RETRACTED: Neural Stem Cells Engineered to Express Three Therapeutic Factors Mediate Recovery from Chronic Stage CNS Autoimmunity

Olig2-enriched exosomes: A novel therapeutic approach for cuprizone-induced demyelination

The research aims to study the therapeutic impact of HEK293-XPack-Olig2 cell-derived exosomes on remyelination of the corpus callosum in a cuprizone-induced demyelinating disease model. A lentiviral vector expressing Olig2 was constructed using XPack technology. The highly abundant Olig2 exosomes (ExoOs) were isolated by centrifugation for subsequent experiments. Western blot, nanoparticle tracking analysis (NTA), and electron microscopy showed no significant difference in particle size and morphology between Exos and ExoOs, and a high level of Olig2 expression could be detected in ExoOs, indicating that exosome modification by XPack technology was successful. The Black Gold/Fluromyelin staining analysis showed that the ExoOs group significantly reduced the demyelination area in the corpus callosum compared to the PBS and Exos groups. Additionally, the PDGFRα/APC staining of the demyelinating region revealed an increase in APC+ oligodendrocytes and a decrease in PDGFRα+ oligodendrocyte progenitor cells (OPCs) in the ExoOs group. Furthermore, there was evident myelin regeneration in the demyelinated areas after ExoOs treatment, with better g-ratio and a higher number of intact myelin compared to the other treatment groups. The level of Sox10 expression in the brain tissue of the ExoOs group were higher compared to those of the PBS and Exos groups. The demyelination process can be significantly slowed down by the XPack-modified exosomes, the differentiation of OPCs promoted, and myelin regeneration accelerated under pathological conditions. This process is presumed to be achieved by changing the expression level of intracellular differentiation-related genes after exosomes transport Olig2 enriched into oligodendrocyte progenitors.

Microglia/macrophage polarization regulates spontaneous remyelination in intermittent cuprizone model of demyelination

Central nervous system (CNS) lesions can repeatedly be de-and remyelinated during demyelinating diseases such as multiple sclerosis (MS). Here, we designed an intermittent demyelination model by 0.3 % Cuprizone feeding in C57/BL6 mice followed by two weeks recovery. Histochemical staining of luxol fast blue (LFB) was used for study of remyelination, detection of glial and endothelial cells was performed by immunohistochemistry staining for the following antibodies: anti Olig2 for oligodendrocyte progenitor cells, anti APC for mature oligodendrocytes, anti GFAP for astrocytes, and anti Iba-1 for microglia/macrophages, anti iNOS for M1 microglia/macrophage phenotype, anti TREM-2 for M2 microglia/macrophage phenotype and anti CD31 for endothelial cells. Also, real-time polymerase chain reaction was performed for assessment of the expression of the targeted genes. LFB staining results showed enhanced remyelination in the intermittent cuprizone (INTRCPZ) group, which was accompanied by improved motor function, increased mature oligodendrocyte cells, and reduction of astrogliosis and microgliosis. Moreover, switching from M1 to M2 polarity increased in the INTRCPZ group that was in association with downregulation of pro-inflammatory and upregulation of anti-inflammatory genes. Finally, evaluation of microvascular changes revealed a remarkable decrease in the endothelial cells in the cuprizone (CPZ) group which recovered in the INTERCPZ group. The outcomes demonstrate enhanced myelin content during recovery in the intermittent demyelination model which is in association with reshaping macrophage polarity and modification of glial and endothelial cells.

Increasing β-hexosaminidase A activity using genetically modified mesenchymal stem cells

GM2 gangliosidoses are a group of autosomal-recessive lysosomal storage disorders. These diseases result from a deficiency of lysosomal enzyme β-hexosaminidase A (HexA), which is responsible for GM2 ganglioside degradation. HexA deficiency causes the accumulation of GM2-gangliosides mainly in the nervous system cells, leading to severe progressive neurodegeneration and neuroinflammation. To date, there is no treatment for these diseases. Cell-mediated gene therapy is considered a promising treatment for GM2 gangliosidoses. This study aimed to evaluate the ability of genetically modified mesenchymal stem cells (MSCs-HEXA-HEXB) to restore HexA deficiency in Tay-Sachs disease patient cells, as well as to analyze the functionality and biodistribution of MSCs in vivo. The effectiveness of HexA deficiency cross-correction was shown in mutant MSCs upon interaction with MSCs-HEXA-HEXB. The results also showed that the MSCs-HEXA-HEXB express the functionally active HexA enzyme, detectable in vivo, and intravenous injection of the cells does not cause an immune response in animals. These data suggest that genetically modified mesenchymal stem cells have the potentials to treat GM2 gangliosidoses.

Genetically engineered neural stem cells (NSCs) therapy for neurological diseases; state-of-the-art

Neural stem cells (NSCs) are multipotent stem cells with remarkable self-renewal potential and also unique competencies to differentiate into neurons, astrocytes, and oligodendrocytes (ODCs) and improve the cellular microenvironment. In addition, NSCs secret diversity of mediators, including neurotrophic factors (e.g., BDNF, NGF, GDNF, CNTF, and NT-3), pro-angiogenic mediators (e.g., FGF-2 and VEGF), and anti-inflammatory biomolecules. Thereby, NSCs transplantation has become a reasonable and effective treatment for various neurodegenerative disorders by their capacity to induce neurogenesis and vasculogenesis and dampen neuroinflammation and oxidative stress. Nonetheless, various drawbacks such as lower migration and survival and less differential capacity to a particular cell lineage concerning the disease pathogenesis hinder their application. Thus, genetic engineering of NSCs before transplantation is recently regarded as an innovative strategy to bypass these hurdles. Indeed, genetically modified NSCs could bring about more favored therapeutic influences post-transplantation in vivo, making them an excellent option for neurological disease therapy. This review for the first time offers a comprehensive review of the therapeutic capability of genetically modified NSCs rather than naïve NSCs in neurological disease beyond brain tumors and sheds light on the recent progress and prospect in this context.

Potency assays and biomarkers for cell-based advanced therapy medicinal products

Advanced Therapy Medicinal Products (ATMPs) based on somatic cells expanded in vitro, with or without genetic modification, is a rapidly growing area of drug development, even more so following the marketing approval of several such products. ATMPs are produced according to Good Manufacturing Practice (GMP) in authorized laboratories. Potency assays are a fundamental aspect of the quality control of the end cell products and ideally could become useful biomarkers of efficacy in vivo. Here we summarize the state of the art with regard to potency assays used for the assessment of the quality of the major ATMPs used clinic settings. We also review the data available on biomarkers that may substitute more complex functional potency tests and predict the efficacy in vivo of these cell-based drugs.

Bryostatin-1: a promising compound for neurological disorders

The central nervous system (CNS) is the most complex system in human body, and there is often a lack of effective treatment strategies for the disorders related with CNS. Natural compounds with multiple pharmacological activities may offer better options because they have broad cellular targets and potentially produce synergic and integrative effects. Bryostatin-1 is one of such promising compounds, a macrolide separated from marine invertebrates. Bryostatin-1 has been shown to produce various biological activities through binding with protein kinase C (PKC). In this review, we mainly summarize the pharmacological effects of bryostatin-1 in the treatment of multiple neurological diseases in preclinical studies and clinical trials. Bryostatin-1 is shown to have great therapeutic potential for Alzheimer's disease, multiple sclerosis, fragile X syndrome, stroke, traumatic brain injury, and depression. It exhibits significant rescuing effects on the deficits of spatial learning, cognitive function, memory and other neurological functions caused by diseases, producing good neuroprotective effects. The promising neuropharmacological activities of bryostatin-1 suggest that it is a potential candidate for the treatment of related neurological disorders although there are still some issues needed to be addressed before its application in clinic.

Immunomodulatory and Anti-inflammatory effect of Neural Stem/Progenitor Cells in the Central Nervous System

Neuroinflammation is a critical event that responds to disturbed homeostasis and governs various neurological diseases in the central nervous system (CNS). The excessive inflammatory microenvironment in the CNS can adversely affect endogenous neural stem cells, thereby impeding neural self-repair. Therapies with neural stem/progenitor cells (NSPCs) have shown significant inhibitory effects on inflammation, which is mainly achieved through intercellular contact and paracrine signalings. The intercellular contact between NSPCs and immune cells, the activated CNS- resident microglia, and astrocyte plays a critical role in the therapeutic NSPCs homing and immunomodulatory effects. Moreover, the paracrine effect mainly regulates infiltrating innate and adaptive immune cells, activated microglia, and astrocyte through the secretion of bioactive molecules and extracellular vesicles. However, the molecular mechanism involved in the immunomodulatory effect of NSPCs is not well discussed. This article provides a systematic analysis of the immunomodulatory mechanism of NSPCs, discusses efficient ways to enhance its immunomodulatory ability, and gives suggestions on clinical therapy.

Regulation of microglia function by neural stem cells

Neural stem and precursor cells (NPCs) build and regenerate the central nervous system (CNS) by maintaining their pool (self-renewal) and differentiating into neurons, astrocytes, and oligodendrocytes (multipotency) throughout life. This has inspired research into pro-regenerative therapies that utilize transplantation of exogenous NPCs or recruitment of endogenous adult NPCs for CNS regeneration and repair. Recent advances in single-cell RNA sequencing and other "omics" have revealed that NPCs express not just traditional progenitor-related genes, but also genes involved in immune function. Here, we review how NPCs exert immunomodulatory function by regulating the biology of microglia, immune cells that are present in NPC niches and throughout the CNS. We discuss the role of transplanted and endogenous NPCs in regulating microglia fates, such as survival, proliferation, migration, phagocytosis and activation, in the developing, injured and degenerating CNS. We also provide a literature review on NPC-specific mediators that are responsible for modulating microglia biology. Our review highlights the immunomodulatory properties of NPCs and the significance of these findings in the context of designing pro-regenerative therapies for degenerating and diseased CNS.

Engineered extracellular vesicles encapsulated Bryostatin-1 as therapy for neuroinflammation

Targeted and effective drug delivery to central nervous system (CNS) lesions is a major challenge in the treatment of multiple sclerosis (MS). Extracellular vesicles (EVs) have great promise as a drug delivery nanosystem given their unique characteristics, including a strong cargo-loading capacity, low immunogenicity, high biocompatibility, inherent stability, high delivery efficiency, ease of manipulation, and blood-brain barrier (BBB) penetration. Clinical applications are, however, limited by their insufficient targeting capability and "dilution effects" upon systemic administration. Neural stem cells (NSCs) provide an abundant source of EVs because of their remarkable capacity for self-renewal. Here, we developed a novel therapeutic strategy for local delivery and treatment using EVPs, which are derived from NSCs with the expression of the CNS lesion targeting ligand-PDGFRα. Furthermore, we used EVPs as a targeting carrier for encapsulating Bryostatin-1 (Bryo-1), a natural compound with remarkable anti-inflammation ability. Our data showed that Bryo-1 delivered by EVPs was more stable and concentrated in the CNS than native Bryo-1. Systemic injection of a low dosage (1 × 10⁸ particles) of EVPs + Bryo-1, versus only EVPs or Bryo-1 administration, significantly ameliorated clinical disease development, decreased the infiltration of pro-inflammatory cells, blocked myelin loss and astrogliosis, protected BBB integrity, and altered microglia pro-inflammatory phenotype in the CNS of EAE mice. Taken as a whole, our study showed that engineered EVs have a CNS targeting capacity, and it provides potentially powerful therapeutic effects for the treatment of various neuroinflammatory diseases.

Encapsulation of bryostatin-1 by targeted exosomes enhances remyelination and neuroprotection effects in the cuprizone-induced demyelinating animal model of multiple sclerosis

Demyelination is a critical neurological disease, and there is still a lack of effective treatment methods. In the past two decades, stem cells have emerged as a novel therapeutic effector for neural regeneration. However, owing to the existence of the blood-brain barrier (BBB) and the complex microenvironment, targeted therapy still faces multiple challenges. Targeted exosome carriers for drug delivery may be considered a promising therapeutic method. Exosomes were isolated from mice neural stem cells. To develop targeting exosomes, we generated a lentivirus armed PDGFRα ligand that could anchor the membrane. Exosome targeting tests were carried out in vitro and in vivo. The modified exosomes showed an apparent ability to target OPCs in the lesion area. Next, the exosomes were loaded with Bryostatin-1 (Bryo), and the cuprizone-fed mice were administered with the targeting exosomes. The data show that Bryo exhibits a powerful therapeutic effect compared with Bryo alone after exosome encapsulation. Specifically, this novel exosome-based targeting delivery of Bryo significantly improves the protection ability of the myelin sheath and promotes remyelination. Moreover, it blocks astrogliosis and axon damage, and also has an inhibitory effect on pro-inflammatory microglia. The results of this investigation provide a straightforward strategy to produce targeting exosomes and indicate a potential therapeutic approach for demyelinating disease.

Targeting central nervous system extracellular vesicles enhanced triiodothyronine remyelination effect on experimental autoimmune encephalomyelitis

The lack of targeted and high-efficiency drug delivery to the central nervous system (CNS) nidus is the main problem in the treatment of demyelinating disease. Extracellular vesicles (EVs) possess great promise as a drug delivery vector given their advanced features. However, clinical applications are limited because of their inadequate targeting ability and the “dilution effects” after systemic administration. Neural stem cells (NSCs) supply a plentiful source of EVs on account of their extraordinary capacity for self-renewal. Here, we have developed a novel therapeutic system using EVs from modified NSCs with high expressed ligand PDGF-A (EVPs) and achieve local delivery. It has been demonstrated that EVPs greatly enhance the target capability on oligodendrocyte lineage. Moreover, EVPs are used for embedding triiodothyronine (T3), a thyroid hormone that is critical for oligodendrocyte development but has serious side effects when systemically administered. Our results demonstrated that systemic injection of EVPs + T3, versus EVPs or T3 administration individually, markedly alleviated disease development, enhanced oligodendrocyte survival, inhibited myelin damage, and promoted myelin regeneration in the lesions of experimental autoimmune encephalomyelitis mice. Taken together, our findings showed that engineered EVPs possess a remarkable CNS lesion targeting potential that offers a potent therapeutic strategy for CNS demyelinating diseases as well as neuroinflammation.

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NSC-derived EV-PDGFA dramatically increased targeting efficiency to the lineage of OLGs and the demyelinated area in the CNS.

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EVPs-T3 exert the therapeutic ability in the lesion suppressed the disease development and protected myelin loss.

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EVPs-T3 increased numbers of OLGs in the lesion and TEM data evidenced that EVPs-T3 promotes myelin regeneration in vivo.

Silybin Alleviates Experimental Autoimmune Encephalomyelitis by Suppressing Dendritic Cell Activation and Th17 Cell Differentiation

Silybin, a peculiar flavonoid compound derived from the fruit and seeds of Silybum marianum, exhibits strong anti-inflammatory activities. In the present study, we found that silybin effectively alleviated experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS), via inhibition of dendritic cell (DC) activation and Th17 cell differentiation. Silybin treatment greatly ameliorated the disease severity and significantly declined inflammation and demyelination of the central nervous system (CNS) of EAE mice. Consistent with the disease development, silybin-treated bone marrow-derived DCs (BM-DCs) exhibited reduced costimulatory molecules (e.g., CD80 and CD86) and MHC II expression. These results demonstrated the distinguished bioactivity of silybin for suppressing DC activation, inhibiting pathogenic Th17 inflammatory cell responses, and, eventually, alleviating EAE severity. Taken together, our results show that silybin has high potential for the development of a novel therapeutic agent for the treatment of autoimmune diseases such as MS.

Stem cells as a potential therapeutic option for treating neurodegenerative diseases

In future, neurodegenerative diseases will take over cancer's place and become the major cause of death in the world, especially in developed countries. Advancements in the medical field and its facilities have led to an increase in the old age population, and thus contributing to the increase in number of people suffering from neurodegenerative diseases. Economically it is of a great burden to society and the affected family. No current treatment aims to replace, protect, and regenerate lost neurons; instead, it alleviates the symptoms, extends the life span by a few months and creates severe side effects. Moreover, people who are affected are physically dependent for performing their basic activities, which makes their life miserable. There is an urgent need for therapy that could be able to overcome the deficits of conventional therapy for neurodegenerative diseases. Stem cells, the unspecialized cells with the properties of self-renewing and potency to differentiate into various cells types can become a potent therapeutic option for neurodegenerative diseases. Stem cells have been widely used in clinical trials to evaluate their potential in curing different types of ailments. In this review, we discuss the various types of stem cells and their potential use in the treatment of neurodegenerative disease based on published preclinical and clinical studies.

Role of Plant-Derived Natural Compounds in Experimental Autoimmune Encephalomyelitis: A Review of the Treatment Potential and Development Strategy

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system that is mainly mediated by pathological T-cells. Experimental autoimmune encephalomyelitis (EAE) is a well-known animal model of MS that is used to study the underlying mechanism and offers a theoretical basis for developing a novel therapy for MS. Good therapeutic effects have been observed after the administration of natural compounds and their derivatives as treatments for EAE. However, there has been a severe lag in the research and development of drug mechanisms related to MS. This review examines natural products that have the potential to effectively treat MS. The relevant data were consulted in order to elucidate the regulated mechanisms acting upon EAE by the flavonoids, glycosides, and triterpenoids derived from natural products. In addition, novel technologies such as network pharmacology, molecular docking, and high-throughput screening have been gradually applied in natural product development. The information provided herein can help improve targeting and timeliness for determining the specific mechanisms involved in natural medicine treatment and lay a foundation for further study.

Montelukast alleviates inflammation in experimental autoimmune encephalomyelitis by altering Th17 differentiation in a mouse model

Montelukast is a leukotriene receptor antagonist that is known to prevent allergic rhinitis and asthma. Blocking the Cysteinyl leukotriene receptor (CysLTR1), one of the primary receptors of leukotrienes, has been demonstrated to be efficacious in ameliorating experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS), through disrupting chemotaxis of infiltrating T cells. However, the role of CysLTR1 in the pathogenesis of MS is not well understood. Here, we show that MS patients had higher expression of CysLTR1 in the circulation and central nervous system (CNS). The majority of CD4⁺ T cells expressed CysLTR1 in MS lesions. Among T-cell subsets, Th17 cells had the highest expression of CysLTR1, and blocking CysLTR1 signalling abrogated their development in vitro. Inhibition of CysLTR1 by montelukast suppressed EAE development in both a prophylactic and therapeutic manner and inhibited myelin loss in EAE mice. Similarly, the in vivo results showed that montelukast inhibited Th17 response in EAE mice and that Th17 cells treated with montelukast had reduced encephalitogenic in adoptive EAE. Our findings strongly suggest that targeting Th17 response by inhibiting CysLTR1 signalling could be a promising therapeutic strategy for the treatment of MS and CNS inflammatory diseases.

Role of extracellular vesicles in neurodegenerative diseases

Extracellular vesicles (EVs) are heterogeneous cell-derived membranous structures that arise from the endosome system or directly detach from the plasma membrane. In recent years, many advances have been made in the understanding of the clinical definition and pathogenesis of neurodegenerative diseases, but translation into effective treatments is hampered by several factors. Current research indicates that EVs are involved in the pathology of diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), and Huntington's disease (HD). Besides, EVs are also involved in the process of myelin formation, and can also cross the blood-brain barrier to reach the sites of CNS injury. It is suggested that EVs have great potential as a novel therapy for the treatment of neurodegenerative diseases. Here, we reviewed the advances in understanding the role of EVs in neurodegenerative diseases and addressed the critical function of EVs in the CNS. We have also outlined the physiological mechanisms of EVs in myelin regeneration and highlighted the therapeutic potential of EVs in neurodegenerative diseases.

Transplantation of Stem Cells as a Potential Therapeutic Strategy in Neurodegenerative Disorders

Stem cells are considered to have significant capacity to differentiate into various cell types in humans and animals. Unlike specialized cells, these cells can proliferate several times to produce millions of cells. Nowadays, pluripotent stem cells are important candidates to provide a renewable source for the replacement of cells in tissues of interest. The damage to neurons and glial cells in the brain or spinal cord is present in neurological disorders such as Amyotrophic lateral sclerosis, stroke, Parkinson's disease, multiple sclerosis, Alzheimer's disease, Huntington's disease, spinal cord injury, lysosomal storage disorder, epilepsy, and glioblastoma. Therefore, stem cell transplantation can be used as a novel therapeutic approach in cases of brain and spinal cord damage. Recently, researchers have generated neuron-like cells and glial-like cells from embryonic stem cells, mesenchymal stem cells, and neural stem cells. In addition, several experimental studies have been performed for developing stem cell transplantation in brain tissue. Herein, we focus on stem cell therapy to regenerate injured tissue resulting from neurological diseases and then discuss possible differentiation pathways of stem cells to the renewal of neurons.

Urolithin A ameliorates experimental autoimmune encephalomyelitis by targeting aryl hydrocarbon receptor

Background

Urolithin A (URA) is an intestinal microbiota metabolic product from ellagitannin-containing foods with multiple biological activities. However, its role in autoimmune diseases is largely unknown. Here, for first time, we demonstrate the therapeutic effect of URA in an experimental autoimmune encephalomyelitis (EAE) animal model.

Methods

Therapeutic effect was evaluated via an active and passive EAE animal model in vivo. The function of URA on bone marrow-derived dendritic cells (BM-DCs), T cells, and microglia were tested in vitro.

Findings

Oral URA (25 mg/kg/d) suppressed disease progression at prevention, induction, and effector phases of preclinical EAE. Histological evaluation showed that significantly fewer inflammatory cells, decreased demyelination, lower numbers of M1-type microglia and activated DCs, as well as reduced infiltrating Th1/Th17 cells were present in the central nervous system (CNS) of the URA-treated group. URA treatment at 25 μM inhibited the activation of BM-DCs in vitro, restrained Th17 cell differentiation in T cell polarization conditions, and in a DC-CD4⁺ T cell co-culture system. Moreover, we confirmed URA inhibited pathogenicity of Th17 cells in adoptive EAE. Mechanism of URA action was directly targeting Aryl Hydrocarbon Receptor (AhR) and modulating the signaling pathways.

Interpretation

Collectively, our study offers new evidence that URA, as a human microbial metabolite, is valuable to use as a prospective therapeutic candidate for autoimmune diseases.

Glycyrrhizic acid promotes neural repair by directly driving functional remyelination

Natural compounds are a rich source of effective candidate drugs for the treatment of neurological disorders. Glycyrrhizic acid (GA), the major water-soluble ingredient isolated from Glycyrrhiza glabra, is reported to show anti-inflammatory and immunomodulatory activities. However, its effect on CNS demyelinating disease is unclear. In this study, we showed that GA ameliorated the clinical disease severity of experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS), especially at the chronic stage of clinical EAE. Histological evaluation demonstrated that, in the prophylactic treatment regimen, GA significantly inhibited inflammatory demyelination in the CNS. During the chronic stage when myelin and axon damage has already occurred, GA induced oligodendrocyte progenitor cell (OPC) differentiation into mature oligodendrocytes, thus effectively accelerating remyelination. Evidence from the cuprizone-induced mouse model of de- and remyelination, ex vivo organotypic slice cultures, and in vitro OPC maturation experiments indicated that the observed efficacy of this compound resulted directly from enhanced remyelination rather than immune suppression. Furthermore, we found that GA promoted oligodendrocyte maturation through modulating GSK-3β signaling pathways. Our data led to the conclusion that GA could be used as a potential therapeutic candidate for the treatment of demyelinating diseases such as MS, which remains refractory to available treatments.

Role of Extracellular Vesicles in Autoimmune Pathogenesis

Autoimmune diseases are conditions that emerge from abnormal immune responses to natural parts of the body. Extracellular vesicles (EVs) are membranous structures found in almost all types of cells. Because EVs often transport “cargo” between cells, their ability to crosstalk may be an important communication pathway within the body. The pathophysiological role of EVs is increasingly recognized in autoimmune diseases, including multiple sclerosis, rheumatoid arthritis, systemic lupus erythematosus, Sjogren's syndrome, Type 1 diabetes, and autoimmune thyroid disease. EVs are considered as biomarkers of these diseases. This article outlines existing knowledge on the biogenesis of EVs, their role as messegers in cellular communication and the function in T/B cell differentiation and maturation, and focusing on their potential application in autoimmune diseases.

PPAR-γ Is Critical for HDAC3-Mediated Control of Oligodendrocyte Progenitor Cell Proliferation and Differentiation after Focal Demyelination

Disruption of remyelination contributes to neurodegeneration and cognitive impairment in chronically disabled patients. Valproic acid (VPA) inhibits histone deacetylase (HDAC) function and probably promotes oligodendrocyte progenitor cell (OPC) proliferation and differentiation; however, the relevant molecular mechanisms remain unknown. Here, focal demyelinating lesions (FDLs) were generated in mice by two-point stereotactic injection of lysophosphatidylcholine (LPC) into the corpus callosum. Cognitive functions, sensorimotor abilities and histopathological changes were assessed for up to 28 days post-injury with or without VPA treatment. Primary OPCs were harvested and used to study the effect of VPA on OPC differentiation under inflammatory conditions. VPA dose-dependently attenuated learning and memory deficits and robustly protected white matter after FDL induction, as demonstrated by reductions in SMI-32 and increases in myelin basic protein staining. VPA also promoted OPC proliferation and differentiation and increased subsequent remyelination efficiency by day 28 post-FDL induction. VPA treatment did not affect HDAC1, HDAC2 or HDAC8 expression but reduced HDAC3 protein levels. In vitro, VPA improved the survival of mouse OPCs and promoted their differentiation into oligodendrocytes following lipopolysaccharide (LPS) stimulation. LPS caused OPCs to overexpress HDAC3, which translocated from the cytoplasm into the nucleus, where it directly interacted with the nuclear transcription factor PPAR-γ and negatively regulated PPAR-γ expression. VPA decreased the expression of HDAC3 and promoted remyelination and functional neurological recovery after FDL. These findings may support the use of strategies modulating HDAC3-mediated regulation of protein acetylation for the treatment of demyelination-related cognitive dysfunction.

Eriodictyol suppresses Th17 differentiation and the pathogenesis of experimental autoimmune encephalomyelitis

T helper 17 (Th17) cells that express interleukin-17 (IL-17) play a key role in various inflammatory diseases, such as multiple sclerosis (MS), and its animal model experimental autoimmune encephalomyelitis (EAE). The retinoic acid receptor-related orphan receptors γt (RORγt) have an indispensable effect on the differentiation of this cell type, and are thus considered a valuable target in the treatment of Th17-related disorders. In this study, we found that eriodictyol (EDT), a natural flavonoid abundant in citrus fruits and peanuts, was located directly in the binding pocket of RORγt, and induced a conformational change that resulted in the effective suppression of the receptor's activity, thus offering insight into the transcriptional inhibition of RORγt-dependent genes. Consistent with this, EDT dose-dependently (5-10 μM) blocked murine Th17 differentiation, and markedly reduced IL-17A secretion in vitro. Furthermore, this compound has been found to have novel properties for directly inhibiting Th1 cell development and promoting Treg cell differentiation at high doses (≥10 μM). EDT administration significantly decreased the clinical severity in the EAE model, with inhibited demyelination and reduced inflammatory responses in the periphery and in the central nervous system (CNS). In the adoptive transfer model, EDT also remarkably suppressed the Th17 cell infiltration and pathogenicity. Collectively, our data demonstrated that EDT, as an agent for the pharmacological inhibition of RORγt, has great potential for immunomodulation, and for use in the treatment of Th17-mediated autoimmune disease.

Polycistronic Delivery of IL-10 and NT-3 Promotes Oligodendrocyte Myelination and Functional Recovery in a Mouse Spinal Cord Injury Model

One million estimated cases of spinal cord injury (SCI) have been reported in the United States and repairing an injury has constituted a difficult clinical challenge. The complex, dynamic, inhibitory microenvironment postinjury, which is characterized by proinflammatory signaling from invading leukocytes and lack of sufficient factors that promote axonal survival and elongation, limits regeneration. Herein, we investigated the delivery of polycistronic vectors, which have the potential to coexpress factors that target distinct barriers to regeneration, from a multiple channel poly(lactide-co-glycolide) (PLG) bridge to enhance spinal cord regeneration. In this study, we investigated polycistronic delivery of IL-10 that targets proinflammatory signaling, and NT-3 that targets axonal survival and elongation. A significant increase was observed in the density of regenerative macrophages for IL-10+NT-3 condition relative to conditions without IL-10. Furthermore, combined delivery of IL-10+NT-3 produced a significant increase of axonal density and notably myelinated axons compared with all other conditions. A significant increase in functional recovery was observed for IL-10+NT-3 delivery at 12 weeks postinjury that was positively correlated to oligodendrocyte myelinated axon density, suggesting oligodendrocyte-mediated myelination as an important target to improve functional recovery. These results further support the use of multiple channel PLG bridges as a growth supportive substrate and platform to deliver bioactive agents to modulate the SCI microenvironment and promote regeneration and functional recovery. Impact statement Spinal cord injury (SCI) results in a complex microenvironment that contains multiple barriers to regeneration and functional recovery. Multiple factors are necessary to address these barriers to regeneration, and polycistronic lentiviral gene therapy represents a strategy to locally express multiple factors simultaneously. A bicistronic vector encoding IL-10 and NT-3 was delivered from a poly(lactide-co-glycolide) bridge, which provides structural support that guides regeneration, resulting in increased axonal growth, myelination, and subsequent functional recovery. These results demonstrate the opportunity of targeting multiple barriers to SCI regeneration for additive effects.

Scopoletin Suppresses Activation of Dendritic Cells and Pathogenesis of Experimental Autoimmune Encephalomyelitis by Inhibiting NF-κB Signaling

Scopoletin, a phenolic coumarin derived from many medical or edible plants, is involved in various pharmacological functions. In the present study, we showed that Scopoletin effectively ameliorated experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS), through novel regulatory mechanisms involving inhibition of NF-κB activity in dendritic cells (DCs). Scopoletin treatment significantly improved the severity of the disease and prominently decreased inflammation and demyelination of central nervous system (CNS) in EAE mice. Disease alleviation correlated with the downregulation of major histocompatibility complex (MHC) class II, CD80 and CD86, expressed on DCs of CNS or spleens, and the infiltration and polarization of encephalitogenic Th1/Th17 cells. Consistent with the in vivo data, Scopoletin-treated, bone marrow-derived dendritic cells (BM-DCs) exhibited reduced expression of MHC class II and costimulatory molecules (e.g., CD80 and CD86) and reduced NF-κB phosphorylation. These findings, for the first time, demonstrated the ability of Scopoletin to impair DC activation, downregulating pathogenic Th1/Th17 inflammatory cell responses and, eventually, reducing EAE severity. Our study demonstrates new evidence that natural products derived from medical or edible plants, such as Scopoletin, will be valuable in developing a novel therapeutic agent for MS in the future.

Treatment with 6-Gingerol Regulates Dendritic Cell Activity and Ameliorates the Severity of Experimental Autoimmune Encephalomyelitis

SCOPE

Multiple sclerosis (MS) is an inflammatory demyelinating autoimmune disorder, with increasing incidence worldwide but unknown etiology. 6-Gingerol (6-GIN), a major dietary compound found in ginger rhizome, has immunomodulatory activity. However, its role in autoimmune diseases, as well as the underlying mechanisms, are unclear. In this study, it is evaluated if 6-GIN can effectively ameliorate the clinical disease severity of experimental autoimmune encephalomyelitis, an animal model of MS.

METHODS AND RESULTS

Clinical scores of experimental autoimmune encephalomyelitis (EAE) mice are recorded daily. Inflammation of periphery and neuroinflammation of EAE mice are determined by flow cytometry analysis, ELISA, and histopathological analysis, and results show that 6-GIN significantly inhibits inflammatory cell infiltration from the periphery into the central nervous system and reduces neuroinflammation and demyelination. Flow cytometry analysis, ELISA, and quantitative PCR show that 6-GIN could suppress lipolysaccharide-induced dendritic cell (DC) activation and induce the tolerogenic DCs. Immunoblot analysis reveals that the phosphorylation of nuclear factor-κB and mitogen-activated protein kinase, two critical regulators of inflammatory signaling, are significantly inhibited in 6-GIN-treated DCs.

CONCLUSION

The results of this study demonstrate that 6-GIN has significant potential as a novel anti-inflammatory agent for the treatment of autoimmune diseases such as MS via direct modulatory effects on DCs.

Generation of Oligodendrocyte Progenitor Cells From Mouse Bone Marrow Cells

Oligodendrocyte progenitor cells (OPCs) are a subtype of glial cells responsible for myelin regeneration. Oligodendrocytes (OLGs) originate from OPCs and are the myelinating cells in the central nervous system (CNS). OLGs play an important role in the context of lesions in which myelin loss occurs. Even though many protocols for isolating OPCs have been published, their cellular yield remains a limit for clinical application. The protocol proposed here is novel and has practical value; in fact, OPCs can be generated from a source of autologous cells without gene manipulation. Our method represents a rapid, and high-efficiency differentiation protocol for generating mouse OLGs from bone marrow-derived cells using growth-factor defined media. With this protocol, it is possible to obtain mature OLGs in 7–8 weeks. Within 2–3 weeks from bone marrow (BM) isolation, after neurospheres formed, the cells differentiate into Nestin⁺ Sox2⁺ neural stem cells (NSCs), around 30 days. OPCs specific markers start to be expressed around day 38, followed by RIP⁺O4⁺ around day 42. CNPase⁺ mature OLGs are finally obtained around 7–8 weeks. Further, bone marrow-derived OPCs exhibited therapeutic effect in shiverer (Shi) mice, promoting myelin regeneration and reducing the tremor. Here, we propose a method by which OLGs can be generated starting from BM cells and have similar abilities to subventricular zone (SVZ)-derived cells. This protocol significantly decreases the timing and costs of the OLGs differentiation within 2 months of culture.

In utero transplantation of neural stem cells ameliorates maternal inflammation-induced prenatal white matter injury

Prenatal white matter injury is a serious problem due to maternal inflammation leading to postnatal disabilities. In this study, we used the periventricular leukomalacia (PVL) model as a common prenatal white matter injury by maternal administration of lipopolysaccharide (LPS). Neural stem cells (NSCs) have shown therapeutic ability in neurological disorders through a different mechanism such as immunomodulation. Here, we studied the preventive potential of NSCs following in utero transplantation into the embryonic lateral ventricle in an LPS-induced white matter injury model. Pregnant animals were divided into three groups and received phosphate buffered saline, LPS, or LPS + NSCs. The brains of offspring were obtained and evaluated by real-time polymerase chain reaction (PCR), immunohistochemy, enzyme-linked immunosorbent assay (ELISA), terminal deoxynucleotidyl transferase-mediated biotinylated-dUTP nick-end labeling (TUNEL), and caspase-3 activity assay. The LPS-induced maternal inflammation degenerated the myelin sheath in the offspring periventricular region which was associated with an increased microglial number, oligodendrocytes degeneration, proinflammatory cytokine secretion, and cell apoptosis. The transplanted NSCs homed into the brain and ameliorated the evaluated parameters. The expression of proinflammatory cytokines interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α), cell apoptosis and caspase-3 activity were inhibited by NSCs. In addition, Olig2 and myelin basic protein immunohistochemy staining showed that prenatal NSCs transplantation augmented the myelination in the periventricular white matter of offspring. In conclusion, we think that prenatal therapeutic strategies, such as in utero NSCs transplantation, may prevent prenatal white matter injury after birth.

Combination Therapy With Fingolimod and Neural Stem Cells Promotes Functional Myelination in vivo Through a Non-immunomodulatory Mechanism

Myelination, which occurs predominantly postnatally and continues throughout life, is important for proper neurologic function of the mammalian central nervous system (CNS). We have previously demonstrated that the combination therapy of fingolimod (FTY720) and transplanted neural stem cells (NSCs) had a significantly enhanced therapeutic effect on the chronic stage of experimental autoimmune encephalomyelitis, an animal model of CNS autoimmunity, compared to using either one of them alone. However, reduced disease severity may be secondary to the immunomodulatory effects of FTY720 and NSCs, while whether this therapy directly affects myelinogenesis remains unknown. To investigate this important question, we used three myelination models under minimal or non-inflammatory microenvironments. Our results showed that FTY720 drives NSCs to differentiate into oligodendrocytes and promotes myelination in an ex vivo brain slice culture model, and in the developing CNS of healthy postnatal mice in vivo. Elevated levels of neurotrophic factors, e.g., brain-derived neurotrophic factor and glial cell line-derived neurotrophic factor, were observed in the CNS of the treated infant mice. Further, FTY720 and NSCs efficiently prolonged the survival and improved sensorimotor function of shiverer mice. Together, these data demonstrate a direct effect of FTY720, beyond its known immunomodulatory capacity, in NSC differentiation and myelin development as a novel mechanism underlying its therapeutic effect in demyelinating diseases.

Carnosol Modulates Th17 Cell Differentiation and Microglial Switch in Experimental Autoimmune Encephalomyelitis

Medicinal plants as a rich pool for developing novel small molecule therapeutic medicine have been used for thousands of years. Carnosol as a bioactive diterpene compound originated from Rosmarinus officinalis (Rosemary) and Salvia officinalis, herbs extensively applied in traditional medicine for the treatment of multiple autoimmune diseases (1). In this study, we investigated the therapeutic effects and molecule mechanism of carnosol in experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS). Carnosol treatment significantly alleviated clinical development in the myelin oligodendrocyte glycoprotein (MOG_35-55) peptide-induced EAE model, markedly decreased inflammatory cell infiltration into the central nervous system and reduced demyelination. Further, carnosol inhibited Th17 cell differentiation and signal transducer and activator of transcription 3 phosphorylation, and blocked transcription factor NF-κB nuclear translocation. In the passive-EAE model, carnosol treatment also significantly prevented Th17 cell pathogenicity. Moreover, carnosol exerted its therapeutic effects in the chronic stage of EAE, and, remarkably, switched the phenotypes of infiltrated macrophage/microglia. Taken together, our results show that carnosol has enormous potential for development as a therapeutic agent for autoimmune diseases such as MS.

Stem Cells as Potential Targets of Polyphenols in Multiple Sclerosis and Alzheimer's Disease

Alzheimer's disease (AD) and multiple sclerosis are major neurodegenerative diseases, which are characterized by the accumulation of abnormal pathogenic proteins due to oxidative stress, mitochondrial dysfunction, impaired autophagy, and pathogens, leading to neurodegeneration and behavioral deficits. Herein, we reviewed the utility of plant polyphenols in regulating proliferation and differentiation of stem cells for inducing brain self-repair in AD and multiple sclerosis. Firstly, we discussed the genetic, physiological, and environmental factors involved in the pathophysiology of both the disorders. Next, we reviewed various stem cell therapies available and how they have proved useful in animal models of AD and multiple sclerosis. Lastly, we discussed how polyphenols utilize the potential of stem cells, either complementing their therapeutic effects or stimulating endogenous and exogenous neurogenesis, against these diseases. We suggest that polyphenols could be a potential candidate for stem cell therapy against neurodegenerative disorders.

Embryonic intraventricular transplantation of neural stem cells augments inflammation-induced prenatal brain injury

OBJECTIVE

Prenatal brain injury results from undesirable circumstances during the embryonic development. Current endeavors for treating this complication are basically excluded to postnatal therapeutic approaches. Neural stem cell therapy has shown great promise for treating neurodevelopmental disorders. To our knowledge, this is the first study that investigates the therapeutic effect of in utero transplantation of neural stem cells (NSCs) in inflammation model of prenatal brain injury.

METHODS

To induce prenatal injury, time-mated C57BL6J mice were intraperitoneally injected with 50 μg/kg lipopolysaccharide (LPS(on the day 15 of gestation. In the treatment group, NSCs were transplanted into the lateral ventricle of embryos on day 17 of gestation. The expression of GFAP, Iba-1, Olig2, and NeuN were assessed by real time PCR and immunohistochemistry. Changes in IL-6, TNF-α and IL-10 cytokines level, and caspase 3 activity were evaluated in the cortex of pups.

RESULTS

Intrauterine transplanted NSCs homed to the brain cortex of offspring. Brain levels of pro-inflammatory cytokines showed a significant downward trend in the NSCs group. Furthermore, NSCs ameliorated inflammation-induced reactive microgliosis and astrogliosis as well as cellular degeneration. Apoptosis inhibition in the treated group was demonstrated by the decline in the caspase 3 activity and dark neurons.

CONCLUSION

This study suggests a promising prospect to initiate the treatment of prenatal brain injury before birth by intrauterine transplantation of NSCs.

Nutshell Extracts of Xanthoceras sorbifolia: A New Potential Source of Bioactive Phenolic Compounds as a Natural Antioxidant and Immunomodulator

The nutshell of Xanthoceras sorbifolia, a waste product in the production of edible oil, is rich in health-promoting phenolic acids. However, the individual constituents, bioactivities, and mechanism of action are largely unknown. In this study, 20 phenolic compounds were characterized in nutshell extract (NE) of X. sorbifolia by gas chromatography-mass spectrometry. Four established in vitro studies showed that NE has significant antioxidant potential. Results in vivo indicated that oral administration of NE effectively ameliorated clinical disease severity of experimental autoimmune encephalomyelitis (EAE) and reduced the neuroinflammation and the central nervous system (CNS) demyelination. The underlying mechanism of NE-induced effects involved decreased penetration of pathogenic immunocyte into the CNS, a reduced production of proinflammatory cytokines and factors, and suppressed differentiation of type 1 T helper and type 17 T helper cells through the Janus kinase/signal transducer and activator of transcription pathway. Taken together, our studies showed that X. sorbifolia nutshell, considered a waste material in the food industry, is a novel source of a natural antioxidant and immunomodulator.

TGFβ1 transduction enhances immunomodulatory capacity of neural stem cells in experimental autoimmune encephalomyelitis

Bone marrow-derived neural stem cells (BM-NSCs) have therapeutic effect on EAE, an animal model of multiple sclerosis. However, the beneficial effect is suboptimal due to the limited immunomodulatory capacity of these cells. In this study, we engineered BM-NSCs with inducible TGFβ1, a potent immunosuppressive cytokine, to enhance their anti-inflammatory capacity. We found that i.v. injected TGFβ1-BM-NSCs more effectively suppressed clinical severity, inflammation and demyelination of the central nervous system of EAE mice. Transduction of TGFβ1 resulted in a higher percentage of Tregs and lower percentage of Th1 and Th17 cells in the periphery, with increased production of IL-10, and reduced production of IFN-γ, IL-17 and GM-CSF. Moreover, myelin-specific splenic proliferation was also inhibited more profoundly by TGFβ1-BM-NSCs. We also found that TGFβ1-BM-NSCs have the capacity to switch microglia from M1 to M2 phenotype. On the other hand, transduction of TGFβ1 did not affect proliferative ability and differentiating potential of BM-NSCs in vitro and in vivo. Together, these findings demonstrate that transduction of TGFβ1 significantly enhanced the immunomodulatory capacity of BM-NSCs for EAE treatment, through inducing Tregs and an M2 phenotype of macrophages/microglia, while retaining their capacity for neural cell differentiation. Thus, our study provides an easily accessible, inducible and effective therapy for CNS inflammatory demyelination.

Stem Cell Therapy for Multiple Sclerosis

Multiple sclerosis (MS) is a chronic inflammatory, autoimmune, and neurodegenerative disease of the central nervous system (CNS). It is characterized by demyelination and neuronal loss that is induced by attack of autoreactive T cells to the myelin sheath and endogenous remyelination failure, eventually leading to functional neurological disability. Although recent evidence suggests that MS relapses are induced by environmental and exogenous triggers such as viral infections in a genetic background, its very complex pathogenesis is not completely understood. Therefore, the efficiency of current immunosuppression-based therapies of MS is too low, and emerging disease-modifying immunomodulatory agents such as fingolimod and dimethyl fumarate cannot stop progressive neurodegenerative process. Thus, the cell replacement therapy approach that aims to overcome neuronal cell loss and remyelination failure and to increase endogenous myelin repair capacity is considered as an alternative treatment option. A wide variety of preclinical studies, using experimental autoimmune encephalomyelitis model of MS, have recently shown that grafted cells with different origins including mesenchymal stem cells (MSCs), neural precursor and stem cells, and induced-pluripotent stem cells have the ability to repair CNS lesions and to recover functional neurological deficits. The results of ongoing autologous hematopoietic stem cell therapy studies, with the advantage of peripheral administration to the patients, have suggested that cell replacement therapy is also a feasible option for immunomodulatory treatment of MS. In this chapter, we overview cell sources and applications of the stem cell therapy for treatment of MS. We also discuss challenges including those associated with administration route, immune responses to grafted cells, integration of these cells to existing neural circuits, and risk of tumor growth. Finally, future prospects of stem cell therapy for MS are addressed.

miR-23b Suppresses Leukocyte Migration and Pathogenesis of Experimental Autoimmune Encephalomyelitis by Targeting CCL7

MicroRNAs (miRNAs) are small, non-coding RNAs involved in immune response regulation. Specific miRNAs have been linked to the development of various autoimmune diseases; however, their contribution to the modulation of CNS-directed cellular infiltration remains unclear. In this study, we found that miR-23b, in addition to its reported functions in the suppression of IL-17-associated autoimmune inflammation, halted the progression of experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS), by directly inhibiting the migration of pathogenic leukocytes to the CNS. We demonstrated that miR-23b was specifically decreased during the acute phase of EAE and that overexpression of miR-23b resulted in a defect in leukocyte migration and strong resistance to EAE. Furthermore, we found that miR-23b suppressed leukocyte migration of EAE by targeting CCL7, a chemokine that attracts monocytes during inflammation and metastasis. Finally, in the adoptive transfer model, miR-23b reduced the severity of EAE by inhibiting the migration of pathogenic T cells to the CNS rather than diminishing the encephalitogenesis of T cells. Taken together, our results characterize a novel aspect of miR-23b function in leukocyte migration, and they identify miR-23b as a potential therapeutic target in the amelioration of MS and likely other autoimmune diseases.

Neural Stem Cell-Based Regenerative Approaches for the Treatment of Multiple Sclerosis

Multiple sclerosis (MS) is a chronic, autoimmune, inflammatory, and demyelinating disorder of the central nervous system (CNS), which ultimately leads to axonal loss and permanent neurological disability. Current treatments for MS are largely comprised of medications that are either immunomodulatory or immunosuppressive and are aimed at reducing the frequency and intensity of relapses. Neural stem cells (NSCs) in the adult brain can differentiate into oligodendrocytes in a context-specific manner and are shown to be involved in the remyelination in these patients. NSCs may exert their beneficial effects not only through oligodendrocyte replacement but also by providing trophic support and immunomodulation, a phenomenon now known as "therapeutic plasticity." In this review, we first provided an update on the current knowledge regarding MS pathogenesis and the role of immune cells, microglia, and oligodendrocytes in MS disease progression. Next, we reviewed the current progress on research aimed toward stimulating endogenous NSC proliferation and differentiation to oligodendrocytes in vivo and in animal models of demyelination. In addition, we explored the neuroprotective and immunomodulatory effects of transplanted exogenous NSCs on T cell activation, microglial activation, and endogenous remyelination and their effects on the pathological process and prognosis in animal models of MS. Finally, we examined various protocols to generate genetically engineered NSCs as a potential therapy for MS. Overall, this review highlights the studies involving the immunomodulatory, neurotrophic, and regenerative effects of NSCs and novel methods aiming at stimulating the potential of NSCs for the treatment of MS.