Bone marrow mesenchymal stem cells in treatment of peripheral nerve injury.

Peripheral nerve injury (PNI) is a common neurological disorder and complete functional recovery is difficult to achieve. In recent years, bone marrow mesenchymal stem cells (BMSCs) have emerged as ideal seed cells for PNI treatment due to their strong differentiation potential and autologous transplantation ability. This review aims to summarize the molecular mechanisms by which BMSCs mediate nerve repair in PNI. The key mechanisms discussed include the differentiation of BMSCs into multiple types of nerve cells to promote repair of nerve injury. BMSCs also create a microenvironment suitable for neuronal survival and regeneration through the secretion of neurotrophic factors, extracellular matrix molecules, and adhesion molecules. Additionally, BMSCs release pro-angiogenic factors to promote the formation of new blood vessels. They modulate cytokine expression and regulate macrophage polarization, leading to immunomodulation. Furthermore, BMSCs synthesize and release proteins related to myelin sheath formation and axonal regeneration, thereby promoting neuronal repair and regeneration. Moreover, this review explores methods of applying BMSCs in PNI treatment, including direct cell transplantation into the injured neural tissue, implantation of BMSCs into nerve conduits providing support, and the application of genetically modified BMSCs, among others. These findings confirm the potential of BMSCs in treating PNI. However, with the development of this field, it is crucial to address issues related to BMSC therapy, including establishing standards for extracting, identifying, and cultivating BMSCs, as well as selecting application methods for BMSCs in PNI such as direct transplantation, tissue engineering, and genetic engineering. Addressing these issues will help translate current preclinical research results into clinical practice, providing new and effective treatment strategies for patients with PNI.

Clinical concentration of sevoflurane had no short-term effect on the myelin sheath in prefrontal cortex of aged marmosets.

Introduction: The fragile brain includes both the developing brain in childhood and the deteriorating brain in elderly. While the effects of general anesthesia on the myelin sheath of developing brain have been well-documented, limited research has explored its impact on degenerating brain in elderly individuals. Methods: In our study, aged marmosets in control group were only anesthetized with 6-8% sevoflurane and 100% oxygen (2 L/min) for 1-2 min for anesthesia induction. In addition to anesthesia induction, the anesthesia group was exposed to a clinical concentration of sevoflurane (1.5-2%) for 6 h to maintain anesthesia. After anesthesia, scanning electron microscopy (SEM) and artificial intelligence-assisted image analysis were utilized to observe the effects of general anesthesia on the myelin sheath in prefrontal cortex (PFC) of aged marmosets. Results: Compared with the control group, our findings revealed no evidence that 6 h of sevoflurane general anesthesia altered the thickness of myelin sheath, the diameter of myelinated axons, and the g-ratio in prefrontal cortex of aged marmosets. Conclusion: Clinical concentration of sevoflurane may have no short-term effect on the myelin sheath in prefrontal cortex of aged marmosets.

The gut microbiota-oligodendrocyte axis: A promising pathway for modulating oligodendrocyte homeostasis and demyelination-associated disorders.

The bidirectional regulation between the gut microbiota and brain, known as gut-brain axis, has received significant attention. The myelin sheath, produced by oligodendrocytes or Schwann cells, is essential for efficient nervous signal transmission and the maintenance of brain function. Growing evidence shows that both oligodendrogenesis and myelination are modulated by gut microbiota and its metabolites, and when dysbiosis occurs, changes in the microbiota composition and/or associated metabolites may impact developmental myelination and the occurrence of neurodevelopmental disabilities. Although the link between the microbiota and demyelinating disease such as multiple sclerosis has been extensively studied, our knowledge about the role of the microbiota in other myelin-related disorders, such as neurodegenerative diseases, is limited. Mechanistically, the microbiota-oligodendrocyte axis is primarily mediated by factors such as inflammation, the vagus nerve, endocrine hormones, and microbiota metabolites as evidenced by metagenomics, metabolomics, vagotomy, and morphological and molecular approaches. Treatments targeting this axis include probiotics, prebiotics, microbial metabolites, herbal bioactive compounds, and specific dietary management. In addition to the commonly used approaches, viral vector-mediated tracing and gene manipulation, integrated multiomics and multicenter clinical trials will greatly promote the mechanistic and interventional studies and ultimately, the development of new preventive and therapeutic strategies against gut-oligodendrocyte axis-mediated brain impairments. Interestingly, recent findings showed that microbiota dysbiosis can be induced by hippocampal myelin damage and is reversible by myelin-targeted drugs, which provides new insights into understanding how hippocampus-based functional impairment (such as in neurodegenerative Alzheimer's disease) regulates the peripheral homeostasis of microbiota and associated systemic disorders.

Myelin basic protein mRNA levels affect myelin sheath dimensions, architecture, plasticity, and density of resident glial cells.

Myelin Basic Protein (MBP) is essential for both elaboration and maintenance of CNS myelin, and its reduced accumulation results in hypomyelination. How different Mbp mRNA levels affect myelin dimensions across the lifespan and how resident glial cells may respond to such changes are unknown. Here, to investigate these questions, we used enhancer-edited mouse lines that accumulate Mbp mRNA levels ranging from 8% to 160% of wild type. In young mice, reduced Mbp mRNA levels resulted in corresponding decreases in Mbp protein accumulation and myelin sheath thickness, confirming the previously demonstrated rate-limiting role of Mbp transcription in the control of initial myelin synthesis. However, despite maintaining lower line specific Mbp mRNA levels into old age, both MBP protein levels and myelin thickness improved or fully normalized at rates defined by the relative Mbp mRNA level. Sheath length, in contrast, was affected only when mRNA levels were very low, demonstrating that sheath thickness and length are not equally coupled to Mbp mRNA level. Striking abnormalities in sheath structure also emerged with reduced mRNA levels. Unexpectedly, an increase in the density of all glial cell types arose in response to reduced Mbp mRNA levels. This investigation extends understanding of the role MBP plays in myelin sheath elaboration, architecture, and plasticity across the mouse lifespan and illuminates a novel axis of glial cell crosstalk.

Characterization of sciatic nerve myelin sheath during development in C57BL/6 mice.

Myelin sheath plays important roles in information conduction and nerve injury repair in the peripheral nerve system (PNS). Enhancing comprehension of the structure and components of the myelin sheath in the PNS during development would contribute to a more comprehensive understanding of the developmental and regenerative processes. In this research, the structure of sciatic nerve myelin sheath in C57BL/6 mice from embryonic day 14 (E14) to postnatal 12 months (12M) was observed with transmission electron microscopy. Myelin structure appeared in the sciatic nerve as early as E14, and the number and thickness of myelin lamellar gradually increased with the development until 12M. Transcriptome analysis was performed to show the expressions of myelin-associated genes and transcriptional factors involved in myelin formation. The genes encoding myelin proteins (Mag, Pmp22, Mpz, Mbp, Cnp and Prx) showed the same expression pattern, peaking at postnatal day 7 (P7) and P28 after birth, whereas the negative regulators of myelination (c-Jun, Tgfb1, Tnc, Cyr61, Ngf, Egr1, Hgf and Bcl11a) showed an opposite expression pattern. In addition, the expression of myelin-associated proteins and transcriptional factors was measured by Western blot and immunofluorescence staining. The protein expressions of MAG, PMP22, MPZ, CNPase and PRX increased from E20 to P14. The key transcriptional factor c-Jun co-localized with the Schwann cells Marker S100ß and decreased after birth, whereas Krox20/Egr2 increased during development. Our data characterized the structure and components of myelin sheath during the early developmental stages, providing insights for further understanding of PNS development.

LY2940094, an NOPR antagonist, promotes oligodendrocyte generation and myelin recovery in an NOPR independent manner.

The myelin sheath plays crucial roles in brain development and neuronal functions. In the central nervous system, myelin is generated by oligodendrocytes, that differentiate from oligodendrocyte progenitor cells (OPC). In demyelinating diseases, the differentiation capacity of OPC is impaired and remyelination is dampened. Boosting remyelination by promoting OPC differentiation is a novel strategy for the treatment of demyelinating diseases. The opioid system, which consists of four receptors and their ligands, has been implicated in OPC differentiation and myelin formation. However, the exact roles of each opioid receptor and the relevant pharmacological molecules in OPC differentiation and myelin formation remain elusive. In the present study, specific agonists and antagonists of each opioid receptor were used to explore the function of opioid receptors in OPC differentiation. Nociceptin/orphanin FQ receptor (NOPR) specific antagonist LY2940094 was found to stimulate OPC differentiation and myelination in both in vitro and in vivo models. Unexpectedly, other NOPR ligands did not affect OPC differentiation, and NOPR knockdown did not mimic or impede the effect of LY2940094. LY2940094 was found to modulate the expression of the oligodendrocytes differentiation-associated transcription factors ID4 and Myrf, although the exact mechanism remains unclear. Since LY2940094 has been tested clinically to treat depression and alcohol dependency and has displayed an acceptable safety profile, it may provide an alternative approach to treat demyelinating diseases.

Deciphering the conformational dynamics of Myelin Oligodendrocyte glycoprotein in the myelin sheath.

Myelin Oligodendrocyte Glycoprotein (MOG) is a transmembrane protein in the myelin sheath. It acts as an auto-antigen under certain unknown conditions causing demyelination, thus resulting in Myelin Oligodendrocyte Glycoprotein Antibody-associated Disease (MOGAD). The significance of glycosylation in the conformational dynamics of the extracellular region (EC1) of the MOG were evident from the previous computational studies. Here, in this study, we performed the molecular dynamics simulation of the entire human MOG in the myelin sheath for 100 ns using the NAMD program. The results indicated that the EC1 and cytoplasmic region (CP) dominate the conformational rigidity of the protein, and enhance its interaction with lipids. This in turn helps in maintaining the myelin integrity in the presence of glycan. The transmembrane regions have reduced interaction with lipids in the glycosylated system. Moreover, the C-terminal extracellular region 2 (EC2) behaves exactly opposite to that of EC1 in the glycan presence. This may be attributed to the glycosylation site in the EC1 region. Hence, not only the region EC1 (having 3 crucial epitopes) but even the CP region were important for understanding the proper function of MOG in the glycan presence.Communicated by Ramaswamy H. Sarma.

A review: oligodendrocytes in neuronal axonal conduction and methods for enhancing their performance.

OBJECTIVES: This review explores the vital role of oligodendrocytes in axon myelination and efficient neuronal transmission and the impact of dysfunction resulting from neurotransmitter deficiencies related disorders. Furthermore, the review also provides insight into the potential of bionanotechnology for addressing neurodegenerative diseases by targeting oligodendrocytes. METHODS: A review of literature in the field was conducted using Google scholar. Systematic searches were performed to identify relevant studies and reviews addressing the role of oligodendrocytes in neural function, the influence of neurotransmitters on oligodendrocyte differentiation, and the potential of nanotechnology-based strategies for targeted therapy of oligodendrocytes. RESULTS: This review indicates the mechanisms underlying oligodendrocyte differentiation and the influence of neurotransmitters on this process. The importance of action potentials and neurotransmission in neural function and the susceptibility of damaged nerve axons to ischemic or toxic damage is provided in detail. The potential of bionanotechnology for targeting neurodegenerative diseases using nanotechnology-based strategies, including polymeric, lipid-based, inorganic, organic, and biomimetic nanoparticles, suggests better management of neurodegenerative disorders. CONCLUSION: While nanotechnology-based biomaterials show promise for targeted oligodendrocyte therapy in addressing neurodegenerative disorders linked to oligodendrocyte dysfunction, encapsulating neuroprotective agents within nanoparticles offers additional advantages. Nano-based delivery systems effectively protect drugs from degradation and prolong their therapeutic effects, holding promise in overcoming the blood-brain barrier by facilitating drug transport. However, a multifaceted approach is essential to enhance oligodendrocyte differentiation, promote myelin repair, and facilitate myelin dynamics with reduced toxicity. Further research is needed to elucidate the optimal therapeutic approaches and enhance patient outcomes.

Interactions between Schwann cell and extracellular matrix in peripheral nerve regeneration.

Peripheral nerve injuries, caused by various reasons, often lead to severe sensory, motor, and autonomic dysfunction or permanent disability, posing a challenging problem in regenerative medicine. Autologous nerve transplantation has been the gold standard in traditional treatments but faces numerous limitations and risk factors, such as donor area denervation, increased surgical complications, and diameter or nerve bundle mismatches. The extracellular matrix (ECM) is a complex molecular network synthesized and released into the extracellular space by cells residing in tissues or organs. Its main components include collagen, proteoglycans/glycosaminoglycans, elastin, laminin, fibronectin, etc., providing structural and biochemical support to surrounding cells, crucial for cell survival and growth. Schwann cells, as the primary glial cells in the peripheral nervous system, play various important roles. Schwann cell transplantation is considered the gold standard in cell therapy for peripheral nerve injuries, making ECM derived from Schwann cells one of the most suitable biomaterials for peripheral nerve repair. To better understand the mechanisms of Schwann cells and the ECM in peripheral nerve regeneration and their optimal application, this review provides an overview of their roles in peripheral nerve regeneration.

Assessing regional intracortical myelination in schizophrenia spectrum and bipolar disorders using the optimized T1w/T2w-ratio.

BACKGROUND: Dysmyelination could be part of the pathophysiology of schizophrenia spectrum (SCZ) and bipolar disorders (BPD), yet few studies have examined myelination of the cerebral cortex. The ratio of T1- and T2-weighted magnetic resonance images (MRI) correlates with intracortical myelin. We investigated the T1w/T2w-ratio and its age trajectories in patients and healthy controls (CTR) and explored associations with antipsychotic medication use and psychotic symptoms. METHODS: Patients with SCZ (n = 64; mean age = 30.4 years, s.d. = 9.8), BPD (n = 91; mean age 31.0 years, s.d. = 10.2), and CTR (n = 155; mean age = 31.9 years, s.d. = 9.1) who participated in the TOP study (NORMENT, University of Oslo, Norway) were clinically assessed and scanned using a General Electric 3 T MRI system. T1w/T2w-ratio images were computed using an optimized pipeline with intensity normalization and field inhomogeneity correction. Vertex-wise regression models were used to compare groups and examine group × age interactions. In regions showing significant differences, we explored associations with antipsychotic medication use and psychotic symptoms. RESULTS: No main effect of diagnosis was found. However, age slopes of the T1w/T2w-ratio differed significantly between SCZ and CTR, predominantly in frontal and temporal lobe regions: Lower T1w/T2w-ratio values with higher age were found in CTR, but not in SCZ. Follow-up analyses revealed a more positive age slope in patients who were using antipsychotics and patients using higher chlorpromazine-equivalent doses. CONCLUSIONS: While we found no evidence of reduced intracortical myelin in SCZ or BPD relative to CTR, different regional age trajectories in SCZ may suggest a promyelinating effect of antipsychotic medication.

Non-Invasive High-Resolution Imaging of In Vivo Human Myelinated Axons.

This work aims to reveal the microscopic (2-3 micrometer resolution) appearance of human myelinated nerve fibers in vivo for the first time. We analyzed the myelinated retinal nerve fibers of a male patient without other neurological disorders in a non-invasive way using the transscleral optical phase imaging method with adaptive optics. We also analyzed the fellow eye with non-myelinated nerve fibers and compared the results with traditional ocular imaging methods such as optical coherence tomography. We documented the microscopic appearance of human myelin and myelinated axons in vivo. This method allowed us to obtain better details than through traditional ocular imaging methods. We hope these findings will be useful to the scientific community to evaluate neuro-retinal structures through new imaging techniques and more accurately document nerve anatomy and the pathophysiology of this disease.

Efficacy and Safety of the Natural Killer T Cell-Stimulatory Glycolipid OCH-NCNP1 for Patients With Relapsing Multiple Sclerosis: Protocol for a Randomized Placebo-Controlled Clinical Trial.

BACKGROUND: Multiple sclerosis (MS) is an autoimmune inflammatory disease of the central nervous system that causes myelin sheath damage and axonal degeneration. The glycolipid (2S, 3S, 4R)-1-O-(α-d-galactosyl)-2-tetracosanoylamino-1,3,4-nonaetriol (OCH-NCNP1 or OCH) exerts an immunoregulatory action that suppresses T helper (Th)1 cell-mediated immune responses through natural killer T cell activation, selective interleukin-4 production, and Th2 bias induction in human CD4-positive natural killer T cells. OBJECTIVE: This trial aims to investigate the efficacy and safety of the immunomodulator OCH in patients with relapsing MS through 24-week repeated administration. METHODS: This protocol describes a double-blind, multicenter, placebo-controlled, randomized phase II clinical trial that was initiated in September 2019. The participants were randomly assigned to either a placebo control group or an OCH-NCNP1 group and the investigational drug (3.0 mg) was orally administered once weekly for the 24-week duration. Major inclusion criteria are as follows: patients had been diagnosed with relapsing MS (relapsing-remitting and/or secondary progressive MS) based on the revised McDonald criteria or were diagnosed with MS by an attending physician as noted in their medical records; patients with at least two medically confirmed clinical exacerbations within 24 months prior to consent or one exacerbation within 12 months prior to consent; patients with at least one lesion suspected to be MS on screening magnetic resonance imaging (MRI); and patients with 7 points or less in the Expanded Disability Status Scale during screening. Major exclusion criteria are as follows: diagnosis of neuromyelitis optica and one of optic neuritis, acute myelitis, and satisfying at least two of the following three items: (1) spinal cord MRI lesion extending across at least three vertebral bodies, (2) no brain MRI lesions during onset (at least four cerebral white matter lesions or three lesions, one of which is around the lateral ventricle), and (3) neuromyelitis optica-immunoglobulin G or antiaquaporin-4 antibody-positive. Outcome measures include the primary outcome of MRI changes (the percentage of subjects with new or newly expanded lesions at 24 weeks on T2-weighted MRI) and the secondary outcomes annual relapse rate (number of recurrences per year), relapse-free period (time to recurrence), sustained reduction in disability (SRD) occurrence rate, period until SRD (time to SRD occurrence), no evidence of disease activity, and exploratory biomarkers from phase I trials (such as gene expression, cell frequency, and intestinal and oral microbiome). RESULTS: We plan to enroll 30 patients in the full analysis set. Enrollment was closed in June 2021 and the study analysis was completed in March 2023. CONCLUSIONS: This randomized controlled trial will determine whether OCH-NCNP1 is effective and safe in patients with MS as well as provide evidence for the potential of OCH-NCNP1 as a therapeutic agent for MS. TRIAL REGISTRATION: ClinicalTrials.gov NCT04211740; https://clinicaltrials.gov/study/NCT04211740. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/46709.

miR-34a/TAN1/CREB Axis Engages in Alleviating Oligodendrocyte Trophic Factor-Induced Myelin Repair Function and Astrocyte-Dependent Neuroinflammation in the Early Stages of Alzheimer's Disease: The Anti-Neurodegenerative Effect of Treadmill Exercise.

Reduced myelin stability observed in the early stages of Alzheimer's disease leads to spatial learning and memory impairment. Exercise has been shown to protect nerves, reduce the risk of Alzheimer's disease, and strengthen synaptic connectivity. However, the underlying mechanisms of how exercise can promote myelin repair and coordinate inflammation and proliferation are still uncertain. In this study, we conducted histological and biochemical assays of cortical lysates after behavioral testing to detect pathological changes, myelin sheath thickness, and mRNA and protein levels. It is notable that D-galactose model mice exhibited elevated miRNA-34a levels, overactive astrocytes, decreased myelin staining scores, increased apoptosis, and decreased synaptic plasticity in the brain. Significantly, after eight weeks of exercise, we observed improvements in LFB scores, NeuN( +) neuron counts, and myelin basic protein (MBP) expression. Additionally, exercise promoted the expression of oligodendrocyte markers Olig2 and PDFGR-α associated with brain proliferation, and improved spatial cognitive function. Furthermore, it decreased the inflammation caused by astrocyte secretions (TNF-α, Cox-2, CXCL2). Interestingly, we also observed downregulation of miR-34a and activation of the TAN1/PI3K/CREB signaling pathway. Our data shed light on a previously unsuspected mechanism by which exercise reduces miR-34a levels and protects neuronal function and survival by preventing excessive demyelination and inflammatory infiltration in the CNS.

Fluorescence and magnetic resonance imaging of ONL-93 cells in a rat model of ischemic.

OBJECTIVES: The current methods for detecting myelin changes in ischemic stroke are indirect and cannot accurately reflect their status. This study aimed to develop a novel fluorescent-magnetic resonance dual-modal molecular imaging probe for direct imaging of myelin. METHODS: Compounds 7a and 7b were synthesized by linking the MeDAS group and Gadolinium (III) 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate. Compound 7a was selected for characterization and further study. Cell uptake, cytotoxicity, and magnetic resonance imaging scans were performed on cells. In vitro experiments on frozen brain sections from 7-day-old, 8-week-old, and ischemic stroke rats were compared with commercially available Luxol Fast Blue staining. After HPLC and MR scanning, brain tissue was soaked in 7a and scanned using T1WI and T1maps sequences. RESULTS: Spectrophotometer results showed that compounds 7a and 7b had fluorescent properties. MR scans indicated that the compounds had contrast agent properties. Cells could uptake 7a and exhibited high signals in imaging scans. Compound 7a brain tissue staining showed more fluorescence in myelin-rich regions and identified injury sites in ischemic stroke rats. MR scanning of brain sections provided clear myelin contrast. CONCLUSION: A novel fluorescent-magnetic resonance dual-modal molecular imaging probe for direct imaging of myelin was successfully developed and tested in rats with ischemic stroke. These findings provide new insights for the clinical diagnosis of demyelinating diseases.

The Effects and Mechanism of Scutellaria baicalensis Georgi Stems and Leaves Flavonoids on Myelin Sheath Degeneration Induced by Composite Aß in Rats.

BACKGROUND: Alzheimer's disease is a degenerative disease of the central nervous system, and its characteristic pathological changes are closely associated with Aß deposition and neurofibrillary tangles. Many studies have found that malignant changes in the myelin sheath and oligodendrocyte (OL) are accompanied by the occurrence and development of AD. Therefore, any method that can resist myelin sheath and OL disorders may be a potential strategy for AD. OBJECTIVE: To investigate the effects and mechanism of Scutellaria baicalensis Georgi stem and leaf flavonoids (SSFs) on the myelin sheath degeneration induced by Aß25-35 combined with AlC13 and RHTGF-ß1 (composite Aß) in rats. METHODS: A rat AD model was established by intracerebroventricular injection of composite Aß. The Morris water maze was used to screen the memory impairment rat model. The successful model rats were divided into the model group and the 35, 70, and 140 mg/kg SSFS groups. The myelin sheath changes in the cerebral cortex were observed with an electron microscope. The expression of the oligodendrocyte- specific protein claudin 11 was detected with immunohistochemistry. The protein expression levels of myelin oligodendrocyte glycoprotein (MOG), myelin-associated glycoprotein (MAG) and myelin basic protein (MBP), sphingomyelin synthase-1 (SMS1), and sphingomyelinase-2 (SMPD2) were assayed by Western blotting. RESULTS: The intracerebroventricular injection of composite Aß caused degeneration of the myelin sheath structure and was accompanied by the decreased claudin 11, MOG, MAG, MBP, and SMS1, and increased SMPD2 protein expression in the cerebral cortex. However, 35, 70, and 140 mg/kg SSFs can differentially ameliorate the above abnormal changes induced by composite Aß. CONCLUSION: SSFs can alleviate myelin sheath degeneration and increase the protein expression of claudin 11, MOG, MAG, and MBP, and the effective mechanism may be related to the positive regulation of SMS1 and SMPD2 activities.

P2Y12 receptor mediates apoptosis and demyelination to affect functional recovery in mice with spinal cord injury.

Among diseases of the central nervous system (CNS), spinal cord injury (SCI) has a high fatality rate. It has been proven that P2Y G protein-coupled purinergic receptors have a neuroprotective role in apoptosis and regeneration inside the damaged spinal cord. The P2Y12 receptor (P2Y12R) has recently been linked to peripheral neuropathy and stroke. However, the role of P2Y12R after SCI remains unclear. Our study randomly divided C57BL/6J female mice into 3 groups: Sham+DMSO, SCI+DMSO, and SCI+MRS2395. MRS2395 as a P2Y12R inhibitor was intraperitoneally injected at a dose of 1.5 mg/kg once daily for 7 days. We showed that the P2Y12R was markedly activated after injury, and it was double labeled with the microglial and neuron. Behavioral tests were employed to assess motor function recovery. By using immunofluorescence staining, the NeuN expression level was detected. The morphology of neurons was observed by hematoxylin-eosin and Nissl staining. P2Y12R, Bax, GFAP, PCNA and calbindin expression levels were detected using Western blot. Meanwhile, mitochondria and myelin sheath were observed by transmission electron microscopy (TEM). Our findings demonstrated that MRS2395 significantly enhanced motor function induced by SCI and that was used to alleviate apoptosis and astrocyte scarring. NeuN positive cells in the SCI group were lower than in the therapy group, although Bax, GFAP, PCNA and calbindin expression levels were considerably higher. Moreover, following MRS2395 therapy, the histological damage was reversed. A notable improvement in myelin sheath and mitochondrial morphology was seen in the therapy group. Together, our findings indicate that activation of P2Y12R in damaged spinal cord may be a critical event and suggest that inhibition of P2Y12R might be a feasible therapeutic strategy for treating SCI.

Characteristics of Patients Diagnosed With Guillain-Barré Syndrome at King Abdulaziz University Hospital, Jeddah, Saudi Arabia, From 2000 to 2018.

BACKGROUND: Guillain-Barré syndrome (GBS) is the leading cause of non-polio acute flaccid paralysis worldwide, emphasizing the importance of epidemiological studies on this condition. Therefore, well-designed epidemiological studies in different populations can provide a better understanding of the characteristics of patients with GBS and the nature of the disease. To our knowledge, no previous study has attempted to describe the characteristics of patients with GBS in Kingdom of Saudi Arabia (KSA) based on disease subtypes and clinical features in both adult and pediatric patients. This study aimed to assess the frequencies of GBS subtypes and their relationships with patient characteristics and clinical data in a tertiary hospital in Jeddah, KSA. METHODS: This was a retrospective review of patients diagnosed with GBS between January 2000 and January 2018 at King Abdulaziz University Hospital (KAUH), a tertiary center in Jeddah, KSA. RESULTS: In total, 47 patients with GBS (median age: seven years for pediatric and 36 years for adult patients) were included in the current study. There were six male and three female pediatric patients and 19 male and 19 female adult patients. Among patients with GBS who were classified into a specific electrophysiological subtype (n = 28), 13 (46.2%) had acute inflammatory demyelinating polyneuropathy (AIDP), 11 (39%) had an axonal subtype, and four (14%) had Miller Fisher syndrome (MFS). Patients required prolonged hospitalization of approximately 20 ± 22 days (2.83 ± 3.11 weeks). Patients with MFS were more likely to have higher cytoalbuminologic dissociation than those with other subtypes. CONCLUSION: AIDP was the most frequent type of GBS, followed by the axonal type. Patients required prolonged hospitalization of approximately 20 ± 22 days (2.83 ± 3.11 weeks). Patients with MFS were more likely to have higher cytoalbuminologic dissociation than those with other subtypes. GBS type did not show a relationship with ICU admission or mechanical ventilation use. There was no association between specific therapies and different GBS subtypes and no significant difference in outcomes between different patterns of clinical presentation. Intravenous immunoglobulin (IVIg) and plasma exchange (PE) treatments both had the same efficacy in relation to outcomes for patients with GBS.

Mechanical Responses of a Single Myelin Layer: A Molecular Simulation Study.

The myelin sheath provides insulation to the brain's neuron cells, which aids in signal transmission and communication with the body. Degenerated myelin hampers the connection between the glial cells, which are the front row responders during traumatic brain injury mitigation. Thus, the structural integrity of the myelin layer is critical for protecting the brain tissue from traumatic injury. At the molecular level, myelin consists of a lipid bilayer, myelin basic proteins (MBP), proteolipid proteins (PLP), water and ions. Structurally, the myelin sheath is formed by repeatedly wrapping forty or more myelin layers around an axon. Here, we have used molecular dynamic simulations to model and capture the tensile response of a single myelin layer. An openly available molecular dynamic solver, LAMMPS, was used to conduct the simulations. The interatomic potentials for the interacting atoms and molecules were defined using CHARMM force fields. Following a standard equilibration process, the molecular model was stretched uniaxially at a deformation rate of 5 Å/ps. We observed that, at around 10% applied strain, the myelin started to cohesively fail via flaw formation inside the bilayers. Further stretching led to a continued expansion of the defect inside the bilayer, both radially and transversely. This study provides the cellular-level mechanisms of myelin damage due to mechanical load.

Radiation-dependent demyelination in normal appearing white matter in glioma patients, determined using quantitative magnetic resonance imaging.

Background and purpose: A brain tumour, especially a glioma, is a rare disease; it is challenging to treat and the prognosis is often poor. Routine care includes surgery and concomitant chemoradiotherapy (CRT). Diagnostic work-up and treatment effects are typically evaluated using magnetic resonance imaging (MRI). Quantitative MRI (qMRI), unlike conventional MRI, has the advantage of providing tissue-specific relaxation rates and proton density. The purpose is to detect changes in normal appearing white matter (NAWM) in brain tumour patients after CRT using qMRI. Materials & methods: NAWM was analysed in 10 patients, in 83 MR examinations performed before and after surgery and after CRT. Relaxation rates R1 and R2, the proton density (PD) and the concentration of myelin (cMy) were calculated from the qMRI scans and analysed in correlation to radiation dose and time after treatment. Results: A significant decrease in cMy between pre-treatment imaging and first follow-up and an increase in PD were observed. For low doses (less than 30 Gy) PD and cMy returned to baseline (=pre-operative status), while for high doses (>30 Gy) the change increased during the full extent of the follow-up period. No difference could be established for R1. For R2 an increase was observed during the first year, which then gradually returned to baseline. For R2, stronger effects were seen as a consequence of higher absorbed doses. Conclusion: In the long-term follow-up for glioma patients, qMRI is a powerful tool for detecting small changes, such as a decrease of myelin concentration, in NAWM after CRT.

Aerobic exercise attenuates abnormal myelination and oligodendrocyte differentiation in 3xTg-AD mice.

Pathological features of Alzheimer's Disease (AD) include alterations in the structure and function of neurons as well as of myelin sheaths. Accumulated evidence shows that aerobic type of exercise can enhance neuroplasticity in mouse models of AD. However, whether and how aerobic exercise can affect myelin sheath repair and neuroprotection in the AD models remains unclear. In this study we tested the hypotheses that 1) myelin structural alterations in 3xTg-AD mice would be related to abnormalities in oligodendrocyte lineage cells, resulting in impaired learning and memory, and 2) a 6-month aerobic exercise intervention would have beneficial effects on such alterations. Two-month-old male 3xTg-AD mice were randomly assigned to a control (AC) or an exercise (AE) group, and age-matched male C57BL/6;129 mice were also randomly assigned to a normal control (NC) or an exercise (NE) group, with n = 12 in each group. Mice in the exercise groups were trained on a motor-drive treadmill, 60 min per day, 5 days per week for 6 months. Cognitive function was assessed at the end of the intervention period. Then, brain specimens were obtained for assessments of morphological and oligodendrocyte lineage cell changes. The results of electron microscopy showed that myelin ultrastructure demonstrated a higher percentage of loose and granulated myelin sheath around axons in the temporal lobe in the AC, as compared with the NC group, along with greater cognitive dysfunction at 8-months of age. These differences were accompanied by significantly greater myelin basic protein (MBP) expression and less neuron-glial antigen-2 (NG2) protein and mRNA levels in the AC, compared to the NC. However, there were no significant between-group differences in the G-ratio (the ratio of axon diameter to axon plus myelin sheath diameter) and 2',3'-cyclic-nucleotide 3'-phosphodiesterase (CNPase) protein and mRNA levels. The aerobic exercise ameliorated cognitive deterioration and appeared to keep components of myelin sheath and oligodendrocyte precursor cells stabilized, resulting in a decrease in the percentage of loose and granulated myelin sheath and MBP protein, and an increase in NG2 protein and mRNA levels in the AE group. Therefore, the 6-month exercise intervention demonstrated beneficial effects on myelin lesions, abnormal differentiation of oligodendrocytes and general brain function in the 3xTg-AD mice, providing further insights into the role of aerobic exercise in management of neurodegeneration in AD by maintaining intact myelination.