Coupling of neurogenesis and angiogenesis after ischemic stroke

Effectiveness of physiotherapy interventions in brain plasticity, balance and functional ability in stroke survivors: A randomized controlled trial

BACKGROUND

Brain injuries such as strokes cause damage and death of the neuron cells. Physiotherapy interventions help to improve patient's performance and ability. However, this is only theorized but the impact of the physiotherapy intervention on brain plasticity is not known.

OBJECTIVE

The present study aimed to investigate the effect of physiotherapy interventions on brain neuroplasticity by evaluating the brain plasticity regeneration, balance and functional ability.

METHODS

A randomized controlled trial was conducted with 64 stroke patients from three hospitals in the Surakarta region, Indonesia. Control groups (n = 32) received conventional physiotherapy and intervention groups (n = 32) received neurorestoration protocol, which both lasted for seven days. Efficacy of the interventions were measured on brain-derived neurotropic factor serum analysis, Berg Balance Scale and Barthel Index, respectively.

RESULTS

Both groups showed improvements in all parameters but only balance and functional performance had a statistically significant outcome.

CONCLUSION

Neurorestoration protocol that combined several established physiotherapy interventions was effective in improving balance and functional ability of stroke patients in only a seven days period.

Delayed Exercise-induced Upregulation of Angiogenic Proteins and Recovery of Motor Function after Photothrombotic Stroke in Mice

Treatments promoting post-stroke functional recovery continue to be an unmet therapeutic problem with physical rehabilitation being the most reproduced intervention in preclinical and clinical studies. Unfortunately, physiotherapy is typically effective at high intensity and early after stroke - requirements that are hardly attainable by stroke survivors. The aim of this study was to directly evaluate and compare the dose-dependent effect of delayed physical rehabilitation (daily 5 h or overnight voluntary wheel running; initiated on post-stroke day 7 and continuing through day 21) on recovery of motor function in the mouse photothrombotic model of ischemic stroke and correlate it with angiogenic potential of the brain. Our observations indicate that overnight but not 5 h access to running wheels facilitates recovery of motor function in mice in grid-walking test. Western blotting and immunofluorescence microscopy experiments evaluating the expression of angiogenesis-associated proteins VEGFR2, doppel and PDGFRβ in the peri-infarct and corresponding contralateral motor cortices indicate substantial upregulation of these proteins (≥2-fold) in the infarct core and surrounding cerebral cortex in the overnight running mice on post-stroke day 21. These findings indicate that there is a dose-dependent relationship between the extent of voluntary exercise, motor recovery and expression of angiogenesis-associated proteins in this expert-recommended mouse ischemic stroke model. Notably, our observations also point out to enhanced angiogenesis and presence of pericytes within the infarct core region during the chronic phase of stroke, suggesting a potential contribution of this tissue area in the mechanisms governing post-stroke functional recovery.

Isoliquiritin exert protective effect on telencephalon infarction injury by regulating multi-pathways in zebrafish model of ischemic stroke

BACKGROUND

Ischemic stroke is a multifactorial disease contributing to mortality and neurological dysfunction. Isoliquiritin (ISL) has been reported to possess a series of pharmacological activities including antioxidant, anti-inflammatory, antifungal, anti-depression, anti-neurotoxicity and pro-angiogenesis activities but whether it can be used for ischemic stroke treatment remains unknown.

PURPOSE

The goal of this study is to explore its therapeutic effect on ischemic stroke and demonstrated the potential mechanism of ISL in zebrafish model.

METHODS

Using the photothrombotic-induced adult zebrafish model of ischemic stroke, we visualized the telencephalon (Tel) and optic tectum (OT) infarction injury at 24 h post-light exposure for 30 min by TTC and H&E staining. The effect of ISL on neurological deficits was analyzed during open tank swimming by video tracking. The antioxidant activity against ischemia injury was quantified by SOD, GSH-Px and MDA assay. Transcriptome analysis of zebrafish Tel revealed how ISL regulating gene expression to exert protective effect, which were also been validated by real-time quantitative PCR assays.

RESULTS

We found for the first time that the Tel tissue was the first damaged site of the whole brain and it showed more sensitivity to the brain ischemic damage compared to the OT. ISL reduced the rate of Tel injury, ameliorated neurological deficits as well as counteracted oxidative damages by increasing SOD, GSH-Px and decreasing MDA activity. GO enrichment demonstrated that ISL protected membrane and membrane function as well as initiate immune regulation in the stress response after ischemia. KEGG pathway analysis pointed out that immune-related pathways, apoptosis as well as necroptosis pathways were more involved in the protective mechanism of ISL. Furthermore, the log2 fold change in expression pattern of 25 genes detected by qRT-PCR was consistent with that by RNA-seq.

CONCLUSIONS

Tel was highly sensitive to the brain ischemia injury in zebrafish model of ischemic stroke. ISL significantly exerted protective effect on Tel injury, neurological deficits and oxidative damages. ISL could regulate a variety of genes related to immune, apoptosis and necrosis pathways against complex cascade reaction after ischemia. These findings enriched the study of ISL, making it a novel multi-target agent for ischemic stroke treatment.

Angiopoietin-like 4 promotes angiogenesis and neurogenesis in a mouse model of acute ischemic stroke

OBJECTIVE

The purpose of the present study is to investigate whether angiopoietin-like 4 (ANGPTL4) can promote angiogenesis and neurogenesis following stroke, as well as to explore the potential underlying mechanisms.

METHODS

ANGPTL4 (40 μg/kg) or a vehicle was administered via tail vein beginning 5 min prior to electrocoagulation-induced stroke in male C57/B6 J mice. Infarct volume was measured via Nissl staining at day 3 post-stroke. Angiogenesis, neurogenesis and activation of microglia were evaluated by immunofluorescence co-labelling bromodeoxyuridine (BrdU) with von Willebrand factor (vWF), doublecortin (DCX), neuronal nuclei (NeuN) and Iba1 at day 7 post-stroke. The levels of p-AKT, T-AKT, VEGF, MPO, Fas and FasL in the ipsilesional brain were detected by Western blot analysis at day 1 post-stroke.

RESULTS

Compared with the Vehicle group, ANGPTL4 reduced infarct volume significantly at day 3 post-stroke. ANGPTL4 significantly increased the number of BrdU+, BrdU+/vWF+and BrdU+/DCX+ cells in the peri-infarct zone, subventricular zone and subgranular zone and inhibited BrdU+/Iba1+ cells in the peri-infarct zone at day 7 post-stroke. The level of p-AKT and the ratio of phospho-AKT to total-AKT in the ipsilesional brain were significantly elevated, the levels of MPO, Fas and FasL were significantly declined; however, there was no significant difference at day 1 post-stroke between the VEGF and total-AKT levels in both groups.

CONCLUSIONS

ANGPTL4 enhances angiogenesis and neurogenesis post-stroke by upregulating the phosphorylation of AKT, reduces neuronal death and inhibits inflammatory response, which resultes from the inhibition of FasL/Fas expression and its downstream pathway.

Promotion of Momordica Charantia polysaccharides on neural stem cell proliferation by increasing SIRT1 activity after cerebral ischemia/reperfusion in rats

The deacetylase SIRT1 has been reported to play a critical role in regulating neurogenesis, which may be an adaptive processes contributing to recovery after stroke. Our previous work showed that the antioxidant capacity of Momordica charantia polysaccharides (MCPs) could protect against cerebral ischemia/reperfusion (I/R) after stroke. However, whether the protective effect of MCPs on I/R injury is related to neural stem cell (NSC) proliferation remains unclear. In the present study, we designed invivo and invitro experiments to elucidate the underlying mechanisms by which MCPs promote endogenous NSC proliferation during cerebral I/R. Invivo results showed that MCPs rescued the memory and learning abilities of rats after I/R damage and enhanced NSC proliferation in the rat subventricular zone (SVZ) and subgrannular zone (SGZ) during I/R. Invitro experiments demonstrated that MCPs could stimulate the proliferation of C17.2 cells under oxygen-glucose deprivation (OGD) conditions. Further studies revealed that the proliferation-promoting mechanism of MCPs relied on increasing the activity of SIRT1, decreasing the level of acetylation of β-catenin in the cytoplasm, and then triggering the translocation of β-catenin into the nucleus. These data provide experimental evidence that the up-regulation of SIRT1 activity by MCPs led to an increased cytoplasmic deacetylation of β-catenin, which promoted translocation of β-catenin to the nucleus to participate in the signaling pathway involved in NSC proliferation. The present study reveals that MCPs function as a therapeutic drug to promote stroke recovery by increasing the activity of SIRT1, decreasing the level of acetylated β-catenin, promoting the nuclear translocation of β-catenin and thereby increasing endogenous NSC proliferation.

Fuyuan Xingnao Decoction Promotes Angiogenesis Through the Rab1/AT1R Pathway in Diabetes Mellitus Complicated With Cerebral Infarction

Fuyuan Xingnao decoction (FYXN), a traditional Chinese formula comprised of seven herbs, has been utilized to treat diabetes mellitus complicated with cerebral infarction (DMCI) for years. Yet, its protective and regulatory mechanism is poorly understood. The aim of the study is to investigate the effects of FYXN on DMCI in vitro and in vivo, as well as its mechanism in angiogenesis. For in vivo experiments, FYXN was administered to DMCI rats with streptozotocin (STZ) injection-induced diabetes. Then middle cerebral artery occlusion (MCAO) was conducted and the cerebral cortex sections of the rats were obtained. The ultrastructure of cerebral microvessels and new vessel density of ischemic penumbra were evaluated by the transmission electron microscopy (TEM) assay and immunohistochemistry, respectively. Protein and mRNA expression levels of Rab1/AT1R in cortex were assayed by Western blotting and real-time fluorescence quantitative real-time polymerase chain reaction (RT-qPCR). In vitro, FYXN serum was produced in rats on the fourth day 2 h after the last FYXN administration. Green fluorescence was observed after transfection with lentivirus packaged Rab1-WT or siRNA for 24 h. The activity of brain microvascular endothelial cells (BMECs) treated with sera from these rats was tested by MTT assay and Transwell assays, respectively. The expression of AT1R on the cell membrane and endoplasmic reticulum of BMECs was evaluated by immunofluorescence staining. Protein expression levels of signaling molecules in the Rab1/AT1R pathways were also detected. Results showed that in vivo, FYXN treatment significantly intensified CD31 staining in the cortical areas and enhanced the mRNA and protein levels of AT1R, Ang II, Rab1a, Rab1b and VEGF expression in ischemic cerebral cortex tissues. In vitro, the expression levels of AT1R, Ang II, Rab1a, Rab1b and VEGF in the cerebral infarction model group were significantly higher than those in the control group, with further increases after administration of FYXN drug serum. FYXN promoted the proliferation and migration of BMECs by activating the Rab1/AT1R signaling pathway. In conclusion, FYXN exerts a protective effect against DMCI by promoting angiogenesis via the Rab1/AT1R pathway, which provides strong evidence for the therapeutic effect of FYXN on DMCI.

XQ-1H promotes cerebral angiogenesis via activating PI3K/Akt/GSK3β/β-catenin/VEGF signal in mice exposed to cerebral ischemic injury

Stroke still ranks as a most lethal disease worldwide. Angiogenesis during the chronic phase of ischemic stroke can alleviate ischemic injury and attenuate neurological deficit. XQ-1H is a new compound derived from the structure modification of ginkgolide B, which exerts anti-inflammation and neuroprotection against cerebral ischemic injury during the acute or subacute phase. However, whether XQ-1H facilitates angiogenesis and neural functional recovery during the chronic phase remains unclear. This research was designed to explore whether XQ-1H promotes angiogenesis after ischemic stroke and to preliminarily elucidate the mechanism. In vitro, XQ-1H was found to facilitate proliferation, migration and tube formation in bEnd.3 cells. In vivo, XQ-1H raised the CD31 positive microvessel number and increased focal cerebral blood flow in mice exposed to cerebral ischemic injury, and improved the neurological function. Mechanism studies revealed that XQ-1H exerted angiogenesis promoting effect via the PI3K/Akt/GSK3β/β-catenin/VEGF signal pathway, which was reversed by LY294002 (the specific inhibitor of PI3K/Akt). In conclusion, XQ-1H exerts angiogenetic effect both in vivo and in vitro, which is a potential agent against ischemic stroke during chronic phase.

Cellular Mechanisms Participating in Brain Repair of Adult Zebrafish and Mammals after Injury

Adult neurogenesis is an evolutionary conserved process occurring in all vertebrates. However, striking differences are observed between the taxa, considering the number of neurogenic niches, the neural stem cell (NSC) identity, and brain plasticity under constitutive and injury-induced conditions. Zebrafish has become a popular model for the investigation of the molecular and cellular mechanisms involved in adult neurogenesis. Compared to mammals, the adult zebrafish displays a high number of neurogenic niches distributed throughout the brain. Furthermore, it exhibits a strong regenerative capacity without scar formation or any obvious disabilities. In this review, we will first discuss the similarities and differences regarding (i) the distribution of neurogenic niches in the brain of adult zebrafish and mammals (mainly mouse) and (ii) the nature of the neural stem cells within the main telencephalic niches. In the second part, we will describe the cascade of cellular events occurring after telencephalic injury in zebrafish and mouse. Our study clearly shows that most early events happening right after the brain injury are shared between zebrafish and mouse including cell death, microglia, and oligodendrocyte recruitment, as well as injury-induced neurogenesis. In mammals, one of the consequences following an injury is the formation of a glial scar that is persistent. This is not the case in zebrafish, which may be one of the main reasons that zebrafish display a higher regenerative capacity.

Neurogenesis After Stroke: A Therapeutic Perspective

Stroke is a major cause of death and disability worldwide. Yet therapeutic strategies available to treat stroke are very limited. There is an urgent need to develop novel therapeutics that can effectively facilitate functional recovery. The injury that results from stroke is known to induce neurogenesis in penumbra of the infarct region. There is considerable interest in harnessing this response for therapeutic purposes. This review summarizes what is currently known about stroke-induced neurogenesis and the factors that have been identified to regulate it. Additionally, some key studies in this field have been highlighted and their implications on future of stroke therapy have been discussed. There is a complex interplay between neuroinflammation and neurogenesis that dictates stroke outcome and possibly recovery. This highlights the need for a better understanding of the neuroinflammatory process and how it affects neurogenesis, as well as the need to identify new mechanisms and potential modulators. Neuroinflammatory processes and their impact on post-stroke repair have therefore also been discussed.

Therapeutic application of exosomes in ischaemic stroke

Ischaemic stroke is a leading cause of long-term disability in the world, with limited effective treatments. Increasing evidence demonstrates that exosomes are involved in ischaemic pathology and exhibit restorative therapeutic effects by mediating cell–cell communication. The potential of exosome therapy for ischaemic stroke has been actively investigated in the past decade. In this review, we mainly discuss the current knowledge of therapeutic applications of exosomes from different cell types, different exosomal administration routes, and current advances of exosome tracking and targeting in ischaemic stroke. We also briefly summarised the pathology of ischaemic stroke, exosome biogenesis, exosome profile changes after stroke as well as registered clinical trials of exosome-based therapy.

Voluntary exercise ameliorates the good limb training effect in a mouse model of stroke

Stroke is the leading cause of long-term disability in the United States, making research on rehabilitation imperative. Stroke rehabilitation typically focuses on recovery of the impaired limb, although this process is tedious. Compensatory use of the intact limb after stroke is more efficient, but it is known to negatively impact the impaired limb. Exercise may help with this problem; research has shown that exercise promotes neuronal growth and prevents cell death. This study used a mouse model to investigate if post-stroke exercise could prevent deterioration of the function of the impaired limb despite compensatory training of the intact limb. Results showed that mice that exercised, in combination with intact limb training, demonstrated improved functional outcome compared to mice that received no training or compensatory limb training only. These findings suggest that exercise can prevent the deterioration of impaired limb functional outcome that is typically seen with intact limb use.

Neuroregeneration and functional recovery after stroke: advancing neural stem cell therapy toward clinical application

Stroke is a main cause of death and disability worldwide. The ability of the brain to self-repair in the acute and chronic phases after stroke is minimal; however, promising stem cell-based interventions are emerging that may give substantial and possibly complete recovery of brain function after stroke. Many animal models and clinical trials have demonstrated that neural stem cells (NSCs) in the central nervous system can orchestrate neurological repair through nerve regeneration, neuron polarization, axon pruning, neurite outgrowth, repair of myelin, and remodeling of the microenvironment and brain networks. Compared with other types of stem cells, NSCs have unique advantages in cell replacement, paracrine action, inflammatory regulation and neuroprotection. Our review summarizes NSC origins, characteristics, therapeutic mechanisms and repair processes, then highlights current research findings and clinical evidence for NSC therapy. These results may be helpful to inform the direction of future stroke research and to guide clinical decision-making.

The Protective and Reparative Role of Colony-Stimulating Factors in the Brain with Cerebral Ischemia/Reperfusion Injury

Stroke is a debilitating disease and has the ability to culminate in devastating clinical outcomes. Ischemic stroke followed by reperfusion entrains cerebral ischemia/reperfusion (I/R) injury, which is a complex pathological process and is associated with serious clinical manifestations. Therefore, the development of a robust and effective poststroke therapy is crucial. Granulocyte colony-stimulating factor (GCSF) and erythropoietin (EPO), originally discovered as hematopoietic growth factors, are versatile and have transcended beyond their traditional role of orchestrating the proliferation, differentiation, and survival of hematopoietic progenitors to one that fosters brain protection/neuroregeneration. The clinical indication regarding GCSF and EPO as an auspicious therapeutic strategy is conferred in a plethora of illnesses, including anemia and neutropenia. EPO and GCSF alleviate cerebral I/R injury through a multitude of mechanisms, involving antiapoptotic, anti-inflammatory, antioxidant, neurogenic, and angiogenic effects. Despite bolstering evidence from preclinical studies, the multiple brain protective modalities of GCSF and EPO failed to translate in clinical trials and thereby raises several questions. The present review comprehensively compiles and discusses key findings from in vitro, in vivo, and clinical data pertaining to the administration of EPO, GCSF, and other drugs, which alter levels of colony-stimulating factor (CSF) in the brain following cerebral I/R injury, and elaborates on the contributing factors, which led to the lost in translation of CSFs from bench to bedside. Any controversial findings are discussed to enable a clear overview of the role of EPO and GCSF as robust and effective candidates for poststroke therapy.

Neuroprotective effect of helium after neonatal hypoxic ischemia: a narrative review

Neonatal hypoxic ischemia is one of the leading causes of permanent morbidity and mortality in newborns, which is caused by difficulty in supplying blood and oxygen to brain tissue and is often associated with epilepsy, cerebral palsy, death, short-term or long-term neurological and cognitive impairment. In recent years, the clinical therapeutic effects of noble gases have been gradually discovered and recognized. Numerous studies have shown that noble gases have unique neuroprotective effects to restore damaged nerve and relieve symptoms in patients. Although research on the neuroprotective mechanisms of xenon and argon has yielded a lot of results, studies on helium have stalled. Helium is a colorless, odorless, monoatomic inert gas. The helium has no hemodynamic or neurocognitive side effects and can be used as an ideal pre-adaptor for future clinical applications. In recent years, studies have shown that heliox (a mixture of helium and oxygen) pretreatment can protect the heart, brain, liver and intestine from damage in several animal models, where a variety of signaling pathways have been proved to be involved. There are numerous studies on it even though the mechanism of helium for protecting newborns has not been fully elucidated. It is urgent to find an effective treatment due to the high death rate and disability rate of neonatal hypoxic ischemia. It is believed that helium will be approved safely and effectively for clinical use in the near future.

Exosomes Derived from CXCR4-Overexpressing BMSC Promoted Activation of Microvascular Endothelial Cells in Cerebral Ischemia/Reperfusion Injury

Background

Ischemic stroke is a severe acute cerebrovascular disease which can be improved with neuroprotective therapies at an early stage. However, due to the lack of effective neuroprotective drugs, most stroke patients have varying degrees of long-term disability. In the present study, we investigated the role of exosomes derived from CXCR4-overexpressing BMSCs in restoring vascular function and neural repair after ischemic cerebral infarction.

Methods

BMSCs were transfected with lentivirus encoded by CXCR4 (BMSC^CXCR4). Exosomes derived from BMSC^CXCR4 (Exo^CXCR4) were isolated and characterized by transmission electron microscopy and dynamic light scattering. Western blot and qPCR were used to analyze the expression of CXCR4 in BMSCs and exosomes. The acute middle cerebral artery occlusion (MCAO) model was prepared, Exo^CXCR4 were injected into the rats, and behavioral changes were analyzed. The role of Exo^CXCR4 in promoting the proliferation and tube formation for angiogenesis and protecting brain endothelial cells was determined in vitro.

Results

Compared with the control groups, the Exo^CXCR4 group showed a significantly lower mNSS score at 7 d, 14 d, and 21 d after ischemia/reperfusion (P < 0.05). The bEnd.3 cells in the Exo^CXCR4 group have stronger proliferation ability than other groups (P < 0.05), while the CXCR4 inhibitor can reduce this effect. Exosomes control (Exo^Con) can significantly promote the migration of bEnd.3 cells (P < 0.05), while there was no significant difference between the Exo^CXCR4 and Exo^Con groups (P > 0.05). Exo^CXCR4 can further promote the proliferation and tube formation for the angiogenesis of the endothelium compared with Exo^Con group (P < 0.05). In addition, cobalt chloride (COCl2) can increase the expression of β-catenin and Wnt-3, while Exo^Con can reduce the expression of these proteins (P < 0.05). Exo^CXCR4 can further attenuate the activation of Wnt-3a/β-catenin pathway (P < 0.05).

Conclusions

In ischemia/reperfusion injury, Exo^CXCR4 promoted the proliferation and tube formation of microvascular endothelial cells and play an antiapoptotic role via the Wnt-3a/β-catenin pathway.

[Chinese medicine Buyang Huanwu decoction promotes neurogenesis and angiogenesis in ischemic stroke rats by upregulating miR-199a-5p expression]

OBJECTIVE

To investigate the mechanism of Chinese medicine Buyang Huanwu decoction (BYHWD) promoting neurogenesis and angiogenesis in ischemic stroke rats.

METHODS

Male SD rats were randomly divided into sham operation group, model group, BYHWD group, antagonist group and antagonist control group with 14 rats in each. Focal cerebral ischemia was induced by occlusion of the right middle cerebral artery for 90 min with intraluminal filament and reperfusion for 14 d in all groups except sham operation group. BYHWD (13 g/kg) was administrated by gastrogavage in BYHWD group, antagonist group and antagonist control group at 24 h after modeling respectively, and BrdU (50 mg/kg) was injected intraperitoneally in all groups once a day for 14 consecutive days. miR-199a-5p antagomir or NC (10 nmol) was injected into the lateral ventricle at d5 after ischemia in antagonist and antagonist control groups, respectively. The neurological deficits were evaluated by the modified neurological severity score (mNSS) and the corner test, and the infract volume was measured by toluidine blue staining. Neurogenesis and angiogenesis were detected by immunofluorescence double labeling method. The expression level of miR-199a-5p was tested by real-time RT-PCR, and the protein expressions of vascular endothelial growth factor (VEGF) and brain-derived neurotrophic factor (BDNF) were determined by Western blotting.

RESULTS

BYHWD treatment significantly promoted the recovery of neurological function (P<0.05 or P<0.01), reduced the infarct volume (P<0.05), increased the number of BrdU+/DCX+, BrdU+/NeuN+ and BrdU+/vWF+ cells (all P<0.01), upregulated the expression of miR-199a-5p (P<0.01), and increased the protein expression of VEGF and BDNF at d14 after cerebral ischemia (all P<0.05). The above effects were reversed by intracerebroventricular injection of miR-199a-5p antagomir.

CONCLUSIONS

Buyang Huanwu decoction promotes neurogenesis and angiogenesis in rats with cerebral ischemia, which may be related to increased protein expression of VEGF and BDNF through upregulating miR-199a-5p.

Subacute functional connectivity correlates with cognitive recovery six months after stroke

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Stroke disrupts ipsilesional and inter-hemispheric functional connectivity of DMN.

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Subacute cognition correlated to inter-hemispheric and ipsilesional DMN connectivity.

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Subacute cognition correlated to weaker contralesional SN connectivity.

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Functional connectivity remapping was not observed after six months.

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Cognitive recovery correlated to DMN and SN connectivity from the subacute phase.

Background and purpose

Cognitive impairment is a common consequence of stroke, and the rewiring of the surviving brain circuits might contribute to cognitive recovery. Studies investigating how the functional connectivity of networks change across time and whether their remapping relates to cognitive recovery in stroke patients are scarce. We aimed to investigate whether resting-state functional connectivity was associated with cognitive performance in stroke patients and if any alterations in these networks were correlated with cognitive recovery.

Methods

Using an fMRI ROI-ROI approach, we compared the ipsilesional, contralesional and interhemispheric functional connectivity of three resting-state networks involved in cognition – the Default Mode (DMN), Salience (SN) and Central Executive Networks (CEN), in subacute ischemic stroke patients (time 1, n = 37, stroke onset: 24.32 ± 7.44 days, NIHSS: 2.66 ± 3.45) with cognitively healthy controls (n = 20). Patients were reassessed six months after the stroke event (time 2, n = 20, stroke onset: 182.05 ± 8.17 days) to verify the subsequent reorganization of functional connections and whether such reorganization was associated with cognitive recovery.

Results

At time 1, patients had weaker interhemispheric connectivity in the DMN than controls; better cognitive performance at time 1 was associated with stronger interhemispheric and ipsilesional DMN connectivity, and weaker contralesional SN connectivity. At time 2, there were no changes in functional connectivity in stroke patients, compared to time 1. Better cognitive recovery measured at time 2 (time 2 – time 1) was associated with stronger functional connectivity in the DMN, and weaker interhemispheric subacute connectivity in the SN, both from time 1.

Conclusions

Stroke disrupts the functional connectivity of the DMN, not only at the lesioned hemisphere but also between hemispheres. Six months after the stroke event, we could not detect the remapping of networks. Cognitive recovery was associated with the connectivity of both the DMN and SN of time 1. Our findings may be helpful for facilitating further understanding of the potential mechanisms underlying post-stroke cognitive performance.

Neuroinflammation evoked by brain injury in a rat model of lacunar infarct

Stroke is the leading cause of long-term, severe disability worldwide. Immediately after the stroke, endogenous inflammatory processes are upregulated, leading to the local neuroinflammation and the potentiation of brain tissue destruction. The innate immune response is triggered as early as 24 h post-brain ischemia, followed by adaptive immunity activation. Together these immune cells produce many inflammatory mediators, i.e., cytokines, growth factors, and chemokines. Our study examines the immune response components in the early stage of deep brain lacunar infarct in the rat brain, highly relevant to the clinical scenario. The lesion was induced by stereotactic injection of ouabain into the adult rat striatum. Ouabain is a Na/K ATPase pump inhibitor that causes excitotoxicity and brings metabolic and structural changes in the cells leading to focal brain injury. We have shown a surge of neurodegenerative changes in the peri-infarct area in the first days after brain injury. Immunohistochemical analysis revealed early microglial activation and the gradual infiltration of immune cells with a significant increase of CD4⁺ and CD8⁺ T lymphocytes in the ipsilateral hemisphere. In our studies, we identified the higher level of pro-inflammatory cytokines, i.e., interleukin-1α, interleukin-1β, tumor necrosis factor-α, and interferon-γ, but a lower level of anti-inflammatory cytokines, i.e., interleukin-10 and transforming growth factor-β2 in the injured brain than in normal rats. Concomitantly focal brain injury showed a significant increase in the level of chemokines, i.e., monocyte chemoattractant protein-1 and CC motif chemokine ligand 5 compared to control. Our findings provide new insights into an early inflammatory reaction in our model of the deep-brain lacunar infarct. The results of this study may highlight future stroke immunotherapies for targeting the acute immune response accompanied by the insult.

Coicis semen protects against focal cerebral ischemia-reperfusion injury by inhibiting oxidative stress and promoting angiogenesis via the TGFβ/ALK1/Smad1/5 signaling pathway

Background: Ischemic stroke is a devastating disease that causes long-term disability. However, its pathogenesis is unclear, and treatments for ischemic stroke are limited. Recent studies indicate that oxidative stress is involved in the pathological progression of ischemic stroke and that angiogenesis participates in recovery from ischemic stroke. Furthermore, previous studies have shown that Coicis Semen has antioxidative and anti-inflammatory effects in a variety of diseases. In the present study, we investigated whether Coicis Semen has a protective effect against ischemic stroke and the mechanism of this protective effect.

Results: Coicis Semen administration significantly decreased the infarct volume and mortality and alleviated neurological deficits at 3, 7 and 14 days after MCAO. In addition, cerebral edema at 3 days poststroke was ameliorated by Coicis Semen treatment. DHE staining showed that ROS levels in the vehicle group were increased at 3 days after reperfusion and then gradually declined, but Coicis Semen treatment reduced ROS levels. The levels of GSH and SOD in the brain were increased by Coicis Semen treatment, while MDA levels were reduced. Furthermore, Coicis Semen treatment decreased the extravasation of EB dye in MCAO mouse brains and elevated expression of the tight junction proteins ZO-1 and Occludin. Double immunofluorescence staining and western blot analysis showed that the expression of angiogenesis markers and TGFβ pathway-related proteins was increased by Coicis Semen administration. Consistent with the in vivo results, cytotoxicity assays showed that Coicis Semen substantially promoted HUVEC survival following OGD/RX in vitro. Additionally, though LY2109761 inhibited the activation of TGFβ signaling in OGD/RX model animals, Coicis Semen cotreatment markedly reversed the downregulation of TGFβ pathway-related proteins and increased VEGF levels.

Methods: Adult male wild-type C57BL/6J mice were used to develop a middle cerebral artery occlusion (MCAO) stroke model. Infarct size, neurological deficits and behavior were evaluated on days 3, 7 and 14 after staining. In addition, changes in superoxide dismutase (SOD), GSH and malondialdehyde (MDA) levels were detected with a commercial kit. Blood-brain barrier (BBB) permeability was assessed with Evans blue (EB) dye. Western blotting was also performed to measure the levels of tight junction proteins of the BBB. Additionally, ELISA was performed to measure the level of VEGF in the brain. The colocalization of CD31, angiogenesis markers, and Smad1/5 was assessed by double immunofluorescent staining. TGFβ pathway-related proteins were measured by western blotting. Furthermore, the cell viability of human umbilical vein endothelial cells (HUVECs) following oxygen-glucose deprivation/reoxygenation (OGD/RX) was measured by Cell Counting Kit (CCK)-8 assay.

Conclusions: Coicis Semen treatment alleviates brain damage induced by ischemic stroke through inhibiting oxidative stress and promoting angiogenesis by activating the TGFβ/ALK1 signaling pathway.

Curcumin promotes neurogenesis of hippocampal dentate gyrus via Wnt/β-catenin signal pathway following cerebral ischemia in mice

OBJECTIVES

To investigate whether curcumin promotes hippocampal neurogenesis in the cerebral ischemia (CI) mice via Wnt/β-catenin signaling pathway.

METHODS

Male C57BL/6 mice were randomly divided into groups: sham operation group (Sham), cerebral ischemic group (CI), curcumin treatment group (50, 100 mg/kg/d, i.p.) and curcumin (100 mg/kg/d) + DKK1 (a blocker of Wnt receptor, 200 ng/d, icv) group. CI was induced by bilateral common carotid arteries occlusion (BCCAO) for 20 min. The Morris water maze test was conducted to detect spatial learning and memory. Immunofluorescence staining was used to examine the proliferation and differentiation of immature neurons in the hippocampal dentate gyrus. The proteins involved in neurogenesis and Wnt signaling pathway were examined using Western blot assay.

RESULTS

Curcumin significantly alleviated cognitive deficits induced by CI. Curcumin dose-dependently increased the proliferation of neural stem cells and promoted the differentiation and maturation of newly generated neural cells into neurons. Curcumin also increased the expression of proteins involved in neurogenesis (including Ngn2, Pax6 and NeuroD 1) and the Wnt/β-catenin signaling pathway. Moreover, the forenamed effects of curcumin were abolished by pretreatment with DKK1, a blocker of Wnt receptor.

CONCLUSION

Curcumin promotes hippocampal neurogenesis by activating Wnt/β-catenin signaling pathway to ameliorate cognitive deficits after acute CI.

Application of stem cell biology in treating neurodegenerative diseases

BACKGROUND

The appropriate strategies are needed for stimulating the endogenous neurogenesis or introducing extrinsic neural progenitors, which could be harnessed as the regenerative resources for cueing the neurodegenerations. Adult neurogenesis is the endogenous continuing physiology in limited brain regions such as hippocampus, olfactory system, and hypothalamus. Besides adult neurogenesis, induced pluripotent stem cells (iPSCs) induced functional neurons could be another option for regenerative therapies.

OBJECTIVE

Current studies are trying to improve the adult neurogenesis and enable the iPSCs induced neurons into neural regeneration. Methods: Here in this review, we mainly introduced the recent progress in neural stem cell biology and its application in the treatment of the neurodegenerations. We main separated the strategy in summarizing the mediators and potential targets to promoting endogenous neural regeneration and transplantation of neural progenitors.

CONCLUSION

By collecting and comparing the advantages disadvantages between above-mentioned two strategies, we will offer the insight on future development of stem cell therapy in treating neurodegenerative patients.

Recent Advances in Cell-Based Therapies for Ischemic Stroke

Stroke is the most prevalent cardiovascular disease worldwide, and is still one of the leading causes of death and disability. Stem cell-based therapy is actively being investigated as a new potential treatment for certain neurological disorders, including stroke. Various types of cells, including bone marrow mononuclear cells, bone marrow mesenchymal stem cells, dental pulp stem cells, neural stem cells, inducible pluripotent stem cells, and genetically modified stem cells have been found to improve neurological outcomes in animal models of stroke, and there are some ongoing clinical trials assessing their efficacy in humans. In this review, we aim to summarize the recent advances in cell-based therapies to treat stroke.

Sphingosine 1-Phosphate Receptors in Cerebral Ischemia

Sphingosine 1-phosphate (S1P) is an important lipid biomolecule that exerts pleiotropic cellular actions as it binds to and activates its five G-protein-coupled receptors, S1P_1-5. Through these receptors, S1P can mediate diverse biological activities in both healthy and diseased conditions. S1P is produced by S1P-producing enzymes, sphingosine kinases (SphK1 and SphK2), and is abundantly present in different organs, including the brain. The medically important roles of receptor-mediated S1P signaling are well characterized in multiple sclerosis because FTY720 (Gilenya™, Novartis), a non-selective S1P receptor modulator, is currently used as a treatment for this disease. In cerebral ischemia, its role is also notable because of FTY720's efficacy in both rodent models and human patients with cerebral ischemia. In particular, some of the S1P receptors, including S1P₁, S1P₂, and S1P₃, have been identified as pathogenic players in cerebral ischemia. Other than these receptors, S1P itself and S1P-producing enzymes have been shown to play certain roles in cerebral ischemia. This review aims to compile the current updates and overviews about the roles of S1P signaling, along with a focus on S1P receptors in cerebral ischemia, based on recent studies that used in vivo rodent models of cerebral ischemia.

Serum BDNF's Role as a Biomarker for Motor Training in the Context of AR-Based Rehabilitation after Ischemic Stroke

BACKGROUND

brain-derived neurotrophic factor (BDNF) may play a role during neurorehabilitation following ischemic stroke. This study aimed to elucidate the possible role of BDNF during early recovery from ischemic stroke assisted by motor training.

METHODS

fifty patients were included after acute recovery from ischemic stroke: 21 first received classical rehabilitation followed by 'motor rehabilitation using motion sensors and augmented reality' (AR-rehabilitation), 14 only received AR-rehabilitation, and 15 were only observed. Serum BDNF levels were measured on the first day of stroke, on the 14th day, before AR-based rehabilitation (median, 45th day), and after the AR-based rehabilitation (median, 82nd day). Motor impairment was quantified clinically using the Fugl-Meyer scale (FMA); functional disability and activities of daily living (ADL) were measured using the Modified Rankin Scale (mRS). For comparison, serum BDNF was measured in 50 healthy individuals.

RESULTS

BDNF levels were found to significantly increase during the phase with AR-based rehabilitation. The pattern of the sequentially measured BDNF levels was similar in the treated patients. Untreated patients had significantly lower BDNF levels at the endpoint.

CONCLUSIONS

the fluctuations of BDNF levels are not consistently related to motor improvement but seem to react to active treatment. Without active rehabilitation treatment, BDNF tends to decrease.

Cell Therapies under Clinical Trials and Polarized Cell Therapies in Pre-Clinical Studies to Treat Ischemic Stroke and Neurological Diseases: A Literature Review

Stroke remains a major cause of serious disability because the brain has a limited capacity to regenerate. In the last two decades, therapies for stroke have dramatically changed. However, half of the patients cannot achieve functional independence after treatment. Presently, cell-based therapies are being investigated to improve functional outcomes. This review aims to describe conventional cell therapies under clinical trial and outline the novel concept of polarized cell therapies based on protective cell phenotypes, which are currently in pre-clinical studies, to facilitate functional recovery after post-reperfusion treatment in patients with ischemic stroke. In particular, non-neuronal stem cells, such as bone marrow-derived mesenchymal stem/stromal cells and mononuclear cells, confer no risk of tumorigenesis and are safe because they do not induce rejection and allergy; they also pose no ethical issues. Therefore, recent studies have focused on them as a cell source for cell therapies. Some clinical trials have shown beneficial therapeutic effects of bone marrow-derived cells in this regard, whereas others have shown no such effects. Therefore, more clinical trials must be performed to reach a conclusion. Polarized microglia or peripheral blood mononuclear cells might provide promising therapeutic strategies after stroke because they have pleiotropic effects. In traumatic injuries and neurodegenerative diseases, astrocytes, neutrophils, and T cells were polarized to the protective phenotype in pre-clinical studies. As such, they might be useful therapeutic targets. Polarized cell therapies are gaining attention in the treatment of stroke and neurological diseases.

Engineering of SPECT/Photoacoustic Imaging/Antioxidative Stress Triple-Function Nanoprobe for Advanced Mesenchymal Stem Cell Therapy of Cerebral Ischemia

The precise transplantation, long-term tracking, and maintenance of stem cells with maximizing therapeutic effect are significant challenges in stem cell-based therapy for stroke treatment. In this study, a unique core-shell labeling nanoagent was prepared by encapsulating a cobalt protoporphyrin IX (CoPP)-loaded mesoporous silica nanoparticle (CPMSN) into a ¹²⁵I-conjugated/spermine-modified dextran polymer (¹²⁵I-SD) by microfluidics for mesenchymal stem cell (MSC) tracking and activity maintenance. The CPMSN core not only exhibits excellent photoacoustic (PA) imaging performance induced by the intermolecular aggregation of CoPP within the mesopores but also protects the MSCs against oxidative stress by sustained release of CoPP. Meanwhile, the addition of a ¹²⁵I-SD shell can increase the uptake efficiency in MSCs without inducing cell variability and enable the single-photon-emission computed tomography (SPECT) nuclear imaging. In vivo results indicated that CPMSN@¹²⁵I-SD labeling could allow for an optimal combination of instant imaging of MSCs, with PA to guide intracerebral injection, followed by multiple time point SPECT imaging to consecutively track the cell homing. Importantly, the sustained release of CoPP from CPMSN@¹²⁵I-SD significantly increased the survival of MSCs after injection into an ischemic mouse brain and promoted neurobehavioral recovery in ischemic mice. Thus, CPMSN@¹²⁵I-SD represents a robust theranostic probe for both MSC tracking and maintaining their therapeutic effect in the treatment of brain ischemia.

MicroRNA-130a regulates neurological deficit and angiogenesis in rats with ischaemic stroke by targeting XIAP

MicroRNAs (miRNAs) have already been proposed to be implicated in the development of ischaemic stroke. We aim to investigate the role of miR-130a in the neurological deficit and angiogenesis in rats with ischaemic stroke by regulating X-linked inhibitor of apoptosis protein (XIAP). Middle cerebral artery occlusion (MCAO) models were established by suture-occluded method, and MCAO rats were then treated with miR-130a mimics/inhibitors or/and altered XIAP for detection of changes of rats' neurological function, nerve damage and angiogenesis in MCAO rats. The oxygen-glucose deprivation (OGD) cellular models were established and respectively treated to determine the roles of miR-130a and XIAP in neuronal viability and apoptosis. The expression levels of miR-130a and XIAP in brain tissues of MCAO rats and OGD-treated neurons were detected. The binding site between miR-130a and XIAP was verified by luciferase activity assay. MiR-130a was overexpressed while XIAP was down-regulated in MCAO rats and OGD-treated neurons. In animal models, suppressed miR-130a improved neurological function, alleviated nerve damage and increased new vessels in brain tissues of rats with MCAO. In cellular models, miR-130a inhibition promoted neuronal viability and suppressed apoptosis. Inhibited XIAP reversed the effect of inhibited miR-130a in both MCAO rats and OGD-treated neurons. XIAP was identified as a target of miR-130a. Our study reveals that miR-130a regulates neurological deficit and angiogenesis in rats with MCAO by targeting XIAP.

The Role of Neurovascular System in Neurodegenerative Diseases

The neurovascular system (NVS), which consisted of neurons, glia, and vascular cells, is a functional and structural unit of the brain. The NVS regulates blood-brain barrier (BBB) permeability and cerebral blood flow (CBF), thereby maintaining the brain's microenvironment for normal functioning, neuronal survival, and information processing. Recent studies have highlighted the role of vascular dysfunction in several neurodegenerative diseases. This is not unexpected since both nervous and vascular systems are functionally interdependent and show close anatomical apposition, as well as similar molecular pathways. However, despite extensive research, the precise mechanism by which neurovascular dysfunction contributes to neurodegeneration remains incomplete. Therefore, understanding the mechanisms of neurovascular dysfunction in disease conditions may allow us to develop potent and effective therapies for prevention and treatment of neurodegenerative diseases. This review article summarizes the current research in the context of neurovascular signaling associated with neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and Huntington's disease (HD). We also discuss the potential implication of neurovascular factor as a novel therapeutic target and prognostic marker in patients with neurodegenerative conditions. Graphical Abstract.

Pigment Epithelium-Derived Factor Improves Paracellular Blood-Brain Barrier Integrity in the Normal and Ischemic Mouse Brain

Pigment epithelium-derived factor (PEDF) is a neurotrophic factor with neuroprotective, antiangiogenic, and antipermeability effects. In the brain, blood-brain barrier (BBB) function is essential for homeostasis. Its impairment plays a crucial role in the pathophysiology of many neurological diseases, including ischemic stroke. We investigated (a) whether PEDF counteracted vascular endothelial growth factor (VEGF)-induced BBB disruption in the mouse brain, (b) the time course and route of BBB permeability and the dynamics of PEDF expression after cerebral ischemia, and (c) whether intraventricular infusion of PEDF ameliorated brain ischemia by reducing BBB impairment. C57Bl6/N mice received intraparenchymal injections of CSF, VEGF, or a combination of VEGF and PEDF. PEDF increased paracellular but not transcellular BBB integrity as indicated by an increase in the tight junction protein claudin-5. In another group of mice undergoing 60-min middle cerebral artery occlusion (MCAO), transcellular BBB permeability (fibrinogen staining in the absence of a loss of claudin-5) increased as early as 6 h after reperfusion. PEDF immunofluorescence increased at 24 h, which paralleled with a decreased paracellular BBB permeability (claudin-5). PEDF after MCAO originated from the blood stream and endogenous pericytes. In the third experiment, the intraventricular infusion of PEDF decreased edema and cell death after MCAO, potentially mediated by the improvement of the paracellular route of BBB permeability (claudin-5) in the absence of an amelioration of Evans Blue extravasation. Together, our data suggest that PEDF improves BBB function after cerebral ischemia by affecting the paracellular but not the transcellular route. However, further quantitative data of the different routes of BBB permeability will be required to validate our findings.

LncRNA MACC1-AS1 attenuates microvascular endothelial cell injury and promotes angiogenesis under hypoxic conditions via modulating miR-6867-5p/TWIST1 in human brain microvascular endothelial cells

Background

Hypoxia following ischemic stroke is a common cause of brain insults. Mounting evidence suggests that long non-coding RNAs (lncRNAs) play a vital role in regulating certain physiological and pathological processes including ischemic stroke. For the first time, the present study investigated the effects and mechanism of LncRNA MACC1-AS1 on hypoxia-induced human brain microvascular endothelial cells (HBMECs).

Methods

LncRNA MACC1-AS1 levels in HBMECs were detected via reverse transcription quantitative polymerase chain reaction (RT-qPCR) assay. Reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase (SOD), and catalase (CAT), were detected using their respective kits. Flow cytometry and clone formation assay were performed to evaluate the effects of lncRNA MACC1-AS1 on cell apoptosis and cell proliferation respectively. Angiogenesis capacity was evaluated via tube formation assay. Transwell migration assay was performed for assessment of cell migration, Western blot assay was performed for measurement of Twist1 and VE-cadherin level, and permeability assay was performed for evaluation of the cell barrier function. The target gene was predicted via bioinformatics online tool and validated through luciferase reporter assay and RNA pull-down assay.

Results

LncRNA MACC1-AS1 was downregulated in hypoxia-induced HBMECs. Overexpression of LncRNA MACC1-AS1 reduced cell apoptosis and oxidative stress, while promoting cell proliferation, migration, and angiogenesis. Moreover, LncRNA MACC1-AS1 overexpression reduced cell permeability and elevated VE-cadherin level, which contributed to maintaining cell barrier function. TWIST1 was validated as the target of miR-6867-5p which was further targeted by lncRNA MACC1-AS1. Thus, LncRNA MACC1-AS1 functions in hypoxia-induced HBMECs by regulating miR-6867-5p/TWIST1.

Conclusions

In this study, we found that LncRNA MACC1-AS1 exerted a protective role in hypoxia-induced HBMECs via regulating miR-6867-5p/TWIST1, indicating a new therapeutic strategy for future ischemic stroke therapy.

Lentivirally administered glial cell line-derived neurotrophic factor promotes post-ischemic neurological recovery, brain remodeling and contralesional pyramidal tract plasticity by regulating axonal growth inhibitors and guidance proteins

Owing to its potent longterm neuroprotective and neurorestorative properties, glial cell line-derived neurotrophic factor (GDNF) is currently studied in neurodegenerative disease clinical trials. However, little is known about the longterm effect of GDNF on neurological recovery, brain remodeling and neuroplasticity in the post-acute phase of ischemic stroke. In a comprehensive set of experiments, we examined the effects of lentiviral GDNF administration after ischemic stroke. GDNF reduced neurological deficits, neuronal injury, blood-brain barrier permeability in the acute phase in mice. As compared with control, enhanced motor-coordination and spontaneous locomotor activity were noted in GDNF-treated mice, which were associated with increased microvascular remodeling, increased neurogenesis and reduced glial scar formation in the peri-infarct tissue. We observed reduced brain atrophy and increased plasticity of contralesional pyramidal tract axons that crossed the midline in order to innervate denervated neurons in the ipsilesional red and facial nuclei. Contralesional axonal plasticity by GDNF was associated with decreased abundance of the axonal growth inhibitors brevican and versican in contralesional and ipsilesional brain tissue, reduced abundance of the growth repulsive guidance molecule ephrin b1 in contralesional brain tissue, increased abundance of the midline growth repulsive protein Slit1 in contralesional brain tissue and reduced abundance of Slit1's receptor Robo2 in ipsilesional brain tissue. These data indicate that GDNF potently induces longterm neurological recovery, peri-infarct brain remodeling and contralesional neuroplasticity, which are associated with the fine-tuned regulation of axonal growth inhibitors and guidance molecules that facilitate the growth of contralesional corticofugal axons in the direction to the ipsilesional hemisphere.

Renshen Shouwu extract enhances neurogenesis and angiogenesis via inhibition of TLR4/NF-κB/NLRP3 signaling pathway following ischemic stroke in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Renshen Shouwu extract (RSSW) is a patented Traditional Chinese Medicine included in Chinese Pharmacopoeia for neurasthenia, forgetfulness, insomnia, inappetence and excessive fatigue. Our previous study had demonstrated the neuroprotective effect of RSSW against ischemic stroke in rats with middle cerebral artery occlusion (MCAO). However, its underlying mechanism remains unknown.

AIM OF THE STUDY

In this study, we investigated the neurogenesis and angiogenesis effects of RSSW in ischemic stroke rats, and further revealed its underlying mechanism focused on TLR4/NF-κB/NLRP3 signaling pathway.

MATERIALS AND METHODS

Firstly, active compounds of RSSW were determined by High Performance Liquid Chromatography (HPLC). Secondly, Middle cerebral artery occlusion (MCAO) was performed to induce ischemic stroke in rats and 2, 3, 5-Triphenyltetrazolium chloride (TTC) staining was employed to evaluate whether MCAO surgery was successfully established. Neurological deficit evaluation was conducted according to the Zea Longa' method. Then, we explored the neurogenesis and angiogenesis effects after oral administration of RSSW (50 mg/kg, 100 mg/kg) in MCAO-induced rats by Immunofluorescence Staining. Moreover, the proteins involved in TLR4/NF-κB/NLRP3 signaling pathway (TLR4, p-NF-κB p65, NF-κB p65, NLRP3, pro-IL-1β, IL-1β, pro-Caspase-1, Caspase-1) were determined by western blotting.

RESULTS

It was observed that RSSW treatment significantly increased the number of newborn neurons and brain microvessel density (MVD) after ischemic stroke. What's more, RSSW treatment significantly downregulated TLR4, p-NF-κB p65/p65, NLRP3, pro-IL-1β, IL-1β, pro-Caspase-1, Caspase-1 proteins involved in TLR4/NF-κB/NLRP3 signaling pathway.

CONCLUSIONS

RSSW enhances neurogenesis and angiogenesis via inhibition of TLR4/NF-κB/NLRP3 inflammatory signaling pathway following ischemic stroke in rats. Hence, RSSW may be a promising Chinese Medicine for the treatment of ischemic stroke.

MiR-195 alleviates oxygen-glucose deprivation/reperfusion-induced cell apoptosis via inhibition of IKKα-mediated NF-κB pathway

OBJECTIVES

Increasing evidence confirmed that miRNA plays a critical role in the occurrence and development of ischemic stroke. Here, the aim of this study was to examine the function and mechanisms of miR-195 in vascular endothelial cell apoptosis induced by oxygen-glucose deprivation (OGD).

METHODS

This study intended to use OGD to simulate ischemia in vitro. The mRNA expression of miR-195, IKKα and NF-κB in human umbilical vein endothelial cells (HUVECs) were detected by RT-qPCR. The proliferation and apoptosis ability of HUVECs were evaluated using MTT assay, colony formation assay and flow cytometry, respectively. Western blot was applied to examine related protein expression. The interaction between miR-195 and IKKα was verified by dual-luciferase reporter gene assay.

RESULTS

OGD significantly inhibited cell viability and induced cell apoptosis in HUVECs. Meanwhile, OGD treatment notably decreased the expression of miR-195, as well as enhanced NF-κB expression. Moreover, miR-195 directly interacted with IKKα and suppressed its expression. Mechanically, overexpression of miR-195 exhibited pro-proliferation and anti-apoptotic effect on HUVECs treated with OGD through targeting IKKα-mediated NF-κB pathway. At the molecular level, through suppressing IKKα/NF-κB pathway, miR-195 inhibited the expression of pro-apoptotic protein Bax and active caspase-3, but increased the expression of anti-apoptotic Bcl-2 in HUVECs.

CONCLUSIONS

Our finding uncovers the protective effect of miR-195 on the biological behavior of HUVECs via suppression of the NF-κB pathway induced by IKKα, which may provide a new potential strategy for ischemic stroke clinical treatment.

Non-Mitogenic Fibroblast Growth Factor 1 Enhanced Angiogenesis Following Ischemic Stroke by Regulating the Sphingosine-1-Phosphate 1 Pathway

Ischemic strokes account for about 80% of all strokes and are associated with a high risk of mortality. Angiogenesis of brain microvascular endothelial cells may contribute to functional restoration following ischemia. Fibroblast growth factor 1 (FGF1), a member of FGF superfamily, involved in embryonic development, angiogenesis, wound healing, and neuron survival. However, the mitogenic activity of FGF1 is known to contribute to several human pathologies, thereby questioning the safety of its clinical applications. Here, we explored the effects and mechanism of action of non-mitogenic FGF1 (nmFGF1) on angiogenesis in mice after ischemia stroke and an oxygen-glucose deprivation (OGD)-induced human brain microvascular endothelial cells (HBMECs) injury model. We found that intranasal administration nmFGF1 significantly promoted angiogenesis in mice after stroke, and significantly increased the formation of matrigel tube and promoted scratch migration in a dose-dependent manner in OGD-induced HBMECs in vitro. However, the co-administration of an FGF receptor 1 (FGFR1)-specific inhibitor PD173074 significantly reversed the effects of nmFGF1 in vitro, suggesting that nmFGF1 functions via FGFR1 activation. Moreover, nmFGF1 activated sphingosine-1-phosphate receptor 1 (S1PR1, S1P1) in mice after stroke in vivo. S1P1 protein antagonist VPC23019 and agonist FTY720 were used to confirm that nmFGF1 promotes angiogenesis in vitro partially through the S1P1 pathway. OGD induced downregulation of S1P1 expression. The S1P1 antagonist VPC23019 blocked the stimulatory effects of nmFGF1, whereas the S1P1 agonist FTY720 exerted effects comparable with those of nmFGF1. Furthermore, PD173074 reversed the effect of nmFGF1 on upregulating S1P1 signaling. In conclusion, nmFGF1 enhanced angiogenesis in mice following stroke and OGD-induced HBMECs through S1P1 pathway regulation mediated via FGFR1 activation. This new discovery suggests the potential therapeutic role of nmFGF1 for the treatment of ischemic strokes.

Lactation ameliorates neurobehavioral outcomes in the ischemic rat dams

Aims: Cardiac arrest and stroke as a life-threatening event that may occur in throughout the female life, especially during pregnancy or after delivery. Previous studies demonstrated that cerebral ischemia during pregnancy or the puerperium is a rare occurrence but is associated with significant mortality and high morbidity. This study was designed to assess the effects of pregnancy and lactation on behavioral deficits, neural density, and angiogenesis in rat dams undergoing global ischemia.Materials and methods: Thirty-two female Wistar rats were divided into four groups: virgin-Sham (Vir-Sham) group, virgin-ischemic (Vir-Isc) group, pregnancy-lactation-sham (P-L-Sham) group, and pregnancy-lactation-ischemic (P-L-Isc) group. Global brain ischemia was induced in ischemic groups by using the 2-vessel occlusion (2-VO) model at the end of lactation phase. Seven days after 2-VO, anxiety-like signals and passive avoidance memory tests were assessed in animals.Key findings: We found that the lactation significantly improved memory and reduced anxiety-like signals in P-L-Isc group as compared with Vir-Isc group. Moreover, angiogenesis and neural density significantly increased in the P-L-Isc group as compared with the Vir-Isc group.Significance: This finding for the first time indicated that lactation protects the maternal brain against ischemic insult partly through promoting angiogenesis and neurogenesis.

CELSR1 Promotes Neuroprotection in Cerebral Ischemic Injury Mainly Through the Wnt/PKC Signaling Pathway

Cadherin epidermal growth factor (EGF) laminin G (LAG) seven-pass G-type receptor 1 (CELSR1) is a member of a special subgroup of adhesion G protein-coupled receptors. Although Celsr1 has been reported to be a sensitive gene for stroke, the effect of CELSR1 in ischemic stroke is still not known. Here, we investigated the effect of CELSR1 on neuroprotection, neurogenesis and angiogenesis in middle cerebral artery occlusion (MCAO) rats. The mRNA expression of Celsr1 was upregulated in the subventricular zone (SVZ), hippocampus and ischemic penumbra after cerebral ischemic injury. Knocking down the expression of Celsr1 in the SVZ with a lentivirus significantly reduced the proliferation of neuroblasts, the number of CD31-positive cells, motor function and rat survival and increased cell apoptosis and the infarct volume in MCAO rats. In addition, the expression of p-PKC in the SVZ and peri-infarct tissue was downregulated after ischemia/ reperfusion. Meanwhile, in the dentate gyrus of the hippocampus, knocking down the expression of Celsr1 significantly reduced the proliferation of neuroblasts; however, it had no influence on motor function, cell apoptosis or angiogenesis. These data indicate that CELSR1 has a neuroprotective effect on cerebral ischemia injury by reducing cell apoptosis in the peri-infarct cerebral cortex and promoting neurogenesis and angiogenesis, mainly through the Wnt/PKC pathway.

Bone mesenchymal stem cell-derived exosomal microRNA-29b-3p prevents hypoxic-ischemic injury in rat brain by activating the PTEN-mediated Akt signaling pathway

BACKGROUND

Mesenchymal stem cells (MSCs) are suspected to exert neuroprotective effects in brain injury, in part through the secretion of extracellular vesicles like exosomes containing bioactive compounds. We now investigate the mechanism by which bone marrow MSCs (BMSCs)-derived exosomes harboring the small non-coding RNA miR-29b-3p protect against hypoxic-ischemic brain injury in rats.

METHODS

We established a rat model of middle cerebral artery occlusion (MCAO) and primary cortical neuron or brain microvascular endothelial cell (BMEC) models of oxygen and glucose deprivation (OGD). Exosomes were isolated from the culture medium of BMSCs. We treated the MCAO rats with BMSC-derived exosomes in vivo, and likewise the OGD-treated neurons and BMECs in vitro. We then measured apoptosis- and angiogenesis-related features using TUNEL and CD31 immunohistochemical staining and in vitro Matrigel angiogenesis assays.

RESULTS

The dual luciferase reporter gene assay showed that miR-29b-3p targeted the protein phosphatase and tensin homolog (PTEN). miR-29b-3p was downregulated and PTEN was upregulated in the brain of MCAO rats and in OGD-treated cultured neurons. MCAO rats and OGD-treated neurons showed promoted apoptosis and decreased angiogenesis, but overexpression of miR-29b-3p or silencing of PTEN could reverse these alterations. Furthermore, miR-29b-3p could negatively regulate PTEN and activate the Akt signaling pathway. BMSCs-derived exosomes also exerted protective effects against apoptosis of OGD neurons and cell apoptosis in the brain samples from MCAO rats, where we also observed promotion of angiogenesis.

CONCLUSION

BMSC-derived exosomal miR-29b-3p ameliorates ischemic brain injury by promoting angiogenesis and suppressing neuronal apoptosis, a finding which may be of great significance in the treatment of hypoxic-ischemic brain injury.

Effects of Exercise Intensity on Acute Circulating Molecular Responses Poststroke

Background. Exercise intensity can influence functional recovery after stroke, but the mechanisms remain poorly understood. Objective. In chronic stroke, an intensity-dependent increase in circulating brain-derived neurotrophic factor (BDNF) was previously found during vigorous exercise. Using the same serum samples, this study tested acute effects of exercise intensity on other circulating molecules related to neuroplasticity, including vascular-endothelial growth factor (VEGF), insulin-like growth factor-1 (IGF1), and cortisol, with some updated analyses involving BDNF. Methods. Using a repeated-measures design, 16 participants with chronic stroke performed 3 exercise protocols in random order: treadmill high-intensity interval training (HIT-treadmill), seated-stepper HIT (HIT-stepper), and treadmill moderate-intensity continuous exercise (MCT-treadmill). Serum molecular changes were compared between protocols. Mediation and effect modification analyses were also performed. Results. VEGF significantly increased during HIT-treadmill, IGF1 increased during both HIT protocols and cortisol nonsignificantly decreased during each protocol. VEGF response was significantly greater for HIT-treadmill versus MCT-treadmill when controlling for baseline. Blood lactate positively mediated the effect of HIT on BDNF and cortisol. Peak treadmill speed positively mediated effects on BDNF and VEGF. Participants with comfortable gait speed ≥0.4 m/s had significantly lower VEGF and higher IGF1 responses, with a lower cortisol response during MCT-treadmill. Conclusions. BDNF and VEGF are promising serum molecules to include in future studies testing intensity-dependent mechanisms of exercise on neurologic recovery. Fast training speed and anaerobic intensity appear to be critical ingredients for eliciting these molecular responses. Serum molecular response differences between gait speed subgroups provide a possible biologic basis for previously observed differences in training responsiveness.

Vascularization in tissue engineering: fundamentals and state-of-art

Vascularization is among the top challenges that impede the clinical application of engineered tissues. This challenge has spurred tremendous research endeavor, defined as vascular tissue engineering (VTE) in this article, to establish a pre-existing vascular network inside the tissue engineered graft prior to implantation. Ideally, the engineered vasculature can be integrated into the host vasculature via anastomosis to supply nutrient to all cells instantaneously after surgery. Moreover, sufficient vascularization is of great significance in regenerative medicine from many other perspectives. Due to the critical role of vascularization in successful tissue engineering, we aim to provide an up-to-date overview of the fundamentals and VTE strategies in this article, including angiogenic cells, biomaterial/bio-scaffold design and bio-fabrication approaches, along with the reported utility of vascularized tissue complex in regenerative medicine. We will also share our opinion on the future perspective of this field.

Therapeutic potential of natural compounds from Chinese medicine in acute and subacute phases of ischemic stroke

Stroke is one of the leading causes of death and disability in adults worldwide, resulting in huge social and financial burdens. Extracts from herbs, especially those used in Chinese medicine, have emerged as new pharmaceuticals for stroke treatment. Here we review the evidence from preclinical studies investigating neuroprotective properties of Chinese medicinal compounds through their application in acute and subacute phases of ischemic stroke, and highlight potential mechanisms underlying their therapeutic effects. It is noteworthy that many herbal compounds have been shown to target multiple mechanisms and in combinations may exert synergistic effects on signaling pathways, thereby attenuating multiple aspects of ischemic pathology. We conclude the paper with a general discussion of the prospects for novel natural compound-based regimens against stroke.

Angiogenesis and neuronal remodeling after ischemic stroke

Increased microvessel density in the peri-infarct region has been reported and has been correlated with longer survival times in ischemic stroke patients and has improved outcomes in ischemic animal models. This raises the possibility that enhancement of angiogenesis is one of the strategies to facilitate functional recovery after ischemic stroke. Blood vessels and neuronal cells communicate with each other using various mediators and contribute to the pathophysiology of cerebral ischemia as a unit. In this mini-review, we discuss how angiogenesis might couple with axonal outgrowth/neurogenesis and work for functional recovery after cerebral ischemia. Angiogenesis occurs within 4 to 7 days after cerebral ischemia in the border of the ischemic core and periphery. Post-ischemic angiogenesis may contribute to neuronal remodeling in at least two ways and is thought to contribute to functional recovery. First, new blood vessels that are formed after ischemia are thought to have a role in the guidance of sprouting axons by vascular endothelial growth factor and laminin/β1-integrin signaling. Second, blood vessels are thought to enhance neurogenesis in three stages: 1) Blood vessels enhance proliferation of neural stem/progenitor cells by expression of several extracellular signals, 2) microvessels support the migration of neural stem/progenitor cells toward the peri-infarct region by supplying oxygen, nutrients, and soluble factors as well as serving as a scaffold for migration, and 3) oxygenation induced by angiogenesis in the ischemic core is thought to facilitate the differentiation of migrated neural stem/progenitor cells into mature neurons. Thus, the regions of angiogenesis and surrounding tissue may be coupled, representing novel treatment targets.

The Sphkl/SlP pathway regulates angiogenesis via NOS/NO synthesis following cerebral ischemia-reperfusion

Aims

Sphingosine kinase 1 (Sphk1) and the signaling molecule sphingosine‐1‐phosphate (S1P) are known to be key regulators of a variety of important biological processes, such as neovascularization. Nitric oxide (NO) is also known to play a role in vasoactive properties, whether Sphk1/S1P signaling is able to alter angiogenesis in the context of cerebral ischemia‐reperfusion injury (IRI), and whether such activity is linked with NO production, however, remains uncertain.

Methods

We used immunofluorescence to detect the expression of Sphk1 and NOS in cerebral epithelial cells (EC) after IR or oxygen‐glucose deprivation (OGDR). Western blotting was used to detect the Sphk1 and NOS protein levels in brain tissues or HBMECs. Adenovirus transfection was used to inhibit Sphk1 and NOS. An NO kit was used to detect NO contents in brain tissues and epithelial cells. Tube formation assays were conducted to measure angiogenesis.

Results

We determined that EC used in a model of cerebral IRI expressed Sphk1, and that inhibiting this expression led to decreased expression of two isoforms of NO synthase (eNOS and iNOS), as well as to decrease neovascularization density and NO production following injury. In HBMECs, knocking down Sphk1 markedly reduced NO production owing to reduced eNOS activity, and inhibiting eNOS directly similarly decreased NO production in a manner which could be reversed via exogenously treating cells with S1P. We further found that knocking down Sphk1 reduced HBMEC eNOS expression, in addition to decreasing the adhesion, migration, and tube formation abilities of these cells under OGDR conditions.

Conclusions

Based on these results, we therefore postulate that Sphk1/S1P signaling is able to mediate angiogenesis following cerebral IRI via the regulation of eNOS activity and NO production. As such, targeting these pathways may potentially represent a novel means of improving patient prognosis in those suffering from cerebral IRI.

Atg7 Silencing Inhibits Laminin-5 Expression to Suppress Tube Formation by Brain Endothelial Cells

Cerebral angiogenesis is a key event during brain development and recovery from brain injury. We previously demonstrated that Atg7 knockout impaired angiogenesis in the mouse brain. However, the role of Atg7 in angiogenesis is not completely understood. In this study, we used human brain microvascular endothelial cells (HBMECs) to investigate the mechanism of Atg7-regulated cerebral angiogenesis. We found that Atg7 depletion specifically diminished the expression of the β3 and γ2 chains of laminin-5, a major component of the extracellular matrix. In contrast, autophagy inhibitors did not affect laminin-5 expression, suggesting that Atg7-regulated laminin-5 expression is autophagy-independent. We also found that Atg7-regulated laminin-5 expression occurred at the transcriptional level through NF-κB signaling. Exogenous laminin-5 or the NF-κB agonist betulinic acid effectively rescued tube formation by Atg7-deficient HBMECs. Taken together, our study identified a novel mechanism by which Atg7 regulates laminin-5 expression via NF-κB to modulate tube formation by brain endothelial cells during cerebral angiogenesis. Anat Rec, 302:2255-2260, 2019. © 2019 American Association for Anatomy.

Endostatin as a novel prognostic biomarker in acute ischemic stroke

BACKGROUND AND AIMS

Endostatin is implicated in the atherosclerosis process and serves as a promising cardiovascular biomarker, while its clinical significance in ischemic stroke patients remains unclear. We aimed to examine the association between endostatin and mortality and disability after ischemic stroke.

METHODS

A total of 3463 acute ischemic stroke patients with measured plasma endostatin from the China Antihypertensive Trial in Acute Ischemic Stroke were included in this study. The primary outcome was death or severe disability (modified Rankin scale score of 4-6), and secondary outcomes included death and vascular events.

RESULTS

After 3-month follow-up, 402 (11.61%) participants experienced severe disability or died. Compared with the lowest quartile of endostatin, odds ratios or hazard ratios (95% confidence intervals) for the highest quartile were 1.47 (1.04-2.09) for the primary outcome, and 2.36 (1.23-4.54) for death after adjustment for multiple covariates, including age, sex, admission NIH Stroke Scale score and systolic blood pressure. Each 1-SD higher log-transformed endostatin was associated with a 20% (6%-36%) increased risk for primary outcome. Adding plasma endostatin to the basic model constructed with conventional factors significantly improved risk stratification of primary outcome, as observed by the category-free net reclassification index of 20.5% (95% CI 10.1%-30.8%; p < 0.001) and integrated discrimination improvement of 0.3% (95% CI 0.01%-0.6%; p = 0.04).

CONCLUSIONS

Increased baseline plasma endostatin levels in acute ischemic stroke were associated with increased risk of mortality and severe disability at 3 months. Plasma endostatin may serve as an important prognostic marker for risk stratification in patients with ischemic stroke.

Brain-Derived Microparticles (BDMPs) Contribute to Neuroinflammation and Lactadherin Reduces BDMP Induced Neuroinflammation and Improves Outcome After Stroke

Microparticles (MPs, ~size between 0.1 and 1 mm) are lipid encased containers derived from intact cells which contain antigen from the parent cells. MPs are involved in intercellular communication and regulate inflammation. Stroke increases secretion of brain derived MP (BDMP) which activate macrophages/microglia and induce neuroinflammation. Lactadherin (Milk fat globule–EGF factor-8) binds to anionic phospholipids and extracellular matrices, promotes apoptotic cell clearance and limits pathogenic antigen cross presentation. In this study, we investigate whether BDMP affects stroke-induced neuroinflammation and whether Lactadherin treatment reduces stroke initiated BDMP-induced neuroinflammation, thereby improving functional outcome after stroke. Middle aged (8–9 months old) male C57BL/6J mice were subjected to distal middle cerebral artery occlusion (dMCAo) stroke, and BDMPs were extracted from ischemic brain 24 h after dMCAo by ultracentrifugation. Adult male C57BL/6J mice were subjected to dMCAo and treated via tail vein injection at 3 h after stroke with: (A) +PBS (n = 5/group); (B) +BDMPs (1.5 × 10⁸, n = 6/group); (C) +Lactadherin (400 μg/kg, n = 5/group); (D) +BDMP+Lactadherin (n = 6/group). A battery of neurological function tests were performed and mice sacrificed for immunostaining at 14 days after stroke. Blood plasma was used for Western blot assay. Our data indicate: (1) treatment of Stroke with BDMP significantly increases lesion volume, neurological deficits, blood brain barrier (BBB) leakage, microglial activation, inflammatory cell infiltration (CD45, microglia/macrophages, and neutrophils) into brain, inflammatory factor (TNFα, IL6, and IL1β) expression in brain, increases axon/white matter (WM) damage identified by decreased axon and myelin density, and increases inflammatory factor expression in the plasma when compared to PBS treated stroke mice; (2) when compared to PBS and BDMP treated stroke mice, Lactadherin and BDMP+Lactadherin treatment significantly improves neurological outcome, and decreases lesion volume, BBB leakage, axon/WM injury, inflammatory cell infiltration and inflammatory factor expression in the ischemic brain, respectively. Lactadherin treatment significantly increases anti-inflammatory factor (IL10) expression in ischemic brain and decreases IL1β expression in plasma compared to PBS and BDMP treated stroke mice, respectively. BDMP increases neuroinflammation and aggravates ischemic brain damage after stroke. Thus, Lactadherin exerts anti-inflammatory effects and improves the clearance of MPs to reduce stroke and BDMP induced neurological deficits.

Granulocyte colony-stimulating factor and stromal cell-derived factor-1 combination therapy: A more effective treatment for cerebral ischemic stroke

BACKGROUND

Drugs that promote angiogenesis include statins, recombinant human granulocyte colony-stimulating factor, and stromal cell-derived factor-1. Low doses of atorvastatin could significantly increase the vascular expressions of endothelial growth factor, and the number of peripheral blood endothelial progenitor cells (EPCs), thus improving angiogenesis and local blood flow. G-CSF is an EPC-mobilization agent used in ischemia studies for targeting angiogenesis after cerebral ischemia via EPCs. In previous clinical trials, consistent conclusions have not been reached about the effectiveness of G-CSF on ischemic stroke. Therefore, the therapeutic effect of G-CSF and its combination with other medicines need further experimental verification. It is known that atorvastatin, rhG-CSF, and SDF-1 are considered the most promising neuroprotective candidates, but a comprehensive comparison of their effects is lacking.

AIMS

To compare the effects of atorvastatin, stromal cell-derived factor-1, and recombinant human granulocyte colony-stimulating factor on ischemic stroke.

METHODS

Adult male Sprague-Dawley rats were randomly allocated to three groups: normal, sham-operated, and middle cerebral artery occlusion operated. Middle cerebral artery occlusion operated rats were further allocated into saline, atorvastatin, recombinant human granulocyte colony-stimulating factor, and recombinant human granulocyte colony-stimulating factor + stromal cell-derived factor-1 groups. Neurological function evaluation, cerebral infarction and the blood-brain barrier integrity analysis, identification of angiogenic factors, assessment of angiogenesis, expression of growth-associated protein-43, neuroglobin, glial cell-derived neurotrophic factor, and cleaved caspase 3, were performed.

RESULTS

Compared with atorvastatin or recombinant human granulocyte colony-stimulating factor alone, recombinant human granulocyte colony-stimulating factor + stromal cell-derived factor-1 treatment improved neurological performance, reduced cerebral infarction and blood-brain barrier disruption after stroke, and increased the content of stromal cell-derived factor-1, vascular endothelial growth factor, monocyte chemotactic protein 1, and basic fibroblast growth factor in peripheral blood. In addition, recombinant human granulocyte colony-stimulating factor + stromal cell-derived factor-1 promoted greater angiogenesis than atorvastatin or recombinant human granulocyte colony-stimulating factor alone and increased the expression of growth-associated protein-43, neuroglobin, and glial cell-derived neurotrophic factor, while decreasing the levels of cleaved caspase 3 in the brain after ischemic stroke.

CONCLUSIONS

Combination therapy with recombinant human granulocyte colony-stimulating factor and stromal cell-derived factor-1 is more effective than atorvastatin or recombinant human granulocyte colony-stimulating factor alone in protecting against stroke-induced damage and could be an optimal therapeutic strategy for stroke.