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

[This corrects the article DOI: 10.3389/fncel.2023.1225504.].

Neuroprotective effects of oral metformin before stroke on cerebral small-vessel disease.

BACKGROUND: Metformin (MET) treatment prior to stroke might have neuroprotective effects other than hypoglycemic effects. This study evaluated whether MET treatment prior to stroke is associated with neurological severity and functional outcome in patients with stroke who were not indicated for endovascular treatment and whether the effects of MET differ for each ischemic stroke subtype. METHODS: We investigated 160 type 2 diabetes mellitus patients with ischemic stroke without endovascular treatment who were taking some oral antidiabetic agents prior to stroke in two tertiary hospitals. Lower neurological severity was defined as a National Institutes of Health Stroke Scale score of 3 or lower on admission, and favorable functional outcome was defined as a modified Rankin Scale score = 0-2 at discharge. We analyzed the effects of MET on the neurological severity and functional outcome in each ischemic stroke subtype on logistic regression analysis with adjustments for multiple confounding factors. RESULTS: MET treatment prior to stroke was associated with lower stroke severity and favorable functional outcome. In the stroke subtypes, MET use affected both neurological severity (P = 0.037) and functional outcome (P = 0.041) in only patients with small-vessel disease (SVD). CONCLUSIONS: MET may be useful to improve the outcome of patients with SVD.

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.

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.

[Disseminated herpes zoster complicated by lumbosacral polyradiculoneuritis and fibular neuropathy: A case report].

A 74-year-old woman who presented with a skin eruption involving the left lateral leg along the L5 dermatome and widespread eruptions on the buttocks and trunk was diagnosed with disseminated herpes zoster (HZ). She also had left lower extremity muscle weakness. The pattern of distribution of muscle weakness and gadolinium-enhanced magnetic resonance imaging findings indicated polyradiculoneuritis mainly affecting the L5 spinal root. Moreover, we observed severe weakness of the left tibialis anterior muscle. Weakness of the other L5 myotomes reduced after antiviral treatment; however, left tibialis anterior muscle weakness persisted. We concluded that lumbosacral polyradiculoneuritis was attributable to varicella-zoster virus (VZV) infection, which also caused fibular neuropathy in this case. Retrograde transport of the VZV may have infected the fibular nerve throughout the sites of skin eruption. It is important to be mindful of simultaneous nerve root and peripheral nerve involvement in cases of motor paralysis associated with HZ infection.

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 Therapy Using Peripheral Mononuclear Cells Preconditioned by Oxygen-Glucose Deprivation for Ischemic Stroke].

Many studies in recent years have reported cell therapies using embryonic stem cells, induced pluripotent stem cells, and bone marrow-derived mononuclear cells for cerebral ischemia. However, obtaining these cells is challenging, and these cell therapies require complicated procedures to prepare cells for administration. Notably, peripheral blood mononuclear cells (PBMCs) are a useful cell source for clinical applications because cell collection is easier. In this review, we report the therapeutic effects of PBMCs preconditioned by oxygen-glucose deprivation (OGD-PBMCs) on cerebral ischemia. Cell therapies using tissue-protective OGD-PBMCs might be a simple and ideal therapeutic strategy against ischemic stroke.

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.

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/ß1-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.

Publisher Correction: A novel therapeutic approach using peripheral blood mononuclear cells preconditioned by oxygen-glucose deprivation.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

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

Cell therapies that invoke pleiotropic mechanisms may facilitate functional recovery in patients with stroke. Based on previous experiments using microglia preconditioned by oxygen-glucose deprivation, we hypothesized that the administration of peripheral blood mononuclear cells (PBMCs) preconditioned by oxygen-glucose deprivation (OGD-PBMCs) to be a therapeutic strategy for ischemic stroke. Here, OGD-PBMCs were identified to secrete remodelling factors, including the vascular endothelial growth factor and transforming growth factor-ß in vitro, while intra-arterial administration of OGD-PBMCs at 7 days after focal cerebral ischemia prompted expression of such factors in the brain parenchyma at 28 days following focal cerebral ischemia in vivo. Furthermore, administration of OGD-PBMCs induced an increasing number of stage-specific embryonic antigen-3-positive cells both in vitro and in vivo. Finally, it was found to prompt angiogenesis and axonal outgrowth, and functional recovery after cerebral ischemia. In conclusion, the administration of OGD-PBMCs might be a novel therapeutic strategy against ischemic stroke.

Microglia and Monocytes/Macrophages Polarization Reveal Novel Therapeutic Mechanism against Stroke.

Stroke is a leading cause of morbidity and mortality worldwide, and consists of two types, ischemic and hemorrhagic. Currently, there is no effective treatment to increase the survival rate or improve the quality of life after ischemic and hemorrhagic stroke in the subacute to chronic phases. Therefore, it is necessary to establish therapeutic strategies to facilitate functional recovery in patients with stroke during both phases. Cell-based therapies, using microglia and monocytes/macrophages preconditioned by optimal stimuli and/or any therapies targeting these cells, might be an ideal therapeutic strategy for managing stroke. Microglia and monocytes/macrophages polarize to the classic pro-inflammatory type (M1-like) or alternative protective type (M2-like) by optimal condition. Cell-based therapies using M2-like microglia and monocytes/macrophages might be protective therapeutic strategies against stroke for three reasons. First, M2-like microglia and monocytes/monocytes secrete protective remodeling factors, thus prompting neuronal network recovery via tissue (including neuronal) and vascular remodeling. Second, these cells could migrate to the injured hemisphere through the blood-brain barrier or choroid-plexus. Third, these cells could mitigate the extent of inflammation-induced injuries by suitable timing of therapeutic intervention. Although future translational studies are required, M2-like microglia and monocytes/macrophages therapies are attractive for managing stroke based on their protective functions.

Apparent diffusion coefficient reduction might be a predictor of poor outcome in patients with posterior reversible encephalopathy syndrome.

It is thought that posterior reversible encephalopathy syndrome (PRES) is both clinically and radiologically reversible. However, its reversible nature has been challenged based on reports of permanent neurological impairments. The factors that predict the development of irreversible neurological impairment are still unclear. In the present study, we investigated clinical manifestations, laboratory findings, and neuroradiological images to identify predictors of functional outcomes in PRES. We investigated 23 PRES patients. Apparent diffusion coefficient (ADC) reduction was observed in 4 patients in the poor outcome group, whereas no patients presented ADC reduction in the favourable outcome group (p<0.01). Further studies are warranted to evaluate the association between ADC reduction and functional outcome after PRES.

[PRES: Posterior Reversible Encephalopathy Syndrome].

Posterior reversible encephalopathy syndrome (PRES) is suggested in patients with acute neurological symptoms in the appropriate clinical context, including acute hypertension, blood pressure fluctuations, renal failure, blood transfusion, immunosuppression, autoimmune disorders, and eclampsia. PRES is a clinical syndrome, and refers to a disorder with reversible subcortical vasogenic brain edema caused by endothelial dysfunction, predominantly involving the bilateral parieto-occipital regions. Although the clinical course and prognosis are favorable in most cases, intracranial hemorrhage and/or restricted diffusion similar to acute infarction could be seen in some lesions on brain magnetic resonance imaging (MRI). The spinal cord may be involved in some patients with posterior fossa lesions. Understanding the pathophysiology of PRES is helpful in making the correct early diagnosis and selecting appropriate therapies to improve its clinical course and outcome. Differentiation of PRES from strokes is critical in the setting of a neurological emergency.