Post-stroke Impairment of the Blood–Brain Barrier and Perifocal Vasogenic Edema Is Alleviated by Endovascular Mesenchymal Stem Cell Administration: Modulation of the PKCδ/MMP9/AQP4-Mediated Pathway

Simvastatin exerts neuroprotective effects post-stroke by ameliorating endoplasmic reticulum stress and regulating autophagy/apoptosis balance through pAMPK/LC3B/ LAMP2 axis

Statins have evident neuroprotective role in acute ischemic stroke(AIS). The pleiotropic effect by which statin exerts neuroprotective effects, needs to be explored for considering it as one of the future adjunctive therapies in AIS. Endoplasmic reticulum(ER) assists cellular survival by reducing protein aggregates during ischemic conditions. ER-stress mediated apoptosis and autophagy are predominant reasons for neuronal death in AIS. Statin exerts both anti-apoptotic and anti-autophagic effect in neurons under ischemic stress. Although the influence of statin on autophagic neuroprotection has been reported with contradictory results. Thus, in our study we have attempted to understand its influence on autophagic protection while inhibiting upregulation of autophagic death(autosis). Previously we reported, statin can alleviate apoptosis via modulating cardiolipin mediated mitochondrial dysfunction. However, the clearance of damaged mitochondria is essential for prolonged cell survival. In our study, we tried to decipher the mechanism by which statin leads to neuronal survival by the mitophagy mediated cellular clearance. Simvastatin was administered to Sprague Dawley(SD) rats both as prophylaxis and treatment. The safety and efficacy of the statin was validated by assessment of infarct size and functional outcome. A reduction in oxidative and ER-stress were observed in both the prophylactic and treatment groups. The influence of statin on autophagy/apoptosis balance was evaluated by molecular assessment of mitophagy and cellular apoptosis. Statin reduces the post-stroke ER-stress and predominantly upregulated autophagolysosome mediated mitophagy than apoptotic cell death by modulating pAMPK/LC3B/LAMP2 axis. Based on the above findings statin could be explored as an adjunctive therapy for AIS in future.

Priming and Combined Strategies for the Application of Mesenchymal Stem Cells in Ischemic Stroke: A Promising Approach

Ischemic stroke (IS) is a leading cause of death and disability worldwide. Tissue plasminogen activator (tPA) administration and mechanical thrombectomy are the main treatments but have a narrow time window. Mesenchymal stem cells (MSCs), which are easily scalable in vitro and lack ethical concerns, possess the potential to differentiate into various types of cells and secrete a great number of growth factors for neuroprotection and regeneration. Moreover, MSCs have low immunogenicity and tumorigenic properties, showing safety and preliminary efficacy both in preclinical studies and clinical trials of IS. However, it is unlikely that MSC treatment alone will be sufficient to maximize recovery due to the low survival rate of transplanted cells and various mechanisms of ischemic brain damage in the different stages of IS. Preconditioning was used to facilitate the homing, survival, and secretion ability of the grafted MSCs in the ischemic region, while combination therapies are alternatives that can maximize the treatment effects, focusing on multiple therapeutic targets to promote stroke recovery. In this case, the combination therapy can yield a synergistic effect. In this review, we summarize the type of MSCs, preconditioning methods, and combined strategies as well as their therapeutic mechanism in the treatment of IS to accelerate the transformation from basic research to clinical application.

Perioperative complications of middle cerebral artery occlusion in rats alleviated by human umbilical cord mesenchymal stem cells

For acute ischemic stroke treatment, the limitations of treatment methods and the high incidence of perioperative complications seriously affect the survival rate and postoperative recovery of patients. Human umbilical cord mesenchymal stem cells (hucMSCs) have multi-directional differentiation potential and immune regulation function, which is a potential cell therapy. The present investigation involved developing a model of cerebral ischemia-reperfusion injury by thrombectomy after middle cerebral artery occlusion (MCAO) for 90 min in rats and utilizing comprehensive multi-system evaluation methods, including the detection of brain tissue ischemia, postoperative survival rate, neurological score, anesthesia recovery monitoring, pain evaluation, stress response, and postoperative pulmonary complications, to elucidate the curative effect of tail vein injection of hucMSCs on MCAO's perioperative complications. Based on our research, it has been determined that hucMSCs treatment can reduce the volume of brain tissue ischemia, promote the recovery of neurological function, and improve the postoperative survival rate of MCAO in rats. At the same time, hucMSCs treatment can prolong the time of anesthesia recovery, relieve the occurrence of delirium during anesthesia recovery, and also have a good control effect on postoperative weight loss, facial pain expression, and lung injury. It can also reduce postoperative stress response by regulating blood glucose and serum levels of stress-related proteins including TNF-α, IL-6, CRP, NE, cortisol, β-endorphin, and IL-10, and ultimately promote the recovery of MCAO's perioperative complications.

Research progress and challenges of stem cell therapy for ischemic stroke

Ischemic stroke is a significant global cause of death and disability. Currently, treatment options for acute ischemic stroke are limited to intravenous thrombolysis and mechanical recanalization. Therefore, novel neuroprotective strategies are imperative. Stem cell transplantation possesses the capabilities of differentiation, proliferation, neuronal replacement, nerve pathway reconstruction, secretion of nerve growth factors, and enhancement of the microenvironment; thus, it is a potential therapeutic approach for ischemic stroke. In addition, the immunomodulatory function of stem cells and the combined treatment of stem cells and exosomes exhibit a favorable protective effect on brain injury and neurological dysfunction following stroke. Meanwhile, the theory of microbiota-gut-brain axis provides us with a novel perspective for comprehending and managing neurological diseases. Lastly, stem cell transplantation has demonstrated promising outcomes not only in treating ischemic stroke but also in dealing with other neurological disorders, such as brain tumors. Furthermore, challenges related to the tissue source, delivery method, immune response, and timing of transplantation still need to be addressed to optimize the treatment.

The impact of mechanical thrombectomy on the blood-brain barrier in patients with acute ischemic stroke: A non-contrast MR imaging study using DP-pCASL and NODDI

BACKGROUND AND PURPOSE

While mechanical thrombectomy (MT) achieves restoration of cerebral blood flow to the area at risk in patients with acute ischemic stroke (AIS), the influx of blood flow may exacerbate the blood-brain barrier (BBB) disruption and extravasation across the BBB, and it therefore remains unclear how reperfusion impacts the blood-brain barrier integrity. In this study, we use diffusion-prepared pseudocontinuous ASL (DP-pCASL) and Neurite Orientation Dispersion and Density Imaging (NODDI) sequence to measure the water exchange rate (kw) in patients who underwent either MT or medical management and determine its impact on the brain tissue microstructure in order to elucidate the impact of MT on BBB complex integrity.

MATERIALS AND METHODS

We prospectively enrolled 21 patients with AIS treated at our institution from 10/2021 to 6/2023 who underwent MR imaging at a 3.0-Tesla scanner. Patients underwent DP-pCASl and NODDI imaging in addition to the standard stroke protocol which generated cerebral blood flow (CBF), arterial transit time (ATT), water exchange rate (kw), orientation dispersion index (ODI), intracellular volume fraction (ICVF), and free water fraction (FWF) parametric maps.

RESULTS

Of the 21 patients, 11 underwent MT and 10 were treated non-operatively. The average age and NIHSS for the MT cohort and non-MT cohorts were 69.3 ± 16.6 years old and 15.0 (12.0-20.0), and 70.2 ± 10.7 (p = 0.882) and 6.0 (3.8-9.0, p = 0.003) respectively. The average CBF, ATT, and kw in the infarcted territory of the MT cohort were 38.2 (18.4-59.6), 1347.6 (1182.5-1842.3), and 107.8 (79.2-140.1) respectively. The average CBF, ATT, and kw in the stroke ROI were 16.0 (8.8-36.6, p = 0.036), 1090.8 (937.1-1258.9, p = 0.013), 89.7 (68.0-122.7, p = 0.314) respectively. Linear regression analysis showed increasing CBF (p = 0.008) and undergoing mechanical thrombectomy (p = 0.048) were significant predictors of increased kw.

CONCLUSION

Using our multimodal non-contrast MRI protocol, we demonstrate that increased CBF and mechanical thrombectomy increased kw, suggesting a better functioning BBB complex. Higher kw suggests less disruption of the BBB complex in the MT cohort.

Lifibrate attenuates blood-brain barrier damage following ischemic stroke via the MLCK/p-MLC/ZO-1 axis

Dysfunction of tight junction proteins-associated damage to the blood-brain barrier (BBB) plays an important role in the pathogenesis of ischemic stroke. Lifibrate, an inhibitor of cholinephosphotransferase (CPT), has been used as an agent for serum lipid lowering. However, the protective effects of Lifibrate in ischemic stroke and the underlying mechanism have not been clearly elucidated. Here, we employed an in vivo mice model of MCAO and an OGD/R model in vitro. In the mice models, neurological deficit scores and infarct volume were assessed. Evans Blue solution was used to detect the BBB permeability. The TEER was examined to determine brain endothelial monolayer permeability. Here, we found that Lifibrate improved neurological dysfunction in stroke. Additionally, increased BBB permeability during stroke was significantly ameliorated by Lifibrate. Correspondingly, the reduced expression of the tight junction protein ZO-1 was restored by Lifibrate at both the mRNA and protein levels. Using an in vitro model, we found that Lifibrate ameliorated OGD/R-induced injury in human bEnd.3 brain microvascular endothelial cells by increasing cell viability but reducing the release of LDH. Importantly, Lifibrate suppressed the increase in endothelial monolayer permeability and the reduction in TEER induced by OGD/R via the rescue of ZO-1 expression. Mechanistically, Lifibrate blocked activation of the MLCK/ p-MLC signaling pathway in OGD/R-stimulated bEnd.3 cells. In contrast, overexpression of MLCK abolished the protective effects of Lifibrate in endothelial monolayer permeability, TEER, as well as the expression of ZO-1. Our results provide a basis for further investigation into the neuroprotective mechanism of Lifibrate during stroke.

The Role of Stem Cells as Therapeutics for Ischaemic Stroke

Stroke remains one of the leading causes of death and disability worldwide. Current reperfusion treatments for ischaemic stroke are limited due to their narrow therapeutic window in rescuing ischaemic penumbra. Stem cell therapy offers a promising alternative. As a regenerative medicine, stem cells offer a wider range of treatment strategies, including long-term intervention for chronic patients, through the reparation and replacement of injured cells via mechanisms of differentiation and proliferation. The purpose of this review is to evaluate the therapeutic role of stem cells for ischaemic stroke. This paper discusses the pathology during acute, subacute, and chronic phases of cerebral ischaemic injury, highlights the mechanisms involved in mesenchymal, endothelial, haematopoietic, and neural stem cell-mediated cerebrovascular regeneration, and evaluates the pre-clinical and clinical data concerning the safety and efficacy of stem cell-based treatments. The treatment of stroke patients with different types of stem cells appears to be safe and efficacious even at relatively higher concentrations irrespective of the route and timing of administration. The priming or pre-conditioning of cells prior to administration appears to help augment their therapeutic impact. However, larger patient cohorts and later-phase trials are required to consolidate these findings.

Emerging diagnostic markers and therapeutic targets in post-stroke hemorrhagic transformation and brain edema

Stroke is a devastating condition that can lead to significant morbidity and mortality. The aftermath of a stroke, particularly hemorrhagic transformation (HT) and brain edema, can significantly impact the prognosis of patients. Early detection and effective management of these complications are crucial for improving outcomes in stroke patients. This review highlights the emerging diagnostic markers and therapeutic targets including claudin, occludin, zonula occluden, s100β, albumin, MMP-9, MMP-2, MMP-12, IL-1β, TNF-α, IL-6, IFN-γ, TGF-β, IL-10, IL-4, IL-13, MCP-1/CCL2, CXCL2, CXCL8, CXCL12, CCL5, CX3CL1, ICAM-1, VCAM-1, P-selectin, E-selectin, PECAM-1/CD31, JAMs, HMGB1, vWF, VEGF, ROS, NAC, and AQP4. The clinical significance and implications of these biomarkers were also discussed.

Stem cells alleviate OGD/R mediated stress response in PC12 cells following a co-culture: modulation of the apoptotic cascade through BDNF-TrkB signaling

Apoptosis mediated by endoplasmic reticulum (ER) stress plays a crucial role in several neurovascular disorders, including ischemia/reperfusion injury (I/R injury). Previous in vitro and in vivo studies have suggested that following I/R injury, ER stress is vital for mediating CCAT-enhancer-binding protein homologous protein (CHOP) and caspase-12-dependent apoptosis. However, its modulation in the presence of stem cells and the underlying mechanism of cytoprotection remains elusive. In vivo studies from our lab have reported that post-stroke endovascular administration of stem cells renders neuroprotection and regulates apoptosis mediated by ER stress. In the current study, a more robust in vitro validation has been undertaken to decipher the mechanism of stem cell-mediated cytoprotection. Results from our study have shown that oxygen-glucose deprivation/reoxygenation (OGD/R) potentiated ER stress and apoptosis in the pheochromocytoma 12 (PC12) cell line as evident by the increase of protein kinase R (PKR)-like ER kinase (p-PERK), p-Eukaryotic initiation factor 2α subunit (EIF2α), activation transcription factor 4 (ATF4), CHOP, and caspase 12 expressions. Following the co-culture of PC12 cells with MSCs, ER stress was significantly reduced, possibly via modulating the brain-derived neurotrophic factor (BDNF) signaling. Furthermore, inhibition of BDNF by inhibitor K252a abolished the protective effects of BDNF secreted by MSCs following OGD/R. Our study suggests that inhibition of ER stress-associated apoptotic pathway with MSCs co-culture following OGD/R may help to alleviate cellular injury and further substantiate the use of stem cells as a therapeutic modality toward neuroprotection following hypoxic injury or stroke in clinical settings.

Nanowired delivery of dl-3-n-butylphthalide with antibodies to alpha synuclein potentiated neuroprotection in Parkinson's disease with emotional stress

Stress is one of the most serious consequences of life leading to several chronic diseases and neurodegeneration. Recent studies show that emotional stress and other kinds of anxiety and depression adversely affects Parkinson's disease symptoms. However, the details of how stress affects Parkinson's disease is still not well known. Traumatic brain injury, stroke, diabetes, post-traumatic stress disorders are well known to modify the disease precipitation, progression and persistence. However, show stress could influence Parkinson's disease is still not well known. The present investigation we examine the role of immobilization stress influencing Parkinson's disease brain pathology in model experiments. In ore previous report we found that mild traumatic brain injury exacerbate Parkinson's disease brain pathology and nanodelivery of dl-3-n-butylphthalide either alone or together with mesenchymal stem cells significantly attenuated Parkinson's disease brain pathology. In this chapter we discuss the role of stress in exacerbating Parkinson's disease pathology and nanowired delivery of dl-3-n-butylphthalide together with monoclonal antibodies to alpha synuclein (ASNC) is able to induce significant neuroprotection. The possible mechanisms of dl-3-n-butylphthalide and ASNC induced neuroprotection and suitable clinical therapeutic strategy is discussed.

Inosine attenuates post-stroke neuroinflammation by modulating inflammasome mediated microglial activation and polarization

To date, various agents and molecules have been developed to treat post-stroke neuroinflammation; however, none of them are clinically successful. Post-stroke neuroinflammation is primarily attributed to microglial polarization as the generation of inflammasome complexes shifts microglia to their M1 phenotype and regulate the downstream cascade. Inosine, an adenosine derivative reported to maintain cellular energy homeostasis in stressed condition. Although, the exact mechanism is still unexplored, various studies have reported that it can stimulate axonal sprouting in different neurodegenerative diseases. Hence, our present study aims to decipher the molecular mechanism of inosine mediated neuroprotection by modulating inflammasome signaling towards altered microglial polarization in ischemic stroke. Inosine was administered intraperitoneally to male Sprague Dawley rats at 1 h post ischemic stroke and were further evaluated for neurodeficit score, motor coordination and long-term neuroprotection. Brains were harvested for infarct size estimation, biochemical assays and molecular studies. Inosine administration at 1 h post ischemic stroke decreased infarct size, neurodeficit score, and improved motor co-ordination. Normalization of biochemical parameters were achieved in the treatment groups. Microglial polarization towards its anti-inflammatory phenotype and modulation of inflammation were evident by relevant gene and protein expression studies. The outcome provides preliminary evidence of inosine mediated alleviation of post-stroke neuroinflammation via modulation of microglial polarization towards its anti-inflammatory form through regulating the inflammasome activation.

Selenium supplementation enhanced the expression of selenoproteins in hippocampus and played a neuroprotective role in LPS-induced neuroinflammation

Selenium (Se) is obtained from organic and inorganic selenium food content, which mainly depends on the regional soil selenium content. Selenium deficiency and decreased selenoprotein functions have been shown to associate with the progression of cognitive decline and neurodegenerations including Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD). Selenoproteins are well recognized for their anti-oxidative activities. Given the high oxygen consumption, mammalian brains preferent@ially supplied with Se. Here, we propose a beneficiary role for dietary supplementation of sodium selenite (300 ng per gram of body weight) in ameliorating neuroinflammation induced by bilateral intracerebroventricular injection of 1 μL LPS (1 μg/μL), evidenced by the significantly reduced oxidative stress, downregulated pro-inflammatory cytokines expression, improved integrity of blood-brain barrier, as well as suppressed glial activation and shifted microglial MI/M2 polarization in Se-sup mouse brain. Se intake also reduced neural cell death and significantly improved the cognition in Se-sup mice following LPS challenge. The neuroprotective role for supplementary Se is likely to be ascribed to the overall elevated expression of selenoproteins, especially Selenoprotein P (SELENOP) and Glutathione peroxidase 4 (GPX4), ranking on top of the change in selenoprotein expression hierarchy. The regional hierarchy of Se induced elevation of SELENOP expression was further characterized. The SELENOP expression in the mediodorsal thalamic nucleus, dendric gyrus (DG) and cornu ammonis 3 (CA3) of hippocampus and lateral habenular nucleus was highly sensitive to dietary Se intake.

miR-211-5p targeting MMP9 regulates the expressions of AQP4 in traumatic brain injury

OBJECTIVE

The abnormal expression of matrix metalloproteinase 9 (MMP9) and Aquaporin 4 (AQP4) closely associates with the traumatic brain injury (TBI) development.

METHODS

Here, we investigated the relationship between miR-211-5p and MMP9/AQP4 axis in TBI patients and astrocyte cells. Demographics, clinical features, and cerebrospinal fluid (CSF) samples were collected from traumatic brain injury (TBI) patients (n = 96) and controls (n = 30) for pathological and gene expression analyses. Luciferase activity assay and gene expression analyses were performed to dissect the regulatory mechanism of miR-211-5p on MMP9/AQP4 in human astrocyte cells.

RESULTS

miR-211-5p mRNA was significantly decreased in the CSF of TBI patients, which positively correlated with the expression of both MMP9 and AQP4. miR-211-5p could target MMP9 directly in SVG P12 cells. Overexpression of miR-211-5p decreased the expression of MMP9, on the contrary, knockdown miR-211-5p through inhibitors increased the expression of both MMP9 and AQP4.

CONCLUSION

miR-211-5p inhibits the MMP9/AQP4 axis in human astrocyte cells, which represents a promising approach for the TBI treatment.

Cardiolipin-Mediated Alleviation of Mitochondrial Dysfunction Is a Neuroprotective Effect of Statin in Animal Model of Ischemic Stroke

In clinical settings, the benefit of statin for stroke is debatable as regular statin users may suffer from myalgia, statin-associated myopathy (SAM), and rarely rhabdomyolysis. Studies suggest that patients on statin therapy show lesser vulnerability toward ischemic stroke and post-stroke frailty. Both pre- and post-treatment benefits of statin have been reported as evident by its neuroprotective effects in both cases. As mitochondrial dysfunction following stroke is the fulcrum for neuronal death, we hereby explore the role of statin in alleviating mitochondrial dysfunction by regulating the mitochondrial dynamics. In the present study, we intend to evaluate the role of statin in modulating cardiolipin-mediated mitochondrial functionality and further providing a therapeutic rationale for repurposing statins either as preventive or an adjunctive therapy for stroke.

Endovascular Stem Cell Therapy Promotes Neuronal Remodeling to Enhance Post Stroke Recovery by Alleviating Endoplasmic Reticulum Stress Modulated by BDNF Signaling

BACKGROUND AND PURPOSE

The impact of increased BDNF expression in brain by endovascular delivered mesenchymal stem cells (MSCs) post stroke towards modulating endoplasmic reticulum (ER) stress mediated neuronal remodeling has not been directly studied. Therefore, the present study investigates ER stress mediated neuronal remodeling following IA MSCs infusion in rodent model of ischemic stroke.

METHODS

Ovariectomized Sprague Dawley rats were subjected to MCAO followed by 1 × 10⁵ IA MSCs administration at 6 h. Infarct and functional outcomes at different time points post-stroke were evaluated. Further, various genes and protein expression studies were performed to determine the underlying mechanisms of the effect of IA MSCs towards ER stress mediated neuronal remodeling.

RESULTS

Post-stroke IA MSCs administration significantly increased BDNF expression and decreased ER stress markers expression at day 1 post-stroke. A gradual rise in the expression of growth associate protein-43 (GAP 43) and spinophilin were observed at 7, 14- and 28-days post-stroke indicating an increase in neuronal remodeling towards functional restoration.

CONCLUSIONS

The results suggest that IA MSCs post-stroke can modulate neuronal remodeling by BDNF-mediated reduction in ER stress that contribute towards functional recovery.

Pharmacological Strategies for Stroke Intervention: Assessment of Pathophysiological Relevance and Clinical Trials

OBJECTIVES

The present review describes stroke pathophysiology in brief and discusses the spectrum of available treatments with different promising interventions that are in clinical settings or are in clinical trials.

METHODS

Relevant articles were searched using Google Scholar, Cochrane Library, and PubMed. Keywords for the search included ischemic stroke, mechanisms, stroke interventions, clinical trials, and stem cell therapy.

RESULTS AND CONCLUSION

Stroke accounts to a high burden of mortality and morbidity around the globe. Time is an important factor in treating stroke. Treatment options are limited; however, agents with considerable efficacy and tolerability are being continuously explored. With the advances in stroke interventions, new therapies are being formulated with a hope that these may aid the ongoing protective and reparative processes. Such therapies may have an extended therapeutic time window in hours, days, weeks, or longer and may have the advantage to be accessible by a majority of the patients.

Mesenchymal stem cell therapy for ischemic stroke: Novel insight into the crosstalk with immune cells

Stroke, a cerebrovascular accident, is prevalent and the second highest cause of death globally across patient populations; it is as a significant cause of morbidity and mortality. Mesenchymal stem cell (MSC) transplantation is emerging as a promising treatment for alleviating neurological deficits, as indicated by a great number of animal and clinical studies. The potential of regulating the immune system is currently being explored as a therapeutic target after ischemic stroke. This study will discuss recent evidence that MSCs can harness the immune system by interacting with immune cells to boost neurologic recovery effectively. Moreover, a notion will be given to MSCs participating in multiple pathological processes, such as increasing cell survival angiogenesis and suppressing cell apoptosis and autophagy in several phases of ischemic stroke, consequently promoting neurological function recovery. We will conclude the review by highlighting the clinical opportunities for MSCs by reviewing the safety, feasibility, and efficacy of MSCs therapy.

Cerebral edema after ischemic stroke: Pathophysiology and underlying mechanisms

Ischemic stroke is associated with increasing morbidity and has become the main cause of death and disability worldwide. Cerebral edema is a serious complication arising from ischemic stroke. It causes an increase in intracranial pressure, rapid deterioration of neurological symptoms, and formation of cerebral hernia, and is an important risk factor for adverse outcomes after stroke. To date, the detailed mechanism of cerebral edema after stroke remains unclear. This limits advances in prevention and treatment strategies as well as drug development. This review discusses the classification and pathological characteristics of cerebral edema, the possible relationship of the development of cerebral edema after ischemic stroke with aquaporin 4, the SUR1-TRPM4 channel, matrix metalloproteinase 9, microRNA, cerebral venous reflux, inflammatory reactions, and cerebral ischemia/reperfusion injury. It also summarizes research on new therapeutic drugs for post-stroke cerebral edema. Thus, this review provides a reference for further studies and for clinical treatment of cerebral edema after ischemic stroke.