A novel therapeutic approach using peripheral blood mononuclear cells preconditioned by oxygen-glucose deprivation

Remote ischemic preconditioning prevents high-altitude cerebral edema by enhancing glucose metabolic reprogramming

AIMS

Incidence of acute mountain sickness (AMS) ranges from 40%-90%, with high-altitude cerebral edema (HACE) representing a life-threatening end stage of severe AMS. However, practical and convenient preventive strategies for HACE are lacking. Remote ischemic preconditioning (RIPC) has demonstrated preventive effects on ischemia- or hypoxia-induced cardiovascular and cerebrovascular diseases. This study aimed to investigate the potential molecular mechanism of HACE and the application of RIPC in preventing HACE onset.

METHODS

A hypobaric hypoxia chamber was used to simulate a high-altitude environment of 7000 meters. Metabolomics and metabolic flux analysis were employed to assay metabolite levels. Transcriptomics and quantitative real-time PCR (q-PCR) were used to investigate gene expression levels. Immunofluorescence staining was performed on neurons to label cellular proteins. The fluorescent probes Mito-Dendra2, iATPSnFR1.0, and CMTMRos were used to observe mitochondria, ATP, and membrane potential in cultured neurons, respectively. TUNEL staining was performed to detect and quantify apoptotic cell death. Hematoxylin and eosin (H&E) staining was utilized to analyze pathological changes, such as tissue swelling in cerebral cortex samples. The Rotarod test was performed to assess motor coordination and balance in rats. Oxygen-glucose deprivation (OGD) of cultured cells was employed as an in vitro model to simulate the hypoxia and hypoglycemia induced by RIPC in animal experiments.

RESULTS

We revealed a causative perturbation of glucose metabolism in the brain preceding cerebral edema. Ischemic preconditioning treatment significantly reprograms glucose metabolism, ameliorating cell apoptosis and hypoxia-induced energy deprivation. Notably, ischemic preconditioning improves mitochondrial membrane potential and ATP production through enhanced glucose-coupled mitochondrial metabolism. In vivo studies confirm that RIPC alleviates cerebral edema, reduces cell apoptosis induced by high-altitude hypoxia, and improves motor dysfunction resulting from cerebral edema.

CONCLUSIONS

Our study elucidates the metabolic basis of HACE pathogenesis. This study provides a new strategy for preventing HACE that RIPC reduces brain edema through reprogramming metabolism, highlighting the potential of targeting metabolic reprogramming for neuroprotective interventions in neurological diseases caused by ischemia or hypoxia.

Oxygen-Glucose Deprived Peripheral Blood Mononuclear Cells Protect Against Ischemic Stroke

Stroke is the leading cause of severe long-term disability. Cell therapy has recently emerged as an approach to facilitate functional recovery in stroke. Although administration of peripheral blood mononuclear cells preconditioned by oxygen-glucose deprivation (OGD-PBMCs) has been shown to be a therapeutic strategy for ischemic stroke, the recovery mechanisms remain largely unknown. We hypothesised that cell-cell communications within PBMCs and between PBMCs and resident cells are necessary for a polarising protective phenotype. Here, we investigated the therapeutic mechanisms underlying the effects of OGD-PBMCs through the secretome. We compared levels of transcriptomes, cytokines, and exosomal microRNA in human PBMCs by RNA sequences, Luminex assay, flow cytometric analysis, and western blotting under normoxic and OGD conditions. We also performed microscopic analyses to assess the identification of remodelling factor-positive cells and evaluate angiogenesis, axonal outgrowth, and functional recovery by blinded examination by administration of OGD-PBMCs after ischemic stroke in Sprague-Dawley rats. We found that the therapeutic potential of OGD-PBMCs was mediated by a polarised protective state through decreased levels of exosomal miR-155-5p, and upregulation of vascular endothelial growth factor and a pluripotent stem cell marker stage-specific embryonic antigen-3 through the hypoxia-inducible factor-1α axis. After administration of OGD-PBMCs, microenvironment changes in resident microglia by the secretome promoted angiogenesis and axonal outgrowth, resulting in functional recovery after cerebral ischemia. Our findings revealed the mechanisms underlying the refinement of the neurovascular unit by secretome-mediated cell-cell communications through reduction of miR-155-5p from OGD-PBMCs, highlighting the therapeutic potential carrier of this approach against ischemic stroke.

Regeneration of the cerebral cortex by direct chemical reprogramming of macrophages into neuronal cells in acute ischemic stroke

Theoretically, direct chemical reprogramming of somatic cells into neurons in the infarct area represents a promising regenerative therapy for ischemic stroke. Previous studies have reported that human fibroblasts and astrocytes transdifferentiate into neuronal cells in the presence of small molecules without introducing ectopic transgenes. However, the optimal combination of small molecules for the transdifferentiation of macrophages into neurons has not yet been determined. The authors hypothesized that a combination of small molecules could induce the transdifferentiation of monocyte-derived macrophages into neurons and that the administration of this combination may be a regenerative therapy for ischemic stroke because monocytes and macrophages are directly involved in the ischemic area. Transcriptomes and morphologies of the cells were compared before and after stimulation using RNA sequencing and immunofluorescence staining. Microscopic analyses were also performed to identify cell markers and evaluate functional recovery by blinded examination following the administration of small molecules after ischemic stroke in CB-17 mice. In this study, an essential combination of six small molecules [CHIR99021, Dorsomorphin, Forskolin, isoxazole-9 (ISX-9), Y27632, and DB2313] that transdifferentiated monocyte-derived macrophages into neurons in vitro was identified. Moreover, administration of six small molecules after cerebral ischemia in model animals generated a new neuronal layer in the infarct cortex by converting macrophages into neuronal cells, ultimately improving neurological function. These results suggest that altering the transdifferentiation of monocyte-derived macrophages by the small molecules to adjust their adaptive response will facilitate the development of regenerative therapies for ischemic stroke.

4R-cembranoid protects neuronal cells from oxygen-glucose deprivation by modulating microglial cell activation

As major immune responsive cells in the central nervous system (CNS), activated microglia can present pro-inflammatory M1 phenotype aggravating the neuronal injury or anti-inflammatory M2 phenotype providing neuroprotection and promoting neuronal survival in neurodegenerative diseases. In this study, we demonstrated that a compound, 4R-cembranoid (4R, 1S, 2E, 4R, 6R,-7E, 11E-2, 7, 11-cembratriene-4, 6-diol cembranoids) promoted M2 phenotype while attenuated M1 phenotype in N9 cells, a microglial cell line. Following Lipopolysaccharides (LPS) or Oxygen-glucose deprivation (OGD) treatment, the N9 cells treated by 1 µM 4R showed an increased Arginase-1 (Arg1, a M2 marker) expression and a reduced inducible nitric oxide synthase (iNOS, M1 marker) expression. In addition, the conditioned medium of 4R-treated post-OGD N9 cells protected neuro2a cells, a neuronal cell line, from OGD-induced injury. The viability of neuro2a cells in OGD condition was increased by 54.5% after treated with the conditioned medium of 4R-treated post-OGD N9 cells. Furthermore, we demonstrated the protective mechanism of 4R was associated with a decreased TNF-α release and an increased IL-10 release from N9 cells. In conclusion, our study demonstrated that the neuroprotective effects of 4R were through the regulation of microglial activation by promoting the protective M2 activation and inhibiting the damaging M1 activation. Therefore, the findings of this study suggest that 4R could be a promising lead structure for the development of drugs for the treatment of ischemic stroke and other neurodegenerative diseases with an inflammatory component involved.

Nonfreezing Low Temperature Maintains the Viability of Menstrual Blood-Derived Endometrial Stem Cells Under Oxygen-Glucose Deprivation Through the Sustained Release of Autophagy-Produced Energy

Between the completion of the mesenchymal stem cell (MSCs) preparation and the transplantation into the patient, there is a time interval during which the quality control and transport of MSC products occur, which usually involves suspending the cells in normal saline in an oxygen-glucose deprivation (OGD) microenvironments. Thus, how to effectively maintain MSC viability during the abovementioned time interval is bound to play a significant role in the therapeutic effect of MSC-based therapies. Recently, menstrual blood-derived endometrial stem cells (MenSCs) have attracted extensive attention in regenerative medicine due to their superior biological characteristics, including noninvasive protocols for their collection, abundant source material, stable donation, and autotransplantation. Therefore, this study aimed to mainly determine the effect of storage temperature on the maintenance of MenSC viabilities in an OGD microenvironment, and to preliminarily explore its potential mechanism. Simultaneously, the effects of solvents commonly used in the clinic on MenSC viability were also examined to support the clinical application of MenSCs. Consequently, our results demonstrated that in the OGD microenvironment, a nonfreezing low temperature (4°C) was suitable and cost-effective for MenSC storage, and the maintenance of MenSC viability stored at 4°C was partly contributed by the sustained releases of autophagy-produced energy. Furthermore, the addition of human serum albumin effectively inhibited the cell sedimentations in the MenSC suspension. These results provide support and practical experience for the extensive application of MenSCs in the clinic.

Cell therapies in the clinic

Cell therapies have emerged as a promising therapeutic modality with the potential to treat and even cure a diverse array of diseases. Cell therapies offer unique clinical and therapeutic advantages over conventional small molecules and the growing number of biologics. Particularly, living cells can simultaneously and dynamically perform complex biological functions in ways that conventional drugs cannot; cell therapies have expanded the spectrum of available therapeutic options to include key cellular functions and processes. As such, cell therapies are currently one of the most investigated therapeutic modalities in both preclinical and clinical settings, with many products having been approved and many more under active clinical investigation. Here, we highlight the diversity and key advantages of cell therapies and discuss their current clinical advances. In particular, we review 28 globally approved cell therapy products and their clinical use. We also analyze >1700 current active clinical trials of cell therapies, with an emphasis on discussing their therapeutic applications. Finally, we critically discuss the major biological, manufacturing, and regulatory challenges associated with the clinical translation of cell therapies.

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.

Strategies to prevent hemorrhagic transformation after reperfusion therapies for acute ischemic stroke: A literature review

BACKGROUND

Reperfusion therapies by tissue plasminogen activator (tPA) and mechanical thrombectomy (MT) have ushered in a new era in the treatment of acute ischemic stroke (AIS). However, reperfusion therapy-related HT remains an enigma.

AIM

To provide a comprehensive review focused on emerging concepts of stroke and therapeutic strategies, including the use of protective agents to prevent HT after reperfusion therapies for AIS.

METHODS

A literature review was performed using PubMed and the ClinicalTrials.gov database.

RESULTS

Risk of HT increases with delayed initiation of tPA treatment, higher baseline glucose level, age, stroke severity, episode of transient ischemic attack within 7 days of stroke onset, and hypertension. At a molecular level, HT that develops after thrombolysis is thought to be caused by reactive oxygen species, inflammation, remodeling factor-mediated effects, and tPA toxicity. Modulation of these pathophysiological mechanisms could be a therapeutic strategy to prevent HT after tPA treatment. Clinical mechanisms underlying HT after MT are thought to involve smoking, a low Alberta Stroke Program Early CT Score, use of general anesthesia, unfavorable collaterals, and thromboembolic migration. However, the molecular mechanisms are yet to be fully investigated. Clinical trials with MT and protective agents have also been planned and good outcomes are expected.

CONCLUSION

To fully utilize the easily accessible drug-tPA-and the high recanalization rate of MT, it is important to reduce bleeding complications after recanalization. A future study direction could be to investigate the recovery of neurological function by combining reperfusion therapies with cell therapies and/or use of pleiotropic protective agents.

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.

Elevated serum pentraxin 3 levels might predict the diagnosis of branch atheromatous disease at a very early stage

BACKGROUND AND PURPOSE

Branch atheromatous disease (BAD) is one of the stroke subtypes caused by occlusion at the origin of a deep penetrating artery of the brain and is associated with a microatheroma or a junctional plaque. Patients with BAD often develop progressive worsening of neurologic deficits, although these patients often present minor stroke with clinical characteristics of lacunar syndrome at the onset. Pentraxin 3 (PTX3) is known to be a key molecule involved in the pathogenesis of atherosclerosis. Although a high level of serum PTX3 is observed in patients with acute coronary syndrome, there are no reports on PTX3 levels in patients with BAD. This study aimed to investigate whether serum PTX3 levels can distinguish BAD from other stroke subtypes.

METHODS

We investigated 93 patients with ischaemic stroke. Serum PTX3 levels on admission were measured using enzyme-linked immunosorbent assay in patients with BAD and those with other stroke subtypes (each n ≥ 20).

RESULTS

The median PTX3 levels in patients with BAD (4840 pg/mL) were higher than those with other subtypes of stroke (3397 pg/mL in lacunar stroke, 1298 pg/mL in large-artery atherosclerosis, 1470 pg/mL in cardioaortic embolism and 1006 pg/mL in control) (all P < 0.01).

CONCLUSION

Our results suggest that elevated serum PTX3 levels might predict the diagnosis of BAD at a very early stage.