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Dean DC, O'Muircheartaigh J, Dirks H, Travers BG, Adluru N, Alexander AL, Deoni SCL. Mapping an index of the myelin g-ratio in infants using magnetic resonance imaging. Neuroimage 2016; 132:225-237. [PMID: 26908314 PMCID: PMC4851913 DOI: 10.1016/j.neuroimage.2016.02.040] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Revised: 02/07/2016] [Accepted: 02/12/2016] [Indexed: 12/03/2022] Open
Abstract
Optimal myelination of neuronal axons is essential for effective brain and cognitive function. The ratio of the axon diameter to the outer fiber diameter, known as the g-ratio, is a reliable measure to assess axonal myelination and is an important index reflecting the efficiency and maximal conduction velocity of white matter pathways. Although advanced neuroimaging techniques including multicomponent relaxometry (MCR) and diffusion tensor imaging afford insight into the microstructural characteristics of brain tissue, by themselves they do not allow direct analysis of the myelin g-ratio. Here, we show that by combining myelin content information (obtained with mcDESPOT MCR) with neurite density information (obtained through NODDI diffusion imaging) an index of the myelin g-ratio may be estimated. Using this framework, we present the first quantitative study of myelin g-ratio index changes across childhood, examining 18 typically developing children 3months to 7.5years of age. We report a spatio-temporal pattern of maturation that is consistent with histological and developmental MRI studies, as well as theoretical studies of the myelin g-ratio. This work represents the first ever in vivo visualization of the evolution of white matter g-ratio indices throughout early childhood.
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Affiliation(s)
- Douglas C Dean
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA.
| | | | - Holly Dirks
- Advanced Baby Imaging Lab, Brown University School of Engineering, Providence, RI 02912, USA
| | - Brittany G Travers
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA; Department of Kinesiology, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Nagesh Adluru
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Andrew L Alexander
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA; Department of Psychiatry, University of Wisconsin-Madison, Madison, WI 53719, USA; Department of Medical Physics, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Sean C L Deoni
- Advanced Baby Imaging Lab, Brown University School of Engineering, Providence, RI 02912, USA; Department of Pediatric Radiology, Children's Hospital Colorado, Aurora, CO, USA; Department of Radiology, University of Colorado Denver, Denver, CO, USA
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202
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Zheng J, Sun J, Lu X, Zhao P, Li K, Li L. BDNF promotes the axonal regrowth after sciatic nerve crush through intrinsic neuronal capability upregulation and distal portion protection. Neurosci Lett 2016; 621:1-8. [PMID: 27057731 DOI: 10.1016/j.neulet.2016.04.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Revised: 03/17/2016] [Accepted: 04/04/2016] [Indexed: 01/10/2023]
Abstract
Nowadays peripheral nerve injurie occurs more common, the outcome is often poor because of the ineffective treatment. Recent researches revealed the duration of BDNF administration acts a positive role during the nerve regeneration, but its potential mechanisms beneath the behavioral recovery and axonal regrowth after peripheral nerve injury are still controversial. To observe the potential mechanisms we established sciatic nerve injury model and detected the expression of several axonal regeneration and function related genes. The results showed that, BDNF promotes axonal regrowth through increasing the activation of neuronal intrinsic growth capacity and strengthening the deference effects against distal portion atrophy. To further study, we determined the expression of protein associated to neuronal intrinsic growth capacity and investigated the ultrastructure of the distal portion of the injured nerve were analyzed. These data revealed that BDNF triggers multiple effects including neuronal intrinsic growth capacity improvement and distal portion atrophy protection to promote behavioral recovery following sciatic nerve crush injury in mouse.
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Affiliation(s)
- Jinyu Zheng
- Department of Neurosurgery, First Affiliated Hospital of Nanjing Medical University, 300 Guangzhou Road, Nanjing, Jiangsu 210029, China; Department of Neurosurgery, The Affiliated Huai'an Hospital of Xuzhou Medical College, No. 62 South Huaihai Road, Huai'an 223002, China
| | - Jian Sun
- Department of Anesthesiology, Huai'an Matenal and Child Health Hospital, Huai'an, Jiangsu 223002, China
| | - Xiaocheng Lu
- Department of Neurosurgery, First Affiliated Hospital of Nanjing Medical University, 300 Guangzhou Road, Nanjing, Jiangsu 210029, China
| | - Penglai Zhao
- Department of Neurosurgery, First Affiliated Hospital of Nanjing Medical University, 300 Guangzhou Road, Nanjing, Jiangsu 210029, China
| | - Kai Li
- Department of Neurosurgery, First Affiliated Hospital of Nanjing Medical University, 300 Guangzhou Road, Nanjing, Jiangsu 210029, China
| | - Lixin Li
- Department of Neurosurgery, First Affiliated Hospital of Nanjing Medical University, 300 Guangzhou Road, Nanjing, Jiangsu 210029, China.
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203
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Melbourne A, Eaton‐Rosen Z, Orasanu E, Price D, Bainbridge A, Cardoso MJ, Kendall GS, Robertson NJ, Marlow N, Ourselin S. Longitudinal development in the preterm thalamus and posterior white matter: MRI correlations between diffusion weighted imaging and T2 relaxometry. Hum Brain Mapp 2016; 37:2479-92. [PMID: 26996400 PMCID: PMC4949539 DOI: 10.1002/hbm.23188] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Revised: 02/01/2016] [Accepted: 03/09/2016] [Indexed: 01/21/2023] Open
Abstract
Infants born prematurely are at increased risk of adverse neurodevelopmental outcome. The measurement of white matter tissue composition and structure can help predict functional performance. Specifically, measurements of myelination and indicators of myelination status in the preterm brain could be predictive of later neurological outcome. Quantitative imaging of myelin could thus serve to develop biomarkers for prognosis or therapeutic intervention; however, accurate estimation of myelin content is difficult. This work combines diffusion MRI and multi-component T2 relaxation measurements in a group of 37 infants born very preterm and scanned between 27 and 58 weeks equivalent gestational age. Seven infants have longitudinal data at two time points that we analyze in detail. Our aim is to show that measurement of the myelin water fraction is achievable using widely available pulse sequences and state-of-the-art algorithmic modeling of the MR imaging procedure and that a multi-component fitting routine to multi-shell diffusion weighted data can show differences in neurite density and local spatial arrangement in grey and white matter. Inference on the myelin water fraction allows us to demonstrate that the change in diffusion properties of the preterm thalamus is not solely due to myelination (that increase in myelin content accounts for about a third of the observed changes) whilst the decrease in the posterior white matter T2 has no significant component that is due to myelin water content. This work applies multi-modal advanced quantitative neuroimaging to investigate changing tissue properties in the longitudinal setting. Hum Brain Mapp 37:2479-2492, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Andrew Melbourne
- Centre for Medical Image Computing (CMIC)University College LondonUnited Kingdom
| | - Zach Eaton‐Rosen
- Centre for Medical Image Computing (CMIC)University College LondonUnited Kingdom
| | - Eliza Orasanu
- Centre for Medical Image Computing (CMIC)University College LondonUnited Kingdom
| | - David Price
- Medical PhysicsUniversity College HospitalLondonUnited Kingdom
| | - Alan Bainbridge
- Medical PhysicsUniversity College HospitalLondonUnited Kingdom
| | - M. Jorge Cardoso
- Centre for Medical Image Computing (CMIC)University College LondonUnited Kingdom
| | | | - Nicola J. Robertson
- Academic NeonatologyEGA UCL Institute for Women's HealthLondonUnited Kingdom
| | - Neil Marlow
- Academic NeonatologyEGA UCL Institute for Women's HealthLondonUnited Kingdom
| | - Sebastien Ourselin
- Centre for Medical Image Computing (CMIC)University College LondonUnited Kingdom
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204
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Pusic KM, Pusic AD, Kraig RP. Environmental Enrichment Stimulates Immune Cell Secretion of Exosomes that Promote CNS Myelination and May Regulate Inflammation. Cell Mol Neurobiol 2016; 36:313-325. [PMID: 26993508 DOI: 10.1007/s10571-015-0269-4] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 09/07/2015] [Indexed: 12/13/2022]
Abstract
Environmental enrichment (EE) consists of increased physical, intellectual, and social activity, and has wide-ranging effects, including enhancing cognition, learning and memory, and motor coordination. Animal studies have demonstrated that EE improves outcome of brain trauma and neurodegenerative disorders, including demyelinating diseases like multiple sclerosis, making it a promising therapeutic option. However, the complexity of applying a robust EE paradigm makes clinical use difficult. A better understanding of the signaling involved in EE-based neuroprotection may allow for development of effective mimetics as an alternative. In prior work, we found that exosomes isolated from the serum of rats exposed to EE impact CNS myelination. Exosomes are naturally occurring nanovesicles containing mRNA, miRNA, and protein, which play important roles in cell function, disease, and immunomodulation. When applied to hippocampal slice cultures or nasally administered to naïve rats, EE-serum exosomes significantly increase myelin content, oligodendrocyte precursor (OPC) and neural stem cell levels, and reduce oxidative stress (OS). We found that rat EE exosomes were enriched in miR-219, which is necessary and sufficient for OPC differentiation into myelinating cells. Thus, peripherally produced exosomes may be a useful therapy for remyelination. Here, we aim to better characterize the impact of EE on CNS health and to determine the cellular source of nutritive exosomes found in serum. We found that exosomes isolated from various circulating immune cell types all increased slice culture myelin content, contained miR-219, and reduced OS, suggesting that EE globally alters immune function in a way that supports brain health.
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Affiliation(s)
- Kae M Pusic
- Department of Neurology The University of Chicago Chicago, IL 60637, USA
| | - Aya D Pusic
- Department of Neurology The University of Chicago Chicago, IL 60637, USA.,Committee on Neurobiology The University of Chicago Chicago, IL 60637, USA
| | - Richard P Kraig
- Department of Neurology The University of Chicago Chicago, IL 60637, USA.,Committee on Neurobiology The University of Chicago Chicago, IL 60637, USA
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205
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Effect of long term-administration of aspartame on the ultrastructure of sciatic nerve. J Microsc Ultrastruct 2016; 4:175-183. [PMID: 30023225 PMCID: PMC6014252 DOI: 10.1016/j.jmau.2016.02.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 01/13/2016] [Accepted: 02/05/2016] [Indexed: 12/01/2022] Open
Abstract
Aspartame is the most widely used artificial sweetener worldwide. There is much controversy about the effect of aspartame on different cells in the body. The aim of this study was to evaluate the effect of aspartame on the structure of the sciatic nerve. Thirty adult male albino rats were divided into three groups. Group I served as control; Group II received aspartame orally in a dose of 250 mg/kg/d for 3 months; Group III received aspartame at the same dose and for the same period, and was allowed to recover for 1 month. Specimens of sciatic nerve were processed, and semithin and ultrathin sections were examined by light and electron microscopy. A morphometric study was done to evaluate the g-ratio, which is the ratio between the axon diameter and total fiber diameter. Long-term aspartame administration resulted in many degenerative changes affecting mainly the myelin sheath, in the form of focal and extensive demyelination; disruption and splitting of myelin lamellae with loss of compact lamellar structure; and excessive enfolding with irregular thickening of myelin sheaths. Less frequent than those observed in the myelin sheath, some axonal changes were detected, such as compression and distortion. Dilated rough endoplasmic reticulum and vacuolation of the cytoplasm of Schwann cells were also detected. Partial improvement was observed in the recovery group. It was concluded that long-term administration of aspartame had a harmful effect on the structure of sciatic nerve and 1 month stoppage of aspartame was not enough to achieve complete recovery.
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206
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Evolution of rapid nerve conduction. Brain Res 2016; 1641:11-33. [PMID: 26879248 DOI: 10.1016/j.brainres.2016.02.015] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 02/04/2016] [Accepted: 02/05/2016] [Indexed: 01/29/2023]
Abstract
Rapid conduction of nerve impulses is a priority for organisms needing to react quickly to events in their environment. While myelin may be viewed as the crowning innovation bringing about rapid conduction, the evolution of rapid communication mechanisms, including those refined and enhanced in the evolution of myelin, has much deeper roots. In this review, a sequence is traced starting with diffusional communication, followed by transport-facilitated communication, the rise of electrical signaling modalities, the invention of voltage-gated channels and "all-or-none" impulses, the emergence of elongate nerve axons specialized for communication and their fine-tuning to enhance impulse conduction speeds. Finally within the evolution of myelin itself, several innovations have arisen and have been interactively refined for speed enhancement, including the addition and sealing of layers, their limitation by space availability, and the optimization of key parameters: channel density, lengths of exposed nodes and lengths of internodes. We finish by suggesting several design principles that appear to govern the evolution of rapid conduction. This article is part of a Special Issue entitled SI: Myelin Evolution.
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207
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Reichert P, Kiełbowicz Z, Dzięgiel P, Puła B, Wrzosek M, Bocheńska A, Gosk J. Effect of Collateral Sprouting on Donor Nerve Function After Nerve Coaptation: A Study of the Brachial Plexus. Med Sci Monit 2016; 22:387-96. [PMID: 26848925 PMCID: PMC4762401 DOI: 10.12659/msm.895397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Background The aim of the present study was to evaluate the donor nerve from the C7 spinal nerve of the rabbit brachial plexus after a coaptation procedure. Assessment was performed of avulsion of the C5 and C6 spinal nerves treated by coaptation of these nerves to the C7 spinal nerve. Material/Methods After nerve injury, fourteen rabbits were treated by end-to-side coaptation (ETS), and fourteen animals were treated by side-to-side coaptation (STS) on the right brachial plexus. Electrophysiological and histomorphometric analyses and the skin pinch test were used to evaluate the outcomes. Results There was no statistically significant difference in the G-ratio proximal and distal to the coaptation in the ETS group, but the differences in the axon, myelin sheath and fiber diameters were statistically significant. The comparison of the ETS and STS groups distal to the coaptation with the controls demonstrated statistically significant differences in the fiber, axon, and myelin sheath diameters. With respect to the G-ratio, the ETS group exhibited no significant differences relative to the control, whereas the G-ratio in the STS group and the controls differed significantly. In the electrophysiological study, the ETS and STS groups exhibited major changes in the biceps and subscapularis muscles. Conclusions The coaptation procedure affects the histological structure of the nerve donor, but it does not translate into changes in nerve conduction or the sensory function of the limb. The donor nerve lesion in the ETS group is transient and has minimal clinical relevance.
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Affiliation(s)
- Pawel Reichert
- Department of Traumatology, Clinic of Traumatology and Hand Surgery, Wrocław Medical University, Wrocław, Poland
| | - Zdzisław Kiełbowicz
- Department of Surgery, The Faculty of Veterinary Medicine, Wrocław University of Environmental and Life Sciences, Wrocław, Poland
| | - Piotr Dzięgiel
- Department of Histology and Embryology, Wrocław Medical University, Wrocław, Poland
| | - Bartosz Puła
- Department of Histology and Embryology, Wrocław Medical University, Wrocław, Poland
| | - Marcin Wrzosek
- Department of Internal Medicine and Clinic of Diseases of Horses, Dogs and Cats, Faculty of Veterinary Medicine, Wrocław University of Environmental and Life Sciences, Wrocław, Poland
| | - Aneta Bocheńska
- Centre of Veterinary Medicine JU-UAK, The University of Agriculture, Cracow, Poland
| | - Jerzy Gosk
- Department of Traumatology, Clinic of Traumatology and Hand Surgery, Wroclaw Medical University, Wrocław, Poland
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208
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Freeman SA, Desmazières A, Fricker D, Lubetzki C, Sol-Foulon N. Mechanisms of sodium channel clustering and its influence on axonal impulse conduction. Cell Mol Life Sci 2016; 73:723-35. [PMID: 26514731 PMCID: PMC4735253 DOI: 10.1007/s00018-015-2081-1] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 10/21/2015] [Accepted: 10/22/2015] [Indexed: 12/16/2022]
Abstract
The efficient propagation of action potentials along nervous fibers is necessary for animals to interact with the environment with timeliness and precision. Myelination of axons is an essential step to ensure fast action potential propagation by saltatory conduction, a process that requires highly concentrated voltage-gated sodium channels at the nodes of Ranvier. Recent studies suggest that the clustering of sodium channels can influence axonal impulse conduction in both myelinated and unmyelinated fibers, which could have major implications in disease, particularly demyelinating pathology. This comprehensive review summarizes the mechanisms governing the clustering of sodium channels at the peripheral and central nervous system nodes and the specific roles of their clustering in influencing action potential conduction. We further highlight the classical biophysical parameters implicated in conduction timing, followed by a detailed discussion on how sodium channel clustering along unmyelinated axons can impact axonal impulse conduction in both physiological and pathological contexts.
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Affiliation(s)
- Sean A Freeman
- ICM-GHU Pitié-Salpêtrière, Sorbonne Universités UPMC Univ Paris 06, UMR_S 1127, 75013, Paris, France.
- Inserm U1127, 75013, Paris, France.
- CNRS UMR7225, 75013, Paris, France.
| | - Anne Desmazières
- ICM-GHU Pitié-Salpêtrière, Sorbonne Universités UPMC Univ Paris 06, UMR_S 1127, 75013, Paris, France.
- Inserm U1127, 75013, Paris, France.
- CNRS UMR7225, 75013, Paris, France.
| | - Desdemona Fricker
- ICM-GHU Pitié-Salpêtrière, Sorbonne Universités UPMC Univ Paris 06, UMR_S 1127, 75013, Paris, France.
- Inserm U1127, 75013, Paris, France.
- CNRS UMR7225, 75013, Paris, France.
| | - Catherine Lubetzki
- ICM-GHU Pitié-Salpêtrière, Sorbonne Universités UPMC Univ Paris 06, UMR_S 1127, 75013, Paris, France.
- Inserm U1127, 75013, Paris, France.
- CNRS UMR7225, 75013, Paris, France.
- Assistance Publique-Hôpitaux de Paris, Hôpital Pitié-Salpêtrière, Paris, France.
| | - Nathalie Sol-Foulon
- ICM-GHU Pitié-Salpêtrière, Sorbonne Universités UPMC Univ Paris 06, UMR_S 1127, 75013, Paris, France.
- Inserm U1127, 75013, Paris, France.
- CNRS UMR7225, 75013, Paris, France.
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209
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Hypoxia-specific, VEGF-expressing neural stem cell therapy for safe and effective treatment of neuropathic pain. J Control Release 2016; 226:21-34. [PMID: 26826306 DOI: 10.1016/j.jconrel.2016.01.047] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Revised: 01/05/2016] [Accepted: 01/26/2016] [Indexed: 12/11/2022]
Abstract
Vascular endothelial growth factor (VEGF) is an angiogenic cytokine that stimulates the differentiation and function of vascular endothelial cells. VEGF has been implicated in improving nervous system function after injury. However, uncontrolled overexpression of VEGF increases the risk of tumor formation at the site of gene delivery. For this reason, VEGF expression needs to be strictly controlled. The goal of the present study was to understand the effects of hypoxia-induced gene expression system to control VEGF gene expression in neural stem cells (NSCs) on the regeneration of neural tissue after sciatic nerve injury. In this study, we used the erythropoietin (Epo) enhancer-SV40 promoter system (EpoSV-VEGF-NSCs) for hypoxia-specific VEGF expression. We used three types of NSCs: DsRed-NSCs as controls, SV-VEGF-NSCs as uncontrolled VEGF overexpressing NSCs, and EpoSV-VEGF-NSCs. For comparison of VEGF expression at normoxia and hypoxia, we measured the amount of VEGF secreted. VEGF expression decreased at normoxia and increased at hypoxia for EpoSV-VEGF-NSCs; thus, EpoSV-VEGF-NSCs controlled VEGF expression, dependent upon oxygenation condition. To demonstrate the therapeutic effect of EpoSV-VEGF-NSCs, we transplanted each cell line in a neuropathic pain sciatic nerve injury rat model. The transplanted EpoSV-VEGF-NSCs improved sciatic nerve functional index (SFI), mechanical allodynia, and re-myelination similar to the SV-VEGF-NSCs. Additionally, the number of blood vessels increased to a level similar to that of the SV-VEGF-NSCs. However, we did not observe tumor generation in the EpoSV-VEGF-NSC animals that were unlikely to have tumor formation in the SV-VEGF-NSCs. From our results, we determined that EpoSV-VEGF-NSCs safely regulate VEGF gene expression which is dependent upon oxygenation status. In addition, we found that they are therapeutically appropriate for treating sciatic nerve injury.
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210
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Schäfer I, Müller C, Luhmann HJ, White R. MOBP levels are regulated by Fyn kinase and affect the morphological differentiation of oligodendrocytes. J Cell Sci 2016; 129:930-42. [PMID: 26801084 DOI: 10.1242/jcs.172148] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 01/20/2016] [Indexed: 01/24/2023] Open
Abstract
Oligodendrocytes are the myelinating glial cells of the central nervous system (CNS). Myelin is formed by extensive wrapping of oligodendroglial processes around axonal segments, which ultimately allows a rapid saltatory conduction of action potentials within the CNS and sustains neuronal health. The non-receptor tyrosine kinase Fyn is an important signaling molecule in oligodendrocytes. It controls the morphological differentiation of oligodendrocytes and is an integrator of axon-glial signaling cascades leading to localized synthesis of myelin basic protein (MBP), which is essential for myelin formation. The abundant myelin-associated oligodendrocytic basic protein (MOBP) resembles MBP in several aspects and has also been reported to be localized as mRNA and translated in the peripheral myelin compartment. The signals initiating local MOBP synthesis are so far unknown and the cellular function of MOBP remains elusive. Here, we show, by several approaches in cultured primary oligodendrocytes, that MOBP synthesis is stimulated by Fyn activity. Moreover, we reveal a new function for MOBP in oligodendroglial morphological differentiation.
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Affiliation(s)
- Isabelle Schäfer
- Institute of Physiology, University Medical Center of the Johannes Gutenberg University, Duesbergweg 6, Mainz 55128, Germany
| | - Christina Müller
- Institute of Physiology, University Medical Center of the Johannes Gutenberg University, Duesbergweg 6, Mainz 55128, Germany
| | - Heiko J Luhmann
- Institute of Physiology, University Medical Center of the Johannes Gutenberg University, Duesbergweg 6, Mainz 55128, Germany
| | - Robin White
- Institute of Physiology, University Medical Center of the Johannes Gutenberg University, Duesbergweg 6, Mainz 55128, Germany
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211
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Vascular endothelial growth factor-expressing neural stem cell for the treatment of neuropathic pain. Neuroreport 2015; 26:399-404. [PMID: 25793634 DOI: 10.1097/wnr.0000000000000359] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Previously, we determined that vascular endothelial growth factor (VEGF) improves the survival of neural stem cells (NSCs) transplanted into an ischemic environment and effectively enhances angiogenesis. Here, we applied NSCs expressing VEGF (SV-VEGF-NSCs) to treat neuropathic pain. In this study, our goal was to verify the therapeutic effect of SV-VEGF-NSCs by transplanting the cells in a sciatic nerve injury model. We compared the amount of VEGF secreted from DsRed-NSCs (control) or SV-VEGF-NSCs and observed that SV-VEGF-NSCs have a much higher expression level of VEGF. We next investigated whether transplantation with SV-VEGF-NSCs aids functional recovery and pain reduction. We confirmed that transplantation with SV-VEGF-NSCs enhances functional recovery, pain reduction, and remyelination as well as the number of blood vessels compared with the control groups. Our results show that VEGF aids functional recovery and pain reduction in a sciatic nerve injury model.
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212
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Prinz J, Karacivi A, Stormanns ER, Recks MS, Kuerten S. Time-Dependent Progression of Demyelination and Axonal Pathology in MP4-Induced Experimental Autoimmune Encephalomyelitis. PLoS One 2015; 10:e0144847. [PMID: 26658811 PMCID: PMC4676607 DOI: 10.1371/journal.pone.0144847] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 11/24/2015] [Indexed: 11/21/2022] Open
Abstract
Background Multiple sclerosis (MS) is an autoimmune disease of the central nervous system (CNS) characterized by inflammation, demyelination and axonal pathology. Myelin basic protein/proteolipid protein (MBP-PLP) fusion protein MP4 is capable of inducing chronic experimental autoimmune encephalomyelitis (EAE) in susceptible mouse strains mirroring diverse histopathological and immunological hallmarks of MS. Limited availability of human tissue underscores the importance of animal models to study the pathology of MS. Methods Twenty-two female C57BL/6 (B6) mice were immunized with MP4 and the clinical development of experimental autoimmune encephalomyelitis (EAE) was observed. Methylene blue-stained semi-thin and ultra-thin sections of the lumbar spinal cord were assessed at the peak of acute EAE, three months (chronic EAE) and six months after onset of EAE (long-term EAE). The extent of lesional area and inflammation were analyzed in semi-thin sections on a light microscopic level. The magnitude of demyelination and axonal damage were determined using electron microscopy. Emphasis was put on the ventrolateral tract (VLT) of the spinal cord. Results B6 mice demonstrated increasing demyelination and severe axonal pathology in the course of MP4-induced EAE. In addition, mitochondrial swelling and a decrease in the nearest neighbor neurofilament distance (NNND) as early signs of axonal damage were evident with the onset of EAE. In semi-thin sections we observed the maximum of lesional area in the chronic state of EAE while inflammation was found to a similar extent in acute and chronic EAE. In contrast to the well-established myelin oligodendrocyte glycoprotein (MOG) model, disease stages of MP4-induced EAE could not be distinguished by assessing the extent of parenchymal edema or the grade of inflammation. Conclusions Our results complement our previous ultrastructural studies of B6 EAE models and suggest that B6 mice immunized with different antigens constitute useful instruments to study the diverse histopathological aspects of MS.
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MESH Headings
- Animals
- Axons/pathology
- Axons/ultrastructure
- Demyelinating Diseases
- Disease Models, Animal
- Disease Progression
- Encephalomyelitis, Autoimmune, Experimental/chemically induced
- Encephalomyelitis, Autoimmune, Experimental/immunology
- Encephalomyelitis, Autoimmune, Experimental/pathology
- Encephalomyelitis, Autoimmune, Experimental/physiopathology
- Female
- Humans
- Immunization
- Lumbar Vertebrae/pathology
- Lumbar Vertebrae/ultrastructure
- Mice
- Mice, Inbred C57BL
- Microtomy
- Mitochondria/pathology
- Mitochondria/ultrastructure
- Mitochondrial Swelling
- Multiple Sclerosis/immunology
- Multiple Sclerosis/pathology
- Multiple Sclerosis/physiopathology
- Myelin Basic Protein/administration & dosage
- Myelin Proteolipid Protein/administration & dosage
- Myelin Sheath/pathology
- Myelin Sheath/ultrastructure
- Recombinant Fusion Proteins/administration & dosage
- Severity of Illness Index
- Time Factors
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Affiliation(s)
- Johanna Prinz
- Department of Anatomy I, University of Cologne, Joseph-Stelzmann-Str. 9, 50931, Cologne, Germany
| | - Aylin Karacivi
- Department of Anatomy I, University of Cologne, Joseph-Stelzmann-Str. 9, 50931, Cologne, Germany
| | - Eva R. Stormanns
- Department of Anatomy I, University of Cologne, Joseph-Stelzmann-Str. 9, 50931, Cologne, Germany
| | - Mascha S. Recks
- Department of Anatomy II, University of Cologne, Joseph-Stelzmann-Str. 9, 50931, Cologne, Germany
| | - Stefanie Kuerten
- Department of Anatomy and Cell Biology, University of Würzburg, Koellikerstraße 6, 97070, Würzburg, Germany
- * E-mail:
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213
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Kraus A, Michalak M. Endoplasmic reticulum quality control and dysmyelination. Biomol Concepts 2015; 2:261-74. [PMID: 25962034 DOI: 10.1515/bmc.2011.028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Dysmyelination contributes to several human diseases including multiple sclerosis, Charcot-Marie-Tooth, leukodystrophies, and schizophrenia and can result in serious neurological disability. Properly formed, compacted myelin sheaths are required for appropriate nerve conduction velocities and the health and survival of neurons. Many different molecular mechanisms contribute to dysmyelination and many of these mechanisms originate at the level of the endoplasmic reticulum. The endoplasmic reticulum is a critical organelle for myelin biosynthesis and maintenance as the site of myelin protein folding quality control, Ca2+ homeostasis, cholesterol biosynthesis, and modulation of cellular stress. This review paper highlights the role of the endoplasmic reticulum and its resident molecules as an upstream and dynamic contributor to myelin and myelin pathologies.
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214
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Goulart CO, Lopes FRP, Monte ZO, Dantas SV, Souto A, Oliveira JT, Almeida FM, Tonda-Turo C, Pereira CC, Borges CP, Martinez AMB. Evaluation of biodegradable polymer conduits--poly(L-lactic acid)--for guiding sciatic nerve regeneration in mice. Methods 2015; 99:28-36. [PMID: 26361830 DOI: 10.1016/j.ymeth.2015.09.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 07/26/2015] [Accepted: 09/08/2015] [Indexed: 01/08/2023] Open
Abstract
Polymeric biomaterials are often used for stimulating nerve regeneration. Among different conduits, poly(lactide acid) - PLA polymer is considered to be a good substrate due to its biocompatibility and resorbable characteristics. This polymer is an aliphatic polyester which has been mostly used in biomedical application. It is an organic compound with low allergenic potential, low toxicity, high biocompatibility and predictable kinetics of degradation. In this study we fabricated and evaluated a PLA microporous hollow fiber as a conduit for its ability to bridge a nerve gap in a mouse sciatic nerve injury model. The PLA conduit was prepared from a polymer solution, throughout extrusion technique. The left sciatic nerve of C57BL/6 mouse was transected and the nerve stumps were placed into a resorbable PLA (PLA group) or a PCL conduit (PCL group), n=5 each group. We have also used another group in which the nerves were repaired by autograft (autograft group, n=5). Motor function was analyzed according to sciatic functional index (SFI). After 56days, the regenerated nerves were processed for light and electron microscopy and morphometric analyses were performed. A quantitative analysis of regenerated nerves showed significant increase in the number of myelinated fibers and blood vessels in animals that received PLA conduit. The PLA group exhibited better overall tissue organization compared to other groups. Presenting well-organized bundles, many regenerating clusters composed of preserved nerve fibers surrounded by layers of compacted perineurium-like cells. Also the SFI revealed a significant improvement in functional recovery. This work suggests that PLA conduits are suitable substrate for cell survival and it provides an effective strategy to be used to support axonal growth becoming a potential alternative to autograft.
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Affiliation(s)
- Camila Oliveira Goulart
- Pós Graduação em Anatomia Patológica, Faculdade de Medicina, HUCFF, UFRJ, Rio de Janeiro, RJ, Brazil; Laboratório de Neurodegeneração e Reparo, Faculdade de Medicina, HUCFF, UFRJ, Rio de Janeiro, RJ, Brazil
| | | | - Zulmira Oliveira Monte
- Laboratório de Neurodegeneração e Reparo, Faculdade de Medicina, HUCFF, UFRJ, Rio de Janeiro, RJ, Brazil; Departamento de Morfologia, UFPI, Piauí, PI, Brazil
| | - Severino Valentim Dantas
- Pós Graduação em Anatomia Patológica, Faculdade de Medicina, HUCFF, UFRJ, Rio de Janeiro, RJ, Brazil
| | - Allana Souto
- Laboratório de Neurodegeneração e Reparo, Faculdade de Medicina, HUCFF, UFRJ, Rio de Janeiro, RJ, Brazil
| | - Júlia Teixeira Oliveira
- Laboratório de Neurodegeneração e Reparo, Faculdade de Medicina, HUCFF, UFRJ, Rio de Janeiro, RJ, Brazil
| | - Fernanda Martins Almeida
- Laboratório de Neurodegeneração e Reparo, Faculdade de Medicina, HUCFF, UFRJ, Rio de Janeiro, RJ, Brazil; Pólo Universitário Macaé, UFRJ, Macaé, RJ, Brazil
| | | | | | | | - Ana Maria Blanco Martinez
- Pós Graduação em Anatomia Patológica, Faculdade de Medicina, HUCFF, UFRJ, Rio de Janeiro, RJ, Brazil; Laboratório de Neurodegeneração e Reparo, Faculdade de Medicina, HUCFF, UFRJ, Rio de Janeiro, RJ, Brazil.
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215
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Stikov N, Campbell JS, Stroh T, Lavelée M, Frey S, Novek J, Nuara S, Ho MK, Bedell BJ, Dougherty RF, Leppert IR, Boudreau M, Narayanan S, Duval T, Cohen-Adad J, Picard PA, Gasecka A, Côté D, Pike GB. In vivo histology of the myelin g-ratio with magnetic resonance imaging. Neuroimage 2015; 118:397-405. [DOI: 10.1016/j.neuroimage.2015.05.023] [Citation(s) in RCA: 207] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Revised: 05/08/2015] [Accepted: 05/08/2015] [Indexed: 11/25/2022] Open
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216
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Mozafari S, Laterza C, Roussel D, Bachelin C, Marteyn A, Deboux C, Martino G, Baron-Van Evercooren A. Skin-derived neural precursors competitively generate functional myelin in adult demyelinated mice. J Clin Invest 2015; 125:3642-56. [PMID: 26301815 DOI: 10.1172/jci80437] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Accepted: 07/07/2015] [Indexed: 12/26/2022] Open
Abstract
Induced pluripotent stem cell-derived (iPS-derived) neural precursor cells may represent the ideal autologous cell source for cell-based therapy to promote remyelination and neuroprotection in myelin diseases. So far, the therapeutic potential of reprogrammed cells has been evaluated in neonatal demyelinating models. However, the repair efficacy and safety of these cells has not been well addressed in the demyelinated adult CNS, which has decreased cell plasticity and scarring. Moreover, it is not clear if these induced pluripotent-derived cells have the same reparative capacity as physiologically committed CNS-derived precursors. Here, we performed a side-by-side comparison of CNS-derived and skin-derived neural precursors in culture and following engraftment in murine models of adult spinal cord demyelination. Grafted induced neural precursors exhibited a high capacity for survival, safe integration, migration, and timely differentiation into mature bona fide oligodendrocytes. Moreover, grafted skin-derived neural precursors generated compact myelin around host axons and restored nodes of Ranvier and conduction velocity as efficiently as CNS-derived precursors while outcompeting endogenous cells. Together, these results provide important insights into the biology of reprogrammed cells in adult demyelinating conditions and support use of these cells for regenerative biomedicine of myelin diseases that affect the adult CNS.
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217
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West KL, Kelm ND, Carson RP, Does MD. A revised model for estimating g-ratio from MRI. Neuroimage 2015; 125:1155-1158. [PMID: 26299793 DOI: 10.1016/j.neuroimage.2015.08.017] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Revised: 08/01/2015] [Accepted: 08/03/2015] [Indexed: 12/01/2022] Open
Abstract
A key measure of white matter health is the g-ratio, which is defined as the ratio between the inner axon radius and the outer, myelinated, axon radius. Recent methods have been proposed to measure the g-ratio non-invasively using the relationship between two magnetic resonance imaging (MRI) measures. While this relationship is intuitive, it predicates on the simplifying assumption that g-ratio is constant across axons. Here, we extend the model to account for a distribution of g-ratio values within an imaging voxel, and evaluate this model with quantitative histology from normal and hypomyelinated mouse brains.
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Affiliation(s)
- Kathryn L West
- Department of Biomedical Engineering, Vanderbilt University, USA; Vanderbilt University Institute of Imaging Science, Vanderbilt University, USA
| | - Nathaniel D Kelm
- Department of Biomedical Engineering, Vanderbilt University, USA; Vanderbilt University Institute of Imaging Science, Vanderbilt University, USA
| | - Robert P Carson
- Department of Pediatric Neurology, Vanderbilt University, USA
| | - Mark D Does
- Department of Biomedical Engineering, Vanderbilt University, USA; Vanderbilt University Institute of Imaging Science, Vanderbilt University, USA; Department of Radiology and Radiological Sciences, Vanderbilt University School of Medicine, USA; Department of Electrical Engineering, Vanderbilt University, USA.
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218
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Early treatment of minocycline alleviates white matter and cognitive impairments after chronic cerebral hypoperfusion. Sci Rep 2015; 5:12079. [PMID: 26174710 PMCID: PMC4502604 DOI: 10.1038/srep12079] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2015] [Accepted: 05/13/2015] [Indexed: 11/16/2022] Open
Abstract
Subcortical ischemic vascular dementia (SIVD) caused by chronic cerebral hypoperfusion develops with progressive white matter and cognitive impairments, yet no effective therapy is available. We investigated the temporal effects of minocycline on an experimental SIVD exerted by right unilateral common carotid arteries occlusion (rUCCAO). Minocycline treated at the early stage (day 0–3), but not the late stage after rUCCAO (day 4–32) alleviated the white matter and cognitive impairments, and promoted remyelination. The actions of minocycline may not involve the inhibition of microglia activation, based on the effects after the application of a microglial activation inhibitor, macrophage migration inhibitory factor, and co-treatment with lipopolysaccharides. Furthermore, minocycline treatment at the early stage promoted the proliferation of oligodendrocyte progenitor cells (OPCs) in subventricular zone, increased OPC number and alleviated apoptosis of mature oligodendrocytes in white matter. In vitro, minocycline promoted OPC proliferation and increased the percentage of OPCs in S and G2/M phases. We provided direct evidence that early treatment is critical for minocycline to alleviate white matter and cognitive impairments after chronic cerebral hypoperfusion, which may be due to its robust effects on OPC proliferation and mature oligodendrocyte loss. So, early therapeutic time window may be crucial for its application in SIVD.
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219
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Bastiani M, Roebroeck A. Unraveling the multiscale structural organization and connectivity of the human brain: the role of diffusion MRI. Front Neuroanat 2015; 9:77. [PMID: 26106304 PMCID: PMC4460430 DOI: 10.3389/fnana.2015.00077] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 05/21/2015] [Indexed: 01/31/2023] Open
Abstract
The structural architecture and the anatomical connectivity of the human brain show different organizational principles at distinct spatial scales. Histological staining and light microscopy techniques have been widely used in classical neuroanatomical studies to unravel brain organization. Using such techniques is a laborious task performed on 2-dimensional histological sections by skilled anatomists possibly aided by semi-automated algorithms. With the recent advent of modern magnetic resonance imaging (MRI) contrast mechanisms, cortical layers and columns can now be reliably identified and their structural properties quantified post-mortem. These developments are allowing the investigation of neuroanatomical features of the brain at a spatial resolution that could be interfaced with that of histology. Diffusion MRI and tractography techniques, in particular, have been used to probe the architecture of both white and gray matter in three dimensions. Combined with mathematical network analysis, these techniques are increasingly influential in the investigation of the macro-, meso-, and microscopic organization of brain connectivity and anatomy, both in vivo and ex vivo. Diffusion MRI-based techniques in combination with histology approaches can therefore support the endeavor of creating multimodal atlases that take into account the different spatial scales or levels on which the brain is organized. The aim of this review is to illustrate and discuss the structural architecture and the anatomical connectivity of the human brain at different spatial scales and how recently developed diffusion MRI techniques can help investigate these.
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Affiliation(s)
- Matteo Bastiani
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University Maastricht, Netherlands
| | - Alard Roebroeck
- Department of Cognitive Neuroscience, Faculty of Psychology and Neuroscience, Maastricht University Maastricht, Netherlands
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220
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Morphometric analysis of the diameter and g-ratio of the myelinated nerve fibers of the human sciatic nerve during the aging process. Anat Sci Int 2015; 91:238-45. [DOI: 10.1007/s12565-015-0287-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 05/05/2015] [Indexed: 11/25/2022]
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221
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Recks MS, Grether NB, van der Broeck F, Ganscher A, Wagner N, Henke E, Ergün S, Schroeter M, Kuerten S. Four different synthetic peptides of proteolipid protein induce a distinct antibody response in MP4-induced experimental autoimmune encephalomyelitis. Clin Immunol 2015; 159:93-106. [PMID: 25959684 DOI: 10.1016/j.clim.2015.04.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Accepted: 04/30/2015] [Indexed: 01/26/2023]
Abstract
Here we studied the autoantibody specificity elicited by proteolipid protein (PLP) in MP4-induced experimental autoimmune encephalomyelitis, a mouse model of multiple sclerosis (MS). In C57BL/6 (B6) mice, antibodies were induced by immunization with one of the two extracellular and by the intracellular PLP domain. Antibodies against extracellular PLP were myelin-reactive in oligodendrocyte cultures and induced mild spinal cord demyelination upon transfer into B cell-deficient J(H)T mice. Remarkably, also antibodies against intracellular PLP showed binding to intact oligodendrocytes and were capable of inducing myelin pathology upon transfer into J(H)T mice. In MP4-immunized mice peptide-specific T(H)1/T(H)17 responses were mainly directed against the extracellular PLP domains, but also involved the intracellular epitopes. These data suggest that both extracellular and intracellular epitopes of PLP contribute to the pathogenesis of MP4-induced EAE already in the setting of intact myelin. It remains to be elucidated if this concept also applies to MS itself.
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Affiliation(s)
- Mascha S Recks
- Department of Anatomy II (Neuroanatomy), University of Cologne, Kerpener Straβe 62, 50924 Cologne, Germany
| | - Nicolai B Grether
- Department of Anatomy and Cell Biology, University of Wuerzburg, Koellikerstr. 6, 97070 Wuerzburg, Germany
| | | | - Alla Ganscher
- Department of Anatomy and Cell Biology, University of Wuerzburg, Koellikerstr. 6, 97070 Wuerzburg, Germany
| | - Nicole Wagner
- Department of Anatomy and Cell Biology, University of Wuerzburg, Koellikerstr. 6, 97070 Wuerzburg, Germany
| | - Erik Henke
- Department of Anatomy and Cell Biology, University of Wuerzburg, Koellikerstr. 6, 97070 Wuerzburg, Germany
| | - Süleyman Ergün
- Department of Anatomy and Cell Biology, University of Wuerzburg, Koellikerstr. 6, 97070 Wuerzburg, Germany
| | - Michael Schroeter
- Department of Neurology, University of Cologne, Kerpener Str. 62, 50924 Cologne, Germany
| | - Stefanie Kuerten
- Department of Anatomy and Cell Biology, University of Wuerzburg, Koellikerstr. 6, 97070 Wuerzburg, Germany.
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222
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Singh S, Pelegri AA, Shreiber DI. Characterization of the three-dimensional kinematic behavior of axons in central nervous system white matter. Biomech Model Mechanobiol 2015; 14:1303-15. [PMID: 25910712 DOI: 10.1007/s10237-015-0675-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 04/02/2015] [Indexed: 01/21/2023]
Abstract
Traumatic injury to axons in white matter of the brain and spinal cord occurs primarily via tensile stretch. During injury, the stress and strain experienced at the tissue level is transferred to the microscopic axons. How this transfer occurs, and the primary constituents dictating this transfer must be better understood to develop more accurate multi-scale models of injury. Previous studies have characterized axon tortuosity and kinematic behavior in 2-dimensions (2-D), where axons have been modeled to exhibit non-affine (discrete), affine (composite-like), or switching behavior. In this study, we characterize axon tortuosity and model axon kinematic behavior in 3-dimensions (3-D). Embryonic chick spinal cords at different development stages were excised and stretched. Cords were then fixed, transversely sectioned, stained, and imaged. 3-D axon tortuosity was measured from confocal images using a custom-built MATLAB script. 2-D kinematic models previously described in Bain et al. (J Biomech Eng 125(6):798, 2003) were extended, re-derived, and validated for the 3-D case. Results showed that 3-D tortuosity decreased with stretch, exhibiting similar trends with changes in development as observed in the 2-D studies. Kinematic parameters also displayed similar general trends. Axons demonstrated more affine behavior with increasing stretch and development. In comparison with 2-D results, a smaller percentage of the populations of 3-D axons were predicted to follow pure non-affine behavior. The data and kinematic models presented herein can be incorporated into multi-scale CNS injury models, which can advance the accuracy of the models and improve the potential to identify axonal injury thresholds.
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Affiliation(s)
- Sagar Singh
- Department of Biomedical Engineering, Rutgers, The State University of New Jersey, 599 Taylor Road, Piscataway, NJ, 08854, USA
| | - Assimina A Pelegri
- Department of Mechanical and Aerospace Engineering, Rutgers, The State University of New Jersey, 98 Brett Road, Piscataway, NJ, 08854, USA
| | - David I Shreiber
- Department of Biomedical Engineering, Rutgers, The State University of New Jersey, 599 Taylor Road, Piscataway, NJ, 08854, USA.
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223
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Abstract
The myelin sheath is a plasma membrane extension that is laid down in regularly spaced segments along axons of the nervous system. This process involves extensive changes in oligodendrocyte cell shape and membrane architecture. In this Cell Science at a Glance article and accompanying poster, we provide a model of how myelin of the central nervous system is wrapped around axons to form a tightly compacted, multilayered membrane structure. This model may not only explain how myelin is generated during brain development, but could also help us to understand myelin remodeling in adult life, which might serve as a form of plasticity for the fine-tuning of neuronal networks.
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Affiliation(s)
- Nicolas Snaidero
- Max Planck Institute of Experimental Medicine, Cellular Neuroscience, Hermann-Rein-Strasse. 3, 37075, Göttingen, Germany Department of Neurology, University of Göttingen, Robert-Koch-Strasse. 40, 37075, Göttingen, Germany
| | - Mikael Simons
- Max Planck Institute of Experimental Medicine, Cellular Neuroscience, Hermann-Rein-Strasse. 3, 37075, Göttingen, Germany Department of Neurology, University of Göttingen, Robert-Koch-Strasse. 40, 37075, Göttingen, Germany
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224
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The evolution of vertebrate and invertebrate myelin: a theoretical computational study. J Comput Neurosci 2015; 38:521-38. [PMID: 25832903 DOI: 10.1007/s10827-015-0552-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 02/20/2015] [Accepted: 03/04/2015] [Indexed: 01/11/2023]
Abstract
Multilayered, lipid-rich myelin increases nerve impulse conduction velocity, contributes to compact nervous systems, and reduces metabolic costs of neural activity. Based on the hypothesis that increased impulse conduction velocity provides a selective advantage that drives the evolution of myelin, we simulated a sequence of plausible intermediate stages of myelin evolution, each of which providing an enhancement of conduction speed. We started with the expansion of insulating glial coverage, which led first to a single layer of myelin surrounding the axon and then to multiple myelin wraps with well-organized nodes. The myelinated fiber was modeled at three levels of complexity as the hypothesized evolutionary progression became more quantitatively exacting: 1) representing the fiber as a mathematically-tractable uniform active cylinder with the effect of myelination approximated by changing its specific capacitance (C(m)); 2) representing it as a chain of simple, cable-model compartments having alternating nodal and internodal parameters subject to optimization, and 3) representing it in a double cable model with the axon and myelin sheath treated separately. Conduction velocity was optimized at each stage. To maintain optimal conduction velocities, increased myelin coverage of axonal surface must be accompanied by an increase in channel density at the evolving nodes, but along with increases in myelin thickness, a reduction in overall average channel density must occur. Leakage under the myelin sheath becomes more of a problem with smaller fiber diameters, which may help explain the tendency for myelin to occur preferentially in larger nerve fibers in both vertebrates and invertebrates.
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225
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Praet J, Orije J, Kara F, Guglielmetti C, Santermans E, Daans J, Hens N, Verhoye M, Berneman Z, Ponsaerts P, Van der Linden A. Cuprizone-induced demyelination and demyelination-associated inflammation result in different proton magnetic resonance metabolite spectra. NMR IN BIOMEDICINE 2015; 28:505-513. [PMID: 25802215 PMCID: PMC4403969 DOI: 10.1002/nbm.3277] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Revised: 01/16/2015] [Accepted: 01/23/2015] [Indexed: 06/04/2023]
Abstract
Conventional MRI is frequently used during the diagnosis of multiple sclerosis but provides only little additional pathological information. Proton MRS ((1) H-MRS), however, provides biochemical information on the lesion pathology by visualization of a spectrum of metabolites. In this study we aimed to better understand the changes in metabolite concentrations following demyelination of the white matter. Therefore, we used the cuprizone model, a well-established mouse model to mimic type III human multiple sclerosis demyelinating lesions. First, we identified CX3 CL1/CX3 CR1 signaling as a major regulator of microglial activity in the cuprizone mouse model. Compared with control groups (heterozygous CX3 CR1(+/-) C57BL/6 mice and wild type CX3 CR1(+/+) C57BL/6 mice), microgliosis, astrogliosis, oligodendrocyte cell death and demyelination were shown to be highly reduced or absent in CX3 CR1(-/-) C57BL/6 mice. Second, we show that (1) H-MRS metabolite spectra are different when comparing cuprizone-treated CX3 CR1(-/-) mice showing mild demyelination with cuprizone-treated CX3 CR1(+/+) mice showing severe demyelination and demyelination-associated inflammation. Following cuprizone treatment, CX3 CR1(+/+) mice show a decrease in the Glu, tCho and tNAA concentrations as well as an increased Tau concentration. In contrast, following cuprizone treatment CX3 CR1(-/-) mice only showed a decrease in tCho and tNAA concentrations. Therefore, (1) H-MRS might possibly allow us to discriminate demyelination from demyelination-associated inflammation via changes in Tau and Glu concentration. In addition, the observed decrease in tCho concentration in cuprizone-induced demyelinating lesions should be further explored as a possible diagnostic tool for the early identification of human MS type III lesions.
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Affiliation(s)
- Jelle Praet
- Experimental Cell Transplantation Group, Laboratory of Experimental Hematology, University of AntwerpAntwerp, Belgium
- Vaccine and Infectious Disease Institute (Vaxinfectio), University of AntwerpAntwerp, Belgium
- Bio-Imaging Laboratory, University of AntwerpAntwerp, Belgium
| | - Jasmien Orije
- Bio-Imaging Laboratory, University of AntwerpAntwerp, Belgium
| | - Firat Kara
- Bio-Imaging Laboratory, University of AntwerpAntwerp, Belgium
| | | | - Eva Santermans
- Center for Statistics, I-BioStat, Hasselt UniversityHasselt, Belgium
| | - Jasmijn Daans
- Experimental Cell Transplantation Group, Laboratory of Experimental Hematology, University of AntwerpAntwerp, Belgium
- Vaccine and Infectious Disease Institute (Vaxinfectio), University of AntwerpAntwerp, Belgium
| | - Niel Hens
- Vaccine and Infectious Disease Institute (Vaxinfectio), University of AntwerpAntwerp, Belgium
- Center for Statistics, I-BioStat, Hasselt UniversityHasselt, Belgium
- Centre for Health Economic Research and Modeling Infectious Diseases (CHERMID), University of AntwerpAntwerp, Belgium
| | - Marleen Verhoye
- Bio-Imaging Laboratory, University of AntwerpAntwerp, Belgium
| | - Zwi Berneman
- Experimental Cell Transplantation Group, Laboratory of Experimental Hematology, University of AntwerpAntwerp, Belgium
- Vaccine and Infectious Disease Institute (Vaxinfectio), University of AntwerpAntwerp, Belgium
| | - Peter Ponsaerts
- Experimental Cell Transplantation Group, Laboratory of Experimental Hematology, University of AntwerpAntwerp, Belgium
- Vaccine and Infectious Disease Institute (Vaxinfectio), University of AntwerpAntwerp, Belgium
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226
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Dias FJ, Issa JPM, Coutinho-Netto J, Fazan VPS, Sousa LG, Iyomasa MM, Papa PC, Watanabe IS. Morphometric and high resolution scanning electron microscopy analysis of low-level laser therapy and latex protein (Hevea brasiliensis) administration following a crush injury of the sciatic nerve in rats. J Neurol Sci 2015; 349:129-37. [PMID: 25619570 DOI: 10.1016/j.jns.2014.12.043] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Revised: 12/03/2014] [Accepted: 12/29/2014] [Indexed: 12/24/2022]
Abstract
This study evaluated the effect of low-level laser therapy (LLLT; 15 J/cm(2)) and a latex protein (F1) on a crush injury of the sciatic (ischiadicus) nerve. Seventy-two rats (male, 250 g) were divided into 6 groups: CG, control; EG, exposed nerve; IG, injured nerve without treatment; LG, injured nerve with LLLT; HG, injured nerve with F1; and LHG, injured nerve with LLLT and F1. After 4 or 8 weeks, the animals were euthanized and samples of the sciatic nerve were collected for morphometric and high-resolution scanning electron microscopy (HRSEM) analysis. After 4 weeks, the morphometry revealed improvements in the treated animals, and the HG appeared to be the most similar to the CG; after 8 weeks, the injured groups showed improvements compared to the previous period, and the results of the treatment groups were more similar to one another. At HRSEM after 4 weeks, the treated groups were similar and showed improvement compared to the IG; after 8 weeks, the LHG and HG had the best results. In conclusion, the treatments resulted in improvement after the nerve injury, and this recovery was time-dependent. In addition, the use of the F1 resulted in the best morphometric and ultrastructural findings.
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Affiliation(s)
- Fernando J Dias
- Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil; Ribeirão Preto Medical School of the University of São Paulo, Ribeirão Preto, Brazil
| | - João Paulo M Issa
- School of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto , Brazil
| | | | - Valéria P S Fazan
- Ribeirão Preto Medical School of the University of São Paulo, Ribeirão Preto, Brazil
| | - Luiz Gustavo Sousa
- School of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto , Brazil
| | - Mamie M Iyomasa
- School of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto , Brazil
| | - Paula C Papa
- School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, Brazil
| | - Ii-Sei Watanabe
- Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil; School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, Brazil.
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227
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Friesland A, Weng Z, Duenas M, Massa SM, Longo FM, Lu Q. Amelioration of cisplatin-induced experimental peripheral neuropathy by a small molecule targeting p75 NTR. Neurotoxicology 2014; 45:81-90. [PMID: 25277379 PMCID: PMC4268328 DOI: 10.1016/j.neuro.2014.09.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Revised: 08/18/2014] [Accepted: 09/22/2014] [Indexed: 12/18/2022]
Abstract
Cisplatin is an effective and widely used first-line chemotherapeutic drug for treating cancers. However, many patients sustain cisplatin-induced peripheral neuropathy (CIPN), often leading to a reduction in drug dosages or complete cessation of treatment altogether. Therefore, it is important to understand cisplatin mechanisms in peripheral nerve tissue mediating its toxicity and identify signaling pathways for potential intervention. Rho GTPase activation is increased following trauma in several models of neuronal injury. Thus, we investigated whether components of the Rho signaling pathway represent important neuroprotective targets with the potential to ameliorate CIPN and thereby optimize current chemotherapy treatment regimens. We have developed a novel CIPN model in the mouse. Using this model and primary neuronal culture, we determined whether LM11A-31, a small-molecule, orally bioavailable ligand of the p75 neurotrophin receptor (p75(NTR)), can modulate Rho GTPase signaling and reduce CIPN. Von Frey filament analysis of sural nerve function showed that LM11A-31 treatment prevented decreases in peripheral nerve sensation seen with cisplatin treatment. Morphometric analysis of harvested sural nerves revealed that cisplatin-induced abnormal nerve fiber morphology and the decreases in fiber area were alleviated with concurrent LM11A-31 treatment. Cisplatin treatment increased RhoA activity accompanied by the reduced tyrosine phosphorylation of SHP2, which was reversed by LM11A-31. LM11A-31 also countered the effects of calpeptin, which activated RhoA by inhibiting SHP2 tyrosine phosphatase. Therefore, suppression of RhoA signaling by LM11A-31 that modulates p75(NTR) or activates SHP2 tyrosine phosphatase downstream of the NGF receptor enhances neuroprotection in experimental CIPN in mouse model.
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Affiliation(s)
- Amy Friesland
- Department of Anatomy and Cell Biology, The Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA; Leo Jenkins Cancer Center, The Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA
| | - Zhiying Weng
- Department of Anatomy and Cell Biology, The Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA; School of Pharmaceutical Science and Yunnan Key Laboratory of Pharmacology for Natural Products, Kunming Medical University, Kunming 650500, China
| | - Maria Duenas
- Department of Anatomy and Cell Biology, The Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA
| | - Stephen M Massa
- Department of Neurology Veterans Administration Medical Center and University of California at San Francisco, San Francisco, CA 94121, USA
| | - Frank M Longo
- Department of Neurology and Neurological Science, Stanford University, Stanford, CA 94305, USA
| | - Qun Lu
- Department of Anatomy and Cell Biology, The Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA; Leo Jenkins Cancer Center, The Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA.
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228
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Amer MG, Mazen NF, Mohamed NM. Role of calorie restriction in alleviation of age-related morphological and biochemical changes in sciatic nerve. Tissue Cell 2014; 46:497-504. [DOI: 10.1016/j.tice.2014.09.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Revised: 08/20/2014] [Accepted: 09/08/2014] [Indexed: 10/24/2022]
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229
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de Campos D. Degree of myelination (g-Ratio), Divine proportion and Fibonacci sequence – A mathematical relationship. J ANAT SOC INDIA 2014. [DOI: 10.1016/j.jasi.2014.09.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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230
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Liśkiewicz A, Właszczuk A, Gendosz D, Larysz-Brysz M, Kapustka B, Łączyński M, Lewin-Kowalik J, Jędrzejowska-Szypułka H. Sciatic nerve regeneration in rats subjected to ketogenic diet. Nutr Neurosci 2014; 19:116-24. [PMID: 25401509 DOI: 10.1179/1476830514y.0000000163] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
OBJECTIVES Ketogenic diet (KD) is a high-fat-content diet with insufficiency of carbohydrates that induces ketogenesis. Besides its anticonvulsant properties, many studies have shown its neuroprotective effect in central nervous system, but its influence on peripheral nervous system has not been studied yet. We examined the influence of KD on regeneration of peripheral nerves in adult rats. METHODS Fifty one rats were divided into three experimental (n = 15) and one control (n = 6) groups. Right sciatic nerve was crushed and animals were kept on standard (ST group) or ketogenic diet, the latter was introduced 3 weeks before (KDB group) or on the day of surgery (KDA group). Functional (CatWalk) tests were performed once a week, and morphometric (fiber density, axon diameter, and myelin thickness) analysis of the nerves was made after 6 weeks. Body weight and blood ketone bodies level were estimated at the beginning and the end of experiment. RESULTS Functional analysis showed no differences between groups. Morphometric evaluation showed most similarities to the healthy (uncrushed) nerves in KDB group. Nerves in ST group differed mostly from all other groups. Ketone bodies were elevated in both KD groups, while post-surgery animals' body weight was lower as compared to ST group. DISCUSSION Regeneration of sciatic nerves was improved in KD - preconditioned rats. These results suggest a neuroprotective effect of KD on peripheral nerves.
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Affiliation(s)
- Arkadiusz Liśkiewicz
- a Medical University of Silesia, School of Medicine in Katowice , Department of Physiology , Poland
| | - Adam Właszczuk
- a Medical University of Silesia, School of Medicine in Katowice , Department of Physiology , Poland
| | - Daria Gendosz
- a Medical University of Silesia, School of Medicine in Katowice , Department of Physiology , Poland
| | - Magdalena Larysz-Brysz
- a Medical University of Silesia, School of Medicine in Katowice , Department of Physiology , Poland
| | - Bartosz Kapustka
- a Medical University of Silesia, School of Medicine in Katowice , Department of Physiology , Poland
| | - Mariusz Łączyński
- a Medical University of Silesia, School of Medicine in Katowice , Department of Physiology , Poland
| | - Joanna Lewin-Kowalik
- a Medical University of Silesia, School of Medicine in Katowice , Department of Physiology , Poland
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231
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de Hoz L, Simons M. The emerging functions of oligodendrocytes in regulating neuronal network behaviour. Bioessays 2014; 37:60-9. [PMID: 25363888 DOI: 10.1002/bies.201400127] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Myelin is required for efficient nerve conduction, but not all axons are myelinated to the same extent. Here we review recent studies that have revealed distinct myelination patterns of different axonal paths, suggesting that myelination is not an all or none phenomenon and that its presence is finely regulated in central nervous system networks. Whereas powerful reductionist biology has led to important knowledge of how oligodendrocytes function by themselves, little is known about their role in neuronal networks. We still do not understand how oligodendrocytes integrate information from neurons to adapt their function to the need of the system. An intricate cross talk between neurons and glia is likely to exist and to determine how neuronal circuits operate as a whole. Dissecting these mechanisms by using integrative systems biology approaches is one of the major challenges ahead.
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Affiliation(s)
- Livia de Hoz
- Department of Neurogenetics, Max-Planck-Institute of Experimental Medicine, Göttingen, Germany
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232
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Bilirubin and its oxidation products damage brain white matter. J Cereb Blood Flow Metab 2014; 34:1837-47. [PMID: 25160671 PMCID: PMC4269762 DOI: 10.1038/jcbfm.2014.154] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Revised: 07/11/2014] [Accepted: 07/31/2014] [Indexed: 12/13/2022]
Abstract
Brain injury after intracerebral hemorrhage (ICH) occurs in cortex and white matter and may be mediated by blood breakdown products, including hemoglobin and heme. Effects of blood breakdown products, bilirubin and bilirubin oxidation products, have not been widely investigated in adult brain. Here, we first determined the effect of bilirubin and its oxidation products on the structure and function of white matter in vitro using brain slices. Subsequently, we determined whether these compounds have an effect on the structure and function of white matter in vivo. In all, 0.5 mmol/L bilirubin treatment significantly damaged both the function and the structure of myelinated axons but not the unmyelinated axons in brain slices. Toxicity of bilirubin in vitro was prevented by dimethyl sulfoxide. Bilirubin oxidation products (BOXes) may be responsible for the toxicity of bilirubin. In in vivo experiments, unmyelinated axons were found more susceptible to damage from bilirubin injection. These results suggest that unmyelinated axons may have a major role in white-matter damage in vivo. Since bilirubin and BOXes appear in a delayed manner after ICH, preventing their toxic effects may be worth investigating therapeutically. Dimethyl sulfoxide or its structurally related derivatives may have a potential therapeutic value at antagonizing axonal damage after hemorrhagic stroke.
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A combination of Schwann-cell grafts and aerobic exercise enhances sciatic nerve regeneration. PLoS One 2014; 9:e110090. [PMID: 25333892 PMCID: PMC4198198 DOI: 10.1371/journal.pone.0110090] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Accepted: 09/15/2014] [Indexed: 01/28/2023] Open
Abstract
Background Despite the regenerative potential of the peripheral nervous system, severe nerve lesions lead to loss of target-organ innervation, making complete functional recovery a challenge. Few studies have given attention to combining different approaches in order to accelerate the regenerative process. Objective Test the effectiveness of combining Schwann-cells transplantation into a biodegradable conduit, with treadmill training as a therapeutic strategy to improve the outcome of repair after mouse nerve injury. Methods Sciatic nerve transection was performed in adult C57BL/6 mice; the proximal and distal stumps of the nerve were sutured into the conduit. Four groups were analyzed: acellular grafts (DMEM group), Schwann cell grafts (3×105/2 µL; SC group), treadmill training (TMT group), and treadmill training and Schwann cell grafts (TMT + SC group). Locomotor function was assessed weekly by Sciatic Function Index and Global Mobility Test. Animals were anesthetized after eight weeks and dissected for morphological analysis. Results Combined therapies improved nerve regeneration, and increased the number of myelinated fibers and myelin area compared to the DMEM group. Motor recovery was accelerated in the TMT + SC group, which showed significantly better values in sciatic function index and in global mobility test than in the other groups. The TMT + SC group showed increased levels of trophic-factor expression compared to DMEM, contributing to the better functional outcome observed in the former group. The number of neurons in L4 segments was significantly higher in the SC and TMT + SC groups when compared to DMEM group. Counts of dorsal root ganglion sensory neurons revealed that TMT group had a significant increased number of neurons compared to DMEM group, while the SC and TMT + SC groups had a slight but not significant increase in the total number of motor neurons. Conclusion These data provide evidence that this combination of therapeutic strategies can significantly improve functional and morphological recovery after sciatic injury.
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Barreiros VCP, Dias FJ, Iyomasa MM, Coutinho-Netto J, de Sousa LG, Fazan VPS, Antunes RDS, Watanabe IS, Issa JPM. Morphological and morphometric analyses of crushed sciatic nerves after application of a purified protein from natural latex and hyaluronic acid hydrogel. Growth Factors 2014; 32:164-70. [PMID: 25257251 DOI: 10.3109/08977194.2014.952727] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Hyaluronic acid hydrogels (HAHs) have been used as a carrier of substances and factors in the repair of nervous tissue. Natural latex protein (Hevea brasiliensis, F1) has shown positive effects in treating various types of tissues, including peripheral nerves. This study evaluated the F1 associated with a HAH in a controlled crush injury (axonotmesis) of the sciatic nerve in Wistar rats. The samples were photomicrographed for morphometric and quantitative analyzes using ImageJ 1.47k software (NIH, Bethesda, MD). Morphological, quantitative (myelin area/nerve area ratio and capillary density) and morphometric (minimum nerve fiber diameter, G-Ratio) data revealed an improvement in the recovery of the sciatic nerve with the application of HAH and the combination of HAH and F1 after 4 and 8 weeks of nerve injury. The most efficacious results were observed with the combination of both substances, F1 and HAH, revealing the regenerative capacity of this new biomaterial, which was hardly tested on nerve tissue.
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235
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Isaacs J, Mallu S, Yan W, Little B. Consequences of oversizing: nerve-to-nerve tube diameter mismatch. J Bone Joint Surg Am 2014; 96:1461-7. [PMID: 25187585 DOI: 10.2106/jbjs.m.01420] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
BACKGROUND Although commercially available nerve conduits are an accepted tool for overcoming short gaps in peripheral nerve repair, unexplained inconsistencies in clinical outcomes are not uncommon. Although exceeding the critical gap size and nerve caliber are most frequently cited as the source of these failures, oversizing of the nerve conduit in relation to the nerve diameter may be a previously unrecognized factor as well. METHODS Sixty female Sprague-Dawley rats underwent excision of a 10-mm section midway between the sciatic notch and the sciatic nerve division of one hindlimb. The defect was immediately repaired by reversing the resected nerve section and suturing it back in place (reverse autograft) (group A, n = 13) or it was repaired with a 14-mm nerve tube of 3 mm in diameter (group B, n = 12), 2 mm in diameter (group C, n = 15), or 1.5 mm in diameter (group D, n = 15). At twelve weeks, the rodents underwent muscle strength testing before harvest of muscle and nerve (including the conduit) for histomorphologic assessment. RESULTS Most conduits from group B were collapsed at final inspection and demonstrated diminished nerve regenerate. Muscle atrophy was most pronounced in groups B and C (p < 0.05), although normalized muscle contraction force was weakest in group B (p < 0.05), indicating inferior reinnervation. The axon counts, axon diameter, and G-ratios at the midpart of the conduit or graft demonstrated more axons and lower G-ratios in the autologous graft group. Among the conduit groups, the axon counts were lowest in group B (p < 0.05) followed by group C (p < 0.05). The G-ratio was highest in group B (p < 0.05), although the axon diameter was highest in group B (p < 0.05) as well. CONCLUSIONS Repair of a 10-mm gap in a rodent nerve with an oversized, poorly fitted nerve conduit resulted in tube collapse, poor nerve regenerate, and decreased muscle reinnervation compared with the findings in the animals treated with more accurately fitted nerve conduits. CLINICAL RELEVANCE Accurate sizing of nerve conduits to the nerve-stump diameter improves nerve recovery.
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Affiliation(s)
- Jonathan Isaacs
- Division of Hand Surgery, Department of Orthopaedic Surgery, Virginia Commonwealth University Medical Center, 1200 East Broad Street, P.O. Box 980153, Richmond, VA 23298. E-mail address for J. Isaacs:
| | - Satya Mallu
- Division of Hand Surgery, Department of Orthopaedic Surgery, Virginia Commonwealth University Medical Center, 1200 East Broad Street, P.O. Box 980153, Richmond, VA 23298. E-mail address for J. Isaacs:
| | - Wo Yan
- Departments of Plastic and Reconstructive Surgery and Anatomy, Shanghai JiaoTong University School of Medicine, Shanghai Ninth People's Hospital, Shanghai 200025, China
| | - Barrett Little
- Division of Hand Surgery, Department of Orthopaedic Surgery, Virginia Commonwealth University Medical Center, 1200 East Broad Street, P.O. Box 980153, Richmond, VA 23298. E-mail address for J. Isaacs:
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Chen P, Cescon M, Bonaldo P. The Role of Collagens in Peripheral Nerve Myelination and Function. Mol Neurobiol 2014; 52:216-25. [PMID: 25143238 DOI: 10.1007/s12035-014-8862-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Accepted: 08/11/2014] [Indexed: 02/07/2023]
Abstract
In the peripheral nervous system, myelin is formed by Schwann cells, which are surrounded by a basal lamina. Extracellular matrix (ECM) molecules in the basal lamina play an important role in regulating Schwann cell functions, including adhesion, survival, spreading, and myelination, as well as in supporting neurite outgrowth. Collagens are a major component of ECM molecules, which include 28 types that differ in structure and function. A growing body of evidence suggests that collagens are key components of peripheral nerves, where they not only provide a structural support but also affect cell behavior by triggering intracellular signals. In this review, we will summarize the main properties of collagen family, discuss the role of extensively studied collagen types (collagens IV, V, VI, and XV) in Schwann cell function and myelination, and provide a detailed overview of the recent advances with respect to these collagens in peripheral nerve function.
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Affiliation(s)
- Peiwen Chen
- Department of Molecular Medicine, University of Padova, Via Ugo Bassi 58/B, 35131, Padova, Italy,
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Tiwari SK, Agarwal S, Chauhan LKS, Mishra VN, Chaturvedi RK. Bisphenol-A impairs myelination potential during development in the hippocampus of the rat brain. Mol Neurobiol 2014; 51:1395-416. [PMID: 25084756 DOI: 10.1007/s12035-014-8817-3] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Accepted: 07/11/2014] [Indexed: 12/01/2022]
Abstract
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.
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Affiliation(s)
- Shashi Kant Tiwari
- Developmental Toxicology Division, Systems Toxicology Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), 80 MG Marg, Lucknow, UP, 226001, India
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Simultaneous inferior alveolar nerve regeneration and osseointegration with a nerve growth factor-supplying implant: a preliminary study. J Oral Maxillofac Surg 2014; 73:410-23. [PMID: 25266595 DOI: 10.1016/j.joms.2014.07.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Revised: 06/20/2014] [Accepted: 07/01/2014] [Indexed: 11/20/2022]
Abstract
PURPOSE Although nerve growth factor (NGF) has been proved to enhance inferior alveolar nerve (IAN) regeneration, its clinical application remains a challenging issue. This study investigated the functional regeneration of IAN injury by supplying NGF using an NGF-supplying implant and its effect on the osseointegration. MATERIALS AND METHODS In canine IAN transection-and-repair models (n = 9), NGF-supplying implants connected to osmotic pumps were installed just above the transection site. In the right IAN, NGF 300 μg in phosphate buffered saline (PBS) 2 mL was loaded in the pump and pure PBS 2 mL was loaded in the left IAN. The gross clinical finding was evaluated by wound healing, inflammation, implant exposure, and loss of fixture. To evaluate IAN regeneration, electrophysiologic (amplitude, latency, conduction velocity, and peak voltage) and histomorphometric (axon count and density, myelin thickness, and ratio of axon diameter to fiber diameter) analyses were performed. Implant stability quotient, bone-to-implant contact ratio, and new bone area were measured to assess the osseointegration of the NGF-supplying implant. RESULTS The conduction velocity (2.675 m/second) and peak voltage (1.940 μV) of the NGF group at 6 weeks were considerably higher than those of the PBS group (1.892 m/second and 1.300 μV, respectively). The same results were observed for axon count (NGF vs PBS, 4,576.107 ± 270.413 vs 3,606.972 ± 242.876), axon density (10,707.458 ± 638.835 vs 7,899.781 ± 1,063.625/mm(2)), and myelin thickness (1.670 ± 0.555 vs 1.173 ± 0.388 μm). There were no meaningful differences for the other parameters. CONCLUSIONS Supplying NGF with specially designed dental implants can be a new therapeutic approach to enable IAN regeneration and osseointegration simultaneously.
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Ding Y, Qu Y, Feng J, Wang M, Han Q, So KF, Wu W, Zhou L. Functional motor recovery from motoneuron axotomy is compromised in mice with defective corticospinal projections. PLoS One 2014; 9:e101918. [PMID: 25003601 PMCID: PMC4087004 DOI: 10.1371/journal.pone.0101918] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Accepted: 06/12/2014] [Indexed: 12/28/2022] Open
Abstract
Brachial plexus injury (BPI) and experimental spinal root avulsion result in loss of motor function in the affected segments. After root avulsion, significant motoneuron function is restored by re-implantation of the avulsed root. How much this functional recovery depends on corticospinal inputs is not known. Here, we studied that question using Celsr3|Emx1 mice, in which the corticospinal tract (CST) is genetically absent. In adult mice, we tore off right C5-C7 motor and sensory roots and re-implanted the right C6 roots. Behavioral studies showed impaired recovery of elbow flexion in Celsr3|Emx1 mice compared to controls. Five months after surgery, a reduced number of small axons, and higher G-ratio of inner to outer diameter of myelin sheaths were observed in mutant versus control mice. At early stages post-surgery, mutant mice displayed lower expression of GAP-43 in spinal cord and of myelin basic protein (MBP) in peripheral nerves than control animals. After five months, mutant animals had atrophy of the right biceps brachii, with less newly formed neuromuscular junctions (NMJs) and reduced peak-to-peak amplitudes in electromyogram (EMG), than controls. However, quite unexpectedly, a higher motoneuron survival rate was found in mutant than in control mice. Thus, following root avulsion/re-implantation, the absence of the CST is probably an important reason to hamper axonal regeneration and remyelination, as well as target re-innervation and formation of new NMJ, resulting in lower functional recovery, while fostering motoneuron survival. These results indicate that manipulation of corticospinal transmission may help improve functional recovery following BPI.
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Affiliation(s)
- Yuetong Ding
- Guangdong-Hongkong-Macau Institute of CNS Regeneration, Jinan University, Guangzhou, P.R. China
- Medical Key Laboratory of Brain Function and Diseases, Jinan University, Guangzhou, P.R. China
| | - Yibo Qu
- Guangdong-Hongkong-Macau Institute of CNS Regeneration, Jinan University, Guangzhou, P.R. China
- Medical Key Laboratory of Brain Function and Diseases, Jinan University, Guangzhou, P.R. China
| | - Jia Feng
- Guangdong-Hongkong-Macau Institute of CNS Regeneration, Jinan University, Guangzhou, P.R. China
- Medical Key Laboratory of Brain Function and Diseases, Jinan University, Guangzhou, P.R. China
| | - Meizhi Wang
- Guangdong-Hongkong-Macau Institute of CNS Regeneration, Jinan University, Guangzhou, P.R. China
- Medical Key Laboratory of Brain Function and Diseases, Jinan University, Guangzhou, P.R. China
| | - Qi Han
- Guangdong-Hongkong-Macau Institute of CNS Regeneration, Jinan University, Guangzhou, P.R. China
- Medical Key Laboratory of Brain Function and Diseases, Jinan University, Guangzhou, P.R. China
| | - Kwok-Fai So
- Guangdong-Hongkong-Macau Institute of CNS Regeneration, Jinan University, Guangzhou, P.R. China
- Medical Key Laboratory of Brain Function and Diseases, Jinan University, Guangzhou, P.R. China
- Department of Anatomy LKS Faculty of Medicine, The University of Hong Kong, Hong Kong, P.R. China
| | - Wutian Wu
- Guangdong-Hongkong-Macau Institute of CNS Regeneration, Jinan University, Guangzhou, P.R. China
- Medical Key Laboratory of Brain Function and Diseases, Jinan University, Guangzhou, P.R. China
- Department of Anatomy LKS Faculty of Medicine, The University of Hong Kong, Hong Kong, P.R. China
| | - Libing Zhou
- Guangdong-Hongkong-Macau Institute of CNS Regeneration, Jinan University, Guangzhou, P.R. China
- Medical Key Laboratory of Brain Function and Diseases, Jinan University, Guangzhou, P.R. China
- Department of Pathophysiology, School of Medicine, Jinan University, Guangzhou, P.R. China
- Co-Innovation Center of Neuroregeneration, Nantong University, Jiangsu, P.R. China
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Unraveling the secrets of white matter--bridging the gap between cellular, animal and human imaging studies. Neuroscience 2014; 276:2-13. [PMID: 25003711 PMCID: PMC4155933 DOI: 10.1016/j.neuroscience.2014.06.058] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2014] [Accepted: 06/25/2014] [Indexed: 12/20/2022]
Abstract
The CNS white matter makes up about half of the human brain, and with advances in human imaging it is increasingly becoming clear that changes in the white matter play a major role in shaping human behavior and learning. However, the mechanisms underlying these white matter changes remain poorly understood. Within this special issue of Neuroscience on white matter, recent advances in our knowledge of the function of white matter, from the molecular level to human imaging, are reviewed. Collaboration between fields is essential to understand the function of the white matter, but due to differences in methods and field-specific 'language', communication is often hindered. In this review, we try to address this hindrance by introducing the methods and providing a basic background to myelin biology and human imaging as a prelude to the other reviews within this special issue.
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The possible protective role of ginseng on the sciatic nerve neuropathy induced experimentally by acrylamide in adult male albino rat. ACTA ACUST UNITED AC 2014. [DOI: 10.1097/01.ehx.0000446580.88948.42] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Fan L, Yu Z, Li J, Dang X, Wang K. Schwann-like cells seeded in acellular nerve grafts improve nerve regeneration. BMC Musculoskelet Disord 2014; 15:165. [PMID: 24885337 PMCID: PMC4036644 DOI: 10.1186/1471-2474-15-165] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Accepted: 05/15/2014] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND This study evaluated whether Schwann-like cells (SLCs) induced from bone marrow-derived mesenchymal stem cells (BM-MSCs) transplanted into acellular nerve grafts (ANGs) could repair nerve defects compared with nerve isografts and ANGs with BM-MSCs. METHODS BM-MSCs extracted, separated and purified from the bone marrow of rats, and some of the BM-MSCs were cultured with mixed induction agents that could induce BM-MSCs into SLCs. Either SLCs or BM-MSCs were seeded onto 10-mm ANGs, and the isografts were chosen as the control. The walking-track test, tibialis anterior muscle weight measurement, electrophysiological examination, toluidine blue staining, transmission electron micrographs and immunostaining of S-100 and VEGF in these three groups were evaluated in a 10-mm rat sciatic injury-repair model. RESULTS The walking-track test, tibialis anterior muscle weight measurement and electrophysiological examination of the sciatic nerve suggested the groups of ANGs with SLCs and isografts obtained better results than the BM-MSC group (P<0.05). Meanwhile, the results of the SLCs and isograft groups were similar (P>0.05). All the histomorphometric analyses (toluidine blue staining, transmission electron micrographs and immunostaining of S-100 and VEGF) showed that there were more regenerating nerve fibers in the group of ANGs with SLCs than the BM-MSCs (P<0.05), but there was no significant difference between the SLC and isograft groups (P>0.05). CONCLUSIONS SLCs seeded in ANGs and isografts show better functional regeneration compared with BM-MSCs seeded in ANGs. Additionally, SLCs combined with ANGs present almost the same outcome as the isografts. Therefore, SLCs with ANGs can be a good choice in nerve defect repairs.
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Affiliation(s)
- Lihong Fan
- The first department of Orthopedics, the Second Affilliated Hospital of Xi’an Jiaotong University, No. 157 Xiwu Road, Xi’an, Shaanxi Province 710004, China
| | - Zefeng Yu
- The first department of Orthopedics, the Second Affilliated Hospital of Xi’an Jiaotong University, No. 157 Xiwu Road, Xi’an, Shaanxi Province 710004, China
| | - Jia Li
- The first department of Orthopedics, the Second Affilliated Hospital of Xi’an Jiaotong University, No. 157 Xiwu Road, Xi’an, Shaanxi Province 710004, China
| | - Xiaoqian Dang
- The first department of Orthopedics, the Second Affilliated Hospital of Xi’an Jiaotong University, No. 157 Xiwu Road, Xi’an, Shaanxi Province 710004, China
| | - Kunzheng Wang
- The first department of Orthopedics, the Second Affilliated Hospital of Xi’an Jiaotong University, No. 157 Xiwu Road, Xi’an, Shaanxi Province 710004, China
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243
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Liu XB, Schumann CM. Optimization of electron microscopy for human brains with long-term fixation and fixed-frozen sections. Acta Neuropathol Commun 2014; 2:42. [PMID: 24721148 PMCID: PMC4003521 DOI: 10.1186/2051-5960-2-42] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Accepted: 03/26/2014] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Abnormal connectivity across brain regions underlies many neurological disorders including multiple sclerosis, schizophrenia and autism, possibly due to atypical axonal organization within white matter. Attempts at investigating axonal organization on post-mortem human brains have been hindered by the availability of high-quality, morphologically preserved tissue, particularly for neurodevelopmental disorders such as autism. Brains are generally stored in a fixative for long periods of time (often greater than 10 years) and in many cases, already frozen and sectioned on a microtome for histology and immunohistochemistry. Here we present a method to assess the quality and quantity of axons from long-term fixed and frozen-sectioned human brain samples to demonstrate their use for electron microscopy (EM) measures of axonal ultrastructure. RESULTS Six samples were collected from white matter below the superior temporal cortex of three typically developing human brains and prepared for EM analyses. Five samples were stored in fixative for over 10 years, two of which were also flash frozen and sectioned on a freezing microtome, and one additional case was fixed for 3 years and sectioned on a freezing microtome. In all six samples, ultrastructural qualitative and quantitative analyses demonstrate that myelinated axons can be identified and counted on the EM images. Although axon density differed between brains, axonal ultrastructure and density was well preserved and did not differ within cases for fixed and frozen tissue. There was no significant difference between cases in axon myelin sheath thickness (g-ratio) or axon diameter; approximately 70% of axons were in the small (0.25 μm) to medium (0.75 μm) range. Axon diameter and g-ratio were positively correlated, indicating that larger axons may have thinner myelin sheaths. CONCLUSION The current study demonstrates that long term formalin fixed and frozen-sectioned human brain tissue can be used for ultrastructural analyses. Axon integrity is well preserved and can be quantified using the methods presented here. The ability to carry out EM on frozen sections allows for investigation of axonal organization in conjunction with other cellular and histological methods, such as immunohistochemistry and stereology, within the same brain and even within the same frozen cut section.
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244
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Statistical physics approach to quantifying differences in myelinated nerve fibers. Sci Rep 2014; 4:4511. [PMID: 24676146 PMCID: PMC3968487 DOI: 10.1038/srep04511] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Accepted: 03/12/2014] [Indexed: 11/08/2022] Open
Abstract
We present a new method to quantify differences in myelinated nerve fibers. These differences range from morphologic characteristics of individual fibers to differences in macroscopic properties of collections of fibers. Our method uses statistical physics tools to improve on traditional measures, such as fiber size and packing density. As a case study, we analyze cross–sectional electron micrographs from the fornix of young and old rhesus monkeys using a semi-automatic detection algorithm to identify and characterize myelinated axons. We then apply a feature selection approach to identify the features that best distinguish between the young and old age groups, achieving a maximum accuracy of 94% when assigning samples to their age groups. This analysis shows that the best discrimination is obtained using the combination of two features: the fraction of occupied axon area and the effective local density. The latter is a modified calculation of axon density, which reflects how closely axons are packed. Our feature analysis approach can be applied to characterize differences that result from biological processes such as aging, damage from trauma or disease or developmental differences, as well as differences between anatomical regions such as the fornix and the cingulum bundle or corpus callosum.
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245
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Early structural and functional defects in synapses and myelinated axons in stratum lacunosum moleculare in two preclinical models for tauopathy. PLoS One 2014; 9:e87605. [PMID: 24498342 PMCID: PMC3912020 DOI: 10.1371/journal.pone.0087605] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Accepted: 12/21/2013] [Indexed: 02/04/2023] Open
Abstract
The stratum lacunosum moleculare (SLM) is the connection hub between entorhinal cortex and hippocampus, two brain regions that are most vulnerable in Alzheimer's disease. We recently identified a specific synaptic deficit of Nectin-3 in transgenic models for tauopathy. Here we defined cognitive impairment and electrophysiological problems in the SLM of Tau.P301L mice, which corroborated the structural defects in synapses and dendritic spines. Reduced diffusion of DiI from the ERC to the hippocampus indicated defective myelinated axonal pathways. Ultrastructurally, myelinated axons in the temporoammonic pathway (TA) that connects ERC to CA1 were damaged in Tau.P301L mice at young age. Unexpectedly, the myelin defects were even more severe in bigenic biGT mice that co-express GSK3β with Tau.P301L in neurons. Combined, our data demonstrate that neuronal expression of protein Tau profoundly affected the functional and structural organization of the entorhinal-hippocampal complex, in particular synapses and myelinated axons in the SLM. White matter pathology deserves further attention in patients suffering from tauopathy and Alzheimer's disease.
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246
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Goodman G, Bercovich D. Electromagnetic induction between axons and their schwann cell myelin-protein sheaths. J Integr Neurosci 2014; 12:475-89. [PMID: 24372067 DOI: 10.1142/s0219635213500295] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Two concepts have long dominated vertebrate nerve electrophysiology: (a) Schwann cell-formed myelin sheaths separated by minute non-myelinated nodal gaps and spiraling around axons of peripheral motor nerves reduce current leakage during propagation of trains of axon action potentials; (b) "jumping" by action potentials between successive nodes greatly increases signal conduction velocity. Long-held and more recent assumptions and issues underlying those concepts have been obscured by research emphasis on axon-sheath biochemical symbiosis and nerve regeneration. We hypothesize: mutual electromagnetic induction in the axon-glial sheath association, is fundamental in signal conduction in peripheral and central myelinated axons, explains the g-ratio and is relevant to animal navigation.
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Affiliation(s)
- G Goodman
- Galil Genetic Analysis, Kazerin 12900, Israel
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Melbourne A, Eaton-Rosen Z, De Vita E, Bainbridge A, Cardoso MJ, Price D, Cady E, Kendall GS, Robertson NJ, Marlow N, Ourselin S. Multi-modal measurement of the myelin-to-axon diameter g-ratio in preterm-born neonates and adult controls. MEDICAL IMAGE COMPUTING AND COMPUTER-ASSISTED INTERVENTION : MICCAI ... INTERNATIONAL CONFERENCE ON MEDICAL IMAGE COMPUTING AND COMPUTER-ASSISTED INTERVENTION 2014; 17:268-75. [PMID: 25485388 DOI: 10.1007/978-3-319-10470-6_34] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Infants born prematurely are at increased risk of adverse functional outcome. The measurement of white matter tissue composition and structure can help predict functional performance and this motivates the search for new multi-modal imaging biomarkers. In this work we develop a novel combined biomarker from diffusion MRI and multi-component T2 relaxation measurements in a group of infants born very preterm and scanned between 30 and 40 weeks equivalent gestational age. We also investigate this biomarker on a group of seven adult controls, using a multi-modal joint model-fitting strategy. The proposed emergent biomarker is tentatively related to axonal energetic efficiency (in terms of axonal membrane charge storage) and conduction velocity and is thus linked to the tissue electrical properties, giving it a good theoretical justification as a predictive measurement of functional outcome.
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248
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Lundgaard I, Luzhynskaya A, Stockley JH, Wang Z, Evans KA, Swire M, Volbracht K, Gautier HOB, Franklin RJM, ffrench-Constant C, Attwell D, Káradóttir RT. Neuregulin and BDNF induce a switch to NMDA receptor-dependent myelination by oligodendrocytes. PLoS Biol 2013; 11:e1001743. [PMID: 24391468 PMCID: PMC3876980 DOI: 10.1371/journal.pbio.1001743] [Citation(s) in RCA: 239] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Accepted: 11/13/2013] [Indexed: 11/20/2022] Open
Abstract
Neuregulin switches oligodendrocytes between two modes of myelination: from a neuronal activity–independent mode to a myelin-increasing, neuronal activity–dependent, mechanism that involves glutamate release and NMDA receptor activation. Myelination is essential for rapid impulse conduction in the CNS, but what determines whether an individual axon becomes myelinated remains unknown. Here we show, using a myelinating coculture system, that there are two distinct modes of myelination, one that is independent of neuronal activity and glutamate release and another that depends on neuronal action potentials releasing glutamate to activate NMDA receptors on oligodendrocyte lineage cells. Neuregulin switches oligodendrocytes from the activity-independent to the activity-dependent mode of myelination by increasing NMDA receptor currents in oligodendrocyte lineage cells 6-fold. With neuregulin present myelination is accelerated and increased, and NMDA receptor block reduces myelination to far below its level without neuregulin. Thus, a neuregulin-controlled switch enhances the myelination of active axons. In vivo, we demonstrate that remyelination after white matter damage is NMDA receptor-dependent. These data resolve controversies over the signalling regulating myelination and suggest novel roles for neuregulin in schizophrenia and in remyelination after white matter damage. Myelination acts as an insulator for neurons and as such is essential for normal brain function, ensuring fast neuronal communication. Oligodendrocytes are the cells that wrap their membrane around nerve cell axons to form the myelin sheath that enables fast action potential propagation. However, what determines whether an individual axon becomes myelinated remains unknown. We show that there are two distinct modes of myelination: one that is independent of neuronal activity and the release of the neurotransmitter glutamate and another that depends on nerve cell action potentials releasing glutamate, which then activates a class of glutamate receptor (NMDA receptors) on oligodendrocyte lineage cells. We find that the protein neuregulin switches oligodendrocytes between these two modes of myelination; neuregulin increases oligodendrocyte lineage cells' sensitivity to glutamate by increasing the current flowing through their glutamate receptors. With neuregulin present, myelination is accelerated and increased. Blocking NMDA receptors reduces the amount of myelination to far below its level without neuregulin. Thus, a neuregulin-controlled switch enhances the myelination of active axons. We also demonstrate that remyelination after white matter damage (as occurs in diseases, such as spinal cord injury and multiple sclerosis) is NMDA receptor-dependent. These data help us understand the signalling that regulates myelination and suggest the possible involvement of neuregulin in schizophrenia and in remyelination after white matter damage.
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Affiliation(s)
- Iben Lundgaard
- Wellcome Trust–Medical Research Council (MRC) Stem Cell Institute, John van Geest Centre for Brain Repair, and Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Aryna Luzhynskaya
- Wellcome Trust–Medical Research Council (MRC) Stem Cell Institute, John van Geest Centre for Brain Repair, and Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - John H. Stockley
- Wellcome Trust–Medical Research Council (MRC) Stem Cell Institute, John van Geest Centre for Brain Repair, and Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Zhen Wang
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Kimberley A. Evans
- Wellcome Trust–Medical Research Council (MRC) Stem Cell Institute, John van Geest Centre for Brain Repair, and Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Matthew Swire
- MRC Centre for Regenerative Medicine, Centre for Multiple Sclerosis Research, University of Edinburgh, Edinburgh, United Kingdom
| | - Katrin Volbracht
- Wellcome Trust–Medical Research Council (MRC) Stem Cell Institute, John van Geest Centre for Brain Repair, and Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Hélène O. B. Gautier
- Wellcome Trust–Medical Research Council (MRC) Stem Cell Institute, John van Geest Centre for Brain Repair, and Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Robin J. M. Franklin
- Wellcome Trust–Medical Research Council (MRC) Stem Cell Institute, John van Geest Centre for Brain Repair, and Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Charles ffrench-Constant
- MRC Centre for Regenerative Medicine, Centre for Multiple Sclerosis Research, University of Edinburgh, Edinburgh, United Kingdom
| | - David Attwell
- Department of Neuroscience, Physiology & Pharmacology, University College London, London, United Kingdom
| | - Ragnhildur T. Káradóttir
- Wellcome Trust–Medical Research Council (MRC) Stem Cell Institute, John van Geest Centre for Brain Repair, and Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
- * E-mail:
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249
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A computational model coupling mechanics and electrophysiology in spinal cord injury. Biomech Model Mechanobiol 2013; 13:883-96. [PMID: 24337934 DOI: 10.1007/s10237-013-0543-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Accepted: 11/21/2013] [Indexed: 01/01/2023]
Abstract
Traumatic brain injury and spinal cord injury have recently been put under the spotlight as major causes of death and disability in the developed world. Despite the important ongoing experimental and modeling campaigns aimed at understanding the mechanics of tissue and cell damage typically observed in such events, the differentiated roles of strain, stress and their corresponding loading rates on the damage level itself remain unclear. More specifically, the direct relations between brain and spinal cord tissue or cell damage, and electrophysiological functions are still to be unraveled. Whereas mechanical modeling efforts are focusing mainly on stress distribution and mechanistic-based damage criteria, simulated function-based damage criteria are still missing. Here, we propose a new multiscale model of myelinated axon associating electrophysiological impairment to structural damage as a function of strain and strain rate. This multiscale approach provides a new framework for damage evaluation directly relating neuron mechanics and electrophysiological properties, thus providing a link between mechanical trauma and subsequent functional deficits.
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250
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Pusic AD, Kraig RP. Youth and environmental enrichment generate serum exosomes containing miR-219 that promote CNS myelination. Glia 2013; 62:284-99. [PMID: 24339157 DOI: 10.1002/glia.22606] [Citation(s) in RCA: 173] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 11/05/2013] [Accepted: 11/09/2013] [Indexed: 12/18/2022]
Abstract
Although commonly considered a disease of white matter, gray matter demyelination is increasingly recognized as an important component of multiple sclerosis (MS) pathogenesis, particularly in the secondary progressive disease phase. Extent of damage to gray matter is strongly correlated to decline in memory and cognitive dysfunction in MS patients. Aging likewise occurs with cognitive decline from myelin loss, and age-associated failure to remyelinate significantly contributes to MS progression. However, recent evidence demonstrates that parabiotic exposure of aged animals to a youthful systemic milieu can promote oligodendrocyte precursor cell (OPC) differentiation and improve remyelination. In the current study, we focus on this potential for stimulating remyelination, and show it involves serum exosomes that increase OPCs and their differentiation into mature myelin-producing cells-both under control conditions and after acute demyelination. Environmental enrichment (EE) of aging animals produced exosomes that mimicked this promyelinating effect. Additionally, stimulating OPC differentiation via exosomes derived from environmentally enriched animals is unlikely to deplete progenitors, as EE itself promotes proliferation of neural stem cells. We found that both young and EE serum-derived exosomes were enriched in miR-219, which is necessary and sufficient for production of myelinating oligodendrocytes by reducing the expression of inhibitory regulators of differentiation. Accordingly, protein transcript levels of these miR-219 target mRNAs decreased following exosome application to slice cultures. Finally, nasal administration of exosomes to aging rats also enhanced myelination. Thus, peripheral circulating cells in young or environmentally enriched animals produce exosomes that may be a useful therapy for remyelination.
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Affiliation(s)
- Aya D Pusic
- Department of Neurology, The University of Chicago, Chicago, Illinois; Committee on Neurobiology, The University of Chicago, Chicago, Illinois
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