Translating basic science research to clinical application: models and strategies for intracerebral hemorrhage

Protective Effects of Adropin in Experimental Subarachnoid Hemorrhage

PURPOSE

We aimed to investigate early effects of exogenously administered adropin (AD) on neurological function, endothelial nitric oxide synthase (eNOS) expression, nitrite/nitrate levels, oxidative stress, and apoptosis in subarachnoid hemorrhage (SAH).

METHODS

Following intracerebroventricular AD administration (10 µg/5 µl at a rate of 1 µl/min) SAH model was carried out in Sprague-Dawley rats by injection of autologous blood into the prechiasmatic cistern. The effects of AD were assessed 24 h following SAH. The modified Garcia score was employed to evaluate functional insufficiencies. Adropin and caspase-3 proteins were measured by ELISA, while nitrite/nitrate levels, total antioxidant capacity (TAC) and reactive oxygen/nitrogen species (ROS/RNS) were assayed by standard kits. eNOS expression and apoptotic neurons were detected by immunohistochemical analysis.

RESULTS

The SAH group performed notably lower on the modified Garcia score compared to sham and SAH + AD groups. Adropin administration increased brain eNOS expression, nitrite/nitrate and AD levels compared to SHAM and SAH groups. SAH produced enhanced ROS/RNS generation and reduced antioxidant capacity in the brain. Adropin boosted brain TAC and diminished ROS/RNS production in SAH rats and no considerable change amongst SHAM and SAH + AD groups were detected. Apoptotic cells were notably increased in intensity and number after SAH and were reduced by AD administration.

CONCLUSIONS

Adropin increases eNOS expression and reduces neurobehavioral deficits, oxidative stress, and apoptotic cell death in SAH model. Presented results indicate that AD provides protection in early brain injury associated with SAH.

Establishment of a rat model of severe spontaneous intracerebral hemorrhage

Background

Severe intracerebral hemorrhage (ICH) is the most devastating subtype of stroke resulting in high mortality and disability. At present, the development of targeted treatments to minimize the high morbidity and mortality is limited partly due to the lack of a severe ICH animal model. In this study, we aimed to establish an accurate severe ICH model in rats and examine the pathological and physiological changes associated with ICH.

Methods

A rat model of severe ICH model was established by intrastriatal injection of autologous blood using different blood volumes (ICH 100 µL group, ICH 130 µL group, ICH 160 µL group, ICH 170 µL group, and ICH 180 µL group). The mortality was assessed during the 28-day post-ICH period. Short- and long-term neurological deficits were evaluated using the Longa method, foot fault, falling latency, and Morris water maze tests. Brain water content, hematoma volume, hemoglobin content, and magnetic resonance imaging were assessed to determine the extent of brain injury. Immunofluorescence staining was conducted to examine microglial activation and neuronal apoptosis. Hematoxylin and eosin (H&E) staining, lung water content, and western blotting were used to assess lung injury following ICH.

Results

The mortality of ICH rats increased significantly with an increase in autologous blood injection. The 28-day mortality in the 100 µL, 130 µL, 160 µL, 170 µL, and 180 µL ICH groups were 5%, 20%, 40%, 75%, and 100%, respectively. A significantly higher 28-day mortality was observed in the ICH 160 µL group compared to the ICH 100 µL group. The ICH 160 µL group exhibited significantly increased neurological deficits, brain edema, hematoma volume, and hemoglobin content compared to the sham group. Compared with the sham operation group, the activation of microglia and neuronal death in ICH 160 µL rats increased. The use of H&E staining and western blotting demonstrated that disruption of the intra-alveolar structure, alveolar edema, and infiltration of inflammatory cells and cytokines into the lung tissue were more severe in the ICH 160 µL group than the sham group.

Conclusions

A severe ICH model in rats was successfully established using an injection of autologous blood at a volume of 160 µL. This model may provide a valuable tool to examine the pathological mechanisms and potential therapeutic interventions of severe ICH.

Early Brain Injury After Subarachnoid Hemorrhage: Incidence and Mechanisms

Aneurysmal subarachnoid hemorrhage is a devastating condition causing significant morbidity and mortality. While outcomes from subarachnoid hemorrhage have improved in recent years, there continues to be significant interest in identifying therapeutic targets for this disease. In particular, there has been a shift in emphasis toward secondary brain injury that develops in the first 72 hours after subarachnoid hemorrhage. This time period of interest is referred to as the early brain injury period and comprises processes including microcirculatory dysfunction, blood-brain-barrier breakdown, neuroinflammation, cerebral edema, oxidative cascades, and neuronal death. Advances in our understanding of the mechanisms defining the early brain injury period have been accompanied by improved imaging and nonimaging biomarkers for identifying early brain injury, leading to the recognition of an elevated clinical incidence of early brain injury compared with prior estimates. With the frequency, impact, and mechanisms of early brain injury better defined, there is a need to review the literature in this area to guide preclinical and clinical study.

A transcriptomic analysis of cerebral microvessels reveals the involvement of Notch1 signaling in endothelial mitochondrial-dysfunction-dependent BBB disruption

Background

Endothelial cells (ECs) in cerebral vessels are considered the primary targets in acute hemorrhagic brain injuries. EC dysfunction can aggravate neuronal injuries by causing secondary inflammatory responses and blood–brain barrier (BBB) disruption. Previous studies have reported that enhancement of mitochondrial function within ECs may reduce BBB disruption and decrease the severity of acute brain injuries. However, the molecular signaling pathways through which enhanced EC mitochondrial function is enhanced to exert this BBB protective effect have not been fully elucidated.

Methods

To identify signaling pathways involved in linking EC-specific mitochondrial dysfunction and BBB disruption, we first performed RNA sequencing using isolated cerebral vessels from TEKCRIF1 KO mice, a mouse strain that displays EC-specific mitochondrial dysfunction. After identification, we assessed the significance of candidate signaling pathways using an intracerebral hemorrhage (ICH) mouse model. BBB integrity was assessed using an IgG leakage assay, and symptomatic changes were evaluated using behavioral assays.

Results

Transcriptome analyses of the TEKCRIF1 KO mouse revealed significant changes in Notch1 signaling, a pathway intimately involved in BBB maintenance. We also observed a decrease in Notch1 signaling and expression of the mitochondrial oxidative phosphorylation (OxPhos) complex in the ICH mouse model, which also exhibits BBB disruption. To further assess the function of Notch1 signaling in relation to BBB disruption, we injected ICH model mice with adropin, a protein that interacts with the Notch1 ligand NB-3 and activates Notch1 signaling. We found that adropin prevented BBB disruption and reduced the extent (area) of the injury compared with that in vehicle controls, in association with alteration of mitochondrial function.

Conclusion

These results suggest that the Notch1 signaling pathway acts as an upstream regulator of DEGs and can be a target to regulate the changes involved with endothelial mitochondrial dysfunction-dependent BBB disruption. Thus, treatment methods that activate Notch1 may be beneficial in acute brain injuries by protecting BBB integrity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12987-022-00363-7.

Translational Intracerebral Hemorrhage Research: Has Current Neuroprotection Research ARRIVEd at a Standard for Experimental Design and Reporting?

One major aim of preclinical intracerebral hemorrhage (ICH) research is to develop and test potential neuroprotectants. Published guidelines for experimental design and reporting stress the importance of clearly and completely reporting results and methodological details to ensure reproducibility and maximize information availability. The current review has two objectives: first, to characterize current ICH neuroprotection research and, second, to analyze aspects of translational design in preclinical ICH studies. Translational design is the adoption and reporting of experimental design characteristics that are thought to be clinically relevant and critical to reproducibility in animal studies (e.g., conducting and reporting experiments according to the STAIR and ARRIVE guidelines, respectively). Given that ICH has no current neuroprotective treatments and an ongoing reproducibility crisis in preclinical research, translational design should be considered by investigators. We conducted a systematic review of ICH research from 2015 to 2019 using the PubMed database. Our search returned 281 published manuscripts studying putative neuroprotectants in animal models. Contemporary ICH research predominantly uses young, healthy male rodents. The collagenase model is the most commonly used. Reporting of group sizes, blinding, and randomization are almost unanimous, but group size calculations, mortality and exclusion criteria, and animal model characteristics are infrequently reported. Overall, current ICH neuroprotection research somewhat aligns with experimental design and reporting guidelines. However, there are areas for improvement. Because failure to consider translational design is associated with inflation of effect sizes (and possibly hindered reproducibility), we suggest that researchers, editors, and publishers collaboratively consider enhanced adherence to published guidelines.

Neuroprotective functions of calycosin against intracerebral hemorrhage-induced oxidative stress and neuroinflammation

Aim: To investigate whether calycosin affects the brain damages induced by intracerebral hemorrhage (ICH). Methods: ICH mouse model was established by injection of collagenase type VII. Results: 50 mg/kg calycosin showed significant inhibitory effects on ICH-induced brain impairment evaluated by modified neurologic severity scores and water content. In addition, the lesion volumes, blood accumulation and hemispheric enlargement were all dramatically reduced by calycosin treatment compared with those of vehicles. It was observed that calycosin repressed oxidative stress by enhancing Nrf2 anti-oxidative pathway and suppressed inflammation by blocking NACHT, NALP3 inflammasome and NF-κB pathway activation. Conclusion: Calycosin could protect the brain against the damages induced by ICH via inhibiting oxidative damages and inflammation.

Uncovering the Rosetta Stone: Report from the First Annual Conference on Key Elements in Translating Stroke Therapeutics from Pre-Clinical to Clinical

The first annual Stroke Translational Research Advancement Workshop (STRAW), entitled “Uncovering the Rosetta Stone: Key Elements in Translating Stroke Therapeutics from Pre-Clinical to Clinical” was held at the University of Kentucky on October 4–5, 2017. This workshop was organized by the Center for Advanced Translational Stroke Science. The workshop consisted of 2 days of activities. These included three presentations establishing the areas of research in stroke therapeutics, discussing the routes for translation from bench to bedside, and identifying successes and failures in the field. On day 2, grant funding opportunities and goals for the National Institute for Neurological Diseases and Stroke were presented. In addition, the meeting also included break-out sessions designed to connect researchers in areas of stroke, and to foster potential collaborations. Finally, the meeting concluded with an open discussion among attendees led by a panel of experts.

A Comparison of Pathophysiology in Humans and Rodent Models of Subarachnoid Hemorrhage

Non-traumatic subarachnoid hemorrhage (SAH) affects an estimated 30,000 people each year in the United States, with an overall mortality of ~30%. Most cases of SAH result from a ruptured intracranial aneurysm, require long hospital stays, and result in significant disability and high fatality. Early brain injury (EBI) and delayed cerebral vasospasm (CV) have been implicated as leading causes of morbidity and mortality in these patients, necessitating intense focus on developing preclinical animal models that replicate clinical SAH complete with delayed CV. Despite the variety of animal models currently available, translation of findings from rodent models to clinical trials has proven especially difficult. While the explanation for this lack of translation is unclear, possibilities include the lack of standardized practices and poor replication of human pathophysiology, such as delayed cerebral vasospasm and ischemia, in rodent models of SAH. In this review, we summarize the different approaches to simulating SAH in rodents, in particular elucidating the key pathophysiology of the various methods and models. Ultimately, we suggest the development of standardized model of rodent SAH that better replicates human pathophysiology for moving forward with translational research.

Experimental subarachnoid hemorrhage in rats: comparison of two endovascular perforation techniques with respect to success rate, confounding pathologies and early hippocampal tissue lesion pattern

Recently aside from the “classic” endovascular monofilament perforation technique to induce experimental subarachnoid hemorrhage (SAH) a modification using a tungsten wire advanced through a guide tube has been described. We aim to assess both techniques for their success rate (induction of SAH without confounding pathologies) as primary endpoint. Further, the early tissue lesion pattern as evidence for early brain injury will be analyzed as secondary endpoint. Sprague Dawley rats (n=39) were randomly assigned to receive either Sham surgery (n=4), SAH using the “classic” technique (n=18) or using a modified technique (n=17). Course of intracranial pressure (ICP) and regional cerebral blood flow (rCBF) was analyzed; subsequent pathologies were documented either 6 or 24 h after SAH. Hippocampal tissue samples were analyzed via immunohistochemistry and western blotting. SAH-induction, regardless of confounding pathologies, was independent from type of technique (p=0.679). There was no significant difference concerning case fatality rate (classic: 40%; modified: 20%; p=0.213). Successful induction of SAH without collateral ICH or SDH was possible in 40% with the classic and in 86.7% with the modified technique (p=0.008). Peak ICP levels differed significantly between the two groups (classic: 94 +/- 23 mmHg; modified: 68 +/- 19 mmHg; p=0.003). Evidence of early cellular stress response and activation of apoptotic pathways 6 h after SAH was demonstrated. The extent of stress response is not dependent on type of technique. Both tested techniques successfully produce SAH including activation of an early stress response and apoptotic pathways in the hippocampal tissue. However, the induction of SAH with less confounding pathologies was more frequently achieved with the modified tungsten wire technique.

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.

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

OBJECTIVES

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

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

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