Oligodendrogenesis from neural stem cells: perspectives for remyelinating strategies

The roles of neural stem cells in myelin regeneration and repair therapy after spinal cord injury

Spinal cord injury (SCI) is a complex tissue injury that results in a wide range of physical deficits, including permanent or progressive disabilities of sensory, motor and autonomic functions. To date, limitations in current clinical treatment options can leave SCI patients with lifelong disabilities. There is an urgent need to develop new therapies for reconstructing the damaged spinal cord neuron-glia network and restoring connectivity with the supraspinal pathways. Neural stem cells (NSCs) possess the ability to self-renew and differentiate into neurons and neuroglia, including oligodendrocytes, which are cells responsible for the formation and maintenance of the myelin sheath and the regeneration of demyelinated axons. For these properties, NSCs are considered to be a promising cell source for rebuilding damaged neural circuits and promoting myelin regeneration. Over the past decade, transplantation of NSCs has been extensively tested in a variety of preclinical models of SCI. This review aims to highlight the pathophysiology of SCI and promote the understanding of the role of NSCs in SCI repair therapy and the current advances in pathological mechanism, pre-clinical studies, as well as clinical trials of SCI via NSC transplantation therapeutic strategy. Understanding and mastering these frontier updates will pave the way for establishing novel therapeutic strategies to improve the quality of recovery from SCI.

Oligodendrocyte progenitor cell-specific delivery of lipid nanoparticles loaded with Olig2 synthetically modified messenger RNA for ischemic stroke therapy

The transcription factor Olig2 is highly expressed throughout oligodendroglial development and is needed for the differentiation of oligodendrocyte progenitor cells (OPCs) into oligodendrocytes and remyelination. Although Olig2 overexpression in OPCs is a possible therapeutic target for enhancing myelin repair in ischemic stroke, achieving Olig2 overexpression in vivo remains a formidable technological challenge. To address this challenge, we employed lipid nanoparticle (LNP)-mediated delivery of Olig2 synthetically modified messenger RNA (mRNA) as a viable method for in vivo Olih2 protein overexpression. Specifically, we developed CD140a-targeted LNPs loaded with Olig2 mRNA (C-Olig2) to achieve targeted Olig2 protein expression within PDGFRα+ OPCs, with the goal of promoting remyelination for ischemic stroke therapy. We show that C-Olig2 promotes the differentiation of PDGFRα+ OPCs derived from mouse neural stem cells into mature oligodendrocytes in vitro, suggesting that mRNA-mediated Olig2 overexpression is a rational approach to promote oligodendrocyte differentiation and remyelination. Furthermore, when C-Olig2 was administered to a murine model of ischemic stroke, it led to improvements in blood‒brain barrier (BBB) integrity, enhanced remyelination, and rescued learning and cognitive deficits. Our comprehensive analysis, which included bulk RNA sequencing (RNA-seq) and single-nucleus RNA-seq (snRNA-seq), revealed upregulated biological processes related to learning and memory in the brains of mice treated with C-Olig2 compared to those receiving empty LNPs (Mock). Collectively, our findings highlight the therapeutic potential of multifunctional nanomedicine targeting mRNA expression for ischemic stroke and suggest that this approach holds promise for addressing various brain diseases. STATEMENT OF SIGNIFICANCE: While Olig2 overexpression in OPCs represents a promising therapeutic avenue for enhancing remyelination in ischemic stroke, in vivo strategies for achieving Olig2 expression pose considerable technological challenges. The delivery of mRNA via lipid nanoparticles is considered aa viable approach for in vivo protein expression. In this study, we engineered CD140a-targeted LNPs loaded with Olig2 mRNA (C-Olig2) with the aim of achieving specific Olig2 overexpression in mouse OPCs. Our findings demonstrate that C-Olig2 promotes the differentiation of OPCs into oligodendrocytes in vitro, providing evidence that mRNA-mediated Olig2 overexpression is a rational strategy to foster remyelination. Furthermore, the intravenous administration of C-Olig2 into a murine model of ischemic stroke not only improved blood-brain barrier integrity but also enhanced remyelination and mitigated learning and cognitive deficits. These results underscore the promising therapeutic potential of multifunctional nanomedicine targeting mRNA expression in the context of ischemic stroke.

The Effects of Nicotine and Cannabinoids on Cytokines

BACKGROUND

The usage of nicotine and cannabinoids has rapidly grown in popularity, leading to increased research into how they can affect people's health, both positively and negatively. Nicotine, Cannabidiol (CBD), and Δ9-tetrahydrocannabinol (THC) have been shown to have significant effects on cytokine function and inflammatory response.

OBJECTIVE

This study aimed to review and summarize the current literature on the effects of nicotine and cannabinoids on cytokines, including interleukins, TNF, IFN, and TGF-β.

METHODS

Literature search was conducted on Medline/PubMed electronic databases utilizing the search terms "nicotine" OR "cannabis" OR "cannabinoids" AND "cytokine" AND "inflammation" AND "stress" AND "immune" from 11/1973 to 02/2024.

RESULTS

THC and CBD usage have been associated with conflicting impacts on immune response, and observed to both exacerbate and inhibit inflammation. Nicotine has been shown to be generally proinflammatory with regards to cytokines. These responses have been reported to have significant effects on bodily response to inflammation-related diseases. Nicotine usage is associated with worsened outcomes for some conditions, like chronic pain, but improved outcomes for others, like arthritis. The impacts of cannabinoid usage tend to be more positive, exerting anti-inflammatory effects across a wide range of diseases. Given the widespread usage of these substances, it is important to understand the nature of their consequences on immune functions and the underlying mechanisms by which they act.

CONCLUSION

This review has covered how cannabinoids and nicotine affect inflammation directly and how these effects can be attributed to the treatment of inflammatory diseases. In summary, the existing research studying the effects of cannabinoids and nicotine supports the major relationship between nicotine and cannabis use and inflammatory diseases.

Pyruvate Dehydrogenase-Dependent Metabolic Programming Affects the Oligodendrocyte Maturation and Remyelination

The metabolic needs of the premature/premyelinating oligodendrocytes (pre-OLs) and mature oligodendrocytes (OLs) are distinct. The metabolic control of oligodendrocyte maturation from the pre-OLs to the OLs is not fully understood. Here, we show that the terminal maturation and higher mitochondrial respiration in the OLs is an integrated process controlled through pyruvate dehydrogenase complex (Pdh). Combined bioenergetics and metabolic studies show that OLs show elevated mitochondrial respiration than the pre-OLs. Our signaling studies show that the increased mitochondrial respiration activity in the OLs is mediated by the activation of Pdh due to inhibition of the pyruvate dehydrogenase kinase-1 (Pdhk1) that phosphorylates and inhibits Pdh activity. Accordingly, when Pdhk1 is directly expressed in the pre-OLs, they fail to mature into the OLs. While Pdh converts pyruvate into the acetyl-CoA by its oxidative decarboxylation, our study shows that Pdh-dependent acetyl-CoA generation from pyruvate contributes to the acetylation of the bHLH family transcription factor, oligodendrocyte transcription factor 1 (Olig1) which is known to be involved in the OL maturation. Pdh inhibition via direct expression of Pdhk1 in the pre-OLs blocks the Olig1-acetylation and OL maturation. Using the cuprizone model of demyelination, we show that Pdh is deactivated during the demyelination phase, which is however reversed in the remyelination phase upon cuprizone withdrawal. In addition, Pdh activity status correlates with the Olig1-acetylation status in the cuprizone model. Hence, the Pdh metabolic node activation allows a robust mitochondrial respiration and activation of a molecular program necessary for the terminal maturation of oligodendrocytes. Our findings open a new dialogue in the developmental biology that links cellular development and metabolism. These findings have far-reaching implications in the development of therapies for a variety of demyelinating disorders including multiple sclerosis.

Tripartite motif 72 inhibits apoptosis and mitochondrial dysfunction in neural stem cells induced by anesthetic sevoflurane by activating PI3K/AKT pathway

Anesthetics exposure induces neurocognitive deficits during brain development and impairs self-renewal and differentiation of neural stem cells (NSCs). Tripartite motif 72 (TRIM72, also known as mitsugumin 53, MG53) is involved in tissue repair and plasma membrane damage repair. The neuroprotective effect of TRIM72 against sevoflurane-induced neurotoxicity of NSCs was investigated in this study. First, human NSCs were exposed to different concentrations of sevoflurane. Results showed that TRIM72 was downregulated in sevoflurane-treated NSCs. Exposure to sevoflurane reduced cell viability in NSCs. Second, sevoflurane-treated NSCs were stimulated with recombinant human TRIM72 (rhTRIM72). Treatment with rhTRIM72 enhanced the cell viability in sevoflurane-treated NSCs. Moreover, treatment with a rhTRIM72-attenuated sevoflurane-induced increase in caspase-3 activity in NSCs. Third, JC-1 aggregates were deceased and JC-1 monomer was increased in sevoflurane-treated NSCs, which were reversed by rhTRIM72. Furthermore, rhTRIM72 also weakened sevoflurane-induced decrease in superoxide dismutase and glutathione peroxidase and increase in malondialdehyde and reactive oxygen species in NSCs. Finally, reduced phosphorylation levels of protein kinase B (AKT) and phosphatidylinositol 3-kinase (PI3K) in sevoflurane-treated NSCs were upregulated by rhTRIM72. In conclusion, TRIM72 inhibited cell apoptosis and reduced the mitochondria membrane potential of sevoflurane-treated NSCs through activation of the PI3K/AKT pathway.

Therapeutic Potential of Mesenchymal Stem Cells in the Treatment of Epilepsy and Their Interaction with Antiseizure Medications

Epilepsy is a life-threatening neurological disease that affects approximately 70 million people worldwide. Although the vast majority of patients may be successfully managed with currently used antiseizure medication (ASM), the search for alternative therapies is still necessary due to pharmacoresistance in about 30% of patients with epilepsy. Here, we review the effects of ASMs on stem cell treatment when they could be, as expected, co-administered. Indeed, it has been reported that ASMs produce significant effects on the differentiation and determination of stem cell fate. In addition, we discuss more recent findings on mesenchymal stem cells (MSCs) in pre-clinical and clinical investigations. In this regard, their ability to differentiate into various cell types, reach damaged tissues and produce and release biologically active molecules with immunomodulatory/anti-inflammatory and regenerative properties make them a high-potential therapeutic tool to address neuroinflammation in different neurological disorders, including epilepsy. Overall, the characteristics of MSCs to be genetically engineered, in order to replace dysfunctional elements with the aim of restoring normal tissue functioning, suggested that these cells could be good candidates for the treatment of epilepsy refractory to ASMs. Further research is required to understand the potential of stem cell treatment in epileptic patients and its interaction with ASMs.

Newly Identified Deficiencies in the Multiple Sclerosis Central Nervous System and Their Impact on the Remyelination Failure

The pathogenesis of multiple sclerosis (MS) remains enigmatic and controversial. Myelin sheaths in the central nervous system (CNS) insulate axons and allow saltatory nerve conduction. MS brings about the destruction of myelin sheaths and the myelin-producing oligodendrocytes (ODCs). The conundrum of remyelination failure is, therefore, crucial in MS. In this review, the roles of epidermal growth factor (EGF), normal prions, and cobalamin in CNS myelinogenesis are briefly summarized. Thereafter, some findings of other authors and ourselves on MS and MS-like models are recapitulated, because they have shown that: (a) EGF is significantly decreased in the CNS of living or deceased MS patients; (b) its repeated administration to mice in various MS-models prevents demyelination and inflammatory reaction; (c) as was the case for EGF, normal prion levels are decreased in the MS CNS, with a strong correspondence between liquid and tissue levels; and (d) MS cobalamin levels are increased in the cerebrospinal fluid, but decreased in the spinal cord. In fact, no remyelination can occur in MS if these molecules (essential for any form of CNS myelination) are lacking. Lastly, other non-immunological MS abnormalities are reviewed. Together, these results have led to a critical reassessment of MS pathogenesis, partly because EGF has little or no role in immunology.

Lumbar spine intrathecal transplantation of neural precursor cells promotes oligodendrocyte proliferation in hot spots of chronic demyelination

Experimental autoimmune encephalomyelitis (EAE) is a basic and reliable model used to study clinical and pathological hallmarks of multiple sclerosis (MS) in rodents. Several studies suggest neural precursor cells (NPCs) as a significant research tool while reporting that transplanted NPCs are a promising therapeutic approach to treating neurological disorders, such as MS. The main objective was to approach a preclinical, in vivo scenario of oligodendrogenesis with NPCs, targeting the main chronic demyelinated lumbosacral milieu of EAE, via the least invasive delivery method which is lumbar puncture. We utilized MOG_35‐55 peptide to induce EAE in C57BL/6 mice and prior to the acute relapse, we intervened with either the traceable GFP⁺ cellular therapy or saline solution in the intrathecal space of their lumbar spine. A BrdU injection, which enabled us to monitor endogenous proliferation, marked the endpoint 50 days post‐induction (50 dpi). Neuropathology with high‐throughput, triple immunofluorescent, and transmission electron microscopy (TEM) data were extracted and analyzed. The experimental treatment attenuated the chronic phase of EAE (50 dpi; score <1) following an acute, clinical relapse. Myelination and axonal integrity were rescued in the NPC‐treated animals along with suppressed immune populations. The differentiation profile of the exogenous NPCs and endogenous BrdU⁺ cells was location‐dependent where GFP⁺‐rich areas drove undifferentiated phenotypes toward the oligodendrocyte lineage. In situ oligodendrocyte enrichment was demonstrated through increased (p < 0.001) gap junction channels of Cx32 and Cx47, reliable markers for proliferative oligodendroglia syncytium. TEM morphometric analysis ultimately manifested an increased g‐ratio in lumbosacral fibers of the recovered animals (p < 0.001). Herein, we suggest that a single, lumbar intrathecal administration of NPCs capacitated a viable cellular load and resulted in clinical and pathological amelioration, stimulating resident OPCs to overcome the remyelination failure in EAE demyelinating locale.

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.

•

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

•

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

•

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

Mouse Neural Stem Cell Differentiation and Human Adipose Mesenchymal Stem Cell Transdifferentiation Into Neuron- and Oligodendrocyte-like Cells With Myelination Potential

Stem cell therapy is an interesting approach for neural repair, once it can improve and increase processes, like angiogenesis, neurogenesis, and synaptic plasticity. In this regard, adult neural stem cells (NSC) are studied for their mechanisms of proliferation, differentiation and functionality in neural repair. Here, we describe novel neural differentiation methods. NSC from adult mouse brains and human adipose-derived stem cells (hADSC) were isolated and characterized regarding their neural differentiation potential based on neural marker expression profiles. For both cell types, their capabilities of differentiating into neuron-, astrocyte- and oligodendrocytes-like cells (NLC, ALC and OLC, respectively) were analyzed. Our methodologies were capable of producing NLC, ALC and OLC from adult murine and human transdifferentiated NSC. NSC showed augmented gene expression of NES, TUJ1, GFAP and PDGFRA/Cnp. Following differentiation induction into NLC, OLC or ALC, specific neural phenotypes were obtained expressing MAP2, GalC/O4 or GFAP with compatible morphologies, respectively. Accordingly, immunostaining for nestin⁺ in NSC, GFAP⁺ in astrocytes and GalC/O4⁺ in oligodendrocytes was detected. Co-cultured NLC and OLC showed excitability in 81.3% of cells and 23.5% of neuron/oligodendrocyte marker expression overlap indicating occurrence of in vitro myelination. We show here that hADSC can be transdifferentiated into NSC and distinct neural phenotypes with the occurrence of neuron myelination in vitro, providing novel strategies for CNS regeneration therapy. Superior Part: Schematic organization of obtaining and generating hNSC from hADSC and differentiation processes and phenotypic expression of neuron, astrocyte and oligodendrocyte markers (MAP2, GFAP and O4, respectively) and stem cell marker (NES) of differentiating hNSC 14 days after induction. The nuclear staining in blue corresponds to DAPI. bar = 100 μm. Inferior part: Neural phenotype fates in diverse differentiation media. NES: nestin; GFAP: Glial fibrillary acidic protein. MAP2: Microtubule-associated protein 2. TUJ1: β-III tubulin. PDGFRA: PDGF receptor alpha. Two-way ANOVA with Bonferroni post-test with n = 3. * p < 0.05 and ** p < 0.01: (NSCiM1 NSC induction medium 1) vs differentiation media.

A review of possible therapies for multiple sclerosis

Multiple sclerosis (MS) is an autoimmune chronic inflammatory disease of the central nervous system with a wide range of symptoms, like executive function defect, cognitive dysfunction, blurred vision, decreased sensation, spasticity, fatigue, and other symptoms. This neurological disease is characterized by the destruction of the blood-brain barrier, loss of myelin, and damage to neurons. It is the result of immune cells crossing the blood-brain barrier into the central nervous system and attacking self-antigens. Heretofore, many treatments proved that they can retard the progression of the disease even though there is no cure. Therefore, treatments aimed at improving patients' quality of life and reducing adverse drug reactions and costs are essential. In this review, the treatment approaches to alleviate the progress of MS include the following: pharmacotherapy, antibody therapy, cell therapy, gene therapy, and surgery. The current treatment methods of MS are described in terms of the prevention of myelin shedding, the promotion of myelin regeneration, and the protection of neurons.

BET bromodomains as novel epigenetic targets for brain health and disease

Epigenetic pharmacotherapy for CNS-related diseases is a burgeoning area of research. In particular, members of the bromodomain and extra-terminal domain (BET) family of proteins have emerged as intriguing therapeutic targets due to their putative involvement in an array of brain diseases. With their ability to bind to acetylated histones and act as a scaffold for chromatin modifying complexes, BET proteins were originally thought of as passive epigenetic 'reader' proteins. However, new research depicts a more complex reality where BET proteins act as key nodes in lineage-specific and signal-dependent transcriptional mechanisms to influence disease-relevant functions. Amid a recent wave of drug development efforts from basic scientists and pharmaceutical companies, BET inhibitors are currently being studied in several CNS-related disease models, but safety and tolerability remain a concern. Here we review the progress in understanding the neurobiological mechanisms of BET proteins and the therapeutic potential of targeting BET proteins for brain health and disease.

The potentials of umbilical cord-derived mesenchymal stem cells in the treatment of multiple sclerosis

Stem cell therapy has indicated a promising treatment capacity for tissue regeneration. Multiple sclerosis is an autoimmune-based chronic disease, in which the myelin sheath of the central nervous system is destructed. Scientists have not discovered any cure for multiple sclerosis, and most of the treatments are rather palliative. The pursuit of a versatile treatment option, therefore, seems essential. The immunoregulatory and non-chronic rejection characteristics of mesenchymal stem cells, as well as their homing properties, recommend them as a prospective treatment option for multiple sclerosis. Different sources of mesenchymal stem cells have distinct characteristics and functional properties; in this regard, choosing the most suitable cell therapy approach seems to be challenging. In this review, we will discuss umbilical cord/blood-derived mesenchymal stem cells, their identified exclusive properties compared to another adult mesenchymal stem cells, and the expectations of their potential roles in the treatment of multiple sclerosis.

Effect of Sox10 on remyelination of the hippocampus in cuprizone-induced demyelinated mice

OBJECTIVE

The low number of oligodendrocytes (OLs) in the hippocampus of patients with schizophrenia suggests that hippocampal demyelination is changed in this condition. Sox10 is expressed throughout OL development. The effect of Sox10 on myelin regeneration is unknown. This study aimed to analyze changes in Sox10 expression in the hippocampus and its regulatory role in hippocampal myelin regeneration in a mouse model of demyelination.

METHODS

Mice were fed 0.2% cuprizone (CPZ) for six weeks to establish the acute demyelinating model (CPZ mice). Behavioral changes of these mice were assessed via open field and tail suspension tests. The ultrastructure of the myelin sheaths in the hippocampus was observed by transmission electron microscopy. The expression levels of myelin sheath-related proteins and the transcription factor Sox10 were detected via immunohistochemistry and Western blots. Furthermore, Sox10-overexpressing adeno-associated virus was injected into the hippocampus after establishing the demyelinating model to investigate effects of Sox10 on remyelination.

RESULTS

CPZ mice showed abnormal behavioral changes, a large number of pathological changes in the myelin sheaths, and significantly reduced protein expression of the myelin sheath markers myelin basic protein and proteolipid protein. This confirmed that the demyelinating model was successfully established. Meanwhile, the protein expression of the oligodendrocyte precursor cell marker neural/glial antigen 2 (NG2) increased, whereas Sox10 expression decreased. After Sox10 overexpression in the hippocampus, the abnormal behavior was improved, the ultrastructure of the myelin sheaths was restored, and the expression of myelin sheath protein was reversed. NG2 expression was upregulated.

CONCLUSION

Overexpression of Sox10 promotes hippocampal remyelination after CPZ-induced acute demyelination.

Differentiation of bone marrow stromal stem cells seeded on silk scaffold to mature oligodendrocyte using cerebrospinal fluid

The differentiation of cultured Bone marrow stromal cells (BMSC) on silk scaffold into mature oligodendrocyte was done in the presence of cerebrospinal fluid (CSF). BMSC were isolated from Sprague-Dawley rats and were seeded on silk scaffold. The seeded cells were cultured in DMEM/F12 medium supplemented with CFS, basic fibroblast growth factor (bFGF), Retinoic acid (RA) and Epidermal growth factor (EGF). The glial differentiation was investigated using Real time-PCR and immunofluorescence techniques for specific glial markers: Oligo 2, NG2, PLP and MBP. Our dates showed that the differentiated cells expressed specific glial markers: Oligo 2, NG2, PLP and MBP. The specific mature oligodendrocyte genes were up regulated in cultured cells on silk scaffold in the presence of CSF. It is concluded that CSF leads to improve glial differentiation of seeded BMSC on silk scaffold using preparation of appropriate niche. This culture condition may be served as an efficient differentiation induction protocol for glial phenotype, with the perspective of therapeutic application in neuroregenerative medicine.

Long non-coding RNA Peg13 attenuates the sevoflurane toxicity against neural stem cells by sponging microRNA-128-3p to preserve Sox13 expression

BACKGROUND

Exposure to anesthetics during brain development may impair neurological function, however, the mechanisms underlying anesthetic neurotoxicity are unclear. Recent studies indicate that long non-coding RNAs (lncRNAs) are crucial for regulating the functional brain development during neurogenesis. This study aimed to determine the regulatory effects and potential mechanisms of lncRNA Peg13 (Peg13) on sevoflurane exposure-related neurotoxicity against neural stem cells (NSCs).

METHODS

Mouse embryotic NSCs were isolated and their self-renewal and differentiation were characterized by immunofluorescence. NSCs were exposed to 4.1% sevoflurane 2 h daily for three consecutive days. The potential toxicities of sevoflurane against NSCs were evaluated by neurosphere formation, 5-ethynyl-2'-deoxyuridine (EdU) incorporation and flow cytometry assays. The Peg13, miR-128-3p and Sox13 expression in NSCs were quantified. The potential interactions among Peg13, miR-128-3p and Sox13 were analyzed by luciferase reporter assay. The effects of Peg13 and/or miR-128-3p over-expression on the sevoflurane-related neurotoxicity and Sox13 expression were determined in NSCs.

RESULTS

The isolated mouse embryotic NSCs displayed potent self-renewal ability and differentiated into neurons, astrocytes and oligodendrocytes in vitro, which were significantly inhibited by sevoflurane exposure. Sevoflurane exposure significantly down-regulated Peg13 and Sox13, but enhanced miR-128-3p expression in NSCs. Transfection with miR-128-3p mimics, but not the control, significantly mitigated the Peg13 or Sox13-regulated luciferase expression in 293T cells. Peg13 over-expression significantly reduced the sevoflurane-related neurotoxicity and increased Sox13 expression in NSCs, which were mitigated by miR-128-3p transfection.

CONCLUSION

Such data indicated that Peg13 mitigated the sevoflurane-related neurotoxicity by sponging miR-128-3p to preserve Sox13 expression in NSCs.

Effects and Mechanism of Action of Neonatal Versus Adult Astrocytes on Neural Stem Cell Proliferation After Traumatic Brain Injury

Due to the limited capacity of brain tissue to self-regenerate after traumatic brain injury (TBI), the mobilization of endogenous neural stem cells (NSCs) is a popular research topic. In the clinic, the neurogenic abilities of adults versus neonates vary greatly, which is likely related to functional differences in NSCs. Recent studies have demonstrated that the molecules secreted from astrocytes play important roles in NSC fate determination. In this study, conditioned media (CM) derived from neonatal or adult rat astrocytes, which were unstimulated or stimulated by lipopolysaccharide (LPS), were prepared to treat NSCs. Our results revealed that neonatal rat astrocytes can significantly promote the proliferation of NSCs, compared with adult rat astrocytes, regardless of whether or not they were stimulated by LPS. Furthermore, we used mass spectrometry to detect the constituents of the CM from each group. We analyzed and screened for a protein, Tenascin-C (TNC), which was highly expressed in the neonatal group but poorly expressed in the adult group. We found that TNC can bind to the NSC surface epidermal growth factor receptor and promote proliferation through the PI3K-AKT pathway in vitro. Additionally, we confirmed in vivo that TNC can promote damage repair in a rat model of TBI, through enhancing the proliferation of endogenous NSCs. We believe that these findings provide a mechanistic understanding of why neonates show better neuroregenerative abilities than adults. This also provides a potential future therapeutic target, TNC, for injury repair after TBI. Stem Cells 2019;37:1344-1356.

In Vivo Optical Imaging of Myelination Events in a Myelin Basic Protein Promoter-Driven Luciferase Transgenic Mouse Model

The compact myelin sheath is important for axonal function, and its loss can lead to neuronal cell death and irreversible functional deficits. Myelin is vulnerable to a variety of metabolic, toxic, and autoimmune insults. In diseases like multiple sclerosis, there is currently no therapy to stop myelin loss, underscoring the need for neuroprotective and remyelinating therapies. Noninvasive, robust techniques are also needed to confirm the effect of such therapies in animal models. This article describes the generation, characterization, and potential uses for a myelin basic protein-luciferase (MBP-luci) transgenic mouse model, in which the firefly luciferase reporter gene is selectively controlled by the MBP promoter. In vivo bioluminescence imaging can be used to visualize and quantify demyelination and remyelination at the transcriptional level, noninvasively, and in real time. Transgenic mice were assessed in the cuprizone-induced model of demyelination, and luciferase activity highly correlated with demyelination and remyelination events as confirmed by both magnetic resonance imaging and postmortem histological analysis. Furthermore, MBP-luci mice demonstrated enhanced luciferase signal and remyelination in the cuprizone model after treatment with a peroxisome proliferator activated receptor-delta selective agonist and quetiapine. Imaging sensitivity was further enhanced by using CycLuc 1, a luciferase substrate, which has greater blood–brain barrier penetration. We demonstrated the utility of MBP-luci model in tracking myelin changes in real time and supporting target and therapeutic validation efforts.

3D-cultured neural stem cell microarrays on a micropillar chip for high-throughput developmental neurotoxicology

Numerous chemicals including environmental toxicants and drugs have not been fully evaluated for developmental neurotoxicity. A key gap exists in the ability to predict accurately and robustly in vivo outcomes based on in vitro assays. This is particularly the case for predicting the toxicity of chemicals on the developing human brain. A critical need for such in vitro assays is choice of a suitable model cell type. To that end, we have performed high-throughput in vitro assessment of proliferation and differentiation of human neural stem cells (hNSCs). Conventional in vitro assays typically use immunofluorescence staining to quantify changes in cell morphology and expression of neural cell-specific biomarkers, which is often time-consuming and subject to variable specificities of available antibodies. To alleviate these limitations, we developed a miniaturized, three-dimensional (3D) hNSC culture with ReNcell VM on microarray chip platforms and established a high-throughput promoter-reporter assay system using recombinant lentiviruses on hNSC spheroids to assess cell viability, self-renewal, and differentiation. Optimum cell viability and spheroid formation of 3D ReNcell VM culture were observed on a micropillar chip over a period of 9 days in a mixture of 0.75% (w/v) alginate and 1 mg/mL growth factor reduced (GFR) Matrigel with 25 mM CaCl₂ as a crosslinker for alginate. In addition, 3D ReNcell VM culture exhibited self-renewal and differentiation on the microarray chip platform, which was efficiently monitored by enhanced green fluorescent protein (EGFP) expression of four NSC-specific biomarkers including sex determining region Y-box 2 (SOX2), glial fibrillary acidic protein (GFAP), synapsin1, and myelin basic protein (MBP) with the promoter-reporter assay system.

Decoding cell signalling and regulation of oligodendrocyte differentiation

Oligodendrocytes are fundamental for the functioning of the nervous system; they participate in several cellular processes, including axonal myelination and metabolic maintenance for astrocytes and neurons. In the mammalian nervous system, they are produced through waves of proliferation and differentiation, which occur during embryogenesis. However, oligodendrocytes and their precursors continue to be generated during adulthood from specific niches of stem cells that were not recruited during development. Deficiencies in the formation and maturation of these cells can generate pathologies mainly related to myelination. Understanding the mechanisms involved in oligodendrocyte development, from the precursor to mature cell level, will allow inferring therapies and treatments for associated pathologies and disorders. Such mechanisms include cell signalling pathways that involve many growth factors, small metabolic molecules, non-coding RNAs, and transcription factors, as well as specific elements of the extracellular matrix, which act in a coordinated temporal and spatial manner according to a given stimulus. Deciphering those aspects will allow researchers to replicate them in vitro in a controlled environment and thus mimic oligodendrocyte maturation to understand the role of oligodendrocytes in myelination in pathologies and normal conditions. In this study, we review these aspects, based on the most recent in vivo and in vitro data on oligodendrocyte generation and differentiation.

A review on stem cell therapy for multiple sclerosis: special focus on human embryonic stem cells

Multiple sclerosis (MS), a complex disorder of the central nervous system (CNS), is characterized with axonal loss underlying long-term progressive disability. Currently available therapies for its management are able to slow down the progression but fail to treat it completely. Moreover, these therapies are associated with major CNS and cardiovascular adverse events, and prolonged use of these treatments may cause life-threatening diseases. Recent research has shown that cellular therapies hold a potential for CNS repair and may be able to provide protection from inflammatory damage caused after injury. Human embryonic stem cell (hESC) transplantation is one of the promising cell therapies; hESCs play an important role in remyelination and help in preventing demylenation of the axons. In this study, an overview of the current knowledge about the unique properties of hESC and their comparison with other cell therapies has been presented for the treatment of patients with MS.

Nicotine and autoimmunity: The lotus' flower in tobacco

Nicotine, the major component of cigarettes, has demonstrated conflicting impact on the immune system: some authors suggest that increases pro-inflammatory cytokines and provokes cellular apoptosis of neutrophils, releasing intracellular components that act as auto-antigens; others claimed that nicotine has a protective and anti-inflammatory effects, especially by binding to α7 subunit of nicotinic acetylcholine receptors. The cholinergic pathway contributes to an anti-inflammatory environment characterized by increasing T regulatory cells response, down-regulating of pro-inflammatory cytokines and a pro-inflammatory cells apoptosis. The effects of nicotine were studied in different autoimmune disease, as multiple sclerosis, type 1 diabetes, rheumatoid arthritis, sarcoidosis, Behçet's disease and inflammatory bowel diseases. The major problems about nicotine are the addiction and the adverse effects of related to each commercialized formulation. We sought in this review to summarize the knowledge accumulated to date concerning the relationship between nicotine and autoimmunity.

Inhibition of neurogenesis in a case of Marburg variant multiple sclerosis

INTRODUCTION

Neural stem cells (NSC) are located essentially in the subventricular zone (SVZ), subgranular zone (SGZ), and along the central canal of the spinal cord. These cells can proliferate in vitro and differentiate into neurons, oligodendrocytes, and astroglia, thus contributing to repair in multiple sclerosis (MS). We conducted a pathological study to analyse neurogenic response in a patient with Marburg variant MS.

METHODS

We present the case of a 27-year-old immunocompetent patient with Marburg variant MS, a fulminant form of the disease. The condition lasted 20 days. Diagnosis was based on clinical symptoms and MRI showed demyelinating lesions located in subependymal areas and histopathological findings. Neurogenic niches (SVZ and dentate gyrus) were analysed by confocal microscopy using markers of proliferation (Ki-67, PCNA), neuroblasts (PSA-NCAM, DCX, Tuj1), stem cells (Nestin, GFAPδ, SOX2, PAX6, Musashi), astrocytes (GFAP, AQ4), oligodendrocytes (NG2, Olig), microglia and cell infiltrates (IBA-1, CD68, MHCII), and cell death (TUNEL).

RESULTS

Expression of the markers GFAPδ, SOX2, and PAX6 in NSC was found to be very low. Likewise, markers of proliferation (Ki-67) and intermediate precursors (NG2) were also reduced. This lack of markers of the first stages of cell differentiation means that neurogenesis is inhibited even in very early stages of the disease.

CONCLUSION

Inhibition of neurogenesis in our patient, which cannot be explained by the fulminant nature of his symptoms, may be related to inflammation and immune response. This finding may further our knowledge of repair mechanisms in MS.

Interplay between H1 and HMGN epigenetically regulates OLIG1&2 expression and oligodendrocyte differentiation

An interplay between the nucleosome binding proteins H1 and HMGN is known to affect chromatin dynamics, but the biological significance of this interplay is still not clear. We find that during embryonic stem cell differentiation loss of HMGNs leads to down regulation of genes involved in neural differentiation, and that the transcription factor OLIG2 is a central node in the affected pathway. Loss of HMGNs affects the expression of OLIG2 as well as that of OLIG1, two transcription factors that are crucial for oligodendrocyte lineage specification and nerve myelination. Loss of HMGNs increases the chromatin binding of histone H1, thereby recruiting the histone methyltransferase EZH2 and elevating H3K27me3 levels, thus conferring a repressive epigenetic signature at Olig1&2 sites. Embryonic stem cells lacking HMGNs show reduced ability to differentiate towards the oligodendrocyte lineage, and mice lacking HMGNs show reduced oligodendrocyte count and decreased spinal cord myelination, and display related neurological phenotypes. Thus, the presence of HMGN proteins is required for proper expression of neural differentiation genes during embryonic stem cell differentiation. Specifically, we demonstrate that the dynamic interplay between HMGNs and H1 in chromatin epigenetically regulates the expression of OLIG1&2, thereby affecting oligodendrocyte development and myelination, and mouse behavior.

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.

Roles of neural stem cells in the repair of peripheral nerve injury

Currently, researchers are using neural stem cell transplantation to promote regeneration after peripheral nerve injury, as neural stem cells play an important role in peripheral nerve injury repair. This article reviews recent research progress of the role of neural stem cells in the repair of peripheral nerve injury. Neural stem cells can not only differentiate into neurons, astrocytes and oligodendrocytes, but can also differentiate into Schwann-like cells, which promote neurite outgrowth around the injury. Transplanted neural stem cells can differentiate into motor neurons that innervate muscles and promote the recovery of neurological function. To promote the repair of peripheral nerve injury, neural stem cells secrete various neurotrophic factors, including brain-derived neurotrophic factor, fibroblast growth factor, nerve growth factor, insulin-like growth factor and hepatocyte growth factor. In addition, neural stem cells also promote regeneration of the axonal myelin sheath, angiogenesis, and immune regulation. It can be concluded that neural stem cells promote the repair of peripheral nerve injury through a variety of ways.

GDNF Enhances Therapeutic Efficiency of Neural Stem Cells-Based Therapy in Chronic Experimental Allergic Encephalomyelitis in Rat

Multiple sclerosis (MS) is an autoimmune disease in the CNS. The current immunomodulating drugs for MS do not effectively prevent the progressive neurological decline. Neural stem cells (NSCs) transplantation has been proven to promote repair and functional recovery of experimental allergic encephalomyelitis (EAE) animal model for MS, and glial cell line-derived neurotrophic factor (GDNF) has also been found to have capability of promoting axonal regeneration and remyelination of regenerating axons. In the present study, to assess whether GDNF would enhance therapeutic effect of NSCs for EAE, GDNF gene-modified NSCs (GDNF/NSCs) and native NSCs were transplanted into each lateral ventricle of rats at 10 days and rats were sacrificed at 60 days after EAE immunization. We found that NSCs significantly reduced the clinical signs, and GDNF gene-modification further promoted functional recovery. GDNF/NSCs more profoundly suppressed brain inflammation and improved density of myelin compared with NSCs. The survival of GDNF/NSCs was significantly higher than that of transplanted NSCs. Transplanted GDNF/NSCs, in contrast to NSCs, differentiated into more neurons and oligodendrocytes. Moreover, the mRNA expression of oligodendrocyte lineage cells in rats with GDNF/NSCs was significantly increased compared to rats with NSCs. These results suggest that GDNF enhances therapeutic efficiency of NSCs-based therapy for EAE.

Effect of Bushen Yisui Capsule () on oligodendrocyte lineage genes 1 and 2 in mice with experimental autoimmune encephalomyelitis

OBJECTIVE

To study the effects of Bushen Yisui Capsule (, BSYSC) on the oligodendrocyte lineage genes (Olig) 1 and Olig2 in C57BL/6 mice with experimental autoimmune encephalomyelitis (EAE) in order to explore the remyelination effect of BSYSC.

METHODS

The mice were randomly divided into normal control (NC), EAE model (EAE-M), prednisone acetate (PA, 6 mg/kg), BSYSC high-dose (3.02 g/kg) and BSYSC low-dose (1.51 g/kg) groups. The mice were induced by immunization with myelin oligodendrocyte glycoprotein (MOG) 35-55. The neurological function scores were assessed once daily. The pathological changes in mice brains were observed with hematoxylin-eosin (HE) staining and transmission electron microscope (TEM). The protein expressions of myelin basic protein (MBP), Olig1 and Olig2 in brains were measured by immunohistochemistry. The mRNA expressions of Olig1 and Olig 2 was also determined by quantitative real-time polymerase chain reaction.

RESULTS

Compared with the EAE-M mice, (1) the neurological function scores were significantly decreased in BSYSC-treated mice on days 22 to 40 (P<0.01); (2) the inflammatory cells and demyelination in brains were reduced in BSYSC-treated EAE mice; (3) the protein expression of MBP was markedly increased in BSYSC-treated groups on day 18 and 40 respectively (P<0.05 or P<0.01); (4) the protein expression of Olig1 was increased in BSYSC (3.02 g/kg)-treated EAE mice on day 40 (P<0.01). Protein and mRNA expression of Olig2 was increased in BSYSC-treated EAE mice on day 18 and 40 (P<0.01).

CONCLUSION

The effects of BSYSC on reducing demyelination and promoting remyelination might be associated with the increase of Olig1 and Olig2.

Transplantation of Neural Stem Cells Cotreated with Thyroid Hormone and GDNF Gene Induces Neuroprotection in Rats of Chronic Experimental Allergic Encephalomyelitis

The present study investigates whether transplantation of NSCs treated with T3 alone (T3/NSCs), or in conjunction with GDNF gene (GDNF-T3/NSCs), provides a better therapeutic effect than NSCs for chronic EAE. EAE rats were, respectively, injected with NSCs, T3/NSCs, GDNF-T3/NSCs, and saline at 10 days and sacrificed at 60 days after EAE immunization. The three cell grafted groups showed a significant reduction in clinical scores, inflammatory infiltration, and demyelination compared with the saline-injected group, and among the cell grafted groups, the reduction in GDNF-T3/NSCs group was the most notable, followed by T3/NSCs group. Grafted T3/NSCs and GDNF-T3/NSCs acquired more MAP2, GalC, and less GFAP in brain compared with grafted NSCs, and grafted GDNF-T3/NSCs acquired most MAP2 and least GalC among the cell grafted groups. Furthermore, T3/NSCs and GDNF-T3/NSCs grafting increased the expression of mRNA for PDGFαR, GalC, and MBP in lesion areas of brain compared with NSCs grafting, and the expression of mRNA for GalC and MBP in GDNF-T3/NSCs group was higher than that in T3/NSCs group. In conclusion, T3/NSCs grafting, especially GDNF-T3/NSCs grafting, provides a better neuroprotective effect for EAE than NSCs transplantation.

Glial Cells and Integrity of the Nervous System

Today, there is enormous progress in understanding the function of glial cells, including astroglia, oligodendroglia, Schwann cells, and microglia. Around 150 years ago, glia were viewed as a glue among neurons. During the course of the twentieth century, microglia were discovered and neuroscientists' views evolved toward considering glia only as auxiliary cells of neurons. However, over the last two to three decades, glial cells' importance has been reconsidered because of the evidence on their involvement in defining central nervous system architecture, brain metabolism, the survival of neurons, development and modulation of synaptic transmission, propagation of nerve impulses, and many other physiological functions. Furthermore, increasing evidence shows that glia are involved in the mechanisms of a broad spectrum of pathologies of the nervous system, including some psychiatric diseases, epilepsy, and neurodegenerative diseases to mention a few. It appears safe to say that no neurological disease can be understood without considering neuron-glia crosstalk. Thus, this book aims to show different roles played by glia in the healthy and diseased nervous system, highlighting some of their properties while considering that the various glial cell types are essential components not only for cell function and integration among neurons, but also for the emergence of important brain homeostasis.

Bromodomains: Translating the words of lysine acetylation into myelin injury and repair

Bromodomains are evolutionarily highly conserved α-helical structural motifs that recognize and bind acetylated lysine residues. Lysine acetylation is being increasingly recognized as a major posttranslational modification involved in diverse cellular processes and protein interactions and its deregulation has been implicated in the pathophysiology of various human diseases, such as multiple sclerosis and cancer. Bromodomain-containing proteins can have a wide variety of functions, ranging from histone acetyltransferase activity and chromatin remodeling to transcriptional mediation and co-activation. The role of bromodomains in translating a deregulated cell acetylome into disease phenotypes was recently unveiled by the development of small molecule bromodomain inhibitors. This breakthrough discovery highlighted bromodomain-containing proteins as key players of inflammatory pathways responsible for myelin injury and also demonstrated their role in several aspects of myelin repair including oligodendrocyte differentiation and axonal regeneration.

Curbing Inflammation in Multiple Sclerosis and Endometriosis: Should Mast Cells Be Targeted?

Inflammatory diseases and conditions can arise due to responses to a variety of external and internal stimuli. They can occur acutely in response to some stimuli and then become chronic leading to tissue damage and loss of function. While a number of cell types can be involved, mast cells are often present and can be involved in the acute and chronic processes. Recent studies in porcine and rabbit models have supported the concept of a central role for mast cells in a “nerve-mast cell-myofibroblast axis” in some inflammatory processes leading to fibrogenic outcomes. The current review is focused on the potential of extending aspects of this paradigm into treatments for multiple sclerosis and endometriosis, diseases not usually thought of as having common features, but both are reported to have activation of mast cells involved in their respective disease processes. Based on the discussion, it is proposed that targeting mast cells in these diseases, particularly the early phases, may be a fruitful avenue to control the recurring inflammatory exacerbations of the conditions.

Paving the way for adequate myelination: The contribution of galectin-3, transferrin and iron

Considering the worldwide incidence of well characterized demyelinating disorders such as Multiple Sclerosis (MS) and the increasing number of pathologies recently found to involve hypomyelinating factors such as micronutrient deficits, elucidating the molecular basis of central nervous system (CNS) demyelination, remyelination and hypomyelination becomes essential to the development of future neuroregenerative therapies. In this context, this review discusses novel findings on the contribution of galectin-3 (Gal-3), transferrin (Tf) and iron to the processes of myelination and remyelination and their potentially positive regulation of oligodendroglial precursor cell (OPC) differentiation. Studies were conducted in cuprizone (CPZ)-induced demyelination and iron deficiency (ID)-induced hypomyelination, and the participation of glial and neural stem cells (NSC) in the remyelination process was evaluated by means of both in vivo and in vitro assays on primary cell cultures.

Modeling neurodevelopmental disorders using human pluripotent stem cells

Neurodevelopmental disorders (NDs) are impairments that affect the development and growth of the brain and the central nervous system during embryonic and early postnatal life. Genetically manipulated animals have contributed greatly to the advancement of ND research, but many of them differ considerably from the human phenotype. Cellular in vitro models are also valuable, but the availability of human neuronal cells is limited and their lifespan in culture is short. Human pluripotent stem cells (hPSCs), including embryonic stem cells and induced pluripotent stem cells, comprise a powerful tool for studying developmentally regulated diseases, including NDs. We reviewed all recent studies in which hPSCs were used as in vitro models for diseases and syndromes characterized by impairment of neurogenesis or synaptogenesis leading to intellectual disability and delayed neurodevelopment. We analyzed their methodology and results, focusing on the data obtained following in vitro neural differentiation and gene expression and profiling of the derived neurons. Electrophysiological recording of action potentials, synaptic currents and response to neurotransmitters is pivotal for validation of the neuronal fate as well as for assessing phenotypic dysfunctions linked to the disease in question. We therefore focused on the studies which included electrophysiological recordings on the in vitro-derived neurons. Finally, we addressed specific issues that are critical for the advancement of this area of research, specifically in providing a reliable human pre-clinical research model and drug screening platform.

Optimizing culture medium composition to improve oligodendrocyte progenitor cell yields in vitro from subventricular zone-derived neural progenitor cell neurospheres

Neural Stem and Progenitor Cells (NSC/NPC) are gathering tangible recognition for their uses in cell therapy and cell replacement therapies for human disease, as well as a model system to continue research on overall neural developmental processes in vitro. The Subventricular Zone is one of the largest NSC/NPC niches in the developing mammalian Central Nervous System, and persists through to adulthood. Oligodendrocyte progenitor cell (OPC) enriched cultures are usefull tools for in vitro studies as well as for cell replacement therapies for treating demyelination diseases. We used Subventricular Zone-derived NSC/NPC primary cultures from newborn mice and compared the effects of different growth factor combinations on cell proliferation and OPC yield. The Platelet Derived Growth Factor-AA and BB homodimers had a positive and significant impact on OPC generation. Furthermore, heparin addition to the culture media contributed to further increase overall culture yields. The OPC generated by this protocol were able to mature into Myelin Basic Protein-expressing cells and to interact with neurons in an in vitro co-culture system. As a whole, we describe an optimized in vitro method for increasing OPC.

Nicotine modulates neurogenesis in the central canal during experimental autoimmune encephalomyelitis

Nicotine has been shown to attenuate experimental autoimmune encephalomyelitis (EAE) through inhibiting inflammation in microglial populations during the disease course. In this study, we investigated whether nicotine modified the regenerative process in EAE by examining nestin-expressing neural stem cells (NSCs) in the spinal cord, which is the primary area of demyelination and inflammation in EAE. Our results show that the endogenous neurogenic responses in the spinal cord after EAE are limited and delayed: while nestin expression is increased, the proliferation of ependymal cells is inhibited compared to healthy animals. Nicotine application significantly reduced nestin expression and partially allowed for the proliferation of ependymal cells. We found that reduction of ependymal cell proliferation correlated with inflammation in the same area, which was relieved by the administration of nicotine. Further, increased numbers of oligodendrocytes (OLs) were observed after nicotine treatment. These findings give a new insight into the mechanism of how nicotine functions to attenuate EAE.

High-content phenotypic screening and triaging strategy to identify small molecules driving oligodendrocyte progenitor cell differentiation

Multiple Sclerosis is a demyelinating disease of the CNS and the primary cause of neurological disability in young adults. Loss of myelinating oligodendrocytes leads to neuronal dysfunction and death and is an important contributing factor to this disease. Endogenous oligodendrocyte precursor cells (OPCs), which on differentiation are responsible for replacing myelin, are present in the adult CNS. As such, therapeutic agents that can stimulate OPCs to differentiate and remyelinate demyelinated axons under pathologic conditions may improve neuronal function and clinical outcome. We describe the details of an automated, cell-based, morphometric-based, high-content screen that is used to identify small molecules eliciting the differentiation of OPCs after 3 days. Primary screening was performed using rat CG-4 cells maintained in culture conditions that normally support a progenitor cell-like state. From a library of 73,000 diverse small molecules within the Sanofi collection, 342 compounds were identified that increased OPC morphological complexity as an indicator of oligodendrocyte maturation. Subsequent to the primary high-content screen, a suite of cellular assays was established that identified 22 nontoxic compounds that selectively stimulated primary rat OPCs but not C2C12 muscle cell differentiation. This rigorous triaging yielded several chemical series for further expansion and bio- or cheminformatics studies, and their compelling biological activity merits further investigation.

Bisphenol-A impairs myelination potential during development in the hippocampus of the rat brain

Myelin is the functional implication of oligodendrocytes (OLs), which is involved in insulation of axons and promoting rapid propagation of action potential in the brain. OLs are derived from oligodendrocyte progenitor cells (OPCs), which proliferate, differentiate, and migrate throughout the central nervous system. Defects in myelination process lead to the onset of several neurological and neurodegenerative disorders. Exposure to synthetic xenoestrogen bisphenol-A (BPA) causes cognitive dysfunction, impairs hippocampal neurogenesis, and causes onset of neurodevelopmental disorders. However, the effects of BPA on OPC proliferation, differentiation and myelination, and associated cellular and molecular mechanism(s) in the hippocampus of the rat brain are still largely unknown. We found that BPA significantly decreased bromodeoxyuridine (BrdU)-positive cell proliferation and number and size of oligospheres. We observed reduced co-localization of BrdU with myelination markers CNPase and platelet-derived growth factor receptor-α (PDGFR-α), suggesting impaired proliferation and differentiation of OPCs by BPA in culture. We studied the effects of BPA exposure during prenatal and postnatal periods on cellular and molecular alteration(s) in the myelination process in the hippocampus region of the rat brain at postnatal day 21 and 90. BPA exposure both in vitro and in vivo altered proliferation and differentiation potential of OPCs and decreased the expression of genes and levels of proteins that are involved in myelination. Ultrastructural electron microscopy analysis revealed that BPA exposure caused decompaction of myelinated axons and altered g-ratio at both the developmental periods as compared to control. These results suggest that BPA exposure both during prenatal and postnatal periods alters myelination in the hippocampus of the rat brain leading to cognitive deficits.

Modulation of subventricular zone oligodendrogenesis: a role for hemopressin?

Neural stem cells (NSCs) from the subventricular zone (SVZ) have been indicated as a source of new oligodendrocytes to use in regenerative medicine for myelin pathologies. Indeed, NSCs are multipotent cells that can self-renew and differentiate into all neural cell types of the central nervous system. In normal conditions, SVZ cells are poorly oligodendrogenic, nevertheless their oligodendrogenic potential is boosted following demyelination. Importantly, progressive restriction into the oligodendrocyte fate is specified by extrinsic and intrinsic factors, endocannabinoids being one of these factors. Although a role for endocannabinoids in oligodendrogenesis has already been foreseen, selective agonists and antagonists of cannabinoids receptors produce severe adverse side effects. Herein, we show that hemopressin (Hp), a modulator of CB1 receptors, increased oligodendroglial differentiation in SVZ neural stem/progenitor cell cultures derived from neonatal mice. The original results presented in this work suggest that Hp and derivates may be of potential interest for the development of future strategies to treat demyelinating diseases.