Experimental animal models of intracerebral hemorrhage

Intracerebral Hemorrhage Models and Behavioral Tests in Rodents

Intracerebral hemorrhage (ICH) is one of the common types of stroke, which can cause neurological dysfunction. In preclinical ICH studies, researchers often established rodent models by donor/autologous whole blood or a collagenase injection. White matter injury (WMI) can result from primary and secondary injuries after ICH. WMI can lead to short- and long-term neurological impairment, and functional recovery can assess the effect of drug therapy after ICH. Therefore, researchers have devised various behavioral tests to assess dysfunction. This review compares the two ICH modeling methods in rodents and summarizes the pathological mechanisms underlying dysfunction after ICH. We also summarize the functions and characteristics of various behavioral methods, including sensation, motion, emotion, and cognition, to assist researchers in selecting the appropriate tests for preclinical ICH research.

A new method for preparing a rat intracerebral hemorrhage model by combining focused ultrasound and microbubbles

BACKGROUND

We aimed to prepare a non-invasive, reproducible, and controllable rat model of intracerebral hemorrhage with focused ultrasound (FUS).

METHODS

A rat intracerebral hemorrhage (ICH) model was established by combining FUS and microbubbles (μBs), and edaravone was used to verify whether the free radical scavenger had a protective effect on the model. The brain tissue of each group was sectioned to observe the gross histology, blood-brain barrier (BBB) permeability, cerebral infarction volume, and histopathological changes.

RESULTS

Compared with the FUS group, the BBB permeability was significantly increased in the FUS + μBs (F&B) group (p = 0.0021). The second coronal slice in the F&B group had an obvious hemorrhage lesion, and the FUS + μBs + edaravone (F&B&E) group had smaller hemorrhage areas; however, ICH did not occur in the FUS group. The cerebral infarction volume in the F&B group was significantly larger than that in the FUS group (p = 0.0030) and F&B&E group (p = 0.0208). HE staining results showed that nerve fibrinolysis, neuronal necrosis, microglia production, and erythrocytes were found in both the F&B group and the F&B&E group, but the areas of the nerve fibrinolysis and neuronal necrosis in the F&B group were larger than the F&B&E group.

CONCLUSIONS

A rat ICH model was successfully prepared using the μBs assisted FUS treatment, and edaravone had a therapeutic effect on this model. This model can be used to study the pathophysiological mechanism of ICH-related diseases and in preclinical research on related new drugs.

Rodent Models of Post-Stroke Dementia

Post-stroke cognitive impairment is one of the most common complications in stroke survivors. Concomitant vascular risk factors, including aging, diabetes mellitus, hypertension, dyslipidemia, or underlying pathologic conditions, such as chronic cerebral hypoperfusion, white matter hyperintensities, or Alzheimer’s disease pathology, can predispose patients to develop post-stroke dementia (PSD). Given the various clinical conditions associated with PSD, a single animal model for PSD is not possible. Animal models of PSD that consider these diverse clinical situations have not been well-studied. In this literature review, diverse rodent models that simulate the various clinical conditions of PSD have been evaluated. Heterogeneous rodent models of PSD are classified into the following categories: surgical technique, special structure, and comorbid condition. The characteristics of individual models and their clinical significance are discussed in detail. Diverse rodent models mimicking the specific pathomechanisms of PSD could provide effective animal platforms for future studies investigating the characteristics and pathophysiology of PSD.

The transient intraluminal filament Middle Cerebral Artery Occlusion stroke model in rats. A step by step guide and technical considerations

OBJECTIVE

Stroke is a leading cause of disability and mortality worldwide. Related research, although already providing significant insights on the underlying pathophysiology and potential treatment strategies, is far from conclusive. In this respect, stroke models are proving of extreme significance for laboratories around the world. The scope of this article is to present in detail the most popular to date focal stroke model, the tifMCAO model in rats. This model mimics reliably stroke in humans and also approximates endovascular thrombectomy.

METHODS

The tifMCAO model was performed on Wistar rats with a weight of 300-400 gr. The surgical technique is described in a step-wise manner, while pictures and/or HD video accompany each step. Complete arteriotomy of the ECA stump is introduced during the procedure.

RESULTS

We performed the tifMCAO in 65 rats (male and female) involved in various experimental protocols. Although that initial mortality was 48%, practice reduced this number to10%. The mean procedural time was 53 min (range, 38 - 85 min). Stroke was confirmed in 87.5% of the cases.

CONCLUSIONS

The tifMCAO stroke model in rats is the most commonly utilized experimental model of focal ischemia because of its clinical relevance. We revisited the procedure and divided it, for instructional purposes, in 15 consecutive distinct steps.

Intracerebral hemorrhage alters α2δ1 and thrombospondin expression in rats

Calcium voltage-gated channel auxiliary subunit (α2δ1) is a non-essential subunit of the voltage-gated calcium channel complex and is ubiquitously expressed in a number of tissues, including the brain. Thrombospondin (TSP)1 and TSP2 are extracellular matrix proteins and belong to the multi-domain glycoprotein family of macromolecular oligomers. TSP1/2 and α2δ1 promote synapse formation and functional recovery following cerebral infarction. However, to the best of our knowledge, the expression levels of α2δ1 and TSP1/2 in brain tissues, and the effects of intracerebral hemorrhage (ICH) on these levels have not yet been elucidated. The present study established a rat model of hemorrhage induced by injecting collagenase IV into the striatum to determine the changes in α2δ1 and TSP1/2 expression following ICH. The protein expression levels of α2δ1 and TSP1 in the striatum after hemorrhage were significantly increased on day 5 and returned to baseline levels on day 21; however, the protein expression levels of TSP2 were decreased on day 5, whereas they increased on day 14, subsequently returning to baseline levels. In addition, using proteomics analysis of tissues from the sham group (saline injection) and at 24 h post-ICH, it was found that both α2δ1 and TSP1 interacted with neural EGFL like 2. Taken together, these findings suggested that the expression levels of α2δ1 and TSP1/2 were altered in brain tissues in response to ICH.

Assessing the Evolution of Intracranial Hematomas by using Animal Models: A Review of the Progress and the Challenges

Stroke has become the second leading cause of death in people aged higher than 60 years, with cancer being the first. Intracerebral hemorrhage (ICH) is the most lethal type of stroke. Using imaging techniques to evaluate the evolution of intracranial hematomas in patients with hemorrhagic stroke is worthy of ongoing research. The difficulty in obtaining ultra-early imaging data and conducting intensive dynamic radiographic imaging in actual clinical settings has led to the application of experimental animal models to assess the evolution of intracranial hematomas. Herein, we review the current knowledge on primary intracerebral hemorrhage mechanisms, focus on the progress of animal studies related to hematoma development and secondary brain injury, introduce preclinical therapies, and summarize related challenges and future directions.

Secondary mechanisms of injury and viable pathophysiological targets in intracerebral hemorrhage

Intracerebral hemorrhage (ICH) can be divided into a primary and secondary phase. In the primary phase, hematoma volume is evaluated and therapies are focused on reducing hematoma expansion. In the secondary, neuroprotective phase, complex systemic inflammatory cascades, direct cellular toxicity, and blood-brain barrier disruption can result in worsening perihematomal edema that can adversely affect functional outcome. To date, all major randomized phase 3 trials for ICH have targeted primary phase hematoma volume and incorporated clot evacuation, intensive blood pressure control, and hemostasis. Reasons for this lack of clinical efficacy in the major ICH trials may be due to the lack of therapeutics involving mitigation of secondary injury and inflexible trial design that favors unilateral mechanisms in a complex pathophysiology. Potential pathophysiological targets for attenuating secondary injury are highlighted in this review and include therapies increasing calcium, antagonizing microglial activation, maintaining macrophage M1 versus M2 balance by decreasing M1 signaling, aquaporin inhibition, NKCCl inhibition, endothelin receptor inhibition, Sur1-TRPM4 inhibition, matrix metalloproteinase inhibition, and sphingosine-1-phosphate receptor modulation. Future clinical trials in ICH focusing on secondary phase injury and, potentially implementing adaptive trial design approaches with multifocal targets, may improve insight into these mechanisms and provide potential therapies that may improve survival and functional outcome.

Animal models of stroke

Stroke is a devastating disease with high morbidity and mortality. Animal models are indispensable tools that can mimic stroke processes and can be used for investigating mechanisms and developing novel therapeutic regimens. As a heterogeneous disease with complex pathophysiology, mimicking all aspects of human stroke in one animal model is impossible. Each model has unique strengths and weaknesses. Models such as transient or permanent intraluminal thread occlusion middle cerebral artery occlusion (MCAo) models and thromboembolic models are the most commonly used in simulating human ischemic stroke. The endovascular filament occlusion model is characterized by easy manipulation and accurately controllable reperfusion and is suitable for studying the pathogenesis of focal ischemic stroke and reperfusion injury. Although the reproducibility of the embolic model is poor, it is more convenient for investigating thrombolysis. Rats are the most frequently used animal model for stroke. This review mainly outlines the stroke models of rats and discusses their strengths and shortcomings in detail.

Zebrafish as a Model for In-Depth Mechanistic Study for Stroke

Stroke is one of the world's leading causes of death and disability, posing enormous burden to the society. However, the pathogenesis and mechanisms that underlie brain injury and brain repair remain largely unknown. There's an unmet need of in-depth mechanistic research in this field. Zebrafish (Danio rerio) is a powerful tool in brain science research mainly due to its small size and transparent body, high genome synteny with human, and similar nervous system structures. It can be used to establish both hemorrhagic and ischemic stroke models easily and effectively through different ways. After the establishment of stroke model, research methods including behavioral test, in vivo imaging, and drug screening are available to explore mechanisms that underlie the brain injury and brain repair after stroke. This review focuses on the advantages and the feasibility of zebrafish stroke model, and will also introduce the key methods available for stroke studies in zebrafish, which may drive future mechanistic studies in the pursuit of discovering novel therapeutic targets for stroke patients.

The utilization of small non-mammals in traumatic brain injury research: A systematic review

Traumatic brain injury (TBI) is the leading cause of death and disability worldwide and has complicated underlying pathophysiology. Numerous TBI animal models have been developed over the past decade to effectively mimic the human TBI pathophysiology. These models are of mostly mammalian origin including rodents and non-human primates. However, the mammalian models demanded higher costs and have lower throughput often limiting the progress in TBI research. Thus, this systematic review aims to discuss the potential benefits of non-mammalian TBI models in terms of their face validity in resembling human TBI. Three databases were searched as follows: PubMed, Scopus, and Embase, for original articles relating to non-mammalian TBI models, published between January 2010 and December 2019. A total of 29 articles were selected based on PRISMA model for critical appraisal. Zebrafish, both larvae and adult, was found to be the most utilized non-mammalian TBI model in the current literature, followed by the fruit fly and roundworm. In conclusion, non-mammalian TBI models have advantages over mammalian models especially for rapid, cost-effective, and reproducible screening of effective treatment strategies and provide an opportunity to expedite the advancement of TBI research.

Inhibition of Dectin-1 Ameliorates Neuroinflammation by Regulating Microglia/Macrophage Phenotype After Intracerebral Hemorrhage in Mice

Polarization of microglia/macrophages toward the pro-inflammatory phenotype is an important contributor to neuroinflammation after intracerebral hemorrhage (ICH). Dectin-1 is a pattern recognition receptor that has been reported to play a key role in regulating neuroinflammation in ischemic stroke and spinal cord injury. However, the role and mechanism of action of Dectin-1 after ICH remains unclear. In this study, we investigated the effect of Dectin-1 on modulating the microglia/macrophage phenotype and neuroinflammation and the possible underlying mechanism after ICH. We found that Dectin-1 expression increased after ICH, and was mainly localized in microglia/macrophages. Neutrophil infiltration and microglia/macrophage polarization toward the pro-inflammatory phenotype increased after ICH. However, treatment with a Dectin-1 inhibitor reversed these phenomena and induced a shift the anti-inflammatory phenotype in microglia/macrophages; this resulted in alleviation of neurological dysfunction and facilitated hematoma clearance after ICH. We also found that Dectin-1 crosstalks with the downstream pro-inflammatory pathway, Card9/NF-κB, by activating spleen tyrosine kinase (Syk) both in vivo and in vitro. In conclusion, our data suggest that Dectin-1 is involved in the microglia/macrophage polarization and functional recovery after ICH, and that this mechanism, at least in part, may contribute to the involvement of the Syk/Card9/NF-kB pathway.

Intracerebral haemorrhage: from clinical settings to animal models

Spontaneous intracerebral haemorrhage (ICH) is a devastating type of stroke with high mortality and morbidity and for which no effective treatments are available to date. Much experimental and clinical research have been performed to explore its mechanisms regard the subsequent inflammatory cascade and to seek the potential therapeutic strategies. The aim of this review is to discuss insights from clinical settings that have led to the development of numerous animal models of ICH. Some of the current and future challenges for clinicians to understand ICH are also surveyed.

Intraventricular Hemorrhage and White Matter Injury in Preclinical and Clinical Studies

Germinal matrix-intraventricular hemorrhage (IVH) occurs in nearly half of infants born at less than 26 weeks' gestation. Up to 50% of survivors with IVH develop cerebral palsy, cognitive deficits, behavioral disorders, posthemorrhagic ventricular dilatation, or a combination of these sequelae. After the initial bleeding and the primary brain injury, inflammation and secondary brain injury might lead to periventricular leukomalacia or diffuse white matter injury. Potential factors that are involved include microglia and astrocyte activation, degradation of blood components with release of "toxic" products, infiltration of the brain by systemic immune cells, death of neuronal and glial cells, and arrest of preoligodendrocyte maturation. In addition, impairment of the blood-brain barrier may play a major role in the pathophysiology. A wide range of animal models has been used to explore causes and mechanisms leading to IVH-induced brain injury. Preclinical studies have identified potential targets for enhancing brain repair. However, little has been elucidated about the effectiveness of potential interventions in clinical studies. A systematic review of available preclinical and clinical studies might help identify research gaps and which types of interventions may be prioritized. Future trials should report clinically robust and long-term outcomes after IVH.

Increased expression of Triad1 is associated with neuronal apoptosis after intracerebral hemorrhage in adult rats

Objective: It has been demonstrated that Triad1 (2 RING fingers and double RING finger linked 1) negatively regulates myeloid cell growth and induces cell apoptosis. However, its functions in intracerebral hemorrhage (ICH) disease have not been conducted. In this study, the role of Triad1 in rat model of ICH was explored.Methods: We observe an increasing expression of Triad1 in areas adjacent to hematoma after ICH. Immunofluorescence shows that Triad1 is colocalized with neurons, while not microglia or astrocyte, indicates its correlation with neuronal activities following ICH.Results: As neuronal apoptosis is the most crucial event in ICH disease, the expression of active caspase-3 and p53 is also enhanced around the hematoma, which is consistent with Triad1 in expression tendency. In turn, Triad1 depletion in primary cortical neurons decreased the apoptosis of neurons after using Triad1 shRNA.Conclusion: We conclude that inhibition of Triad1 expression might protect the brain from secondary damage following ICH.

Serial Metabolic Evaluation of Perihematomal Tissues in the Intracerebral Hemorrhage Pig Model

Purpose

Perihematomal edema (PHE) occurs in patients with intracerebral hemorrhage (ICH) and is often used as surrogate of secondary brain injury. PHE resolves over time, but little is known about the functional integrity of the tissues that recover from edema. In a pig ICH model, we aimed to assess metabolic integrity of perihematoma tissues by using non-invasive magnetic resonance spectroscopy (MRS).

Materials and Methods

Fourteen male Yorkshire pigs with an average age of 8 weeks were intracerebrally injected with autologous blood to produce ICH. Proton MRS data were obtained at 1, 7, and 14 days after ICH using a whole-body 3.0T MRI system. Point-resolved spectroscopy (PRESS)-localized 2D chemical shift imaging (CSI) was acquired. The concentration of N-Acetylaspartate (NAA), Choline (Cho), and Creatine (Cr) were measured within the area of PHE, tissues adjacent to the injury with no or negligible edema (ATNE), and contralesional brain tissue. A linear mixed model was used to analyze the evolution of metabolites in perihematomal tissues, with p-value < 0.05 indicating statistical significance.

Results

The perihematoma volume gradually decreased from 2.38 ± 1.23 ml to 0.41 ± 0.780 ml (p < 0.001) over 2 weeks. Significant (p < 0.001) reductions in NAA, Cr, and Cho concentrations were found in the PHE and ATNE regions compared to the contralesional hemisphere at day 1 and 7 after ICH. All three metabolites were significantly (p < 0.001) restored in the PHE tissue on day 14, but remained persistently low in the ATNE area, and unaltered in the contralesional voxel.

Conclusion

This study highlights the potential of MRS to probe salvageable tissues within the perihematoma in the sub-acute phase of ICH. Altered metabolites within the PHE and ATNE regions in addition to edema and hematoma volumes were explored as possible markers for tissue recovery. Perihematomal tissue with PHE demonstrated a more reversible injury compared to the tissue adjacent to the injury without edema, suggesting a potentially beneficial role of edema.

Changes in the Lectin Pathway Following Intracerebral or Spontaneous Subarachnoid Hemorrhage

Previous research indicates that the complement system is activated after occurrence of intracerebral hemorrhage (ICH) and spontaneous subarachnoid hemorrhage (SAH). The role of the lectin pathway (LP) of the complement system in this activation has only scarcely been investigated. The aim of this study was to determine the plasma concentration of the LP proteins in patients with ICH or SAH at admission compared to healthy individuals. Secondly, ICH and SAH patients were followed during the initial 24 h of disease, to investigate changes in LP protein concentrations during the critical acute phase. This prospective, observational study included 30 ICH and 33 SAH patients. EDTA plasma samples were collected at admission, 6 and 24 h after symptom onset. Time-resolved immuno-flourometric assays (TRIFMA) were used to measure all proteins of the LP in patient samples and in samples from age- and gender-matched healthy individuals. Compared to healthy individuals, ICH and SAH patients had increased levels of H-ficolin (p = 0.04, p = 0.03), M-ficolin (both p < 0.0001), and MAp44 (both p = 0.01) at admission. M-ficolin, H-ficolin, CL-L1, MASP-1, MASP-3, and MAp44 decreased significantly in both ICH and SAH patients during the initial 24 h after symptom onset. In conclusion, we observed significant differences in lectin pathway protein concentrations between patients with ICH or SAH and healthy individuals. Significant dynamics in lectin pathway protein levels were demonstrated during the initial 24 h after symptom onset. This indicates a potential role of the LP proteins during the acute phase of SAH and ICH.

HO-1 protects the nerves of rats with cerebral hemorrhage by regulating the PI3K/AKT signaling pathway

Objective: This study aimed to investigate the neuroprotective effect of heme oxygenase-1 (HO-1) on the PI3K/AKT signaling pathway in rats with cerebral hemorrhage. Materials and methods: Adult male Sprague-Dawley rats were randomly divided into: a sham group, a model group and an HO-1 inhibitor group (ZnPP group). Functional defects after surgery were scored according to the Longa5 standard. Hemotoxylin and eosin staining was used to detect whether the model was constructed successfully. Superoxide dismutase (SOD) vitality and malondialdehyde (MDA) content were calculated by the xanthine oxidase method and thiobarbituric acid method, respectively. Blood-brain barrier permeability was measured by Evans Blue. Apoptosis was detected by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assay. The expression of Bcl-2 and BAX was evaluated by immunohistochemistry and the expression of PI3K, p-PI3K, AKT and p-AKT was tested by Western blotting. Results: The rat intracerebral hemorrhage model was successfully constructed. Compared with the model group, the bleeding in the ZnPP group was more serious, the cell edema and deformation were aggravated, and the neurological deficit score in the rat was significantly increased. In addition, the content of Evans blue, MDA, the number of apoptotic cells, the water content of brain tissue and the expression of BAX were significantly increased, while the SOD activity and the expressions of Bcl-2, p-PI3K and p-AKT protein were decreased. Conclusion: HO-1 could protect the nerves of rats with cerebral hemorrhage by regulating the PI3K/AKT signaling pathway.

Using zebrafish larval models to study brain injury, locomotor and neuroinflammatory outcomes following intracerebral haemorrhage

Intracerebral haemorrhage (ICH) is a devastating condition with limited treatment options, and current understanding of pathophysiology is incomplete. Spontaneous cerebral bleeding is a characteristic of the human condition that has proven difficult to recapitulate in existing pre-clinical rodent models. Zebrafish larvae are frequently used as vertebrate disease models and are associated with several advantages, including high fecundity, optical translucency and non-protected status prior to 5 days post-fertilisation. Furthermore, other groups have shown that zebrafish larvae can exhibit spontaneous ICH. The aim of this study was to investigate whether such models can be utilised to study the pathological consequences of bleeding in the brain, in the context of pre-clinical ICH research.

Here, we compared existing genetic (bubblehead) and chemically inducible (atorvastatin) zebrafish larval models of spontaneous ICH and studied the subsequent disease processes. Through live, non-invasive imaging of transgenic fluorescent reporter lines and behavioural assessment we quantified brain injury, locomotor function and neuroinflammation following ICH. We show that ICH in both zebrafish larval models is comparable in timing, frequency and location. ICH results in increased brain cell death and a persistent locomotor deficit. Additionally, in haemorrhaged larvae we observed a significant increase in macrophage recruitment to the site of injury. Live in vivo imaging allowed us to track active macrophage-based phagocytosis of dying brain cells 24 hours after haemorrhage. Morphological analyses and quantification indicated that an increase in overall macrophage activation occurs in the haemorrhaged brain.

Our study shows that in zebrafish larvae, bleeding in the brain induces quantifiable phenotypic outcomes that mimic key features of human ICH. We hope that this methodology will enable the pre-clinical ICH community to adopt the zebrafish larval model as an alternative to rodents, supporting future high throughput drug screening and as a complementary approach to elucidating crucial mechanisms associated with ICH pathophysiology.

Large animal models of stroke and traumatic brain injury as translational tools

Acute central nervous system injury, encompassing traumatic brain injury (TBI) and stroke, accounts for a significant burden of morbidity and mortality worldwide. Studies in animal models have greatly enhanced our understanding of the complex pathophysiology that underlies TBI and stroke and enabled the preclinical screening of over 1,000 novel therapeutic agents. Despite this, the translation of novel therapeutics from experimental models to clinical therapies has been extremely poor. One potential explanation for this poor clinical translation is the choice of experimental model, given that the majority of preclinical TBI and ischemic stroke studies have been conducted in small animals, such as rodents, which have small lissencephalic brains. However, the use of large animal species such as nonhuman primates, sheep, and pigs, which have large gyrencephalic human-like brains, may provide an avenue to improve clinical translation due to similarities in neuroanatomical structure when compared with widely adopted rodent models. This purpose of this review is to provide an overview of large animal models of TBI and ischemic stroke, including the surgical considerations, key benefits, and limitations of each approach.

Melatonin Alleviates Intracerebral Hemorrhage-Induced Secondary Brain Injury in Rats via Suppressing Apoptosis, Inflammation, Oxidative Stress, DNA Damage, and Mitochondria Injury

Intracerebral hemorrhage (ICH) is a cerebrovascular disease with high mortality and morbidity, and the effective treatment is still lacking. We designed this study to investigate the therapeutic effects and mechanisms of melatonin on the secondary brain injury (SBI) after ICH. An in vivo ICH model was induced via autologous whole blood injection into the right basal ganglia in Sprague-Dawley (SD) rats. Primary rat cortical neurons were treated with oxygen hemoglobin (OxyHb) as an in vitro ICH model. The results of the in vivo study showed that melatonin alleviated severe brain edema and behavior disorders induced by ICH. Indicators of blood-brain barrier (BBB) integrity, DNA damage, inflammation, oxidative stress, apoptosis, and mitochondria damage showed a significant increase after ICH, while melatonin reduced their levels. Meanwhile, melatonin promoted further increasing of expression levels of antioxidant indicators induced by ICH. Microscopically, TUNEL and Nissl staining showed that melatonin reduced the numbers of ICH-induced apoptotic cells. Inflammation and DNA damage indicators exhibited an identical pattern compared to those above. Additionally, the in vitro study demonstrated that melatonin reduced the apoptotic neurons induced by OxyHb and protected the mitochondrial membrane potential. Collectively, our investigation showed that melatonin ameliorated ICH-induced SBI by impacting apoptosis, inflammation, oxidative stress, DNA damage, brain edema, and BBB damage and reducing mitochondrial membrane permeability transition pore opening, and melatonin may be a potential therapeutic agent of ICH.

White Matter Injury and Recovery after Hypertensive Intracerebral Hemorrhage

Hypertensive intracerebral hemorrhage (ICH) could very probably trigger white matter injury in patients. Through the continuous study of white matter injury after hypertensive ICH, we achieve a more profound understanding of the pathophysiological mechanism of its occurrence and development. At the same time, we found a series of drugs and treatment methods for the white matter repair. In the current reality, the research paradigm of white matter injury after hypertensive ICH is relatively obsolete or incomplete, and there are still lots of deficiencies in the research. In the face of the profound changes of stroke research perspective, we believe that the combination of the lenticulostriate artery, nerve nuclei of the hypothalamus-thalamus-basal ganglia, and the white matter fibers located within the capsula interna will be beneficial to the research of white matter injury and repair. This paper has classified and analyzed the study of white matter injury and repair after hypertensive ICH and also rethought the shortcomings of the current research. We hope that it could help researchers further explore and study white matter injury and repair after hypertensive ICH.

Minimally Invasive Surgery for Evacuating the Intracerebral Hematoma in Early Stages Decreased Secondary Damages to the Internal Capsule in Dog Model of ICH Observed by Diffusion Tensor Imaging

BACKGROUND

Diffusion tensor imaging was used to observe the effects of performing early minimally invasive surgery (MIS) on internal capsule in dog model of intracerebral hemorrhage (ICH).

METHODS

Twenty-five male dogs were selected to prepare an ICH model, and then they were randomly distributed into a model control (MC) group (5 dogs) or an MIS group (20 dogs). In the MIS group, the intracerebral hematoma was evacuated by stereotactic minimally invasive procedures over 6 hours (5 dogs), 12 hours (5 dogs), 18 hours (5 dogs), or 24 hours (5 dogs) after successful induction of ICH. The same procedure was performed in the MC group but without evacuating the hematoma. All the animals were sacrificed within 2 weeks after the hematoma was surgically evacuated. The neurologic deficit score and diffusion tensor imaging (DTI) were observed before and after the MIS. The perihematomal blood-brain barrier (BBB) permeability and the brain water content (BWC) were measured 2 weeks after the hematoma was surgically evacuated.

RESULTS

The DTI demonstrated that integrity of the internal capsule restored largely after surgery and the fractional anisotropy (FA) values of the internal capsule on the hematoma side increased significantly as compared with those in the MC group or those before surgery in the same group. The postoperative ratios of FA values of each MIS subgroup increased compared with the MC group and those before surgery in the same subgroup before operation. The neurologic deficit score, the perihematomal BBB permeability, and the BWC of each MIS subgroup decreased significantly compared with those of the MC group. The 6-12-hour group displayed a more favorable result.

CONCLUSIONS

Performing the MIS in the early stage (6-12 hours) after ICH could decrease the secondary damages to the internal capsule so as to promote the recovery of motor function. The optimal time window for MIS should be within 6-12 hours after onset of ICH.

Protective role of free and quercetin-loaded nanoemulsion against damage induced by intracerebral haemorrhage in rats

Intracerebral haemorrhage (ICH) is a worldwide public health problem. Experimental studies have shown that oxidative stress plays an important role in the pathogenesis of ICH and could represent a target for its treatment. However, the blood-brain barrier is an obstacle to be overcome, as it hampers the administration of compounds to the central nervous system. In this study, we compared the effects of a quercetin-loaded nanoemulsion (QU-N) with the free form of the drug (QU-SP) in a collagenase-induced ICH rat model. Quercetin (QU) is a polyphenol that has an antioxidant effect in vitro, but due to its high lipophilicity, it has low bioavailability in vivo. In this study, animals submitted or not to ICH were treated with a single intraperitoneal QU dose (free or nanoemulsion) of 30 mg kg(-1). Motor assessment was evaluated by the open field, foot fault and beam walking behavioural tests. 72 h after surgery the haematoma size was evaluated and biochemical measurements were performed. Animals treated with QU-N had a significant improvement in the beam walking and open field tests. Also, QU-N was able to reduce the size of the haematoma, preserving the activity of glutathione S-transferase (GST), increasing GSH content, and the total antioxidant capacity. QU-SP recovered locomotor activity and increased the GSH content and the total antioxidant capacity. Thus, it can be observed that QU presented antioxidant activity in both formulations, but the incorporation into nanoemulsions increased its antioxidant effect, which was reflected in the improvement of the motor skills and in the haematoma size decrement. These results suggest that the nanoemulsion containing QU developed in this study could be promising for future studies on treatments for ICH.

A review on animal models of stroke: An update

Stroke is one of the major healthcare challenges prevailing across the globe due to its significant rate of mortality and morbidity. Stroke is multifactorial in nature and involves several cellular and molecular signaling cascades that make the pathogenesis complex and treatment difficult. For a deeper understanding of the diverse pathological mechanisms and molecular & cellular cascades during stroke, animal modeling serves as a reliable and an effective tool. This also helps to develop and critically analyse various neuroprotective strategies for the mitigation of this devastating disease. Animal modeling for stroke has been revolutionized with the development of newer and more relevant models or approaches that mimic the clinical setting of stroke to a greater extent. This review analyses experimental models of stroke (ischemic and hemorrhagic) and their reliability in stroke situation. Besides this, the review also stresses upon the use of various preclinical models to understand the pathophysiological mechanisms that operate during stroke and to elucidate new, safe and effective neuroprotective agents to combat this life threatening healthcare concern.

Effect of Yi-nao-jie-yu decoction on γ-aminobutyric acid type A receptor in the hippocampus and serum inflammatory factors in a rat model of poststroke anxiety

BACKGROUND

The Yi-nao-jie-yu decoction (YNJYD) is a herbal preparation widely used in the clinics of traditional Chinese medicine and has been recently used as an important new therapeutic agent in poststroke anxiety (PSA). The neuroendocrine-immune system plays an important role in PSA mechanisms, although the modulating effects of YNJYD remain unknown. This study investigated the potential effects of YNJYD on the neuroendocrine-immune system in a rat model of PSA.

MATERIALS AND METHODS

The PSA model was induced by injecting collagenase (type VII) into the right globus pallidus, accompanied by empty water bottle stimulation for 2 weeks. The sham group and the PSA model group were gavaged with saline, while the treatment groups received buspirone (BuSpar) or YNJYD. Behavior was evaluated with the open field test and elevated plus maze once a week. Pathological changes were observed by hematoxylin and eosin staining. Serum levels of tumor necrosis factor, interleukin (IL)-6, adrenocorticotropic hormone, thyroid stimulating hormone, free triiodothyronine, free thyroxine, IL-1α, and cortisol were detected by radioimmunoassay. Expression of the γ-aminobutyric acid type A receptor (GABA_AR) α₂ subunit was examined by Western blot and real-time polymerase chain reaction.

RESULTS

YNJYD-treated rats exhibited significantly better recovery than BuSpar-treated rats at 21 days and 28 days in the open field test and elevated plus maze. Hematoxylin and eosin staining revealed neural repair in the hippocampus in the treatment groups. Serum levels of IL-1α in the YNJYD group were significantly less than those in the model group and the BuSpar group. GABA_AR protein and mRNA expressions were higher in the PSA model group than in the sham group, and YNJYD reversed these effects.

CONCLUSION

YNJYD alleviated the symptoms of PSA mainly by decreasing IL-1α levels and downregulating GABA_AR expression in the hippocampus to maintain a neuroendocrine-mmune system balance.

Animal Stroke Model: Ischemia-Reperfusion and Intracerebral Hemorrhage

Stroke is a major health issue worldwide-one with serious financial and public health implications. As a result, ongoing clinical research on novel and improved stroke therapies is not only pertinent but also paramount. Due to the complexity of a stroke-like event and its many sequelae, devising usable methods and experimental models are necessary to study and better understand the pathophysiological processes that ensue. As it stands, animal models that simulate stroke-like events have proven to be the most logical and effective options in regards to experimental studies. A number of animal stroke models exist and have been demonstrated in previous studies on ischemic as well as hemorrhagic stroke. Considering the efficiency and reproducibility of animal models, here, we introduce an ischemic stroke model induced by middle cerebral artery occlusion (MCAO) and an intracerebral hemorrhagic stroke model induced by collagenase injection. The models outlined here have been proven to demonstrate the clinical relevance desired for use in continued research on stroke pathophysiology and the study of future therapeutic options.

Neuroprotection as a Potential Therapeutic Perspective in Neurodegenerative Diseases: Focus on Antiepileptic Drugs

Neuroprotection is conceived as one of the potential tool to prevent or slow neuronal death and hence a therapeutic hope to treat neurodegenerative diseases, like Parkinson's and Alzheimer's diseases. Increase of oxidative stress, mitochondrial dysfunction, excitotoxicity, inflammatory changes, iron accumulation, and protein aggregation have been identified as main causes of neuronal death and adopted as targets to test experimentally the putative neuroprotective effects of various classes of drugs. Among these agents, antiepileptic drugs (AEDs), both the old and the newer generations, have shown to exert protective effects in different experimental models. Their mechanism of action is mediated mainly by modulating the activity of sodium, calcium and potassium channels as well as the glutamatergic and GABAergic (gamma-aminobutyric acid) synapses. Neurological pathologies in which a neuroprotective action of AEDs has been demonstrated in specific experimental models include: cerebral ischemia, Parkinson's disease, and Alzheimer's disease. Although the whole of experimental data indicating that neuroprotection can be achieved is remarkable and encouraging, no firm data have been produced in humans so far and, at the present time, neuroprotection still remains a challenge for the future.

Delayed localized hypothermia reduces intracranial pressure following collagenase-induced intracerebral hemorrhage in rat

Brain injury, such as from intracerebral hemorrhage (ICH), causes edema and raises intracranial pressure (ICP)--a potentially life-threatening complication. Clinical studies suggest that therapeutic hypothermia (TH) reduces edema and ICP after ICH. Similarly, animal studies show that TH can sometimes reduce edema, but whether ICP would be attenuated is not known. Here we tested whether 24-h delayed TH reduces edema and ICP in rats with severe striatal ICH (collagenase model). First, we showed that ICH increased epidural ICP (mean of 18 vs. 6.5mm Hg in controls), measured via telemetry. Second, we confirmed that delayed TH did not affect hematoma size at 7d ay (~65 vs. ~61 µL in controls). A cranial cooling device lowered striatal temperature to ~33 °C from 24 to 72 h after ICH. Third, we compared normothermic rats to those with TH that were rewarmed immediately or over 6h. Both TH protocols significantly reduced average and peak ICP by the second treatment day, and benefits persisted after rewarming. However, TH with slow rewarming failed to mitigate edema at 96 h (83.2% vs. 83.6% in controls) whereas rapid rewarming worsened edema (85.7%). Finally, we compared normothermic and TH rats without rewarming and found no impact on edema at 72 h (~81%). In summary, it appears that 24-h delayed local TH lowers ICP by a mechanism other than edema. Rapid rewarming worsens edema after local cooling, but this did not markedly impact ICP. Thus, TH should reduce ICP in patients with severe ICH, but not necessarily through mitigating edema.

Stem cell-based therapies for intracerebral hemorrhage in animal model: a meta-analysis

Stem cell to be a new intervention for treating intracerebral hemorrhage (ICH) might benefit humans. Therefore, we collected animal studies to find the effect of this innovative treatment. In July 2014, we searched Medline (from 1950), Embase (from 1980), China Biology Medicine disk (from 1978) for studies on stem cells used for treating experimental ICH in animal models that reported neurobehavioral and structural outcome. We evaluated the quality of these studies and used a weighted mean difference random affects model for the meta-analysis. We have collected 30 studies from 650 publications identified through systematic review describing the effects of 5 different type of stem cells on 12 different neurobehavioral scales with 1101 rodents or monkeys. Although there is lack of uniformity of the evaluation methods, these researches showed consistent improvements both in neurobehavioral function and structural outcomes. Besides, the quality of these studies needs to be raised. In conclusion, stem cells hold extensive potential in treating ICH, which should be further evaluated with more evidence-based, high-quality animal studies.

Up-regulation of VCAM1 Relates to Neuronal Apoptosis After Intracerebral Hemorrhage in Adult Rats

Vascular cell adhesion molecule 1 (VCAM1) is a member of the Immunoglobulin superfamily and encodes a cell surface sialoglycoprotein expressed in cytokine-activated endothelium. This type I membrane protein mediates leukocyte-endothelial cell adhesion, facilitates the downstream signaling, and may play a role in the development of artherosclerosis and rheumatoid arthritis. Accumulating evidence has demonstrated that VCAM1 exerts an anti-apoptotic effect in several tumor tissues such as ovarian cancer and breast cancer. Intracerebral hemorrhage (ICH) is the second most common subtype of stroke with high morbidity and mortality, which imposes a big burden on individuals and the whole society. These together prompted us to question whether VCAM1 has some association with neuron apoptosis during the pathological process of ICH. An ICH rat model was established and assessed by behavioral tests in order to explore the role of VCAM1 after ICH. Up-regulation of VCAM1 was observed in brain areas surrounding the hematoma following ICH by western blotting and immunohistochemistry. Immunofluorescence manifested VCAM1 was strikingly increased in neurons, but not in astrocytes and microglia. Furthermore, we detected that neuronal apoptosis marker active caspase-3 had co-localizations with VCAM1. At the same time, Bcl-2 was also co-localized with VCAM1. Taken together, our findings suggested that VCAM1 might be involved in the neuronal apoptosis and pathophysiology of ICH.

Perihematomal glutamate level is associated with the blood-brain barrier disruption in a rabbit model of intracerebral hemorrhage

Objective

To observe the relationship between the perihematomal glutamate levels and the blood–brain barrier (BBB) permeability in a rabbit model of intracerebral hemorrhage (ICH).

Methods

Seventy-two rabbits were randomly divided into an intracerebral hemorrhage (ICH) model group and a normal control (NC) group, and each group of 36 rabbits was subsequently divided into 6, 12, 18, 24, 48 and 72 h groups (n = 6 each). An ICH model was induced by stereotactic injection of autologous, arterial, non-anticoagulated blood into rabbit basal ganglia. The same procedures were performed in the NC group, but blood was not injected. The rabbits were sacrificed at specific time points after the experiment began depending on their group. Perihematomal brain tissues were collected to determine glutamate levels, BBB permeability and brain water content (BWC).

Results

All of the assessed parameters were increased 6 hour after blood infusion and continued to gradually increase, peaking at 48 hours. Differences were observed when ICH values were compared with those of the NC group (p < 0.05).

Conclusions

Perihematomal glutamate increased significantly after ICH. High levels of glutamate are closely associated with BBB disruption and the brain edema. Therefore, glutamate may play an important role in the pathogenesis of secondary brain injury after (ICH).

Early stage minimally invasive procedures reduce perihematomal MMP-9 and blood-brain barrier disruption in a rabbit model of intracerebral hemorrhage

INTRODUCTION

The effects of performing a minimally invasive procedure at different stages after intracerebral hemorrhage (ICH) on perifocal MMP-9 expression and blood-brain barrier (BBB) permeability were evaluated.

METHODS

Thirty-six rabbits were randomly distributed into a normal control group (NC group, six rabbits), a model control group (MC group, six rabbits), and a minimally invasive group (MI group, 24 rabbits). A model of ICH was established in the MC and MI groups. In the MI group, the intracerebral hematoma was evacuated by stereotactic minimally invasive procedures over 6 hours (six rabbits), 12 hours (six rabbits), 18 hours (six rabbits), and 24 hours (six rabbits), following successful induction of ICH. All animals were sacrificed within 48 hours after the hematoma was surgically evacuated. A neurological deficit score was determined, and the perihematomal MMP-9 level and the BBB permeability were measured.

RESULTS

The neurological deficit score, the perihematomal MMP-9 level, and the BBB permeability of the MI group were decreased significantly compared with the MC group. Performing the MI procedure 6-12 hours after ICH showed the most significant decrease in MMP-9, BBB permeability, and neurological deficit score.

CONCLUSION

The optimal time window of performing MI procedures for the intracerebral hematoma evacuation might be within 6-12 hours after hemorrhage.

Systematic review and meta-analysis of the efficacy of sphingosine-1-phosphate (S1P) receptor agonist FTY720 (fingolimod) in animal models of stroke

BACKGROUND AND PURPOSE

FTY720 (fingolimod) is a known sphingosine-1-phosphate (S1P) receptor agonist, which has been used in clinical trials for treating multiple sclerosis, renal transplantation, and decreasing reperfusion injury in heart, liver, and kidney. Most of these clinical trials have showed a positive effect. Especially, the trials of MS showed a reduction of relapse rate in FTY720-treated patients. Now, some animal experiments indicated that FTY720 could be a new compound available treatment for stroke patients by exerting neuroprotection via S1P1 mediated antiapoptotic mechanisms. Whether it could be effective in animals is unclear, so we conducted a systematic review to make it clear.

METHODS

We conducted a systematic review and meta-analysis of the efficacy of FTY720 in animal models of focal cerebral ischemia by electronic and manual searches of the literature. Data on study quality, FTY720 dose, time of administration, and outcome measured as infarct volume or functional deficit were extracted. Data from all studies were analyzed by means of a standardized mean difference meta-analysis.

RESULTS

Of the 19 identified studies, 9 were included. Among all the included studies, 178 animals were calculated for infarct size and 194 animals were assessed of neurological deficits. The methodological quality of the studies ranged from 2 to 10 according to a published 11-item quality scale. Of the nine studies selected, only one reported a negative result of FTY720. The result indicated that FTY720 reduced the infarct volume (SMD = -1.31, 95% CI -1.99 to -0.63) and improve the functional outcome (SMD = -1.61, 95% CI -2.17 to -1.05).

CONCLUSIONS

The data we included supporting FTY720 was a candidate drug for stroke, but it should be considered with caution. More good quality experimental studies should be performed to evaluate the safety of FTY720 in the future. Whether FTY720 is effective in aged animals that mimicked human with comorbidities like diabetes and hypertension should also be deliberated.

Evaluation of the hematoma consequences, neurobehavioral profiles, and histopathology in a rat model of pontine hemorrhage

OBJECT

Primary pontine hemorrhage (PPH) represents approximately 7% of all intracerebral hemorrhages (ICHs) and is a clinical condition of which little is known. The aim of this study was to characterize the early brain injury, neurobehavioral outcome, and long-term histopathology in a novel preclinical rat model of PPH.

METHODS

The authors stereotactically infused collagenase (Type VII) into the ventral pontine tegmentum of the rats, in accordance with the most commonly affected clinical region. Measures of cerebrovascular permeability (brain water content, hemoglobin assay, Evans blue, collagen Type IV, ZO-1, and MMP-2 and MMP-9) and neurological deficit were quantified at 24 hours postinfusion (Experiment 1). Functional outcome was measured over a 30-day period using a vertebrobasilar scale (the modified Voetsch score), open field, wire suspension, beam balance, and inclined-plane tests (Experiment 2). Neurocognitive ability was determined at Week 3 using the rotarod (motor learning), T-maze (working memory), and water maze (spatial learning and memory) (Experiment 3), followed by histopathological analysis 1 week later (Experiment 4).

RESULTS

Stereotactic collagenase infusion caused dose-dependent elevations in hematoma volume, brain edema, neurological deficit, and blood-brain barrier rupture, while physiological variables remained stable. Functional outcomes mostly normalized by Week 3, whereas neurocognitive deficits paralleled the cystic cavitary lesion at 30 days. Obstructive hydrocephalus did not develop despite a clinically relevant 30-day mortality rate (approximately 54%).

CONCLUSIONS

These results suggest that the model can mimic several translational aspects of pontine hemorrhage in humans and can be used in the evaluation of potential preclinical therapeutic interventions.

Minimally invasive procedures for intracerebral hematoma evacuation in early stages decrease perihematomal glutamate level and improve neurological function in a rabbit model of ICH

INTRODUCTION

To observe the effects of performing a minimally invasive procedure at different stages after intracerebral hemorrhage (ICH) on perihematomal glutamate level and neurological function.

METHODS

Forty-eight rabbits were randomly placed into a model control group (MC group, 24 rabbits) or a minimally invasive group (MI group, 24 rabbits). An ICH model was established in all of the animals. In the MI group, the ICH was evacuated by minimally invasive procedures in 6h (6 rabbits), 12h (6 rabbits), 18h (6 rabbits) and 24h (6 rabbits) after the ICH model was successfully induced. All of the animals were sacrificed within 48h after the hematoma was evacuated by surgery. A neurological deficit score was determined, and the perihematomal glutamate level and the BBB permeability were measured.

RESULTS

The neurological deficit score, perihematomal glutamate level and BBB permeability of the MI group were decreased significantly compared with the MC group. Performing the minimally invasive procedures in 6-12 h after ICH showed the most significant decreases of the glutamate level, BBB permeability and neurological deficit score.

CONCLUSIONS

The optimal time window of performing the minimally invasive procedures for the intracerebral hematoma evacuation might be within 6-12 h after hemorrhage.

Elevated blood pressure causes larger hematoma in a rat model of intracerebral hemorrhage

Hypertension has been recognized as an independent risk factor for intracerebral hemorrhage (ICH). The objective of this study was to assess the effect of chronically elevated blood pressure on amount of hematoma in a rat model of ICH. A total of 46 rats were divided into two groups-normotensive group (n = 18) and spontaneously hypertensive group (n = 28). To induce ICH, we delivered 2 μL of collagenase solution (0.1 U/1 μL normal saline) into the striatum. Each animal's brain was removed 24 h post-surgery for spectrophotometric hemoglobin assay. Equal or unequal variance t tests were performed to assess changes in variables between the hypertensive and normotensive groups. Tissue analysis revealed a statistically significant difference in optical density percent change at 540-nm wavelength for the hypertensive vs. the normotensive group (261.47 ± 103.68 and 133.33 ± 58.53, p < 0.0001, respectively). As compared to the normotensive rats, hypertensive rats exhibited a higher neurological deficit, loss of balance and coordination, and loss of motor function. Our results demonstrated that hypertensive rats had significantly higher amounts of hemorrhage in comparison to normotensive ones. These findings support the need for further adequately powered studies to investigate differences in amount of hematoma and corresponding functional impairments due to ICH among hypertensive vs. normotensive rats.

The pathophysiological time window study of performing minimally invasive procedures for the intracerebral hematoma evacuation in rabbit

The objective of this study was to observe the pathophysiological time window of performing minimally invasive procedures for the intracerebral hematoma evacuation. Thirty-six rabbits were randomly placed in either a normal control group (NC group, 6 rabbits), a model control group (MC group, 6 rabbits) or a minimally invasive group (MI group, 24 rabbits). A model of intracerebral hemorrhage (ICH) was established in the MC and MI groups. In the MI group, the intracerebral hematoma was evacuated by stereotactic minimally invasive procedures over 6h (6 rabbits), 12h (6 rabbits), 18 h (6 rabbits) and 24h (6 rabbits), following successful induction of ICH. All of the animals in each group were sacrificed 48 h after the successful induction of ICH. Perihematomal brain tissues were removed to determine the glutamate level, BBB permeability and brain water content (BWC). The perihematomal glutamate level, BBB permeability and the BWC in the MI group were significantly decreased compared with those of the MC group. Performing minimally invasive procedures for evacuation of ICH in 6h showed the most remarkable decrease of the glutamate level, BBB permeability and BWC, followed by a significant difference observed at 12h within the MI subgroups. Performing minimally invasive procedures in early stages after ICH for the hematoma evacuation could decrease the perihematomal glutamate level, BBB permeability and BWC significantly. The pathophysiological time window of minimally invasive procedures for hematoma evacuation might be 6-12h after hemorrhage.

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.

Comparison of humoral neuroinflammation and adhesion molecule expression in two models of experimental intracerebral hemorrhage

Background

Inflammatory cascades contribute to secondary injury after intracerebral hemorrhage (ICH) via humoral factors and cell-mediated cytotoxicity. Several experimental models were previously developed to analyze post-hemorrhagic neuroinflammation. However, neuroinflammatory markers have not been compared face-to-face between these models so far, and therefore, pathophysiological conclusions drawn from only one individual model may not be valid.

Methods

We compared neuroinflammatory pathways in the two most common murine models: striatal injection of autologous blood or collagenase. Expression of pro- and anti-inflammatory cytokines (IL-1, TNF-α, IFN-γ, IL-6, TGF-β and IL-10) as well adhesion molecule expression (VCAM-1, ICAM-1) was analyzed by RT-PCR at several time points after ICH induction. Outcome and physiological parameters were compared between the models.

Results

Both models induced a profound and dynamic increase in the expression of pro-inflammatory cytokines and adhesion molecules. However, blood injection resulted in significantly more pronounced alteration of these markers than collagenase injection. This difference was associated with worse outcome after blood injection compared to the collagenase model despite equal ICH volumes.

Conclusions

This is the first study performing a face-to-face comparison of neuroinflammatory pathways in the two most widely used murine ICH models, revealing substantial differences between the models. This discrepancies need to be taken into account in designing future studies employing experimental ICH models, especially when analyzing neuroinflammatory pathways and therapies.

Treatment of intracerebral hemorrhage in animal models: meta-analysis

OBJECTIVE

Interventions that improve functional outcome after acute intracerebral hemorrhage (ICH) in animals might benefit humans. Therefore, we systematically reviewed the literature to find studies of nonsurgical treatments tested in animal models of ICH.

METHODS

In July 2009 we searched Ovid Medline (from 1950), Embase (from 1980), and ISI Web of Knowledge (from 1969) for controlled animal studies of nonsurgical interventions given after the induction of ICH that reported neurobehavioral outcome. We assessed study quality and performed meta-analysis using a weighted mean difference random effects model.

RESULTS

Of 13,343 publications, 88 controlled studies described the effects of 64 different medical interventions (given a median of 2 hours after ICH induction) on 38 different neurobehavioral scales in 2,616 treated or control animals (median 14 rodents per study). Twenty-seven (31%) studies randomized treatment allocation, and 7 (8%) reported allocation concealment; these studies had significantly smaller effect sizes than those without these attributes (p < 0.001). Of 64 interventions stem cells, calcium channel blockers, anti-inflammatory drugs, iron chelators, and estrogens improved both structural outcomes and neurobehavioral scores in >1 study. Meta-regression revealed that together, structural outcome and the intervention used accounted for 65% of the observed heterogeneity in neurobehavioral score (p < 0.001, adjusted r(2) = 0.65).

INTERPRETATION

Further animal studies of the interventions that we found to improve both functional and structural outcomes in animals, using better experimental designs, could target efforts to translate effective treatments for ICH in animals into randomized controlled trials in humans.

The postpartum period of pregnancy worsens brain injury and functional outcome after cerebellar hemorrhage in rats

BACKGROUND

Intracerebral hemorrhage (ICH) is one of the most common causes of maternal deaths related to the postpartum period. This is a devastating form of stroke for which there is no available treatment. Although premenopausal females tend to have better outcomes after most forms of brain injury, the effects of pregnancy and child birth lead to wide maternal physiological changes that may predispose the mother to an increased risk for stroke and greater initial injury.

METHODS

Three different doses of collagenase were used to generate models of mild, moderate and severe cerebellar hemorrhage in postpartum female and male control rats. Brain water, blood-brain barrier rupture, hematoma size and neurological evaluations were performed 24 h later.

RESULTS

Postpartum female rats had worsened brain water, blood-brain barrier rupture, hematoma size and neurological evaluations compared to their male counterparts.

CONCLUSION

The postpartum state reverses the cytoprotective effects commonly associated with the hormonal neuroprotection of (premenopausal) female gender, and leads to greater initial injury and worsened neurological function after cerebellar hemorrhage. This experimental model can be used for the study of future treatment strategies after postpartum brain hemorrhage, to gain a better understanding of the mechanistic basis for stroke in this important patient subpopulation.

A novel preclinical model of germinal matrix hemorrhage using neonatal rats

BACKGROUND

Germinal matrix hemorrhage (GMH) is a neurological disorder associated with very low birth weight premature infants. This event can lead to post-hemorrhagic hydrocephalus, cerebral palsy, and mental retardation. This study developed a novel animal model for pre-clinical investigations.

METHODS

Neonatal rats underwent infusion of clostridial collagenase into the right germinal matrix (anterior caudate) region using stereotaxic techniques. Developmental milestones were evaluated over 10 days, cognitive function at 3 weeks, and sensorimotor function at 4 weeks after collagenase infusion. This was accomplished by anthropometric quantifications of cranial, cerebral, cardiac, and splenic growths.

RESULTS

Collagenase infusion led to delays in neonatal developmental milestones, followed by cognitive and sensorimotor dysfunctions in the juvenile animals. Cranial growth was accelerated during the first week after injury, and this was followed by significant brain atrophy, splenomegaly, and cardiac hypertrophy 3 weeks later.

CONCLUSION

This study characterized the developmental delays, mental retardation, and cerebral palsy features resembling the long-term clinical course after germinal matrix hemorrhage in premature infants. Pre-clinical testing of therapeutics in this experimental model could lead to improved patient outcomes while expanding upon the pathophysiological understanding of this disease.

History of preclinical models of intracerebral hemorrhage

In order to understand a disease process, effective modeling is required that can assist scientists in understanding the pathophysiological processes that take place. Intracerebral hemorrhage (ICH), a devastating disease representing 15% of all stroke cases, is just one example of how scientists have developed models that can effectively mimic human clinical scenarios. Currently there are three models of hematoma injections that are being used to induce an ICH in subjects. They include the microballoon model introduced in 1987 by Dr. David Mendelow, the bacterial collagenase injection model introduced in 1990 by Dr. Gary Rosenberg, and the autologous blood injection model introduced by Dr. Guo-Yuan Yang in 1994. These models have been applied on various animal models beginning in 1963 with canines, followed by rats and rabbits in 1982, pigs in 1996, and mice just recently in 2003. In this review, we will explore in detail the various injection models and animal subjects that have been used to study the ICH process while comparing and analyzing the benefits and disadvantages of each.

The persisting burden of intracerebral haemorrhage: can effective treatments be found?

Colin Josephson, Rustam Al-Shahi Salman, and colleagues discuss the effectiveness of treatments for intracerebral haemorrhage.