The interaction between depression and stroke is highly complex. Post‐stroke depression (PSD) is among the most frequent neuropsychiatric consequences of stroke. Depression also negatively impacts ...stroke outcome with increased morbidity, mortality and poorer functional recovery. Antidepressants such as the commonly prescribed selective serotonin reuptake inhibitors improve stroke outcome, an effect that may extend far beyond depression, e.g., to motor recovery. The main biological theory of PSD is the amine hypothesis. Conceivably, ischaemic lesions interrupt the projections ascending from midbrain and brainstem, leading to a decreased bioavailability of the biogenic amines – serotonin (5HT), dopamine (DA) and norepinephrine (NE). Acetylcholine would also be involved. So far, preclinical and translational research on PSD is largely lacking. The implementation and characterization of suitable animal models is clearly a major prerequisite for deeper insights into the biological basis of post‐stroke mood disturbances. Equally importantly, experimental models may also pave the way for the discovery of novel therapeutic targets. If we cannot prevent stroke, we shall try to limit its long‐term consequences. This review therefore presents animal models of PSD and summarizes potential underlying mechanisms including genomic signatures, neurotransmitter and neurotrophin signalling, hippocampal neurogenesis, cellular plasticity in the ischaemic lesion, secondary degenerative changes, activation of the hypothalamo‐pituitary‐adrenal (HPA) axis and neuroinflammation. As stroke is a disease of the elderly, great clinical benefit may especially accrue from deciphering and targeting basic mechanisms underlying PSD in aged animals.
•Experimental procedures did not require any manual animal handling.•Animals showed robust learning performance without dietary restrictions being applied.•A voluntary, automated radial 8-arm maze ...contributes to the application of 3R principles.
The radial arm maze (RAM) is a common behavioral test to assess spatial working and reference memory in mice. However, conventional RAM experiments require a substantial degree of manual handling and animals are usually subjected to prolonged periods of food or water deprivation to achieve sufficient learning motivation resulting in stress-induced confounding effects and unwanted intra- and inter-subject variation.
In a proof-of-concept approach to improve reliability and repeatability of results by refining the conventional maze methodology, we developed a voluntary, fully automated 8-arm RAM and tested its feasibility and usability using both spatial working and combined working/reference memory paradigms in ten female C57BL/6J mice.
We demonstrate that experimental procedures of up to 7 days duration could be conducted without any manual animal handling and that mice up to 18 months of age showed robust spatial learning performance without any food or water restrictions being applied.
Therefore, a voluntary, automated 8-arm RAM can serve to minimize variation in experimental results by reducing an animal’s distress, suffering, and pain, which, in turn, contributes to the comprehensive application of 3R principles.
► We characterized short- and long-term functional outcome in a mouse model of mild brain ischemia. ► Pole test is most suited for evaluation of functional deficits 1–3 weeks after ischemia. ► Corner ...test and adhesive removal test detect deficits for 3–4 weeks after mild ischemia. ► Catwalk and paw preference test are sensitive long-term tests of clinically relevant deficits. ► Corner rotation is a novel test that improves objectivity and applicability of classic corner test.
Evaluation of functional outcome over the course of several weeks after ischemia is a key component in improving the clinical relevance of experimental stroke studies. Using a battery of behavioral tests, we characterized functional outcome in mice over 4 weeks following 30min of proximal middle cerebral artery occlusion (MCAo). We evaluated rotarod, chimney, pole and cylinder tests to assess short term functional deficits in a transient stroke model which induces infarcts mainly in the striatum. The corner test, adhesive removal test, cylinder test, catwalk, paw preference test and novel tests of rotation were evaluated for long-term functional outcome. Rotarod detected deficits within the first week and pole test was reliable up to intermediate time points after MCAo. Corner test, adhesive removal test, catwalk and paw preference test detected deficits for up to 4 weeks, as did the novel corner rotation and bowl tests. Chimney and cylinder test did not prove useful in our model of mild stroke. In summary, we established the pole test and rotarod as useful tools to evaluate sensory motor deficits early after mild stroke, and corner test and adhesive removal test at later time-points. Alternatively, corner rotation may be a suitable test of long-term function. Test batteries may be further complemented by catwalk and paw preference test for clinically relevant deficits. There was no correlation of behavioral outcome with lesion size at 28 days, and determining whether these tests are useful for detecting a potential benefit of neuroprotective or regenerative therapies requires further testing.
Chemotherapy-induced peripheral neuropathy (CIPN) is a frequent, potentially irreversible adverse effect of cytotoxic chemotherapy often leading to a reduction or discontinuation of treatment which ...negatively impacts patients' prognosis. To date, however, neither predictive biomarkers nor preventive treatments for CIPN are available, which is partially due to a lack of suitable experimental models. We therefore aimed to evaluate whether sensory neurons derived from induced pluripotent stem cells (iPSC-DSN) can serve as human disease model system for CIPN. Treatment of iPSC-DSN for 24 h with the neurotoxic drugs paclitaxel, bortezomib, vincristine and cisplatin led to axonal blebbing and a dose dependent decline of cell viability in clinically relevant IC50 ranges, which was not observed for the non-neurotoxic compounds doxorubicin and 5-fluorouracil. Paclitaxel treatment effects were less pronounced after 24 h but prominent when treatment was applied for 72 h. Global transcriptome analyses performed at 24 h, i.e. before paclitaxel-induced cell death occurred, revealed the differential expression of genes of neuronal injury, cellular stress response, and sterol pathways. We further evaluated if known neuroprotective strategies can be reproduced in iPSC-DSN and observed protective effects of lithium replicating findings from rodent dorsal root ganglia cells. Comparing sensory neurons derived from two different healthy donors, we found preliminary evidence that these cell lines react differentially to neurotoxic drugs as expected from the variable presentation of CIPN in patients. In conclusion, iPSC-DSN are a promising platform to study the pathogenesis of CIPN and to evaluate neuroprotective treatment strategies. In the future, the application of patient-specific iPSC-DSN could open new avenues for personalized medicine with individual risk prediction, choice of chemotherapeutic compounds and preventive treatments.
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Stroke–Heart Syndrome: Recent Advances and Challenges Scheitz, Jan F.; Sposato, Luciano A.; Schulz‐Menger, Jeanette ...
Journal of the American Heart Association,
09/2022, Letnik:
11, Številka:
17
Journal Article
Recenzirano
Odprti dostop
After ischemic stroke, there is a significant burden of cardiovascular complications, both in the acute and chronic phase. Severe adverse cardiac events occur in 10% to 20% of patients within the ...first few days after stroke and comprise a continuum of cardiac changes ranging from acute myocardial injury and coronary syndromes to heart failure or arrhythmia. Recently, the term stroke–heart syndrome was introduced to provide an integrated conceptual framework that summarizes neurocardiogenic mechanisms that lead to these cardiac events after stroke. New findings from experimental and clinical studies have further refined our understanding of the clinical manifestations, pathophysiology, and potential long‐term consequences of the stroke–heart syndrome. Local cerebral and systemic mediators, which mainly involve autonomic dysfunction and increased inflammation, may lead to altered cardiomyocyte metabolism, dysregulation of (tissue‐resident) leukocyte populations, and (micro‐) vascular changes. However, at the individual patient level, it remains challenging to differentiate between comorbid cardiovascular conditions and stroke‐induced heart injury. Therefore, further research activities led by joint teams of basic and clinical researchers with backgrounds in both cardiology and neurology are needed to identify the most relevant therapeutic targets that can be tested in clinical trials.
Cerebral edema caused by the disruption of the blood-brain barrier is a major complication after stroke. Therefore, strategies to accelerate and enhance neurovascular recovery after stroke are of ...prime interest. Our main aim was to study the role of ephrinB2/EphB4 signaling in mediating the vascular repair and in blood-brain barrier restoration after mild cerebral ischemia occlusion/reperfusion.
Here, we show that the guidance molecule ephrinB2 plays a key role in neurovascular protection and blood-brain barrier restoration after stroke. In a focal stroke model, we characterize the stroke-induced damage to cerebral blood vessels and their subsequent endogenous repair on a cellular, molecular, and functional level. EphrinB2 and its tyrosine kinase receptor EphB4 are upregulated early after stroke by endothelial cells and perivascular support cells, in parallel to their reassembly during neurovascular recovery. Using both retroviral and pharmacological approaches, we show that the inhibition of ephrinB2/EphB4 signaling suppresses post-middle cerebral artery occlusion neurovascular repair mechanisms resulting in an aggravation of brain swelling. In contrast, the activation of ephrinB2 after brain ischemia leads to an increased pericyte recruitment and increased endothelial-pericyte interaction, resulting in an accelerated neurovascular repair after ischemia.
We show that reducing swelling could result in improved outcome because of reduction in damaged brain tissue. We also identify a novel role for ephrinB2/EphB4 signaling in the maintenance of the neurovascular homeostasis and provide a novel therapeutic approach in reducing brain swelling after stroke.
Peri-infarct depolarizations (PIDs) are seemingly spontaneous spreading depression-like waves that negatively impact tissue outcome in both experimental and human stroke. Factors triggering PIDs are ...unknown. Here, we show that somatosensory activation of peri-infarct cortex triggers PIDs when the activated cortex is within a critical range of ischemia. We show that the mechanism involves increased oxygen utilization within the activated cortex, worsening the supply-demand mismatch. We support the concept by clinical data showing that mismatch predisposes stroke patients to PIDs as well. Conversely, transient worsening of mismatch by episodic hypoxemia or hypotension also reproducibly triggers PIDs. Therefore, PIDs are triggered upon supply-demand mismatch transients in metastable peri-infarct hot zones due to increased demand or reduced supply. Based on the data, we propose that minimizing sensory stimulation and hypoxic or hypotensive transients in stroke and brain injury would reduce PID incidence and their adverse impact on outcome.
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•Sensory stimuli, episodic hypoxia, or hypotension trigger peri-infarct depolarizations•Mechanism involves transient worsening in O2 supply-demand mismatch in penumbra•In light of the data, clinical management of brain injury may need to be revisited
Peri-infarct depolarizations (PIDs) worsen tissue outcome in stroke. Von Bornstädt et al. show that somatosensory activation, and episodic hypoxemia or hypotension all trigger PIDs by worsening the oxygen supply-demand mismatch. Therefore, minimizing sensory stimulation and hypoxic or hypotensive transients may be beneficial in acute brain injury.
Summary Background Many patients with stroke are precluded from thrombolysis treatment because the time from onset of their symptoms is unknown. We aimed to test whether a mismatch in visibility of ...an acute ischaemic lesion between diffusion-weighted MRI (DWI) and fluid-attenuated inversion recovery (FLAIR) MRI (DWI-FLAIR mismatch) can be used to detect patients within the recommended time window for thrombolysis. Methods In this multicentre observational study, we analysed clinical and MRI data from patients presenting between Jan 1, 2001, and May 31, 2009, with acute stroke for whom DWI and FLAIR were done within 12 h of observed symptom onset. Two neurologists masked to clinical data judged the visibility of acute ischaemic lesions on DWI and FLAIR imaging, and DWI-FLAIR mismatch was diagnosed by consensus. We calculated predictive values of DWI-FLAIR mismatch for the identification of patients with symptom onset within 4·5 h and within 6 h and did multivariate regression analysis to identify potential confounding covariates. This study is registered with ClinicalTrials.gov , number NCT01021319. Findings The final analysis included 543 patients. Mean age was 66·0 years (95% CI 64·7–67·3) and median National Institutes of Health Stroke Scale score was 8 (IQR 4–15). Acute ischaemic lesions were identified on DWI in 516 patients (95%) and on FLAIR in 271 patients (50%). Interobserver agreement for acute ischaemic lesion visibility on FLAIR imaging was moderate (κ=0·569, 95% CI 0·504–0·634). DWI-FLAIR mismatch identified patients within 4·5 h of symptom onset with 62% (95% CI 57–67) sensitivity, 78% (72–84) specificity, 83% (79–88) positive predictive value, and 54% (48–60) negative predictive value. Multivariate regression analysis identified a longer time to MRI (p<0·0001), a lower age (p=0·0009), and a larger DWI lesion volume (p=0·0226) as independent predictors of lesion visibility on FLAIR imaging. Interpretation Patients with an acute ischaemic lesion detected with DWI but not with FLAIR imaging are likely to be within a time window for which thrombolysis is safe and effective. These findings lend support to the use of DWI-FLAIR mismatch for selection of patients in a future randomised trial of thrombolysis in patients with unknown time of symptom onset. Funding Else Kröner-Fresenius-Stiftung, National Institutes of Health.
Poststroke angiogenesis contributes to long-term recovery after stroke. Signal transducer and activator of transcription-3 (Stat3) is a key regulator for various inflammatory signals and ...angiogenesis. It was the aim of this study to determine its function in poststroke outcome.
We generated a tamoxifen-inducible and endothelial-specific Stat3 knockout mouse model by crossbreeding Stat3(floxed/KO) and Tie2-Cre(ERT2) mice. Cerebral ischemia was induced by 30 minutes of middle cerebral artery occlusion. We demonstrated that endothelial Stat3 ablation did not alter lesion size 2 days after ischemia but did worsen functional outcome at 14 days and increase lesion size at 28 days. At this late time point vascular Stat3 expression and phosphorylation were still increased in wild-type mice. Gene array analysis of a CD31-enriched cell population of the neurovascular niche showed that endothelial Stat3 ablation led to a shift toward an antiangiogenic and axon growth-inhibiting micromilieu after stroke, with an increased expression of Adamts9. Remodeling and glycosylation of the extracellular matrix and microglia proliferation were increased, whereas angiogenesis was reduced.
Endothelial Stat3 regulates angiogenesis, axon growth, and extracellular matrix remodeling and is essential for long-term recovery after stroke. It might serve as a potent target for stroke treatment after the acute phase by fostering angiogenesis and neuroregeneration.
Statins reduce the risk for myocardial infarctions and stroke which may in part depend on cholesterol-independent (pleiotropic) vasoprotective effects. Here, we review evidence to suggest that the ...abrupt discontinuation of statin medication exerts negative vascular effects in patients with acute vascular events.
It is increasingly recognized that statins (HMG-CoA reductase inhibitors) exert rapid cholesterol-independent effects. Cessation of statin treatment confers overshoot activation of heterotrimeric G-proteins Rho and Rac causing production of reactive oxygen species and suppression of NO bioavailability. In humans, discontinuation of statin therapy leads to a proinflammatory, prothrombotic state with impaired endothelium function. In patients with acute coronary syndromes, abrupt discontinuation of statin therapy significantly increases morbidity and mortality, whereas in stable vascular patients discontinuation may be safe. Recent prospective data indicated that the cessation of statin medication in acute ischemic stroke patients confers a significantly higher likelihood of early neurological deterioration and poor outcome.
We propose that in all acute ischemic stroke patients chronically treated with statins before the event, treatment should be continued and the patient should receive medication at the day of the stroke.
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