex (ACC). In CPSP mice, ipsilateral S1HLCaMKIIα and ACCCaMKIIα neurons exhibited robust activation. Chemogenetic manipulation further demonstrated that activation of these neurons induced pain behaviors, whereas their inhibition alleviated pain. Notably, specific activation of the S1HLCaMKIIα-ACCCaMKIIα circuit produced mechanical allodynia, and optogenetic stimulation of VPLCaMKIIα projections to S1HL similarly evoked pain responses while enhancing ACC neuronal firing. These findings underscore the critical role of the VPL-S1HL-ACC circuit in pain abnormalities and provide novel insights into the central sensitization underlying CPSP, suggesting promising therapeutic strategies for its management.

Histopathological and functional Characterization of a neonatal mouse model of intraventricular hemorrhage

Germinal matrix hemorrhage-intraventricular hemorrhage (GMH-IVH) is a major neurological problem of premature infants that leads to white matter injury and posthemorrhagic hydrocephalus. There is no optimal treatment for IVH-induced complications. Several animal models of IVH have been developed, but they have significant limitations. We employed a one-day-old C57BL/6 mouse (P1) and injected hemolyzed whole blood or saline into both cerebral ventricles under hypothermia-induced anesthesia. The blood was obtained from one of the C57BL/6 inbred mouse strains. We evaluated a range of parameters, including apoptosis, cerebral inflammation, myelination, ventricle size, and neurobehavioral functions. The weight gain was comparable between blood- and saline-injected mouse pups. The ventricle size and head dimensions were larger in blood-injected pups compared to saline controls at P21 through P60. We demonstrated greater apoptotic cell death, neuronal degeneration, and microglia infiltration in the periventricular white matter of blood-treated pups relative to controls at P3 and P7. Myelination was reduced, and astrogliosis was increased in blood-injected mice relative to saline controls at P21. Post-hemorrhagic hydrocephalus was noted in blood-treated mice at both P21 and P60. Neurobehavior evaluation revealed motor and cognitive deficits in blood-injected animals relative to controls at P60. A comparison between hemolyzed and non-hemolyzed whole blood-treated pups showed that the hemolyzed blood produced more consistent hydrocephalus and reduction in myelination compared to non-hemolyzed blood injections. The study provides comprehensive analyses of a novel model of IVH that can be employed to understand the mechanisms and develop therapeutic strategies for white matter injury and hydrocephalus in IVH survivors.

DPA714 PET Imaging Shows That Inflammation of the Choroid Plexus Is Active in Chronic-Phase Intracerebral Hemorrhage

PURPOSE

Our aims were to investigate the presence of choroid plexus (CP) inflammation in chronic-phase intracerebral hemorrhage (ICH) patients and to characterize any inflammatory cells in the CP.

PATIENTS AND METHODS

An in vivo 18 F-DPA714 PET study was undertaken in 22 chronic-phase ICH patients who were admitted to the First Affiliated Hospital of Fujian Medical University or Tianjin Medical University General Hospital from April 2017 to June 2020. Ten control participants with nonhemorrhagic central nervous system diseases were included. Choroid plexus 18 F-DPA714 uptake was calculated as the average SUVR. To aid the interpretation of the 18 F-DPA714 uptake results at the CP level, Cy5-DPA714 in vivo imaging and immunofluorescence staining were used to show the presence of CP inflammation in an ICH mouse model during the chronic phase (14 weeks after ICH). Then immunofluorescence staining against translocator protein and other specific biomarkers was used to characterize the cells present in the inflamed CP of ICH mice in the chronic phase.

RESULTS

PET imaging showed that CP DPA714 SUVRs in chronic-phase ICH patients were higher than in controls (mean CP SUVR ± SD; ICH group: 1.05 ± 0.35; control group: 0.81 ± 0.21; P = 0.006). Immunofluorescence staining of the CP in ICH model mice identified a population of CD45 + immune cells, peripheral monocyte-derived CD14 + cells, CD68 + phagocytes, and CD11b + resident microglia/macrophages expressing translocator protein, possibly contributing to the increased 18 F-DPA714 uptake.

CONCLUSIONS

Our study shows that CP DPA714 uptake in chronic-phase ICH patients was higher than that of participants with nonhemorrhagic central nervous system diseases, which means that CP inflammation is still active in chronic-phase ICH patients.

Animal models for the study of intracranial hematomas (Review)

Intracranial hematomas (ICH) are a frequent condition in neurosurgical and neurological practices, with several mechanisms of primary and secondary injury. Experimental research has been fundamental for the understanding of the pathophysiology implicated with ICH and the development of therapeutic interventions. To date, a variety of different animal approaches have been described that consider, for example, the ICH evolutive phase, molecular implications and hemodynamic changes. Therefore, choosing a test protocol should consider the scope of each particular study. The present review summarized investigational protocols in experimental research on the subject of ICH. With this subject, injection of autologous blood or bacterial collagenase, inflation of intracranial balloon and avulsion of cerebral vessels were the models identified. Rodents (mice) and swine were the most frequent species used. These different models allowed improvements on the understanding of intracranial hypertension establishment, neuroinflammation, immunology, brain hemodynamics and served to the development of therapeutic strategies.

Zebrafish for modeling stroke and their applicability for drug discovery and development

INTRODUCTION

The global health burden of stroke is significant and few therapeutic treatment options currently exist for patients. Pre-clinical research relies heavily on rodent stroke models but the limitations associated with using these systems alone has meant translation of drug compounds to the clinic has not been greatly successful to date. Zebrafish disease modeling offers a potentially complementary platform for pre-clinical compound screening to aid the drug discovery process for translational stroke research.

AREAS COVERED

In this review, the authors introduce stroke and describe the issues associated with the current pre-clinical drug development pipeline and the advantages that zebrafish disease modeling can offer. Existing zebrafish models of ischemic and hemorrhagic stroke are reviewed. Examples of how zebrafish models have been utilized for drug discovery in other disease disciplines are also discussed.

EXPERT OPINION

Zebrafish disease modeling holds the capacity and potential to significantly enhance the stroke drug development pipeline. However, for this system to be more widely accepted and incorporated into translational stroke research, continued improvement of the existing zebrafish stroke models, as well as focussed collaboration between zebrafish and stroke researchers, is essential.

Endogenous zinc protoporphyrin formation critically contributes to hemorrhagic stroke-induced brain damage

Hemorrhagic stroke is a leading cause of death. The causes of intracerebral hemorrhage (ICH)-induced brain damage are thought to include lysis of red blood cells, hemin release and iron overload. These mechanisms, however, have not proven very amenable to therapeutic intervention, and so other mechanistic targets are being sought. Here we report that accumulation of endogenously formed zinc protoporphyrin (ZnPP) also critically contributes to ICH-induced brain damage. ICH caused a significant accumulation of ZnPP in brain tissue surrounding hematoma, as evidenced by fluorescence microscopy of ZnPP, and further confirmed by fluorescence spectroscopy and supercritical fluid chromatography-mass spectrometry. ZnPP formation was dependent upon both ICH-induced hypoxia and an increase in free zinc accumulation. Notably, inhibiting ferrochelatase, which catalyzes insertion of zinc into protoporphyrin, greatly decreased ICH-induced endogenous ZnPP generation. Moreover, a significant decrease in brain damage was observed upon ferrochelatase inhibition, suggesting that endogenous ZnPP contributes to the damage in ICH. Our findings reveal a novel mechanism of ICH-induced brain damage through ferrochelatase-mediated formation of ZnPP in ICH tissue. Since ferrochelatase can be readily inhibited by small molecules, such as protein kinase inhibitors, this may provide a promising new and druggable target for ICH therapy.

MiR-18a Aggravates Intracranial Hemorrhage by Regulating RUNX1-Occludin/ZO-1 Axis to Increase BBB Permeability

OBJECTIVES

To study the molecular mechanisms of miR-18a aggravating intracranial hemorrhage (ICH) by increasing the blood-brain barrier (BBB) permeability.

METHODS

Brain microvascular endothelial cells (BMVECs) and astrocytes were isolated, identified, and co-cultured to establish in vitro BBB model. BMVECs co-cultured with astrocytes were stimulated with or without thrombase and then transfected with miR-18a mimic and/or si-RUNX1. The trans-endothelial electric resistance (TEER) and FlNa flux were measured, respectively. The potential interaction between RUNX1 and miR-18a was also detected. Additionally, SD rats were injected with fresh autologous non-anticoagulant blood into the brain basal ganglia to establish ICH model. After administration with miR-18a, sh-miR-18a, miR-18a+RUNX1, sh-miR-18a+sh-RUNX1, respectively, BBB permeability was assessed.

RESULTS

After overexpressing miR-18a, the expression levels of RUNX1, Occludin and ZO-1 were decreased, but the Evan's blue contents and brain water contents were significantly increased in ICH rats. Additionally, rat neurological function was impaired, accompanying with an increase of TEER and fluorescein sodium flux. MiR-18a was a direct target of RUNX1 and it could bind to the promoters of RUNX1 to inhibit the expression of Occuldin and ZO-1. Consistently, these phenomena could also be observed in the corresponding cell model. Conversely, miR-18a knockdown or RUNX1 overexpression just presented an improvement effect on ICH.

CONCLUSIONS

MiR-18a plays a critical role during ICH because it targets to RUNX1 to inhibit the expression of tight junction proteins (Occludin and ZO-1) and then disrupt BBB permeability. MiR-18a might be a probable therapeutic target for ICH diseases.

Estimation of intracranial pressure by ultrasound of the optic nerve sheath in an animal model of intracranial hypertension

BACKGROUND

Ultrasound of the optic nerve sheath diameter (ONSD) has been used as a non-invasive and cost-effective bedside alternative to invasive intracranial pressure (ICP) monitoring. However, ONSD time-lapse behavior in intracranial hypertension (ICH) and its relief by means of either saline infusion or surgery are still unknown. The objective of this study was to correlate intracranial pressure (ICP) and ultrasonography of the optic nerve sheath (ONS) in an experimental animal model of ICH and determine the interval needed for ONSD to return to baseline levels.

METHODS

An experimental study was conducted on 30 pigs. ONSD was evaluated by ultrasound at different ICPs generated by intracranial balloon inflation, saline infusion, and balloon deflation, and measured using an intraventricular catheter.

RESULTS

All variables obtained by ONS ultrasonography such as left, right, and average ONSD (AON) were statistically significant to estimate the ICP value. ONSD changed immediately after balloon inflation and returned to baseline after an average delay of 30 min after balloon deflation (p = 0.016). No statistical significance was observed in the ICP and ONSD values with hypertonic saline infusion. In this swine model, ICP and ONSD showed linear correlation and ICP could be estimated using the formula: -80.5 + 238.2 × AON.

CONCLUSION

In the present study, ultrasound to measure ONSD showed a linear correlation with ICP, although a short delay in returning to baseline levels was observed in the case of sudden ICH relief.

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

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

Relationship Between Hematoma Expansion Induced by Hypertension and Hyperglycemia and Blood-brain Barrier Disruption in Mice and Its Possible Mechanism: Role of Aquaporin-4 and Connexin43

We aimed to select an optimized hematoma expansion (HE) model and investigate the possible mechanism of blood-brain barrier (BBB) damage in mice. The results showed that HE occurred in the group with hypertension combined with hyperglycemia (HH-HE) from 3 to 72 h after intracerebral hemorrhage; this was accompanied by neurological deficits and hardly influenced the survival rate. The receiver operating characteristic curve suggested the criterion for this model was hematoma volume expansion ≥ 45.0%. Meanwhile, HH-HE aggravated BBB disruption. A protector of the BBB reduced HH-HE, while a BBB disruptor induced a further HH-HE. Aquaporin-4 (AQP4) knock-out led to larger hematoma volume and more severe BBB disruption. Furthermore, hematoma volume and BBB disruption were reduced by multiple connexin43 (Cx43) inhibitors in the wild-type group but not in the AQP4 knock-out group. In conclusion, the optimized HE model is induced by hypertension and hyperglycemia with the criterion of hematoma volume expanding ≥ 45.0%. HH-HE leads to BBB disruption, which is dependent on AQP4 and Cx43.

Neuroprotective Methodologies of Co-Enzyme Q10 Mediated Brain Hemorrhagic Treatment: Clinical and Pre-Clinical Findings

Cerebral brain hemorrhage is associated with the highest mortality and morbidity despite only constituting approximately 10-15% of all strokes classified into intracerebral and intraventricular hemorrhage where most of the patients suffer from impairment in memory, weakness or paralysis in arms or legs, headache, fatigue, gait abnormality and cognitive dysfunctions. Understanding molecular pathology and finding the worsening cause of hemorrhage will lead to explore the therapeutic interventions that could prevent and cure the disease. Mitochondrial ETC-complexes dysfunction has been found to increase neuroinflammatory cytokines, oxidative free radicals, excitotoxicity, neurotransmitter and energy imbalance that are the key neuropathological hallmarks of cerebral hemorrhage. Coenzyme Q10 (CoQ10), as a part of the mitochondrial respiratory chain can effectively restore these neuronal dysfunctions by preventing the opening of mitochondrial membrane transition pore, thereby counteracting cell death events as well as exerts an anti-inflammatory effect by influencing the expression of NF-kB1 dependent genes thus preventing the neuroinflammation and energy restoration. Due to behavior and biochemical heterogeneity in post cerebral brain hemorrhagic pattern different preclinical autologous blood injection models are required to precisely investigate the forthcoming therapeutic strategies. Despite emerging pre-clinical research and resultant large clinical trials for promising symptomatic treatments, there are very less pharmacological interventions demonstrated to improve post operative condition of patients where intensive care is required. Therefore, in current review, we explore the disease pattern, clinical and pre-clinical interventions under investigation and neuroprotective methodologies of CoQ10 precursors to ameliorate post brain hemorrhagic conditions.

Acute Treatment With Gleevec Does Not Promote Early Vascular Recovery Following Intracerebral Hemorrhage in Adult Male Rats

Intracerebral hemorrhage (ICH) remains one of the most debilitating types of stroke and is characterized by a sudden bleeding from a ruptured blood vessel. ICH often results in high mortality and in survivors, permanent disability. Most studies have focused on neuroprotective strategies designed to minimize secondary consequences and prevent further pathology. Lacking is an understanding of how ICH acutely affects cerebrovascular components and their response to therapeutic interventions. We hypothesized that ICH alters cortical vessel complexity in the parenchyma adjacent to site of the initial vascular disruption and that vascular abnormalities would be mitigated by administration of the PDGFR inhibitor, Imatinib mesylate (Gleevec). Briefly, ICH was induced in male adult rats by injection of collagenase into basal ganglia, followed by Gleevec administration (60 mg/kg) 1 h after injury. Rats were then perfused using vessel painting methodology (Salehi et al., 2018b) to stain whole brain vascular networks at 1 day post-ICH. Axial and coronal wide field fluorescence microscopy was performed. Analyses for vascular features were undertaken and fractal analysis for vascular complexity. Data were collected from four groups of rats: Sham + Vehicle; Sham + Gleevec; ICH + Vehicle; ICH + Gleevec. Microscopy revealed that cortical vessels in both ipsi- and contralateral hemispheres exhibited significantly reduced density and branching by 22 and 34%, respectively. Fractal measures confirmed reduced complexity as well. Gleevec treatment further reduced vascular parameters, including reductions in vessel density in tissues adjacent to the ICH. The reductions in brain wide vascular networks after Gleevec in the current study after ICH is contrasted by previous reports of improved behavioral outcomes and decreased lCH lesion volumes Reductions in the vascular network after Gleevec may be involved in long-term repair mechanisms by pruning injured vessels to ultimately promote new vessel growth.

Characterization of Axon Damage, Neurological Deficits, and Histopathology in Two Experimental Models of Intracerebral Hemorrhage

Spontaneous intracerebral hemorrhage (ICH) is one of the most lethal forms of stroke. From the limited previous studies and our preliminary data, white matter is considered a key predictor of the outcome and potential target of recovery. The traditional ICH model induced by injection of autologous blood or bacterial collagenase into striatum (ST) demonstrated a spontaneous functional recovery within one or 2 months. We hypothesis that an internal capsule (IC) lesion might lead to long-term axonal damage and long lasting functional deficits. Thus in this study, a modified internal capsule ICH model was conducted in rats, and the axonal damage, neurological deficits, histopathology as well as electrophysiology were characterized. The finding demonstrated that compared to ST group, the modified IC lesioned model exhibited a relatively smaller lesion volume with consistent axonal loss/degeneration and long-lasting neurological dysfunction at 2 months after ICH. Functionally, the impairment of the mNSS, ratio of contralateral forelimb usage, four limb stand index, contralateral duty cycle and ipsilateral SSEPs amplitude remained significant at 56 days. Structurally, the significant loss of PKCγ in ipsilateral cortical spinal tracts of IC group and the consistent axonal degeneration with several axonal retraction bulbs and enlarged tubular space was observed at 56 days after ICH. This study suggested that a modified IC lesioned model was proved to have long lasting neurological deficits. A comprehensive understanding of the dynamic progression after experimental ICH should aid further successful clinic translation in animal ICH studies, and provide new insights into the role of whiter matter injury in the mechanism and therapeutic targets of ICH.

Biomarker and Drug Target Discovery Using Quantitative Proteomics Post-Intracerebral Hemorrhage Stroke in the Rat Brain

The pathological mechanisms of acute intracerebral hemorrhage (ICH) remain unknown and unverified. In the present study, we used quantitative proteomics to elucidate the pathological mechanisms and to identify novel biomarker and therapeutic target candidates via tissue proteome in a rat model of acute ICH. Rats were experimentally induced with ICH (n = 6) or Sham (n = 6), and their brain tissue was obtained by 24 h. The TMT-LC–MS/MS-based proteomics approach was used to quantify the differential proteomes across brain tissue, and the results were further analyzed by ingenuity pathway analysis to explore canonical pathways and the relationship involved in the uploaded data. Upon quantification, we found that 96 secreted proteins that were identified in the ICH 24-h group were significantly different those in the control group (P < 0.05); among these proteins, 57 increased and 39 decreased in abundance. Bioinformatic analyses of differentially expressed proteins demonstrated that the protein localization and ERK1 and ERK2 cascade were the top two biological processes with the highest concentrations of differentially proteins. The top protein-protein action network with high confidence levels of protein was the albumin and ERK signaling pathways. Albumin, ERK, and p-ERK were assessed in brain tissue by western blot analysis, and higher expression levels of albumin and p-ERK were observed in the ICH group. Our proteomic results highlight important change in the biological processes of ERK1 and ERK2 cascade, which are possible targets for future interventions of ICH. To our knowledge, this study provides in-depth analysis of ICH in brain tissue, and we propose 96 new biomarker candidates for ICH, including albumin and ERK.

Comparison of the clinical efficacy of craniotomy and craniopuncture therapy for the early stage of moderate volume spontaneous intracerebral haemorrhage in basal ganglia: Using the CTA spot sign as an entry criterion

OBJECTIVES

Surgical treatment is widely used for haematoma removal in spontaneous intracerebral haemorrhage (ICH) patients, but there is controversy about the selection of surgical methods. The CT angiography (CTA) spot sign has been proven to be a promising factor predicting haematoma expansion and is recommended as an entry criterion for haemostatic therapy in patients with ICH. This trial was designed to evaluate the clinical efficacy of two surgical methods (haematoma removal by craniotomy and craniopuncture combined with urokinase infusion) for patients in the early stage (≤6h from symptom onset) of spontaneous ICH with a moderate haematoma volume (30 ml - 60 ml).

PATIENTS AND METHODS

From January 2012 to July 2017, 196 eligible patients treated in our institution were enrolled according to the inclusion criteria. The patients were divided into the CTA spot sign positive type and CTA spot sign negative type according to the presence or absence of the CTA spot sign. For each type, the patients were randomly assigned to two groups, i.e., the craniotomy group, in which patients underwent craniotomy with haematoma removal, and the craniopuncture group, in which patients underwent minimally invasive craniopuncture combined with urokinase infusion therapy. Neurological function was evaluated with the Scandinavian Stroke Scale (SSS) at day 14. The disability level and the activities of daily living were assessed using a modified Rankin Scale (mRS) and Barthel Index (BI) at day 90. Case fatalities were recorded at day 14 and 90. Complications were recorded during hospitalization.

RESULTS

For the CTA spot sign positive type, the craniotomy group had a higher SSS than that in the craniopuncture group (P < 0.05) at day 14. The rebleeding rate was higher in the craniopuncture group than that in the craniotomy group (P < 0.05) during hospitalization. The craniotomy group had a lower mRS than that in the craniopuncture group (P < 0.01) and had a higher BI than that in the craniopuncture group (P < 0.05) at day 90. There was no statistically significant difference in the fatality rate between the two groups. For the CTA spot sign negative type, there were no significant differences in the SSS, mRS, BI, fatality rate and complication rate between the two groups.

CONCLUSION

ICH can be divided into the CTA spot sign positive and negative type according to the presence or absence of the CTA spot sign. For the CTA spot sign positive type, patients can benefit from craniotomy with haematoma removal, which can reduce the postoperative rebleeding rate and improve the prognosis. For the CTA spot sign negative type, both craniotomy and craniopuncture are applicable. Considering simple procedure and minor surgical injury, craniopuncture can be a more reasonable choice.

Neuroprotective effect of neuroserpin in non-tPA-induced intracerebral hemorrhage mouse models

BACKGROUND

The neuroprotective effects of neuroserpin (NSP) have been well documented in both patients and animal models with cerebral ischemia; however, have never been investigated in hemorrhagic stroke. The aim of this study is to verify the neuroprotection of NSP in the non-tPA-induced intracerebral hemorrhage (ICH) mouse model.

METHODS

C57BL/6J male mice (n = 198) were involved in this study. ICH models were established with infusion of autologous blood into the brain parenchyma. We then detected NSP expression in ICH brains by morphological methods and western blotting analysis. We measured the brain water content and detected blood-brain barrier (BBB) permeability to verify the neuroprotective effects of NSP.

RESULTS

We found that NSP protein expression was upregulated in ICH models, with a peak at 48 h after ICH induction. NSP local administration reduced the brain edema and the BBB permeability in ICH models. The neurological deficits were also ameliorated. Thus, the neuroprotection of NSP in ICH state was confirmed. Additionally, we also found that the distribution pattern of occludin-expressing cells was obviously changed by the ICH procedure but partly recovered after NSP administration. This finding indicated that protecting and/or repairing the injured vascular endothelial cells may be a potential mechanism involved in NSP neuroprotection, which needs further verification.

CONCLUSIONS

Our results supported the fact that NSP may be considered as a potential therapy for ICH for the neuroprotective effects including amelioration of the edema.

Discovery of a ROCK inhibitor, FPND, which prevents cerebral hemorrhage through maintaining vascular integrity by interference with VE-cadherin

Hemorrhagic stroke occurs when a weakened vessel ruptures and bleeds into the surrounding brain, leading to high rates of death and disability worldwide. A series of complex pathophysiological cascades contribute to the risk of hemorrhagic stroke, and no therapies have proven effective to prevent hemorrhagic stroke. Stabilization of vascular integrity has been considered as a potential therapeutic target for hemorrhagic stroke. ROCKs, which belong to the serine/threonine protein kinase family and participate in the organization of actin cytoskeleton, have become attractive targets for the treatment of strokes. In this study, in vitro enzyme-based assays revealed that a new compound (FPND) with a novel scaffold identified by docking-based virtual screening could inhibit ROCK1 specifically at low micromolar concentration. Molecular modeling showed that FPND preferentially interacted with ROCK1, and the difference between the binding affinity of FPND toward ROCK1 and ROCK2 primarily resulted from non-polar contributions. Furthermore, FPND significantly prevented statin-induced cerebral hemorrhage in a zebrafish model. In addition, in vitro studies using the xCELLigence RTCA system, immunofluorescence and western blotting revealed that FPND prevented statin-induced cerebral hemorrhage by enhancing endothelial cell–cell junctions through inhibiting the ROCK-mediated VE-cadherin signaling pathway. As indicated by the extremely low toxicity of FPND against mice, it is safe and can potentially prevent vascular integrity loss-related diseases, such as hemorrhagic stroke.

Diabetic aggravation of stroke and animal models

Cerebral ischemia in diabetics results in severe brain damage. Different animal models of cerebral ischemia have been used to study the aggravation of ischemic brain damage in the diabetic condition. Since different disease conditions such as diabetes differently affect outcome following cerebral ischemia, the Stroke Therapy Academic Industry Roundtable (STAIR) guidelines recommends use of diseased animals for evaluating neuroprotective therapies targeted to reduce cerebral ischemic damage. The goal of this review is to discuss the technicalities and pros/cons of various animal models of cerebral ischemia currently being employed to study diabetes-related ischemic brain damage. The rational use of such animal systems in studying the disease condition may better help evaluate novel therapeutic approaches for diabetes related exacerbation of ischemic brain damage.

Neuro-regeneration therapy using human Muse cells is highly effective in a mouse intracerebral hemorrhage model

A novel type of non-tumorigenic pluripotent stem cell, the Muse cell (multi-lineage, differentiating stress enduring cell), resides in the connective tissue and in cultured mesenchymal stem cells (MSCs) and is reported to differentiate into multiple cell types according to the microenvironment to repair tissue damage. We examined the efficiency of Muse cells in a mouse intracerebral hemorrhage (ICH) model. Seventy μl of cardiac blood was stereotactically injected into the left putamen of immunodeficient mice. Five days later, 2 × 10⁵ of human bone marrow MSC-derived Muse cells (n = 6) or cells other than Muse cells in MSCs (non-Muse, n = 6) or the same volume of PBS (n = 11) was injected into the ICH cavity. Water maze and motor function tests were implemented for 68 days, and immunohistochemistry for NeuN, MAP2 and GFAP was done. The Muse group showed impressive recovery: Recovery was seen in the water maze after day 19, and motor functions after 5 days was compared with the other two groups, with a significant statistical difference (p < 0.05). The survival rate of the engrafted cells in the Muse group was significantly higher than in the non-Muse group (p < 0.05) at day 69, and those cells showed positivity for NeuN (~57%) and MAP-2 (~41.6%). Muse cells could remain in the ICH brain, differentiate into neural-lineage cells and restore functions without inducing them into neuronal cells by gene introduction and cytokine treatment prior to transplantation. A simple collection of Muse cells and their supply to the brain in naïve state facilitates regenerative therapy in ICH.

Perihemorrhagic ischemia occurs in a volume-dependent manner as assessed by multimodal cerebral monitoring in a porcine model of intracerebral hemorrhage

BACKGROUND

Changes in the perihemorrhagic zone (PHZ) of intracerebral hemorrhage (ICH) are variable. Different mechanisms contribute to secondary neuronal injury after ICH. This multimodal monitoring study investigated early changes in the PHZ of ICH.

METHODS

Twenty-four swine were anesthetized, ventilated, and underwent monitoring of vital parameters. Next to an intracranial pressure-probe (ICP), microdialysis (MD), thermodiffusion cerebral blood flow (td-CBF), and oxygen probes (PbrO2) were placed into the gray white matter junction for 12 h of monitoring. ICH was induced using the autologous blood injection model. Pre-defined volumes were 0 ml (sham), 1.5 ml ipsilateral (1.5 ml), 3.0 ml ipsilateral (3.0 ml), and 3.0 ml contralateral (3.0 ml contra).

RESULTS

ICP equally increased in all groups after ICH. In the 3.0 ml group tissue oxygenation decreased to ischemic values of 9 ± 7 mmHg early after 6 h of monitoring. This decrease was associated with a significant perfusion reduction from 36 ± 8 ml/100 g/min to 20 ± 10 ml/100 g/min. MD correlated with a threefold lactate/pyruvate ratio increase. Measurements in all other groups were unchanged.

CONCLUSION

Multimodal monitoring demonstrates volume-dependent changes of tissue oxygenation, blood flow, and ischemic MD markers in the PHZ independent of increased ICP suggesting early moderate ischemia. No evidence was found for the existence of a perihemorrhagic ischemia in the small hematoma groups.

Effects of intracerebral hemorrhage on 5-hydroxymethylcytosine modification in mouse brains

The past decade has resulted in an increase in the knowledge of molecular mechanisms underlying brain injury induced by intracerebral hemorrhage (ICH). Recent advances have provided a link between epigenetic modification and the regulation of gene expression. 5-hydroxymethylcytosine (5hmC) converted from 5-methylcytosine by the ten-eleven translocation (TET) family of proteins has emerged as a new epigenetic modification. While the dynamics of 5hmC during cerebral ischemia have recently been reported, whether 5hmC is involved in ICH remains unexplored. In this study, we investigated the effects of ICH on DNA hydroxymethylation. We showed that the global level of 5hmC rapidly decreased as early as 24 hours after ICH and persisted until 72 hours. Furthermore, the level of 5hmC in the CpG-rich regions of Akt2, Pdpk1 and Vegf genes was significantly decreased with a minimum level observed at 48 hours or 72 hours. Decreased 5hmC was observed in parallel with an increase in 5-methylcytosine over this time course, and mRNA levels of Akt2, Pdpk1 and Vegf were downregulated upon ICH injury. Finally, Tet1, Tet2 and Tet3 mRNA levels were dramatically decreased in the ICH brain. Our study for the first time established the correlation between DNA hydroxymethylation and ICH injury. Further investigations should examine whether 5hmC modification could be a therapeutic target for the treatment of ICH injury.

Experimental animal models and inflammatory cellular changes in cerebral ischemic and hemorrhagic stroke

Stroke, including cerebral ischemia, intracerebral hemorrhage, and subarachnoid hemorrhage, is the leading cause of long-term disability and death worldwide. Animal models have greatly contributed to our understanding of the risk factors and the pathophysiology of stroke, as well as the development of therapeutic strategies for its treatment. Further development and investigation of experimental models, however, are needed to elucidate the pathogenesis of stroke and to enhance and expand novel therapeutic targets. In this article, we provide an overview of the characteristics of commonly-used animal models of stroke and focus on the inflammatory responses to cerebral stroke, which may provide insights into a framework for developing effective therapies for stroke in humans.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

TLR2-induced astrocyte MMP9 activation compromises the blood brain barrier and exacerbates intracerebral hemorrhage in animal models

BACKGROUND

The innate immune response plays an important role in the pathogenesis of intracerebral hemorrhage (ICH). Recent studies have shown that Toll-like receptor 2 (TLR2) is involved in the innate immune response in various neurological diseases, yet neither its role in ICH nor the mechanisms by which it functions have yet been elucidated. We examined these in this study using a collagenase-induced mouse ICH model with TLR2 knock-out (KO) mice.

RESULTS

TLR2 expression was upregulated in the ipsilateral hemorrhagic tissues of the collagenase-injected mice. Brain injury volume and neurological deficits following ICH were reduced in TLR2 KO mice compared to wild-type (WT) control mice. Heterologous blood-transfer experiments show that TLR2 signaling in brain-resident cells, but not leukocytes, contributes to the injury. In our study to elucidate underlying mechanisms, we found that damage to blood-brain barrier (BBB) integrity following ICH was attenuated in TLR2 KO mice compared to WT mice, which may be due to reduced matrix metalloproteinase-9 (MMP9) activation in astrocytes. The reduced BBB damage accompanies decreased neutrophil infiltration and proinflammatory gene expression in the injured brain parenchyma, which may account for the attenuated brain damage in TLR2 KO mice after ICH.

CONCLUSIONS

TLR2 plays a detrimental role in ICH-induced brain damage by activating MMP9 in astrocytes, compromising BBB, and enhancing neutrophils infiltration and proinflammatory gene expression.

Intracerebral hemorrhage in mouse models: therapeutic interventions and functional recovery

There has been strong pre-clinical research on mechanisms of initial cell death and tissue injury in intracerebral hemorrhage (ICH). This data has led to the evaluation of several therapeutics for neuroprotection or the mitigation of early tissue damage. Most of these studies have been done in the rat. Also, there has been little study of the mechanisms of tissue repair and recovery. This review examines the testing of candidate therapeutics in mouse models of ICH for their effect on tissue protection and repair. This review will help the readers compare it to the extensively researched rat model of ICH and thus enhance work that are pending in mouse model.

Nerve regeneration and functional recovery by collagen-binding brain-derived neurotrophic factor in an intracerebral hemorrhage model

Brain-derived neurotrophic factor (BDNF) exerts therapeutic effects following intracerebral hemorrhage (ICH). However, it is difficult to maintain sufficient concentrations in the hemorrhage hemisphere. We demonstrated previously that BDNF fused to a collagen-binding domain (CBD) could bind to collagen in the ventricular ependyma and stimulate cell proliferation in the subventricular zone (SVZ). In this study, we verified the therapeutic effects of CBD-BDNF in the rat ICH model induced by bacterial collagenase by injecting CBD-BDNF into the lateral ventricle of ICH rats. The results demonstrated that CBD-BDNF was retained at high levels in the hemorrhage hemisphere, where it promoted neural regeneration and angiogenesis, reduced tissue loss, and improved functional recovery.

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.

Bilirubin and its oxidation products damage brain white matter

Brain injury after intracerebral hemorrhage (ICH) occurs in cortex and white matter and may be mediated by blood breakdown products, including hemoglobin and heme. Effects of blood breakdown products, bilirubin and bilirubin oxidation products, have not been widely investigated in adult brain. Here, we first determined the effect of bilirubin and its oxidation products on the structure and function of white matter in vitro using brain slices. Subsequently, we determined whether these compounds have an effect on the structure and function of white matter in vivo. In all, 0.5 mmol/L bilirubin treatment significantly damaged both the function and the structure of myelinated axons but not the unmyelinated axons in brain slices. Toxicity of bilirubin in vitro was prevented by dimethyl sulfoxide. Bilirubin oxidation products (BOXes) may be responsible for the toxicity of bilirubin. In in vivo experiments, unmyelinated axons were found more susceptible to damage from bilirubin injection. These results suggest that unmyelinated axons may have a major role in white-matter damage in vivo. Since bilirubin and BOXes appear in a delayed manner after ICH, preventing their toxic effects may be worth investigating therapeutically. Dimethyl sulfoxide or its structurally related derivatives may have a potential therapeutic value at antagonizing axonal damage after hemorrhagic stroke.

The role of aquaporin 4 in apoptosis after intracerebral hemorrhage

Background

We previously reported that aquaporin-4 deletion (AQP4^−/−) in mice increased edema and altered blood-brain barrier integrity following intracerebral hemorrhage (ICH). To date, little is known about the role of AQP4 in apoptosis after ICH. The purpose of this study was to examine the role of AQP4 in apoptosis and its mechanisms after ICH using AQP4^−/− mice.

Methods

We compared the survival rate and neurological deficits in wild-type (AQP4^+/+) mice with those in AQP4^−/− mice following ICH. Histological changes were detected with terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) staining and Hoechst staining. The cell types involved were determined by immunocytochemical studies. We also measured activated caspase-3, caspase-9, caspase-8, Bax, and Bcl-2 with Western blotting at 1, 3, and 7 days after ICH. A cytokine protein assay was used to detect cytokines in AQP4^+/+ and AQP4^−/− mice following ICH, and the results were verified by ELISA.

Results

We found more apoptotic cells in AQP4^−/− mice following ICH; the cell types involved were predominantly neurons and astrocytes. Western blotting showed that the expression of activated caspase-3 and caspase-8 was significantly increased (P <0.05). Moreover, we demonstrated a greater enhancement in the release of TNF-α and IL-1β, as well as their receptors, in AQP4^−/− mice following ICH than in AQP4^+/+ mice by cytokine protein assay and Western blotting (P <0.05). The inhibitors of TNF-α and IL-1β reduced apoptotic cells after ICH in AQP4^−/− mice compared with wild-type mice (P <0.05).

Conclusions

AQP4 deletion increases apoptosis following ICH, and the underlying mechanism may be through cytokines, especially TNF-α and IL-1β, initiating the apoptotic cascade, as well as activation of caspase-3 and caspase-8.

Mouse intracerebral hemorrhage models produce different degrees of initial and delayed damage, axonal sprouting, and recovery

The mechanisms of delayed damage and recovery after intracerebral hemorrhage (ICH) remain poorly defined. Two rodent models of ICH are commonly used: injection of the enzyme collagenase (cICH) and injection of autologous blood (bICH). In mice, we compared the effects of these two models on initial and delayed tissue damage, motor system connections, and behavioral recovery. There is no difference in lesion size between models. Injection of autologous blood causes greater mass effect and early mortality. However, cICH produces greater edema, inflammation, and cell death. Injection of the enzyme collagenase causes greater loss of cortical connections and secondary shrinkage of the striatum. Intracerebral hemorrhage occurs within the motor system connections of the striatum. Mapping of the projections of the forelimb motor area shows a significant sprouting in motor cortex projections only in cICH. Both models of ICH produce deficits in forelimb motor control. Behavioral recovery occurs by 5 weeks in cICH and 9 weeks in bICH. In summary, cICH and bICH differ in almost every facet of initial and delayed stroke pathophysiology, with cICH producing greater initial and secondary tissue damage and greater motor system axonal sprouting than bICH. Motor recovery occurs in both models, suggesting that motor system axonal sprouting in cICH is not causally associated with recovery.

Neuroprotective effects of argatroban and C5a receptor antagonist (PMX53) following intracerebral haemorrhage

Intracerebral haemorrhage (ICH) is a subtype of stroke that associated with neurological dysfunction and inflammation, which may be ameliorated by a neuroprotective strategy targeting the complement cascade. The protective effect of C5a-receptor antagonist (PMX53) solely and in combination with thrombin antagonist (argatroban) was investigated in the ICH mouse model, respectively. Adult male C57BL/6J wild-type (WT) mice and C3(-/-) mice were randomized to receive PMX53/argatroban 1, 3 and 5 days after ICH. A double injection technique was used to infuse 25 μl of autologous whole blood into the right striatum. Mice in the sham group received only needle insertion. Brain water content and mRNA of inflammatory factors were measured on the first, third and fifth days after ICH, respectively. Neurological dysfunction was assessed using a 28-point neurological scoring system in the three cohorts, namely, on days 1, 3 and 5 following ICH. Animals treated with PMX53/argatroban demonstrated significant improvements in neurological function and fewer neurological apoptosis detected by TUNEL [terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end-labelling] and βIII-tubulin dual-staining compared with vehicle-treated animals. Compared with sham-treated mice, the brain water content in argatroban/PMX53-treated mice was decreased significantly in both the ipsilateral cortex and ipsilateral striatum. Administration of PMX53/argatroban provided a synergistic neuroprotective effect via reducing inflammatory factors and brain oedema, leading to improvements in neurofunctional outcome. The results of this study indicated that simultaneous blockade of the thrombin and C5a receptors represent a promising neuroprotective strategy in haemorrhagic stroke.

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.

Frameless stereotactic aspiration for spontaneous intracerebral hemorrhage and subsequent fibrinolysis using urokinase

Objectives

The optimal management of patients with spontaneous intracerebral hemorrhage (ICH) remains controversial. The aim of this study was to evaluate technical results and clinical outcomes of frameless stereotactic aspiration and fibrinolysis using urokinase performed in a single center.

Materials and Methods

The subjects of this study were 62 consecutive patients with spontaneous ICH who were treated with frameless stereotactic aspiration and subsequent fibrinolysis using urokinase between February 2009 and June 2010 in our hospital. The surgical results, procedure-related complications, and clinical outcomes were evaluated.

Results

A total of 62 patients were enrolled in the study. The median age was 54 years (range, 32-86). The mean initial Glasgow coma scale score was 7.7 (range 5-11). The mean initial hemorrhage volume was 43 cm³ (range 30-70). Seven patients (11.2%) died of respiratory failure (four patients), postoperative edema (two patients), and heart disease (one patient). There were seven cases of procedure-related complications (11.2%), including malpositioning of catheters (two patients), pneumocephalus (one patient), and rebleeding (four patients, 6.4%). At the three-month follow-up, a good outcome (three-month Glasgow outcome scale > 3) was noted in 32 patients (51.6%).

Conclusions

Frameless stereotactic aspiration and subsequent fibrinolytic thearpy using urokinase for spontaneous ICH is a simple and safe procedure with low mortality and rebleeding rate.

Alpha 1-antitrypsin therapy mitigated ischemic stroke damage in rats

Our objective is to develop a new therapy for the treatment of stroke. Currently, the only effective therapy for acute ischemic stroke is the thrombolytic agent recombinant tissue plasminogen activator. α1-Antitrypsin (AAT), a serine proteinase inhibitor with potent anti-inflammatory, anti-apoptotic, antimicrobial, and cytoprotective activities, could be beneficial in stroke. The goal of this study is to test whether AAT can improve ischemic stroke outcome in an established rat model. Middle cerebral artery occlusion was induced in male rats via intracranial (i.c.) microinjection of endothelin-1. Five to 10 minutes after stroke induction, rats received either i.c. or intravenous delivery of human AAT. Cylinder and vibrissae tests were used to evaluate sensorimotor function before and 72 hours after middle cerebral artery occlusion. Infarct volumes were examined via either 2,3,5-triphenyltetrazolium chloride assay or magnetic resonance imaging 72 hours after middle cerebral artery occlusion. Despite equivalent initial strokes, at 72 hours, the infarct volumes of the human AAT treatment groups (local and systemic injection) were statistically significantly reduced by 83% and 63% (P < .0001 and P < .05, respectively) compared with control rats. Human AAT significantly limited sensory motor system deficits. Human AAT could be a potential novel therapeutic drug for the protection against neurodegeneration after ischemic stroke, but more studies are needed to investigate the protective mechanisms and efficacy in other animal models.

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.

Intracerebral hematomas disappear on T2*-weighted images during normobaric oxygen therapy

BACKGROUND AND PURPOSE

The aim of the present study was to investigate the effects of normobaric oxygen (NBO) therapy on T2*-weighted images of intracranial hemorrhages (ICHs).

METHODS

Two common models of ICH were performed in mice, and longitudinal T2*-weighted images of the hematomas were acquired under normoxia or NBO. The effects of NBO were also investigated on perfusion-weighted imaging, susceptibility-weighted imaging, and molecular imaging of vascular cell adhesion molecule-1 after ICH. Last, we performed neurological testing, including neuroscore, actimetry, and gait analysis (Catwalk), to study the influence of NBO on neurological outcome of mice presenting ICH.

RESULTS

Our results demonstrated that NBO, even during a short period of time, dramatically reduces the sensitivity of T2*-weighted imaging to detect ICH. Moreover, we provide evidence that the disappearance of ICH on T2*-weighted imaging could be used to improve accuracy of perfusion-weighted imaging and to allow molecular imaging after ICH. Importantly, a 30-minute NBO preparation 24 hours after ICH onset does not influence neurological outcome.

CONCLUSIONS

We provide an experimental demonstration that NBO significantly affects T2*-weighted imaging in ICH. Although this phenomenon could lead to inaccurate assessment of ICH volume, it could also be safely used to allow perfusion-weighted imaging and molecular imaging.

Matrix metalloproteinase-2 deletions protect against hemorrhagic transformation after 1 h of cerebral ischemia and 23 h of reperfusion

Although elevated matrix metalloproteinase (MMP)-2 levels were highly related to the degradation of tight junction (TJ) proteins and basal lamina and neuronal injury after ischemia, until very recently, little experimental evidence was available to test the role of the MMP-2 knockout (KO) in blood-brain-barrier (BBB) injury and the development of hemorrhage transformation (HT). Here, we assessed the role of the MMP-2 KO in BBB injury, HT and other brain injuries after 1h of ischemia and 23 h of reperfusion. Middle cerebral artery occlusion (MCAO) was performed in MMP-2 KO mice. Reperfusion was started 1h after the onset of MCAO. All mice were sacrificed 24h after the MCAO. MMP-2 deficiency reduced the decrease in protein levels of collagen IV and cellular membrane occludin (p<0.01 and 0.05 vs. wild-type (WT), respectively) and attenuated increase in cytosol occludin level in ischemic brain (p<0.01 vs. WT). The hemorrhage volume and brain infarction were significantly decreased in both the cortex and striatum in the MMP-2 KO mice (p<0.01 vs. WT). The MMP-2 KO also had reduced brain swelling in the cortex and improved neurological deficits (p<0.01 vs. WT). These studies provide direct evidence that targeting MMP-2 will effectively protect against collagen and occludin loss and HT after ischemia and reperfusion.

Protection of Vascular Endothelial Growth Factor to Brain Edema Following Intracerebral Hemorrhage and Its Involved Mechanisms: Effect of Aquaporin-4

Vascular endothelial growth factor (VEGF) has protective effects on many neurological diseases. However, whether VEGF acts on brain edema following intracerebral hemorrhage (ICH) is largely unknown. Our previous study has shown aquaporin-4 (AQP4) plays an important role in brain edema elimination following ICH. Meanwhile, there is close relationship between VEGF and AQP4. In this study, we aimed to test effects of VEGF on brain edema following ICH and examine whether they were AQP4 dependent. Recombinant human VEGF165 (rhVEGF165) was injected intracerebroventricularly 1 d after ICH induced by microinjecting autologous whole blood into striatum. We detected perihemotomal AQP4 protein expression, then examined the effects of rhVEGF165 on perihemotomal brain edema at 1 d, 3 d, and 7 d after injection in wild type (AQP4^+/+) and AQP4 knock-out (AQP4^−/−) mice. Furthermore, we assessed the possible signal transduction pathways activated by VEGF to regulate AQP4 expression via astrocyte cultures. We found perihemotomal AQP4 protein expression was highly increased by rhVEGF165. RhVEGF165 alleviated perihemotomal brain edema in AQP4^+/+ mice at each time point, but had no effect on AQP4^−/− mice. Perihemotomal EB extravasation was increased by rhVEGF165 in AQP4^−/− mice, but not AQP4^+/+ mice. RhVEGF165 reduced neurological deficits and increased Nissl’s staining cells surrounding hemotoma in both types of mice and these effects were related to AQP4. RhVEGF165 up-regulated phospharylation of C-Jun amino-terminal kinase (p-JNK) and extracellular signal-regulated kinase (p-ERK) and AQP4 protein in cultured astrocytes. The latter was inhibited by JNK and ERK inhibitors. In conclusion, VEGF reduces neurological deficits, brain edema, and neuronal death surrounding hemotoma but has no influence on BBB permeability. These effects are closely related to AQP4 up-regulation, possibly through activating JNK and ERK pathways. The current study may present new insights to treatment of brain edema following ICH.

Experimental high-altitude intracerebral hemorrhage in minipigs: histology, behavior, and intracranial pressure in a double-injection model

BACKGROUND

Specific pathophysiological mechanism in intracerebral hemorrhage (ICH) at high altitude is unclear, and at present, there is no relevant and suitable animal model.

METHODS

A hypobaric chamber was used to simulate an altitude of 4,000 m. Autologous arterial blood (3 ml) was slowly infused into the right basal ganglia of minipigs by a double-injection method for producing ICH.

RESULTS

The intracranial pressure and neurological score of the high-altitude group were significantly higher than those of the low-altitude (plain) group. The brain water contents and pathological lesions of perihematoma tissue were more severe in the high-altitude group.

CONCLUSIONS

The injury resulting from ICH at high altitude was more severe than that in the plain group. This model was able to produce controllable and reproducible hematomas and visible neurological deficits, which may be useful for future studies of the pathophysiology and functional rehabilitation of high-altitude ICH disease.

Prognostic factors of motor recovery after stereotactic evacuation of intracerebral hematoma

Spontaneous intracerebral hemorrhage represents 20 to 30% of all stroke patients in Japan. However, the treatment strategy of intracerebral hematoma remains controversial. Stereotactic hematoma evacuation is minimally invasive surgery and is beneficial for clot removal with limited tissue damage. The purpose of this study was to investigate the factors affecting motor recovery after stereotactic hematoma evacuation. This retrospective analysis included 30 patients with spontaneous thalamic or putaminal hemorrhage who underwent stereotactic hematoma evacuation. We compared age, presurgical muscle strength, hematoma volume and removal rate between the patients who showed improvement of motor function (improved group) and the patients associated with no motor improvement (unchanged group). Twenty-one patients were classified into the improved group and nine patients into the unchanged group. Statistical analysis revealed that age in the improved group was significantly younger than in the unchanged group (p < 0.01), whereas there was no significant difference in presurgical muscle strength, hematoma volume and removal rate between the two groups. The present results revealed that stereotactic hematoma evacuation is attributable to the improvement of motor function, especially in the younger population, indicating the importance of cortical reorganization during post-surgical rehabilitation. In addition, this procedure could provide functional improvement in severely disabled patients. Proper patient selection to receive this therapy would be beneficial for further advances of this technique. The present result might be useful in elucidating the mechanism of motor recovery and proper patient selection for this technique.

Modeling intracerebral hemorrhage in mice: injection of autologous blood or bacterial collagenase

Spontaneous intracerebral hemorrhage (ICH) defines a potentially life-threatening neurological malady that accounts for 10-15% of all stroke-related hospitalizations and for which no effective treatments are available to date(1,2). Because of the heterogeneity of ICH in humans, various preclinical models are needed to thoroughly explore prospective therapeutic strategies(3). Experimental ICH is commonly induced in rodents by intraparenchymal injection of either autologous blood or bacterial collagenase(4). The appropriate model is selected based on the pathophysiology of hemorrhage induction and injury progression. The blood injection model mimics a rapidly progressing hemorrhage. Alternatively, bacterial collagenase enzymatically disrupts the basal lamina of brain capillaries, causing an active bleed that generally evolves over several hours(5). Resultant perihematomal edema and neurofunctional deficits can be quantified from both models. In this study, we described and evaluated a modified double injection model of autologous whole blood(6) as well as an ICH injection model of bacterial collagenase(7), both of which target the basal ganglia (corpus striatum) of male CD-1 mice. We assessed neurofunctional deficits and brain edema at 24 and 72 hr after ICH induction. Intrastriatal injection of autologous blood (30 μl) or bacterial collagenase (0.075U) caused reproducible neurofunctional deficits in mice and significantly increased brain edema at 24 and 72 hr after surgery (p<0.05). In conclusion, both models yield consistent hemorrhagic infarcts and represent basic methods for preclinical ICH research.

Etiology of stroke and choice of models

Animal models of stroke contribute to the development of better stroke prevention and treatment through studies investigating the pathophysiology of different stroke subtypes and by testing promising treatments before trials in humans. There are two broad types of animal models: those in which stroke is induced through artificial means, modeling the consequences of a vascular insult but not the vascular pathology itself; and those in which strokes occur spontaneously. Most animal models of stroke are in rodents due to cost, ethical considerations, availability of standardized neurobehavioral assessments, and ease of physiological monitoring. While there are similarities in cerebrovascular anatomy and pathophysiology between rodents and humans, there are also important differences, including brain size, length and structure of perforating arteries, and gray to white matter ratio, which is substantially lower in humans. The wide range of rodent models of stroke includes models of global and focal ischemia, and of intracerebral and sub-arachnoid hemorrhage. The most widely studied model of spontaneous stroke is the spontaneously hypertensive stroke-prone rat, in which the predominant lesions are small subcortical infarcts resulting from a vascular pathology similar to human cerebral small vessel disease. Important limitations of animal models of stroke - they generally model only certain aspects of the disease and do not reflect the heterogeneity in severity, pathology and comorbidities of human stroke - and key methodological issues (especially the need for adequate sample size, randomization, and blinding in treatment trials) must be carefully considered for the successful translation of pathophysiological concepts and therapeutics from bench to bedside.

Matrix metalloproteinase-2 or -9 deletions protect against hemorrhagic transformation during early stage of cerebral ischemia and reperfusion

MMP-9 deficiency protected against photochemical thrombosis-induced brain hemorrhagic transformation (HT), but it did not protect against tissue plasminogen activator-induced brain hemorrhage. The roles of MMP-2 and/or MMP-9 knockout (KO) in mechanical reperfusion induced HT after ischemia have not been investigated. Here we assessed the effects of MMP-2 KO, MMP-9 KO and MMP-2/9 double KO (dKO) in protecting against mechanical reperfusion induced HT and other brain injuries after the early stages of cerebral ischemia in mice of the same genetic background. Middle cerebral artery occlusion (MCAO) was performed in mice. Reperfusion was started at 1 or 1.5h after onset of MCAO. All mice were sacrificed 8h after MCAO. We found that both pro- and active MMP-2 and MMP-9 levels were significantly elevated in the early ischemic brain. After the early stages of ischemia and reperfusion, the hemorrhagic incidence was reduced in the cortex of MMP-2 KO mice (p<0.05 vs. WT). The hemorrhagic volume was significantly decreased in the cortexes of MMP-2 and/or -9 knockout mice (MMP-9 KO vs. WT: p<0.01, MMP-2 KO and dKO vs. WT: p<0.001). In the basal ganglia, MMP-2 KO and MMP-2/9 dKO mice displayed a remarkable decrease in hemorrhagic volume (p<0.01 or 0.05 vs. WT), but MMP-9 KOs did not protect against hemorrhage. MMP-2 and/or -9 knockout mice displayed significantly decreased infarction volume in both the cortex and striatum, in addition to improved neurological function (p<0.001 vs. WT). The results suggested that MMP-2 deficiency and MMP-2 and MMP-9 double deficiency were more protective than MMP-9 deficiency against HT after the early stages of ischemia and reperfusion. These studies increase our understanding of MMP-2 and MMP-9 in HT development and will help to selectively target MMPs to protect the post-ischemic brain from injury and HT.

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.