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Tisoncik-Go J, Stokes C, Whitmore LS, Newhouse DJ, Voss K, Gustin A, Sung CJ, Smith E, Stencel-Baerenwald J, Parker E, Snyder JM, Shaw DW, Rajagopal L, Kapur RP, Adams Waldorf KM, Gale M. Disruption of myelin structure and oligodendrocyte maturation in a macaque model of congenital Zika infection. Nat Commun 2024; 15:5173. [PMID: 38890352 PMCID: PMC11189406 DOI: 10.1038/s41467-024-49524-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Accepted: 06/06/2024] [Indexed: 06/20/2024] Open
Abstract
Zika virus (ZikV) infection during pregnancy can cause congenital Zika syndrome (CZS) and neurodevelopmental delay in infants, of which the pathogenesis remains poorly understood. We utilize an established female pigtail macaque maternal-to-fetal ZikV infection/exposure model to study fetal brain pathophysiology of CZS manifesting from ZikV exposure in utero. We find prenatal ZikV exposure leads to profound disruption of fetal myelin, with extensive downregulation in gene expression for key components of oligodendrocyte maturation and myelin production. Immunohistochemical analyses reveal marked decreases in myelin basic protein intensity and myelinated fiber density in ZikV-exposed animals. At the ultrastructural level, the myelin sheath in ZikV-exposed animals shows multi-focal decompaction, occurring concomitant with dysregulation of oligodendrocyte gene expression and maturation. These findings define fetal neuropathological profiles of ZikV-linked brain injury underlying CZS resulting from ZikV exposure in utero. Because myelin is critical for cortical development, ZikV-related perturbations in oligodendrocyte function may have long-term consequences on childhood neurodevelopment, even in the absence of overt microcephaly.
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Affiliation(s)
- Jennifer Tisoncik-Go
- Center for Innate Immunity and Immune Disease, Department of Immunology, University of Washington, Seattle, WA, USA.
- Washington National Primate Research Center, University of Washington, Seattle, WA, USA.
| | - Caleb Stokes
- Center for Innate Immunity and Immune Disease, Department of Immunology, University of Washington, Seattle, WA, USA.
- Department of Pediatrics, University of Washington, Seattle, WA, USA.
| | - Leanne S Whitmore
- Center for Innate Immunity and Immune Disease, Department of Immunology, University of Washington, Seattle, WA, USA
| | - Daniel J Newhouse
- Center for Innate Immunity and Immune Disease, Department of Immunology, University of Washington, Seattle, WA, USA
| | - Kathleen Voss
- Center for Innate Immunity and Immune Disease, Department of Immunology, University of Washington, Seattle, WA, USA
| | - Andrew Gustin
- Center for Innate Immunity and Immune Disease, Department of Immunology, University of Washington, Seattle, WA, USA
| | - Cheng-Jung Sung
- Center for Innate Immunity and Immune Disease, Department of Immunology, University of Washington, Seattle, WA, USA
| | - Elise Smith
- Center for Innate Immunity and Immune Disease, Department of Immunology, University of Washington, Seattle, WA, USA
| | - Jennifer Stencel-Baerenwald
- Center for Innate Immunity and Immune Disease, Department of Immunology, University of Washington, Seattle, WA, USA
| | - Edward Parker
- Department of Ophthalmology, NEI Core for Vision Research, University of Washington, Seattle, WA, USA
| | - Jessica M Snyder
- Department of Comparative Medicine, University of Washington, Seattle, WA, USA
| | - Dennis W Shaw
- Department of Radiology, University of Washington, Seattle, WA, USA
| | - Lakshmi Rajagopal
- Department of Pediatrics, University of Washington, Seattle, WA, USA
- Department of Global Health, University of Washington, Seattle, WA, USA
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Raj P Kapur
- Department of Pathology, University of Washington, Seattle, WA, USA
- Department of Pathology, Seattle Children's Hospital, Seattle, WA, USA
| | - Kristina M Adams Waldorf
- Department of Global Health, University of Washington, Seattle, WA, USA
- Department of Obstetrics & Gynecology, University of Washington, Seattle, WA, USA
| | - Michael Gale
- Center for Innate Immunity and Immune Disease, Department of Immunology, University of Washington, Seattle, WA, USA.
- Washington National Primate Research Center, University of Washington, Seattle, WA, USA.
- Department of Global Health, University of Washington, Seattle, WA, USA.
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Ancău M, Tanti GK, Butenschoen VM, Gempt J, Yakushev I, Nekolla S, Mühlau M, Scheunemann C, Heininger S, Löwe B, Löwe E, Baer S, Fischer J, Reiser J, Ayachit SS, Liesche-Starnecker F, Schlegel J, Matiasek K, Schifferer M, Kirschke JS, Misgeld T, Lueth T, Hemmer B. Validating a minipig model of reversible cerebral demyelination using human diagnostic modalities and electron microscopy. EBioMedicine 2024; 100:104982. [PMID: 38306899 PMCID: PMC10850420 DOI: 10.1016/j.ebiom.2024.104982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Revised: 01/11/2024] [Accepted: 01/12/2024] [Indexed: 02/04/2024] Open
Abstract
BACKGROUND Inflammatory demyelinating diseases of the central nervous system, such as multiple sclerosis, are significant sources of morbidity in young adults despite therapeutic advances. Current murine models of remyelination have limited applicability due to the low white matter content of their brains, which restricts the spatial resolution of diagnostic imaging. Large animal models might be more suitable but pose significant technological, ethical and logistical challenges. METHODS We induced targeted cerebral demyelinating lesions by serially repeated injections of lysophosphatidylcholine in the minipig brain. Lesions were amenable to follow-up using the same clinical imaging modalities (3T magnetic resonance imaging, 11C-PIB positron emission tomography) and standard histopathology protocols as for human diagnostics (myelin, glia and neuronal cell markers), as well as electron microscopy (EM), to compare against biopsy data from two patients. FINDINGS We demonstrate controlled, clinically unapparent, reversible and multimodally trackable brain white matter demyelination in a large animal model. De-/remyelination dynamics were slower than reported for rodent models and paralleled by a degree of secondary axonal pathology. Regression modelling of ultrastructural parameters (g-ratio, axon thickness) predicted EM features of cerebral de- and remyelination in human data. INTERPRETATION We validated our minipig model of demyelinating brain diseases by employing human diagnostic tools and comparing it with biopsy data from patients with cerebral demyelination. FUNDING This work was supported by the DFG under Germany's Excellence Strategy within the framework of the Munich Cluster for Systems Neurology (EXC 2145 SyNergy, ID 390857198) and TRR 274/1 2020, 408885537 (projects B03 and Z01).
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Affiliation(s)
- Mihai Ancău
- Department of Neurology, Klinikum Rechts der Isar, School of Medicine and Health, Technical University of Munich, Munich, Germany; Munich Cluster for Systems Neurology (SyNergy), Munich, Germany; Institute of Neuronal Cell Biology, School of Medicine and Health, Technical University of Munich, Munich, Germany
| | - Goutam Kumar Tanti
- Department of Neurology, Klinikum Rechts der Isar, School of Medicine and Health, Technical University of Munich, Munich, Germany
| | - Vicki Marie Butenschoen
- Department of Neurosurgery, Klinikum Rechts der Isar, School of Medicine and Health, Technical University of Munich, Germany
| | - Jens Gempt
- Department of Neurosurgery, Klinikum Rechts der Isar, School of Medicine and Health, Technical University of Munich, Germany; Department of Neurosurgery, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Igor Yakushev
- Department of Nuclear Medicine, Klinikum Rechts der Isar, School of Medicine and Health, Technical University of Munich, Germany
| | - Stephan Nekolla
- Department of Nuclear Medicine, Klinikum Rechts der Isar, School of Medicine and Health, Technical University of Munich, Germany
| | - Mark Mühlau
- Department of Neurology, Klinikum Rechts der Isar, School of Medicine and Health, Technical University of Munich, Munich, Germany
| | - Christian Scheunemann
- Institute of Micro Technology and Medical Device Technology, Technical University of Munich, Garching, Germany; Ergosurg GmbH, Ismaning, Germany
| | - Sebastian Heininger
- Institute of Micro Technology and Medical Device Technology, Technical University of Munich, Garching, Germany; Ergosurg GmbH, Ismaning, Germany
| | - Benjamin Löwe
- Institute of Micro Technology and Medical Device Technology, Technical University of Munich, Garching, Germany; Ergosurg GmbH, Ismaning, Germany
| | - Erik Löwe
- Institute of Micro Technology and Medical Device Technology, Technical University of Munich, Garching, Germany; Ergosurg GmbH, Ismaning, Germany
| | - Silke Baer
- Centre for Preclinical Research, Department of Veterinary Medicine, Technical University of Munich, Munich, Germany
| | - Johannes Fischer
- Centre for Preclinical Research, Department of Veterinary Medicine, Technical University of Munich, Munich, Germany
| | - Judith Reiser
- Centre for Preclinical Research, Department of Veterinary Medicine, Technical University of Munich, Munich, Germany
| | - Sai S Ayachit
- Department of Neurology, Klinikum Rechts der Isar, School of Medicine and Health, Technical University of Munich, Munich, Germany; Graduate School of Systemic Neurosciences, Ludwig Maximilian University of Munich, Germany
| | - Friederike Liesche-Starnecker
- Department of Neuropathology, Institute of Pathology, Technical University of Munich School of Medicine, Munich, Germany; Medical Faculty, Institute of Pathology and Molecular Diagnostics, University of Augsburg, Augsburg, Germany
| | - Jürgen Schlegel
- Department of Neuropathology, Institute of Pathology, Technical University of Munich School of Medicine, Munich, Germany
| | - Kaspar Matiasek
- Clinical and Comparative Neuropathology, Centre for Clinical Veterinary Medicine, Ludwig-Maximilians-University, Munich, Germany
| | - Martina Schifferer
- Munich Cluster for Systems Neurology (SyNergy), Munich, Germany; German Center for Neurodegenerative Diseases (DZNE), Munich, Germany
| | - Jan S Kirschke
- Department of Neuroradiology, Klinikum Rechts der Isar, School of Medicine and Health, Technical University of Munich, Germany
| | - Thomas Misgeld
- Munich Cluster for Systems Neurology (SyNergy), Munich, Germany; German Center for Neurodegenerative Diseases (DZNE), Munich, Germany; Institute of Neuronal Cell Biology, School of Medicine and Health, Technical University of Munich, Munich, Germany
| | - Tim Lueth
- Institute of Micro Technology and Medical Device Technology, Technical University of Munich, Garching, Germany; Ergosurg GmbH, Ismaning, Germany
| | - Bernhard Hemmer
- Department of Neurology, Klinikum Rechts der Isar, School of Medicine and Health, Technical University of Munich, Munich, Germany; Munich Cluster for Systems Neurology (SyNergy), Munich, Germany.
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Pollock NM, Fernandes JP, Woodfield J, Moussa E, Hlavay B, Branton WG, Wuest M, Mohammadzadeh N, Schmitt L, Plemel JR, Julien O, Wuest F, Power C. Gasdermin D activation in oligodendrocytes and microglia drives inflammatory demyelination in progressive multiple sclerosis. Brain Behav Immun 2024; 115:374-393. [PMID: 37914099 DOI: 10.1016/j.bbi.2023.10.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 10/20/2023] [Accepted: 10/22/2023] [Indexed: 11/03/2023] Open
Abstract
Neuroinflammation coupled with demyelination and neuro-axonal damage in the central nervous system (CNS) contribute to disease advancement in progressive multiple sclerosis (P-MS). Inflammasome activation accompanied by proteolytic cleavage of gasdermin D (GSDMD) results in cellular hyperactivation and lytic death. Using multiple experimental platforms, we investigated the actions of GSDMD within the CNS and its contributions to P-MS. Brain tissues from persons with P-MS showed significantly increased expression of GSDMD, NINJ1, IL-1β, and -18 within chronic active demyelinating lesions compared to MS normal appearing white matter and nonMS (control) white matter. Conditioned media (CM) from stimulated GSDMD+/+ human macrophages caused significantly greater cytotoxicity of oligodendroglial and neuronal cells, compared to CM from GSDMD-/- macrophages. Oligodendrocytes and CNS macrophages displayed increased Gsdmd immunoreactivity in the central corpus callosum (CCC) of cuprizone (CPZ)-exposed Gsdmd+/+ mice, associated with greater demyelination and reduced oligodendrocyte precursor cell proliferation, compared to CPZ-exposed Gsdmd-/- animals. CPZ-exposed Gsdmd+/+ mice exhibited significantly increased G-ratios and reduced axonal densities in the CCC compared to CPZ-exposed Gsdmd-/- mice. Proteomic analyses revealed increased brain complement C1q proteins and hexokinases in CPZ-exposed Gsdmd-/- animals. [18F]FDG PET imaging showed increased glucose metabolism in the hippocampus and whole brain with intact neurobehavioral performance in Gsdmd-/- animals after CPZ exposure. GSDMD activation in CNS macrophages and oligodendrocytes contributes to inflammatory demyelination and neuroaxonal injury, offering mechanistic and potential therapeutic insights into P-MS pathogenesis.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Laura Schmitt
- Department of Laboratory Medicine & Pathology, University of Alberta, Edmonton AB, Canada.
| | | | | | | | - Christopher Power
- Department of Medicine (Neurology), Canada; Department of Medical Microbiology & Immunology, Canada.
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4
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Tisoncik-Go J, Stokes C, Whitmore LS, Newhouse DJ, Voss K, Gustin A, Sung CJ, Smith E, Stencel-Baerenwald J, Parker E, Snyder JM, Shaw DW, Rajagopal L, Kapur RP, Waldorf KA, Gale M. Disruption of myelin structure and oligodendrocyte maturation in a pigtail macaque model of congenital Zika infection. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.11.561759. [PMID: 37873381 PMCID: PMC10592731 DOI: 10.1101/2023.10.11.561759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Zika virus (ZikV) infection during pregnancy can cause congenital Zika syndrome (CZS) and neurodevelopmental delay in non-microcephalic infants, of which the pathogenesis remains poorly understood. We utilized an established pigtail macaque maternal-to-fetal ZikV infection/exposure model to study fetal brain pathophysiology of CZS manifesting from ZikV exposure in utero. We found prenatal ZikV exposure led to profound disruption of fetal myelin, with extensive downregulation in gene expression for key components of oligodendrocyte maturation and myelin production. Immunohistochemical analyses revealed marked decreases in myelin basic protein intensity and myelinated fiber density in ZikV-exposed animals. At the ultrastructural level, the myelin sheath in ZikV-exposed animals showed multi-focal decompaction consistent with perturbation or remodeling of previously formed myelin, occurring concomitant with dysregulation of oligodendrocyte gene expression and maturation. These findings define fetal neuropathological profiles of ZikV-linked brain injury underlying CZS resulting from ZikV exposure in utero. Because myelin is critical for cortical development, ZikV-related perturbations in oligodendrocyte function may have long-term consequences on childhood neurodevelopment, even in the absence of overt microcephaly.
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Affiliation(s)
- Jennifer Tisoncik-Go
- Center for Innate Immunity and Immune Disease, Department of Immunology, University of Washington, Seattle, Washington, USA
| | - Caleb Stokes
- Center for Innate Immunity and Immune Disease, Department of Immunology, University of Washington, Seattle, Washington, USA
- Department of Pediatrics, University of Washington, Seattle, Washington, USA
| | - Leanne S Whitmore
- Center for Innate Immunity and Immune Disease, Department of Immunology, University of Washington, Seattle, Washington, USA
| | - Daniel J Newhouse
- Center for Innate Immunity and Immune Disease, Department of Immunology, University of Washington, Seattle, Washington, USA
| | - Kathleen Voss
- Center for Innate Immunity and Immune Disease, Department of Immunology, University of Washington, Seattle, Washington, USA
| | - Andrew Gustin
- Center for Innate Immunity and Immune Disease, Department of Immunology, University of Washington, Seattle, Washington, USA
| | - Cheng-Jung Sung
- Center for Innate Immunity and Immune Disease, Department of Immunology, University of Washington, Seattle, Washington, USA
| | - Elise Smith
- Center for Innate Immunity and Immune Disease, Department of Immunology, University of Washington, Seattle, Washington, USA
| | - Jennifer Stencel-Baerenwald
- Center for Innate Immunity and Immune Disease, Department of Immunology, University of Washington, Seattle, Washington, USA
| | - Edward Parker
- Department of Ophthalmology, NEI Core for Vision Research, University of Washington, Seattle, Washington, USA
| | - Jessica M Snyder
- Department of Comparative Medicine, University of Washington, Seattle, Washington, USA
| | - Dennis W Shaw
- Department of Radiology, University of Washington, Seattle Washington, USA
| | - Lakshmi Rajagopal
- Department of Pediatrics, University of Washington, Seattle, Washington, USA
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, Washington, USA
- Department of Global Health, University of Washington, Seattle, Washington, USA
| | - Raj P Kapur
- Department of Pathology, University of Washington, Seattle, Washington, USA
- Department of Pathology, Seattle Children's Hospital, Seattle, Washington, USA
| | - Kristina Adams Waldorf
- Department of Global Health, University of Washington, Seattle, Washington, USA
- Department of Obstetrics & Gynecology, University of Washington, Seattle, Washington, USA
- Sahlgrenska Academy, Gothenburg University, Gothenburg, Sweden
| | - Michael Gale
- Center for Innate Immunity and Immune Disease, Department of Immunology, University of Washington, Seattle, Washington, USA
- Department of Global Health, University of Washington, Seattle, Washington, USA
- Department of Obstetrics & Gynecology, University of Washington, Seattle, Washington, USA
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5
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Drobyshevsky A, Synowiec S, Goussakov I, Lu J, Gascoigne D, Aksenov DP, Yarnykh V. Temporal trajectories of normal myelination and axonal development assessed by quantitative macromolecular and diffusion MRI: Ultrastructural and immunochemical validation in a rabbit model. Neuroimage 2023; 270:119974. [PMID: 36848973 PMCID: PMC10103444 DOI: 10.1016/j.neuroimage.2023.119974] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 02/15/2023] [Accepted: 02/22/2023] [Indexed: 02/27/2023] Open
Abstract
INTRODUCTION Quantitative and non-invasive measures of brain myelination and maturation during development are of great importance to both clinical and translational research communities. While the metrics derived from diffusion tensor imaging, are sensitive to developmental changes and some pathologies, they remain difficult to relate to the actual microstructure of the brain tissue. The advent of advanced model-based microstructural metrics requires histological validation. The purpose of the study was to validate novel, model-based MRI techniques, such as macromolecular proton fraction mapping (MPF) and neurite orientation and dispersion indexing (NODDI), against histologically derived indexes of myelination and microstructural maturation at various stages of development. METHODS New Zealand White rabbit kits underwent serial in-vivo MRI examination at postnatal days 1, 5, 11, 18, and 25, and as adults. Multi-shell, diffusion-weighted experiments were processed to fit NODDI model to obtain estimates, intracellular volume fraction (ICVF) and orientation dispersion index (ODI). Macromolecular proton fraction (MPF) maps were obtained from three source (MT-, PD-, and T1-weighted) images. After MRI sessions, a subset of animals was euthanized and regional samples of gray and white matter were taken for western blot analysis, to determine myelin basic protein (MBP), and electron microscopy, to estimate axonal, myelin fractions and g-ratio. RESULTS MPF of white matter regions showed a period of fast growth between P5 and P11 in the internal capsule, with a later onset in the corpus callosum. This MPF trajectory was in agreement with levels of myelination in the corresponding brain region, as assessed by western blot and electron microscopy. In the cortex, the greatest increase of MPF occurred between P18 and P26. In contrast, myelin, according to MBP western blot, saw the largest hike between P5 and P11 in the sensorimotor cortex and between P11 and P18 in the frontal cortex, which then seemingly plateaued after P11 and P18 respectively. G-ratio by MRI markers decreased with age in the white matter. However, electron microscopy suggest a relatively stable g-ratio throughout development. CONCLUSION Developmental trajectories of MPF accurately reflected regional differences of myelination rate in different cortical regions and white matter tracts. MRI-derived estimation of g-ratio was inaccurate during early development, likely due to the overestimation of axonal volume fraction by NODDI due to the presence of a large proportion of unmyelinated axons.
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Affiliation(s)
- Alexander Drobyshevsky
- Department of Pediatrics, NorthShore University HealthSystem Research Institute, Evanston, IL, USA.
| | - Sylvia Synowiec
- Department of Pediatrics, NorthShore University HealthSystem Research Institute, Evanston, IL, USA
| | - Ivan Goussakov
- Department of Pediatrics, NorthShore University HealthSystem Research Institute, Evanston, IL, USA
| | - Jing Lu
- Department of Pediatrics, University of Chicago, Chicago, IL, USA
| | - David Gascoigne
- Center for Basic MR Research, NorthShore University HealthSystem Research Institute, Evanston, IL, USA
| | - Daniil P Aksenov
- Center for Basic MR Research, NorthShore University HealthSystem Research Institute, Evanston, IL, USA
| | - Vasily Yarnykh
- Department of Radiology, University of Washington, Seattle, WA, USA
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6
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Mapping myelin in white matter with T1-weighted/T2-weighted maps: discrepancy with histology and other myelin MRI measures. Brain Struct Funct 2023; 228:525-535. [PMID: 36692695 PMCID: PMC9944377 DOI: 10.1007/s00429-022-02600-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 11/18/2022] [Indexed: 01/25/2023]
Abstract
The ratio of T1-weighted/T2-weighted magnetic resonance images (T1w/T2w MRI) has been successfully applied at the cortical level since 2011 and is now one of the most used myelin mapping methods. However, no reports have explored the histological validity of T1w/T2w myelin mapping in white matter. Here we compare T1w/T2w with ex vivo postmortem histology and in vivo MRI methods, namely quantitative susceptibility mapping (QSM) and multi-echo T2 myelin water fraction (MWF) mapping techniques. We report a discrepancy between T1w/T2w myelin maps of the human corpus callosum and the histology and analyse the putative causes behind such discrepancy. T1w/T2w does not positively correlate with Luxol Fast Blue (LFB)-Optical Density but shows a weak to moderate, yet significant, negative correlation. On the contrary, MWF is strongly and positively correlated with LFB, whereas T1w/T2w and MWF maps are weakly negatively correlated. The discrepancy between T1w/T2w MRI maps, MWF and histological myelin maps suggests caution in using T1w/T2w as a white matter mapping method at the callosal level. While T1w/T2w imaging may correlate with myelin content at the cortical level, it is not a specific method to map myelin density in white matter.
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7
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van den Bosch AMR, Hümmert S, Steyer A, Ruhwedel T, Hamann J, Smolders J, Nave KA, Stadelmann C, Kole MHP, Möbius W, Huitinga I. Ultrastructural Axon-Myelin Unit Alterations in Multiple Sclerosis Correlate with Inflammation. Ann Neurol 2022; 93:856-870. [PMID: 36565265 DOI: 10.1002/ana.26585] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 12/13/2022] [Accepted: 12/17/2022] [Indexed: 12/25/2022]
Abstract
OBJECTIVE Changes in the normal-appearing white matter (NAWM) in multiple sclerosis (MS) may contribute to disease progression. Here, we systematically quantified ultrastructural and subcellular characteristics of the axon-myelin unit in MS NAWM and determined how this correlates with low-grade inflammation. METHODS Human brain tissue obtained with short postmortem delay and fixation at autopsy enables systematic quantification of ultrastructural characteristics. In this study, we performed high-resolution immunohis tochemistry and quantitative transmission electron microscopy to study inflammation and ultrastructural characteristics of the axon-myelin unit in MS NAWM (n = 8) and control white matter (WM) in the optic nerve. RESULTS In the MS NAWM, there were more activated and phagocytic microglia cells (HLA+ P2RY12- and Iba1+ CD68+ ) and more T cells (CD3+ ) compared to control WM, mainly located in the perivascular space. In MS NAWM compared to control WM, there were, as expected, longer paranodes and juxtaparanodes and larger overlap between paranodes and juxtaparanodes. There was less compact myelin wrapping, a lower g-ratio, and a higher frequency of axonal mitochondria. Changes in myelin and axonal mitochondrial frequency correlated positively with the number of active and phagocytic microglia and lymphocytes in the optic nerve. INTERPRETATION These data suggest that in MS NAWM myelin detachment and uncompact myelin wrapping occurs, potassium channels are unmasked at the nodes of Ranvier, and axonal energy demand is increased, or mitochondrial transport is stagnated, accompanied by increased presence of activated and phagocytic microglia and T cells. These subclinical alterations to the axon-myelin unit in MS NAWM may contribute to disease progression. ANN NEUROL 2023.
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Affiliation(s)
- Aletta M R van den Bosch
- Department of Neuroimmunology, Netherlands Institute for Neuroscience, Royal Netherlands Academy for Arts and Sciences, Amsterdam, the Netherlands
| | - Sophie Hümmert
- Department of Neurogenetics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Anna Steyer
- Department of Neurogenetics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Torben Ruhwedel
- Department of Neurogenetics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Jörg Hamann
- Department of Neuroimmunology, Netherlands Institute for Neuroscience, Royal Netherlands Academy for Arts and Sciences, Amsterdam, the Netherlands.,Department of Experimental Immunology, Amsterdam Institute for Infection and Immunity, Amsterdam University Medical Centers, Amsterdam, the Netherlands
| | - Joost Smolders
- Department of Neuroimmunology, Netherlands Institute for Neuroscience, Royal Netherlands Academy for Arts and Sciences, Amsterdam, the Netherlands.,Department of Neurology and Immunology, Multiple Sclerosis Center ErasMS, Erasmus Medical Center, Rotterdam, the Netherlands
| | - Klaus-Armin Nave
- Department of Neurogenetics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Christine Stadelmann
- Department of Neuropathology, University Medical Center Göttingen, Göttingen, Germany
| | - Maarten H P Kole
- Department of Axonal Signaling, Netherlands Institute for Neuroscience, Royal Netherlands Academy for Arts and Sciences, Amsterdam, the Netherlands.,Cell Biology, Neurobiology, and Biophysics, Department of Biology, Faculty of Science, University of Utrecht, Utrecht, the Netherlands
| | - Wiebke Möbius
- Department of Neurogenetics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Inge Huitinga
- Department of Neuroimmunology, Netherlands Institute for Neuroscience, Royal Netherlands Academy for Arts and Sciences, Amsterdam, the Netherlands.,Center for Neuroscience, Swammerdam Institute for Life Sciences, Faculty of Science, University of Amsterdam, Amsterdam, the Netherlands
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8
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Liu Y, Yue W, Yu S, Zhou T, Zhang Y, Zhu R, Song B, Guo T, Liu F, Huang Y, Wu T, Wang H. A physical perspective to understand myelin II: The physical origin of myelin development. Front Neurosci 2022; 16:951998. [PMID: 36263368 PMCID: PMC9574017 DOI: 10.3389/fnins.2022.951998] [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] [Received: 05/24/2022] [Accepted: 09/05/2022] [Indexed: 11/13/2022] Open
Abstract
The physical principle of myelin development is obtained from our previous study by explaining Peter’s quadrant mystery: an externally applied negative and positive E-field can promote and inhibit the growth of the inner tongue of the myelin sheath, respectively. In this study, this principle is considered as a fundamental hypothesis, named Hypothesis-E, to explain more phenomena about myelin development systematically. Specifically, the g-ratio and the fate of the Schwann cell’s differentiation are explained in terms of the E-field. Moreover, an experiment is proposed to validate this theory.
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Affiliation(s)
- Yonghong Liu
- Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology (SIAT), Chinese Academy of Sciences (CAS), Shenzhen, China
| | - Wenji Yue
- Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology (SIAT), Chinese Academy of Sciences (CAS), Shenzhen, China
| | - Shoujun Yu
- Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology (SIAT), Chinese Academy of Sciences (CAS), Shenzhen, China
| | - Tian Zhou
- Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology (SIAT), Chinese Academy of Sciences (CAS), Shenzhen, China
| | - Yapeng Zhang
- Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology (SIAT), Chinese Academy of Sciences (CAS), Shenzhen, China
| | - Ran Zhu
- Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology (SIAT), Chinese Academy of Sciences (CAS), Shenzhen, China
| | - Bing Song
- Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology (SIAT), Chinese Academy of Sciences (CAS), Shenzhen, China
| | - Tianruo Guo
- Key Laboratory of Health Bioinformatics, Chinese Academy of Sciences, Shenzhen, China
| | - Fenglin Liu
- Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology (SIAT), Chinese Academy of Sciences (CAS), Shenzhen, China
| | - Yubin Huang
- Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology (SIAT), Chinese Academy of Sciences (CAS), Shenzhen, China
| | - Tianzhun Wu
- Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology (SIAT), Chinese Academy of Sciences (CAS), Shenzhen, China
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, NSW, Australia
- *Correspondence: Tianzhun Wu,
| | - Hao Wang
- Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology (SIAT), Chinese Academy of Sciences (CAS), Shenzhen, China
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, NSW, Australia
- Hao Wang,
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9
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Watson CM, Sherwood CC, Phillips KA. Myelin characteristics of the corpus callosum in capuchin monkeys (Sapajus [Cebus] apella) across the lifespan. Sci Rep 2022; 12:8786. [PMID: 35610294 PMCID: PMC9130294 DOI: 10.1038/s41598-022-12893-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Accepted: 05/18/2022] [Indexed: 11/09/2022] Open
Abstract
The midsagittal area of the corpus callosum (CC) is frequently studied in relation to brain development, connectivity, and function. Here we quantify myelin characteristics from electron microscopy to understand more fully differential patterns of white matter development occurring within the CC. We subdivided midsagittal regions of the CC into: I-rostrum and genu, II-rostral body, III-anterior midbody, IV-posterior midbody, and V-isthmus and splenium. The sample represented capuchin monkeys ranging in age from 2 weeks to 35 years (Sapajus [Cebus] apella, n = 8). Measurements of myelin thickness, myelin fraction, and g-ratio were obtained in a systematic random fashion. We hypothesized there would be a period of rapid myelin growth within the CC in early development. Using a locally weighted regression analysis (LOESS), we found regional differences in myelin characteristics, with posterior regions showing more rapid increases in myelin thickness and sharper decreases in g-ratio in early development. The most anterior region showed the most sustained growth in myelin thickness. For all regions over the lifespan, myelin fraction increased, plateaued, and decreased. These results suggest differential patterns of nonlinear myelin growth occur early in development and well into adulthood in the CC of capuchin monkeys.
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Affiliation(s)
- Chase M Watson
- Department of Psychology and Neuroscience Program, Trinity University, San Antonio, TX, USA
| | - Chet C Sherwood
- Department of Anthropology and Center for the Advanced Study of Human Paleobiology, The George Washington University, Washington, DC, USA
| | - Kimberley A Phillips
- Department of Psychology and Neuroscience Program, Trinity University, San Antonio, TX, USA.
- Southwest National Primate Research Center, Texas Biomedical Research Institute, San Antonio, TX, USA.
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10
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Hori M, Maekawa T, Kamiya K, Hagiwara A, Goto M, Takemura MY, Fujita S, Andica C, Kamagata K, Cohen-Adad J, Aoki S. Advanced Diffusion MR Imaging for Multiple Sclerosis in the Brain and Spinal Cord. Magn Reson Med Sci 2022; 21:58-70. [PMID: 35173096 PMCID: PMC9199983 DOI: 10.2463/mrms.rev.2021-0091] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Diffusion tensor imaging (DTI) has been established its usefulness in evaluating normal-appearing white matter (NAWM) and other lesions that are difficult to evaluate with routine clinical MRI in the evaluation of the brain and spinal cord lesions in multiple sclerosis (MS), a demyelinating disease. With the recent advances in the software and hardware of MRI systems, increasingly complex and sophisticated MRI and analysis methods, such as q-space imaging, diffusional kurtosis imaging, neurite orientation dispersion and density imaging, white matter tract integrity, and multiple diffusion encoding, referred to as advanced diffusion MRI, have been proposed. These are capable of capturing in vivo microstructural changes in the brain and spinal cord in normal and pathological states in greater detail than DTI. This paper reviews the current status of recent advanced diffusion MRI for assessing MS in vivo as part of an issue celebrating two decades of magnetic resonance in medical sciences (MRMS), an official journal of the Japanese Society of Magnetic Resonance in Medicine.
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Affiliation(s)
- Masaaki Hori
- Department of Radiology, Toho University Omori Medical Center.,Department of Radiology, Juntendo University School of Medicine
| | - Tomoko Maekawa
- Department of Radiology, Juntendo University School of Medicine
| | - Kouhei Kamiya
- Department of Radiology, Toho University Omori Medical Center.,Department of Radiology, Juntendo University School of Medicine
| | | | - Masami Goto
- Department of Radiological Technology, Faculty of Health Science, Juntendo University
| | | | - Shohei Fujita
- Department of Radiology, Juntendo University School of Medicine
| | | | - Koji Kamagata
- Department of Radiology, Juntendo University School of Medicine
| | | | - Shigeki Aoki
- Department of Radiology, Juntendo University School of Medicine
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11
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Lazari A, Lipp I. Can MRI measure myelin? Systematic review, qualitative assessment, and meta-analysis of studies validating microstructural imaging with myelin histology. Neuroimage 2021; 230:117744. [PMID: 33524576 PMCID: PMC8063174 DOI: 10.1016/j.neuroimage.2021.117744] [Citation(s) in RCA: 74] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 01/05/2021] [Accepted: 01/09/2021] [Indexed: 12/16/2022] Open
Abstract
Recent years have seen an increased understanding of the importance of myelination in healthy brain function and neuropsychiatric diseases. Non-invasive microstructural magnetic resonance imaging (MRI) holds the potential to expand and translate these insights to basic and clinical human research, but the sensitivity and specificity of different MR markers to myelination is a subject of debate. To consolidate current knowledge on the topic, we perform a systematic review and meta-analysis of studies that validate microstructural imaging by combining it with myelin histology. We find meta-analytic evidence for correlations between various myelin histology metrics and markers from different MRI modalities, including fractional anisotropy, radial diffusivity, macromolecular pool, magnetization transfer ratio, susceptibility and longitudinal relaxation rate, but not mean diffusivity. Meta-analytic correlation effect sizes range widely, between R2 = 0.26 and R2 = 0.82. However, formal comparisons between MRI-based myelin markers are limited by methodological variability, inconsistent reporting and potential for publication bias, thus preventing the establishment of a single most sensitive strategy to measure myelin with MRI. To facilitate further progress, we provide a detailed characterisation of the evaluated studies as an online resource. We also share a set of 12 recommendations for future studies validating putative MR-based myelin markers and deploying them in vivo in humans.
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Affiliation(s)
- Alberto Lazari
- Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, UK
| | - Ilona Lipp
- Department of Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany.
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12
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Mu J, Wang T, Li M, Guan T, Guo Y, Zhang X, Zhang G, Kong J. Ketogenic diet protects myelin and axons in diffuse axonal injury. Nutr Neurosci 2021; 25:1534-1547. [PMID: 33487123 DOI: 10.1080/1028415x.2021.1875300] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
BACKGROUND Ketogenic diet (KD) has been identified as a potential therapy to enhance recovery after traumatic brain injury (TBI). Diffuse axonal injury (DAI) is a common type of traumatic brain injury that is characterized by delayed axonal disconnection. Previous studies showed that demyelination resulting from oligodendrocyte damage contributes to axonal degeneration in DAI. AIM The present study tests a hypothesis that ketone bodies from the ketogenic diet confers protection for myelin and attenuates degeneration of demyelinated axon in DAI. METHODS A modified Marmarou's model of DAI was induced in adult rats. The DAI rats were fed with KD and analyzed with western blot, transmission electron microscope, ELISA test and immunohistochemistry. Meanwhile, a co-culture of primary oligodendrocytes and neurons was treated with ketone body β-hydroxybutryate (βHB) to test for its effects on the myelin-axon unit. RESULTS Here we report that rats fed with KD showed an increased fatty acid metabolism and ketonemia. This dietary intervention significantly reduced demyelination and attenuated axonal damage in rats following DAI, likely through inhibition of DAI-induced excessive mitochondrial fission and promoting mitochondrial fusion. In an in vitro model of myelination, the ketone body βHB increased myelination significantly and reduced axonal degeneration induced by glucose deprivation (GD). βHB robustly increased cell viability, inhibited GD-induced collapse of mitochondrial membrane potential and attenuated death of oligodendrocytes. CONCLUSION Ketone bodies protect myelin-forming oligodendrocytes and reduce axonal damage. Ketogenic diet maybe a promising therapy for DAI.
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Affiliation(s)
- Jiao Mu
- Department of Forensic Medicine, Hebei North University, Zhangjiakou, People's Republic of China.,Department of Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing, People's Republic of China.,Department of Human Anatomy and Cell Science, Rady Faculty of Health Sciences, Max Rady College of Medicine, University of Manitoba, Winnipeg, Canada
| | - Tingting Wang
- Department of Forensic Medicine, Hebei North University, Zhangjiakou, People's Republic of China
| | - Meiyu Li
- Department of Forensic Medicine, Hebei North University, Zhangjiakou, People's Republic of China
| | - Teng Guan
- Department of Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing, People's Republic of China
| | - Ying Guo
- Department of Forensic Medicine, Hebei North University, Zhangjiakou, People's Republic of China.,Department of Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing, People's Republic of China
| | - Xiaoli Zhang
- Department of Life Science Research Center, Hebei North University, Zhangjiakou, People's Republic of China
| | - Guohui Zhang
- Department of Forensic Medicine, Hebei North University, Zhangjiakou, People's Republic of China
| | - Jiming Kong
- Department of Forensic Medicine, Hebei North University, Zhangjiakou, People's Republic of China.,Department of Human Anatomy and Cell Science, Rady Faculty of Health Sciences, Max Rady College of Medicine, University of Manitoba, Winnipeg, Canada
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13
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Andersson M, Kjer HM, Rafael-Patino J, Pacureanu A, Pakkenberg B, Thiran JP, Ptito M, Bech M, Bjorholm Dahl A, Andersen Dahl V, Dyrby TB. Axon morphology is modulated by the local environment and impacts the noninvasive investigation of its structure-function relationship. Proc Natl Acad Sci U S A 2020; 117:33649-33659. [PMID: 33376224 PMCID: PMC7777205 DOI: 10.1073/pnas.2012533117] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Axonal conduction velocity, which ensures efficient function of the brain network, is related to axon diameter. Noninvasive, in vivo axon diameter estimates can be made with diffusion magnetic resonance imaging, but the technique requires three-dimensional (3D) validation. Here, high-resolution, 3D synchrotron X-ray nano-holotomography images of white matter samples from the corpus callosum of a monkey brain reveal that blood vessels, cells, and vacuoles affect axonal diameter and trajectory. Within single axons, we find that the variation in diameter and conduction velocity correlates with the mean diameter, contesting the value of precise diameter determination in larger axons. These complex 3D axon morphologies drive previously reported 2D trends in axon diameter and g-ratio. Furthermore, we find that these morphologies bias the estimates of axon diameter with diffusion magnetic resonance imaging and, ultimately, impact the investigation and formulation of the axon structure-function relationship.
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Affiliation(s)
- Mariam Andersson
- Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, 2650 Hvidovre, Denmark;
- Department of Applied Mathematics and Computer Science, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
| | - Hans Martin Kjer
- Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, 2650 Hvidovre, Denmark
- Department of Applied Mathematics and Computer Science, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
| | - Jonathan Rafael-Patino
- Signal Processing Laboratory (LTS5), École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | | | - Bente Pakkenberg
- Research Laboratory for Stereology and Neuroscience, Copenhagen University Hospital, Bispebjerg, 2400 Copenhagen, Denmark
| | - Jean-Philippe Thiran
- Signal Processing Laboratory (LTS5), École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
- Radiology Department, Centre Hospitalier Universitaire Vaudois and University of Lausanne, 1011 Lausanne, Switzerland
- Center for Biomedical Imaging, 1015 Lausanne, Switzerland
| | - Maurice Ptito
- School of Optometry, University of Montreal, Montreal, QC H3T 1P1, Canada
- Department of Neuroscience, Faculty of Health Science, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Martin Bech
- Division of Medical Radiation Physics, Department of Clinical Sciences, Lund University, 221 85 Lund, Sweden
| | - Anders Bjorholm Dahl
- Department of Applied Mathematics and Computer Science, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
| | - Vedrana Andersen Dahl
- Department of Applied Mathematics and Computer Science, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
| | - Tim B Dyrby
- Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, 2650 Hvidovre, Denmark;
- Department of Applied Mathematics and Computer Science, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
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14
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Ineichen BV, Zhu K, Carlström KE. Axonal mitochondria adjust in size depending on g-ratio of surrounding myelin during homeostasis and advanced remyelination. J Neurosci Res 2020; 99:793-805. [PMID: 33368634 PMCID: PMC7898477 DOI: 10.1002/jnr.24767] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Accepted: 11/14/2020] [Indexed: 12/11/2022]
Abstract
Demyelinating pathology is common in many neurological diseases such as multiple sclerosis, stroke, and Alzheimer's disease and results in axonal energy deficiency, dysfunctional axonal propagation, and neurodegeneration. During myelin repair and also during myelin homeostasis, mutual regulative processes between axons and myelin sheaths are known to be essential. However, proficient tools are lacking to characterize axon‐myelin interdependence during (re)myelination. Thus, we herein investigated adaptions in myelin sheath g‐ratio as a proxy for myelin thickness and axon metabolic status during homeostasis and myelin repair, by using axonal mitochondrial size as a proxy for axonal metabolic status. We found that axons with thinner myelin sheaths had larger axonal mitochondria; this was true for across different central nervous system tracts as well as across species, including humans. The link between myelin sheath thickness and mitochondrial size was temporarily absent during demyelination but reestablished during advanced remyelination, as shown in two commonly used animal models of toxic demyelination. By further exploring this association in mice with either genetically induced mitochondrial or myelin dysfunction, we show that axonal mitochondrial size adjusts in response to the thickness of the myelin sheath but not vice versa. This pinpoints the relevance of mitochondrial adaptation upon myelin repair and might open a new therapeutic window for remyelinating therapies.
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Affiliation(s)
- Benjamin V Ineichen
- Department of Clinical Neurosciences, Karolinska Institutet, Center for Molecular Medicine, Karolinska Hospital at Solna, Stockholm, Sweden
| | - Keying Zhu
- Department of Clinical Neurosciences, Karolinska Institutet, Center for Molecular Medicine, Karolinska Hospital at Solna, Stockholm, Sweden
| | - Karl E Carlström
- Department of Clinical Neurosciences, Karolinska Institutet, Center for Molecular Medicine, Karolinska Hospital at Solna, Stockholm, Sweden.,Laboratory of Molecular Neurobiology, Department Medical Biochemistry and Biophysics, Biomedicum, Karolinska Institutet, Stockholm, Sweden
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15
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Salas-Lucia F, Pacheco-Torres J, González-Granero S, García-Verdugo JM, Berbel P. Transient Hypothyroidism During Lactation Alters the Development of the Corpus Callosum in Rats. An in vivo Magnetic Resonance Image and Electron Microscopy Study. Front Neuroanat 2020; 14:33. [PMID: 32676012 PMCID: PMC7333461 DOI: 10.3389/fnana.2020.00033] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2019] [Accepted: 05/28/2020] [Indexed: 12/20/2022] Open
Abstract
Magnetic resonance imaging (MRI) data of children with late diagnosed congenital hypothyroidism and cognitive alterations such as abnormal verbal memory processing suggest altered telencephalic commissural connections. The corpus callosum (CC) is the major inter-hemispheric commissure that contra-laterally connects neocortical areas. However, in late diagnosed neonates with congenital hypothyroidism, the possible effect of early transient and chronic postnatal hypothyroidism still remains unknown. We have studied the development of the anterior, middle and posterior CC, using in vivo MRI and electron microscopy in hypothyroid and control male rats. Four groups of methimazole (MMI) treated rats were studied. One group, as a model for early transient hypothyroidism, was MMI-treated from postnatal day (P) 0 to P21; some of these rats were also treated with L-thyroxine (T4) from P15 to 21. Another group modeling chronic hypothyroid, were treated with MMI from P0 to 150 and from embryonic day 10 to P170. The results obtained from these groups were compared with same age control rats. The normalized T2 signal obtained using MRI was higher in MMI-treated rats and correlated with a low number and percentage of myelinated axons. The number and density of myelinated axons decreased in transient and chronic hypothyroid rats at P150. The g-ratio (inner to outer diameter ratio) and the estimated conduction velocity of myelinated axons were similar between MMI-treated and controls, but the conduction delay decreased in the posterior CC of MMI-treated rats compared to controls. These data show that early postnatal transient and chronic hypothyroidism alters CC maturation in a way that may affect the callosal transfer of information. These alterations cannot be reversed after delayed T4-treatment. Our data support the findings of neurocognitive delay in late T4-treated children with congenital hypothyroidism.
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Affiliation(s)
- Federico Salas-Lucia
- Departamento de Histología y Anatomía, Facultad de Medicina, Universidad Miguel Hernández (UMH), Sant Joan d’Alacant, Spain
| | - Jesús Pacheco-Torres
- Instituto de Neurociencias de Alicante, UMH – Consejo Superior de Investigaciones Científicas, Sant Joan d’Alacant, Spain
| | - Susana González-Granero
- Laboratorio de Neurobiología Comparada, Instituto Cavanilles de Biodiversidad y Biología Evolutiva, Universitat de València - Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Valencia, Spain
| | - José Manuel García-Verdugo
- Laboratorio de Neurobiología Comparada, Instituto Cavanilles de Biodiversidad y Biología Evolutiva, Universitat de València - Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Valencia, Spain
| | - Pere Berbel
- Departamento de Histología y Anatomía, Facultad de Medicina, Universidad Miguel Hernández (UMH), Sant Joan d’Alacant, Spain
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16
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Saliani A, Zaimi A, Nami H, Duval T, Stikov N, Cohen-Adad J. Construction of a rat spinal cord atlas of axon morphometry. Neuroimage 2019; 202:116156. [PMID: 31491525 DOI: 10.1016/j.neuroimage.2019.116156] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 08/26/2019] [Accepted: 09/02/2019] [Indexed: 12/27/2022] Open
Abstract
Atlases of the central nervous system are essential for understanding the pathophysiology of neurological diseases, which remains one of the greatest challenges in neuroscience research today. These atlases provide insight into the underlying white matter microstructure and have been created from a variety of animal models, including rats. Although existing atlases of the rat spinal cord provide some details of axon microstructure, there is currently no histological dataset that quantifies axon morphometry exhaustively in the entire spinal cord. In this study, we created the first comprehensive rat spinal cord atlas of the white matter microstructure with quantifiable axon and myelin morphometrics. Using full-slice scanning electron microscopy images and state-of-the-art segmentation algorithms, we generated an atlas of microstructural metrics such as axon diameter, axonal density and g-ratio. After registering the Watson spinal cord white matter atlas to our template, we computed statistics across metrics, spinal levels and tracts. We notably found that g-ratio is relatively constant, whereas axon diameter showed the greatest variation. The atlas, data and full analysis code are freely available at: https://github.com/neuropoly/atlas-rat.
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Affiliation(s)
- Ariane Saliani
- NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montreal, Montreal, QC, Canada.
| | - Aldo Zaimi
- NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montreal, Montreal, QC, Canada
| | - Harris Nami
- NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montreal, Montreal, QC, Canada
| | - Tanguy Duval
- NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montreal, Montreal, QC, Canada
| | - Nikola Stikov
- NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montreal, Montreal, QC, Canada; Montreal Heart Institute, Montreal, QC, Canada
| | - Julien Cohen-Adad
- NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montreal, Montreal, QC, Canada; Functional Neuroimaging Unit, CRIUGM, Université de Montréal, Montréal, QC, Canada.
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17
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Abdollahzadeh A, Belevich I, Jokitalo E, Tohka J, Sierra A. Automated 3D Axonal Morphometry of White Matter. Sci Rep 2019; 9:6084. [PMID: 30988411 PMCID: PMC6465365 DOI: 10.1038/s41598-019-42648-2] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Accepted: 04/02/2019] [Indexed: 12/14/2022] Open
Abstract
Axonal structure underlies white matter functionality and plays a major role in brain connectivity. The current literature on the axonal structure is based on the analysis of two-dimensional (2D) cross-sections, which, as we demonstrate, is precarious. To be able to quantify three-dimensional (3D) axonal morphology, we developed a novel pipeline, called ACSON (AutomatiC 3D Segmentation and morphometry Of axoNs), for automated 3D segmentation and morphometric analysis of the white matter ultrastructure. The automated pipeline eliminates the need for time-consuming manual segmentation of 3D datasets. ACSON segments myelin, myelinated and unmyelinated axons, mitochondria, cells and vacuoles, and analyzes the morphology of myelinated axons. We applied the pipeline to serial block-face scanning electron microscopy images of the corpus callosum of sham-operated (n = 2) and brain injured (n = 3) rats 5 months after the injury. The 3D morphometry showed that cross-sections of myelinated axons were elliptic rather than circular, and their diameter varied substantially along their longitudinal axis. It also showed a significant reduction in the myelinated axon diameter of the ipsilateral corpus callosum of rats 5 months after brain injury, indicating ongoing axonal alterations even at this chronic time-point.
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Affiliation(s)
- Ali Abdollahzadeh
- Biomedical Imaging Unit, A.I.Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Ilya Belevich
- Electron Microscopy Unit, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Eija Jokitalo
- Electron Microscopy Unit, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Jussi Tohka
- Biomedical Imaging Unit, A.I.Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Alejandra Sierra
- Biomedical Imaging Unit, A.I.Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland.
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18
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Berman S, Filo S, Mezer AA. Modeling conduction delays in the corpus callosum using MRI-measured g-ratio. Neuroimage 2019; 195:128-139. [PMID: 30910729 DOI: 10.1016/j.neuroimage.2019.03.025] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 03/12/2019] [Accepted: 03/12/2019] [Indexed: 11/26/2022] Open
Abstract
Conduction of action potentials along myelinated axons is affected by their structural features, such as the axonal g-ratio, the ratio between the inner and outer diameters of the myelin sheath surrounding the axon. The effect of g-ratio variance on conduction properties has been quantitatively evaluated using single-axon models. It has recently become possible to estimate a g-ratio weighted measurement in vivo using quantitative MRI. Nevertheless, it is still unclear whether the variance in the g-ratio in the healthy human brain leads to significant differences in conduction velocity. In this work we tested whether the g-ratio MRI measurement can be used to predict conduction delays in the corpus callosum. We present a comprehensive framework in which the structural properties of fibers (i.e. length and g-ratio, measured using MRI), are incorporated in a biophysical model of axon conduction, to model conduction delays of long-range white matter fibers. We applied this framework to the corpus callosum, and found conduction delay estimates that are compatible with previously estimated values of conduction delays. We account for the variance in the velocity given the axon diameter distribution in the splenium, mid-body and genu, to further compare the fibers within the corpus callosum. Conduction delays have been suggested to increase with age. Therefore, we investigated whether there are differences in the g-ratio and the fiber length between young and old adults, and whether this leads to a difference in conduction speed and delays. We found very small differences between the predicted delays of the two groups in the motor fibers of the corpus callosum. We also found that the motor fibers of the corpus callosum have the fastest conduction estimates. Using the axon diameter distributions, we found that the occipital fibers have the slowest estimations, while the frontal and motor fiber tracts have similar estimates. Our study provides a framework for predicting conduction latencies in vivo. The framework could have major implications for future studies of white matter diseases and large range network computations. Our results highlight the need for improving additional in vivo measurements of white matter microstructure.
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Affiliation(s)
- S Berman
- Edmond & Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel.
| | - S Filo
- Edmond & Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - A A Mezer
- Edmond & Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
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19
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Petiet A, Adanyeguh I, Aigrot MS, Poirion E, Nait-Oumesmar B, Santin M, Stankoff B. Ultrahigh field imaging of myelin disease models: Toward specific markers of myelin integrity? J Comp Neurol 2019; 527:2179-2189. [PMID: 30520034 DOI: 10.1002/cne.24598] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 10/26/2018] [Accepted: 10/29/2018] [Indexed: 12/20/2022]
Abstract
Specific magnetic resonance imaging (MRI) markers of myelin are critical for the evaluation and development of regenerative therapies for demyelinating diseases. Several MRI methods have been developed for myelin imaging, based either on acquisition schemes or on mathematical modeling of the signal. They generally showed good sensitivity but validation for specificity toward myelin is still warranted to allow a reliable interpretation in an in vivo complex pathological environment. Experimental models of dys-/demyelination are characterized by various levels of myelin disorders, axonal damage, gliosis and inflammation, and offer the opportunity for powerful correlative studies between imaging metrics and histology. Here, we review how ultrahigh field MRI markers have been correlated with histology in these models and provide insights into the trends for future developments of MRI tools in human myelin diseases. To this end, we present the biophysical basis of the main MRI methods for myelin imaging based on T1 , T2 , water diffusion, and magnetization transfer signal, the characteristics of animal models used and the outcomes of histological validations. To date such studies are limited, and demonstrate partial correlations with immunohistochemical and electron microscopy measures of myelin. These MRI metrics also often correlate with axons, glial, or inflammatory cells in models where axonal degeneration or inflammation occur as potential confounding factors. Therefore, the MRI markers' specificity for myelin is still perfectible and future developments should improve mathematical modeling of the MR signal based on more complex systems or provide multimodal approaches to better disentangle the biological processes underlying the MRI metrics.
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Affiliation(s)
- Alexandra Petiet
- Sorbonne Université, UPMC Paris 06, Brain and Spine Institute, ICM, Hôpital de la Pitié Salpêtrière, Paris, France.,Center for Neuroimaging Research, Brain and Spine Institute, Paris, France
| | - Isaac Adanyeguh
- Sorbonne Université, UPMC Paris 06, Brain and Spine Institute, ICM, Hôpital de la Pitié Salpêtrière, Paris, France.,Center for Neuroimaging Research, Brain and Spine Institute, Paris, France
| | - Marie-Stéphane Aigrot
- Sorbonne Université, UPMC Paris 06, Brain and Spine Institute, ICM, Hôpital de la Pitié Salpêtrière, Paris, France
| | - Emilie Poirion
- Sorbonne Université, UPMC Paris 06, Brain and Spine Institute, ICM, Hôpital de la Pitié Salpêtrière, Paris, France
| | - Brahim Nait-Oumesmar
- Sorbonne Université, UPMC Paris 06, Brain and Spine Institute, ICM, Hôpital de la Pitié Salpêtrière, Paris, France
| | - Mathieu Santin
- Sorbonne Université, UPMC Paris 06, Brain and Spine Institute, ICM, Hôpital de la Pitié Salpêtrière, Paris, France.,Center for Neuroimaging Research, Brain and Spine Institute, Paris, France
| | - Bruno Stankoff
- Sorbonne Université, UPMC Paris 06, Brain and Spine Institute, ICM, Hôpital de la Pitié Salpêtrière, Paris, France.,Department of Neurology, AP-HP, Saint-Antoine hospital, Paris, France
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20
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Lee BY, Zhu XH, Li X, Chen W. High-resolution imaging of distinct human corpus callosum microstructure and topography of structural connectivity to cortices at high field. Brain Struct Funct 2018; 224:949-960. [PMID: 30511335 DOI: 10.1007/s00429-018-1804-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 11/25/2018] [Indexed: 02/01/2023]
Abstract
Characterization of the microstructural properties and topography of the human corpus callosum (CC) is key to understanding interhemispheric neural communication and brain function. In this work, we tested the hypothesis that high-resolution T1 relaxometry at high field has adequate sensitivity and specificity for characterizing microstructural properties of the human CC, and elucidating the structural connectivity of the callosal fibers to the cortices of origin. The high-resolution parametric T1 images acquired from healthy subjects (N = 16) at 7 T clearly showed a consistent T1 distribution among individuals with substantial variation along the human CC axis, which is highly similar to the spatial patterns of myelin density and myelinated axon size based on the histology study. Compared to the anterior part of the CC, the posterior midbody and splenium had significantly higher T1 values. In conjunction with T1-based classification method, the splenial T1 values were decoded more reliably compared to a conventional partitioning method, showing a much higher T1 value in the inferior splenium than in the middle/superior splenium. Moreover, the T1 profile of the callosal subdivision represented the topology of the fiber connectivity to the projected cortical regions: the fibers in the posterior midbody and inferior splenium with a higher T1 (inferring a larger axon size) were mainly connected to motor-sensory and visual cortical areas, respectively; in contrast, the fibers in the anterior/posterior CC with a lower T1 (inferring a smaller axon size) were primarily connected to the frontal/parietal-temporal areas. These findings indicate that high-resolution T1 relaxometry imaging could provide a complementary and robust neuroimaging tool, useful for exploring the complex tissue properties and topographic organization of the human corpus callosum.
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Affiliation(s)
- Byeong-Yeul Lee
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota Medical School, 2021 Sixth Street SE, Minneapolis, MN, 55455, USA.
| | - Xiao-Hong Zhu
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota Medical School, 2021 Sixth Street SE, Minneapolis, MN, 55455, USA
| | - Xiufeng Li
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota Medical School, 2021 Sixth Street SE, Minneapolis, MN, 55455, USA
| | - Wei Chen
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota Medical School, 2021 Sixth Street SE, Minneapolis, MN, 55455, USA.
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21
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van Gelderen P, Duyn JH. White matter intercompartmental water exchange rates determined from detailed modeling of the myelin sheath. Magn Reson Med 2018; 81:628-638. [PMID: 30230605 DOI: 10.1002/mrm.27398] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Revised: 04/24/2018] [Accepted: 05/19/2018] [Indexed: 12/13/2022]
Abstract
PURPOSE Magnetization exchange (ME) between hydrogen protons of water and large molecules (semisolids [SS]) in lipid bilayers is an important factor in MRI signal generation and can be exploited to study white matter pathology. Current models used to quantify ME in white matter generally consider water to reside in 1 or 2 distinct compartments, ignoring the complexities of the myelin sheath's multicompartment structure of alternating myelin SS and myelin water (MW) layers. Here, we investigated the effect of this by fitting ME data obtained from human brain at 7 T with a multilayer model of myelin. METHODS A multi-echo acquisition for a T2 * -based separation of MW from other water signals was combined with various preparation pulses to change the (relative) state of the SS and water pools and analyzed by fitting with a multilayer exchange model. RESULTS The estimated lifetime within a single MW layer was 260 µs, corresponding to a lipid bilayer permeability of 6.7 µm/s. The magnetization lifetime of the aggregate of all MW was estimated at 13 ms, shorter than previously reported values in the range of 40 to 140 ms. CONCLUSION Contrary to expectations and previous reports, ME between protons in myelin SS and water is not limited by the myelin sheath but rather by the exchange between SS and water protons. The analysis of ME contrast should account for the relatively short MW lifetime and affects the interpretation of tissue compartmentalization from MRI contrasts such as T1 - and diffusion-weighting.
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Affiliation(s)
- Peter van Gelderen
- Advanced MRI Section, Laboratory of Functional and Molecular Imaging, National Institute of Neurological, Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
| | - Jeff H Duyn
- Advanced MRI Section, Laboratory of Functional and Molecular Imaging, National Institute of Neurological, Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
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22
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Hori M, Hagiwara A, Fukunaga I, Ueda R, Kamiya K, Suzuki Y, Liu W, Murata K, Takamura T, Hamasaki N, Irie R, Kamagata K, Kumamaru KK, Suzuki M, Aoki S. Application of Quantitative Microstructural MR Imaging with Atlas-based Analysis for the Spinal Cord in Cervical Spondylotic Myelopathy. Sci Rep 2018; 8:5213. [PMID: 29581458 PMCID: PMC5979956 DOI: 10.1038/s41598-018-23527-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Accepted: 03/15/2018] [Indexed: 12/14/2022] Open
Abstract
Mapping of MR fiber g-ratio, which is the ratio of the diameter of the axon to the diameter of the neuronal fiber, is introduced in this article. We investigated the MR fiber g-ratio, the axon volume fraction (AVF) and the myelin volume fraction (MVF) to evaluate microstructural changes in the spinal cord in patients with cervical spondylotic myelopathy (CSM) in vivo, using atlas-based analysis. We used diffusion MRI data acquired with a new simultaneous multi-slice accelerated readout-segmented echo planar imaging sequence for diffusion analysis for AVF calculation and magnetization transfer saturation imaging for MVF calculation. The AVFs of fasciculus gracilis in the affected side spinal cord, fasciculus cuneatus and lateral corticospinal tracts (LSCT) in the affected and unaffected side spinal cord were significantly lower (P = 0.019, 0.001, 0019, 0.000, and 0.002, respectively) than those of normal controls. No difference was found in the MVFs. The fiber g-ratio of LSCT was significantly lower (P = 0.040) in the affected side spinal cords than in the normal controls. The pathological microstructural changes in the spinal cord in patients with CSM, presumably partial axonal degenerations with preserved myelin. This technique has the potential to be a clinical biomarker in patients with CSM in vivo.
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Affiliation(s)
- Masaaki Hori
- Department of Radiology, Juntendo University School of Medicine, Tokyo, Japan.
| | - Akifumi Hagiwara
- Department of Radiology, Juntendo University School of Medicine, Tokyo, Japan.,Department of Radiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Issei Fukunaga
- Department of Radiology, Juntendo University School of Medicine, Tokyo, Japan
| | - Ryo Ueda
- Health Science, Tokyo Metropolitan University, Tokyo, Japan
| | - Kouhei Kamiya
- Department of Radiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Yuichi Suzuki
- Department of Radiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Wei Liu
- Siemens Shenzhen Magnetic Resonance Ltd, Shenzhen, China
| | | | - Tomohiro Takamura
- Department of Radiology, Juntendo University School of Medicine, Tokyo, Japan
| | - Nozomi Hamasaki
- Department of Radiology, Juntendo University School of Medicine, Tokyo, Japan
| | - Ryusuke Irie
- Department of Radiology, Juntendo University School of Medicine, Tokyo, Japan.,Department of Radiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Koji Kamagata
- Department of Radiology, Juntendo University School of Medicine, Tokyo, Japan
| | | | - Michimasa Suzuki
- Department of Radiology, Juntendo University School of Medicine, Tokyo, Japan
| | - Shigeki Aoki
- Department of Radiology, Juntendo University School of Medicine, Tokyo, Japan
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23
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Mahajan KR, Ontaneda D. The Role of Advanced Magnetic Resonance Imaging Techniques in Multiple Sclerosis Clinical Trials. Neurotherapeutics 2017; 14:905-923. [PMID: 28770481 PMCID: PMC5722766 DOI: 10.1007/s13311-017-0561-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Magnetic resonance imaging has been crucial in the development of anti-inflammatory disease-modifying treatments. The current landscape of multiple sclerosis clinical trials is currently expanding to include testing not only of anti-inflammatory agents, but also neuroprotective, remyelinating, neuromodulating, and restorative therapies. This is especially true of therapies targeting progressive forms of the disease where neurodegeneration is a prominent feature. Imaging techniques of the brain and spinal cord have rapidly evolved in the last decade to permit in vivo characterization of tissue microstructural changes, connectivity, metabolic changes, neuronal loss, glial activity, and demyelination. Advanced magnetic resonance imaging techniques hold significant promise for accelerating the development of different treatment modalities targeting a variety of pathways in MS.
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Affiliation(s)
- Kedar R Mahajan
- Mellen Center for Multiple Sclerosis Treatment and Research, Cleveland Clinic, 9500 Euclid Avenue, U-10, Cleveland, OH, 44195, USA
| | - Daniel Ontaneda
- Mellen Center for Multiple Sclerosis Treatment and Research, Cleveland Clinic, 9500 Euclid Avenue, U-10, Cleveland, OH, 44195, USA.
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24
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Campbell JSW, Leppert IR, Narayanan S, Boudreau M, Duval T, Cohen-Adad J, Pike GB, Stikov N. Promise and pitfalls of g-ratio estimation with MRI. Neuroimage 2017; 182:80-96. [PMID: 28822750 DOI: 10.1016/j.neuroimage.2017.08.038] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 07/28/2017] [Accepted: 08/12/2017] [Indexed: 12/13/2022] Open
Abstract
The fiber g-ratio is the ratio of the inner to the outer diameter of the myelin sheath of a myelinated axon. It has a limited dynamic range in healthy white matter, as it is optimized for speed of signal conduction, cellular energetics, and spatial constraints. In vivo imaging of the g-ratio in health and disease would greatly increase our knowledge of the nervous system and our ability to diagnose, monitor, and treat disease. MRI based g-ratio imaging was first conceived in 2011, and expanded to be feasible in full brain white matter with preliminary results in 2013. This manuscript reviews the growing g-ratio imaging literature and speculates on future applications. It details the methodology for imaging the g-ratio with MRI, and describes the known pitfalls and challenges in doing so.
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Affiliation(s)
- Jennifer S W Campbell
- Montreal Neurological Institute, McGill University, Montreal, QC, Canada; NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montréal, Montréal, QC, Canada.
| | - Ilana R Leppert
- Montreal Neurological Institute, McGill University, Montreal, QC, Canada
| | - Sridar Narayanan
- Montreal Neurological Institute, McGill University, Montreal, QC, Canada
| | - Mathieu Boudreau
- Montreal Neurological Institute, McGill University, Montreal, QC, Canada
| | - Tanguy Duval
- NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montréal, Montréal, QC, Canada
| | - Julien Cohen-Adad
- NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montréal, Montréal, QC, Canada; Functional Neuroimaging Unit, CRIUGM, Université de Montréal, Montréal, QC, Canada
| | | | - Nikola Stikov
- NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montréal, Montréal, QC, Canada; Montreal Heart Institute, Université de Montréal, Montréal, QC, Canada
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25
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Sound-Evoked Activity Influences Myelination of Brainstem Axons in the Trapezoid Body. J Neurosci 2017; 37:8239-8255. [PMID: 28760859 PMCID: PMC5566870 DOI: 10.1523/jneurosci.3728-16.2017] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 05/31/2017] [Accepted: 06/25/2017] [Indexed: 11/21/2022] Open
Abstract
Plasticity of myelination represents a mechanism to tune the flow of information by balancing functional requirements with metabolic and spatial constraints. The auditory system is heavily myelinated and operates at the upper limits of action potential generation frequency and speed observed in the mammalian CNS. This study aimed to characterize the development of myelin within the trapezoid body, a central auditory fiber tract, and determine the influence sensory experience has on this process in mice of both sexes. We find that in vitro conduction speed doubles following hearing onset and the ability to support high-frequency firing increases concurrently. Also in this time, the diameter of trapezoid body axons and the thickness of myelin double, reaching mature-like thickness between 25 and 35 d of age. Earplugs were used to induce ∼50 dB elevation in auditory thresholds. If introduced at hearing onset, trapezoid body fibers developed thinner axons and myelin than age-matched controls. If plugged during adulthood, the thickest trapezoid body fibers also showed a decrease in myelin. These data demonstrate the need for sensory activity in both development and maintenance of myelin and have important implications in the study of myelin plasticity and how this could relate to sensorineural hearing loss following peripheral impairment.SIGNIFICANCE STATEMENT The auditory system has many mechanisms to maximize the dynamic range of its afferent fibers, which operate at the physiological limit of action potential generation, precision, and speed. In this study we demonstrate for the first time that changes in peripheral activity modifies the thickness of myelin in sensory neurons, not only in development but also in mature animals. The current study suggests that changes in CNS myelination occur as a downstream mechanism following peripheral deficit. Given the required submillisecond temporal precision for binaural auditory processing, reduced myelination might augment sensorineural hearing impairment.
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26
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Berman S, West KL, Does MD, Yeatman JD, Mezer AA. Evaluating g-ratio weighted changes in the corpus callosum as a function of age and sex. Neuroimage 2017; 182:304-313. [PMID: 28673882 DOI: 10.1016/j.neuroimage.2017.06.076] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2017] [Revised: 06/26/2017] [Accepted: 06/27/2017] [Indexed: 11/16/2022] Open
Abstract
Recent years have seen a growing interest in relating MRI measurements to the structural-biophysical properties of white matter fibers. The fiber g-ratio, defined as the ratio between the inner and outer radii of the axon myelin sheath, is an important structural property of white matter, affecting signal conduction. Recently proposed modeling methods that use a combination of quantitative-MRI signals, enable a measurement of the fiber g-ratio in vivo. Here we use an MRI-based g-ratio estimation to observe the variance of the g-ratio within the corpus callosum, and evaluate sex and age related differences. To estimate the g-ratio we used a model (Stikov et al., 2011; Duval et al., 2017) based on two different WM microstructure parameters: the relative amounts of myelin (myelin volume fraction, MVF) and fibers (fiber volume fraction, FVF) in a voxel. We derived the FVF from the fractional anisotropy (FA), and estimated the MVF by using the lipid and macromolecular tissue volume (MTV), calculated from the proton density (Mezer et al., 2013). In comparison to other methods of estimating the MVF, MTV represents a stable parameter with a straightforward route of acquisition. To establish our model, we first compared histological MVF measurements (West et al., 2016) with the MRI derived MTV. We then implemented our model on a large database of 92 subjects (44 males), aged 7 to 81, in order to evaluate age and sex related changes within the corpus callosum. Our results show that the MTV provides a good estimation of MVF for calculating g-ratio, and produced values from the corpus callosum that correspond to those found in animals ex vivo and are close to the theoretical optimum, as well as to published in vivo data. Our results demonstrate that the MTV derived g-ratio provides a simple and reliable in vivo g-ratio-weighted (GR*) measurement in humans. In agreement with theoretical predictions, and unlike other tissue parameters measured with MRI, the g-ratio estimations were found to be relatively stable with age, and we found no support for a significant sexual dimorphism with age.
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Affiliation(s)
- Shai Berman
- The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Kathryn L West
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA; Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, TN, USA
| | - Mark D Does
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA; Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, TN, USA
| | - Jason D Yeatman
- Institute for Learning & Brain Sciences and Department of Speech & Hearing Sciences, University of Washington, Seattle, WA, USA
| | - Aviv A Mezer
- The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel.
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27
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Björnholm L, Nikkinen J, Kiviniemi V, Nordström T, Niemelä S, Drakesmith M, Evans JC, Pike GB, Veijola J, Paus T. Structural properties of the human corpus callosum: Multimodal assessment and sex differences. Neuroimage 2017; 152:108-118. [DOI: 10.1016/j.neuroimage.2017.02.056] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Revised: 02/15/2017] [Accepted: 02/21/2017] [Indexed: 11/17/2022] Open
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28
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Eid L, Parent M. Preparation of Non-human Primate Brain Tissue for Pre-embedding Immunohistochemistry and Electron Microscopy. J Vis Exp 2017. [PMID: 28448038 DOI: 10.3791/55397] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Despite all the technological advances at the light microscopy level, electron microscopy remains the only tool in neuroscience to examine and characterize ultrastructural and morphological details of neurons, such as synaptic contacts. Good preservation of brain tissue for electron microscopy can be obtained by rigorous cryo-fixation methods, but these techniques are rather costly and limit the use of immunolabeling, which is crucial to understand the connectivity of identified neuronal systems. Freeze-substitution methods have been developed to allow the combination of cryo-fixation with immunolabeling. However, the reproducibility of these methodological approaches usually relies on costly freezing devices. Moreover, achieving reliable results with this technique is very time-consuming and skill-challenging. Hence, the traditional chemically fixed brain, particularly with acrolein fixative, remains a time-efficient and low-cost method to combine electron microscopy with immunohistochemistry. Here, we provide a reliable experimental protocol using chemical acrolein fixation that leads to the preservation of primate brain tissue and is compatible with pre-embedding immunohistochemistry and transmission electron microscopic examination.
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Affiliation(s)
- Lara Eid
- Centre de recherche de l'Institut universitaire en santé mentale de Québec, Department of Psychiatry and Neuroscience, Université Laval; Centre de recherche du CHU Sainte-Justine;
| | - Martin Parent
- Centre de recherche de l'Institut universitaire en santé mentale de Québec, Department of Psychiatry and Neuroscience, Université Laval
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29
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Abstract
Quantitative magnetic resonance imaging can be combined with advanced biophysical models to measure microstructural features of white matter. Non-invasive microstructural imaging has the potential to revolutionize neuroscience, and acquiring these measures in clinically feasible times would greatly improve patient monitoring and clinical studies of drug efficacy. However, a good understanding of microstructural imaging techniques is essential to set realistic expectations and to prevent over-interpretation of results. This review explains the methodology behind microstructural modeling and imaging, and gives an overview of the breakthroughs and challenges associated with it.
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30
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Duval T, Le Vy S, Stikov N, Campbell J, Mezer A, Witzel T, Keil B, Smith V, Wald LL, Klawiter E, Cohen-Adad J. g-Ratio weighted imaging of the human spinal cord in vivo. Neuroimage 2017; 145:11-23. [PMID: 27664830 PMCID: PMC5179300 DOI: 10.1016/j.neuroimage.2016.09.018] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Revised: 08/22/2016] [Accepted: 09/08/2016] [Indexed: 12/13/2022] Open
Abstract
The fiber g-ratio is defined as the ratio of the inner to the outer diameter of the myelin sheath. This ratio provides a measure of the myelin thickness that complements axon morphology (diameter and density) for assessment of demyelination in diseases such as multiple sclerosis. Previous work has shown that an aggregate g-ratio map can be computed using a formula that combines axon and myelin density measured with quantitative MRI. In this work, we computed g-ratio weighted maps in the cervical spinal cord of nine healthy subjects. We utilized the 300mT/m gradients from the CONNECTOM scanner to estimate the fraction of restricted water (fr) with high accuracy, using the CHARMED model. Myelin density was estimated using the lipid and macromolecular tissue volume (MTV) method, derived from normalized proton density (PD) mapping. The variability across spinal level, laterality and subject were assessed using a three-way ANOVA. The average g-ratio value obtained in the white matter was 0.76+/-0.03, consistent with previous histology work. Coefficients of variation of fr and MTV were respectively 4.3% and 13.7%. fr and myelin density were significantly different across spinal tracts (p=3×10-7 and 0.004 respectively) and were positively correlated in the white matter (r=0.42), suggesting shared microstructural information. The aggregate g-ratio did not show significant differences across tracts (p=0.6). This study suggests that fr and myelin density can be measured in vivo with high precision and that they can be combined to produce a g-ratio-weighted map robust to free water pool contamination from cerebrospinal fluid or veins. Potential applications include the study of early demyelination in multiple sclerosis, and the quantitative assessment of remyelination drugs.
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Affiliation(s)
- T Duval
- NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montreal, Montreal, QC, Canada
| | - S Le Vy
- NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montreal, Montreal, QC, Canada; Functional Neuroimaging Unit, CRIUGM, Université de Montréal, Montréal, QC, Canada
| | - N Stikov
- NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montreal, Montreal, QC, Canada; Montreal Heart Institute, Montreal, QC, Canada
| | - J Campbell
- Montreal Neurological Institute, McGill University, Montreal, QC, Canada
| | - A Mezer
- Edmond and Lily Safra Center for Brain Sciences (ELSC), The Hebrew University of Jerusalem, Jerusalem, Israel
| | - T Witzel
- A.A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States
| | - B Keil
- A.A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States
| | - V Smith
- A.A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States
| | - L L Wald
- A.A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States
| | - E Klawiter
- A.A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States
| | - J Cohen-Adad
- NeuroPoly Lab, Institute of Biomedical Engineering, Polytechnique Montreal, Montreal, QC, Canada; Functional Neuroimaging Unit, CRIUGM, Université de Montréal, Montréal, QC, Canada.
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31
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Cercignani M, Giulietti G, Dowell NG, Gabel M, Broad R, Leigh PN, Harrison NA, Bozzali M. Characterizing axonal myelination within the healthy population: a tract-by-tract mapping of effects of age and gender on the fiber g-ratio. Neurobiol Aging 2016; 49:109-118. [PMID: 27792897 PMCID: PMC5156474 DOI: 10.1016/j.neurobiolaging.2016.09.016] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Revised: 09/22/2016] [Accepted: 09/22/2016] [Indexed: 11/21/2022]
Abstract
The g-ratio, equal to the ratio of the inner-to-outer diameter of a myelinated axon, is associated with the speed of conduction, and thus reflects axonal function and integrity. It is now possible to estimate an “aggregate” g-ratio in vivo using MRI. The aim of this study was to assess the variation of the MRI-derived fiber g-ratio in the brain of healthy individuals, and to characterize its variation across the lifespan. Thirty-eight healthy participants, aged between 20 and 76, were recruited. Whole-brain g-ratio maps were computed and analyzed voxel-wise. Median tract g-ratio values were also extracted. No significant effect of gender was found, whereas age was found to be significantly associated with the g-ratio within the white matter. The tract-specific analysis showed this relationship to follow a nearly-linear increase, although the slope appears to slow down slightly after the 6th decade of life. The most likely interpretation is a subtle but consistent reduction in myelin throughout adulthood, with the density of axons beginning to decrease between the 4th and 5th decade.
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Affiliation(s)
- Mara Cercignani
- Department of Neuroscience, Clinical Imaging Sciences Centre, Brighton and Sussex Medical School, University of Sussex, Brighton, East Sussex, UK; Neuroimaging Laboratory, Santa Lucia Foundation, Rome, Italy.
| | | | - Nick G Dowell
- Department of Neuroscience, Clinical Imaging Sciences Centre, Brighton and Sussex Medical School, University of Sussex, Brighton, East Sussex, UK
| | - Matt Gabel
- Department of Neuroscience, Clinical Imaging Sciences Centre, Brighton and Sussex Medical School, University of Sussex, Brighton, East Sussex, UK
| | - Rebecca Broad
- Neuroimaging Laboratory, Santa Lucia Foundation, Rome, Italy
| | - P Nigel Leigh
- Neuroimaging Laboratory, Santa Lucia Foundation, Rome, Italy
| | - Neil A Harrison
- Department of Neuroscience, Clinical Imaging Sciences Centre, Brighton and Sussex Medical School, University of Sussex, Brighton, East Sussex, UK
| | - Marco Bozzali
- Neuroimaging Laboratory, Santa Lucia Foundation, Rome, Italy
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32
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Zaimi A, Duval T, Gasecka A, Côté D, Stikov N, Cohen-Adad J. AxonSeg: Open Source Software for Axon and Myelin Segmentation and Morphometric Analysis. Front Neuroinform 2016; 10:37. [PMID: 27594833 PMCID: PMC4990549 DOI: 10.3389/fninf.2016.00037] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 08/08/2016] [Indexed: 01/21/2023] Open
Abstract
Segmenting axon and myelin from microscopic images is relevant for studying the peripheral and central nervous system and for validating new MRI techniques that aim at quantifying tissue microstructure. While several software packages have been proposed, their interface is sometimes limited and/or they are designed to work with a specific modality (e.g., scanning electron microscopy (SEM) only). Here we introduce AxonSeg, which allows to perform automatic axon and myelin segmentation on histology images, and to extract relevant morphometric information, such as axon diameter distribution, axon density and the myelin g-ratio. AxonSeg includes a simple and intuitive MATLAB-based graphical user interface (GUI) and can easily be adapted to a variety of imaging modalities. The main steps of AxonSeg consist of: (i) image pre-processing; (ii) pre-segmentation of axons over a cropped image and discriminant analysis (DA) to select the best parameters based on axon shape and intensity information; (iii) automatic axon and myelin segmentation over the full image; and (iv) atlas-based statistics to extract morphometric information. Segmentation results from standard optical microscopy (OM), SEM and coherent anti-Stokes Raman scattering (CARS) microscopy are presented, along with validation against manual segmentations. Being fully-automatic after a quick manual intervention on a cropped image, we believe AxonSeg will be useful to researchers interested in large throughput histology. AxonSeg is open source and freely available at: https://github.com/neuropoly/axonseg.
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Affiliation(s)
- Aldo Zaimi
- Institute of Biomedical Engineering, Polytechnique Montreal Montreal, QC, Canada
| | - Tanguy Duval
- Institute of Biomedical Engineering, Polytechnique Montreal Montreal, QC, Canada
| | - Alicja Gasecka
- Institut Universitaire en Santé Mentale de QuébecQuebec, QC, Canada; Centre d'Optique, Photonique et Laser, Université LavalQuebec, QC, Canada
| | - Daniel Côté
- Institut Universitaire en Santé Mentale de QuébecQuebec, QC, Canada; Centre d'Optique, Photonique et Laser, Université LavalQuebec, QC, Canada
| | - Nikola Stikov
- Institute of Biomedical Engineering, Polytechnique MontrealMontreal, QC, Canada; Montreal Heart InstituteMontreal, QC, Canada
| | - Julien Cohen-Adad
- Institute of Biomedical Engineering, Polytechnique MontrealMontreal, QC, Canada; Functional Neuroimaging Unit, CRIUGM, Université de MontréalMontreal, QC, Canada
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33
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Zarei K, Scheetz TE, Christopher M, Miller K, Hedberg-Buenz A, Tandon A, Anderson MG, Fingert JH, Abràmoff MD. Automated Axon Counting in Rodent Optic Nerve Sections with AxonJ. Sci Rep 2016; 6:26559. [PMID: 27226405 PMCID: PMC4881014 DOI: 10.1038/srep26559] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 05/05/2016] [Indexed: 01/17/2023] Open
Abstract
We have developed a publicly available tool, AxonJ, which quantifies the axons in optic nerve sections of rodents stained with paraphenylenediamine (PPD). In this study, we compare AxonJ's performance to human experts on 100x and 40x images of optic nerve sections obtained from multiple strains of mice, including mice with defects relevant to glaucoma. AxonJ produced reliable axon counts with high sensitivity of 0.959 and high precision of 0.907, high repeatability of 0.95 when compared to a gold-standard of manual assessments and high correlation of 0.882 to the glaucoma damage staging of a previously published dataset. AxonJ allows analyses that are quantitative, consistent, fully-automated, parameter-free, and rapid on whole optic nerve sections at 40x. As a freely available ImageJ plugin that requires no highly specialized equipment to utilize, AxonJ represents a powerful new community resource augmenting studies of the optic nerve using mice.
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Affiliation(s)
- Kasra Zarei
- Stephen A. Wynn Institute for Vision Research, University of Iowa, Iowa City, IA 52242, USA.,Department of Biomedical Engineering, University of Iowa, Iowa City, IA 52242, USA
| | - Todd E Scheetz
- Stephen A. Wynn Institute for Vision Research, University of Iowa, Iowa City, IA 52242, USA.,Department of Biomedical Engineering, University of Iowa, Iowa City, IA 52242, USA.,Department of Ophthalmology and Visual Sciences, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, Iowa City, IA 52242, USA
| | - Mark Christopher
- Stephen A. Wynn Institute for Vision Research, University of Iowa, Iowa City, IA 52242, USA.,Department of Biomedical Engineering, University of Iowa, Iowa City, IA 52242, USA.,Department of Ophthalmology and Visual Sciences, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, Iowa City, IA 52242, USA
| | - Kathy Miller
- Stephen A. Wynn Institute for Vision Research, University of Iowa, Iowa City, IA 52242, USA.,Department of Ophthalmology and Visual Sciences, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, Iowa City, IA 52242, USA
| | - Adam Hedberg-Buenz
- Stephen A. Wynn Institute for Vision Research, University of Iowa, Iowa City, IA 52242, USA.,Department of Veterans Affairs, Iowa City VA Medical Center, 601 Highway 6 West, Iowa City, IA 55242, USA.,Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA 52242, USA
| | - Anamika Tandon
- Stephen A. Wynn Institute for Vision Research, University of Iowa, Iowa City, IA 52242, USA.,Department of Ophthalmology and Visual Sciences, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, Iowa City, IA 52242, USA
| | - Michael G Anderson
- Stephen A. Wynn Institute for Vision Research, University of Iowa, Iowa City, IA 52242, USA.,Department of Ophthalmology and Visual Sciences, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, Iowa City, IA 52242, USA.,Department of Veterans Affairs, Iowa City VA Medical Center, 601 Highway 6 West, Iowa City, IA 55242, USA.,Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA 52242, USA
| | - John H Fingert
- Stephen A. Wynn Institute for Vision Research, University of Iowa, Iowa City, IA 52242, USA.,Department of Ophthalmology and Visual Sciences, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, Iowa City, IA 52242, USA
| | - Michael David Abràmoff
- Stephen A. Wynn Institute for Vision Research, University of Iowa, Iowa City, IA 52242, USA.,Department of Biomedical Engineering, University of Iowa, Iowa City, IA 52242, USA.,Department of Ophthalmology and Visual Sciences, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, Iowa City, IA 52242, USA.,Department of Veterans Affairs, Iowa City VA Medical Center, 601 Highway 6 West, Iowa City, IA 55242, USA.,Department of Electrical and Computer Engineering, University of Iowa, Iowa City, IA 52242, USA
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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: 71] [Impact Index Per Article: 8.9] [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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35
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Quantitative analysis of mouse corpus callosum from electron microscopy images. Data Brief 2015; 5:124-8. [PMID: 26504893 PMCID: PMC4576400 DOI: 10.1016/j.dib.2015.08.022] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 08/24/2015] [Indexed: 12/22/2022] Open
Abstract
This article provides morphometric analysis of 72 electron microscopy images from control (n=4) and hypomyelinated (n=2) mouse corpus callosum. Measures of axon diameter and g-ratio were tabulated across all brains from two regions of the corpus callosum and a non-linear relationship between axon diameter and g-ratio was observed. These data are related to the accompanying research article comparing multiple methods of measuring g-ratio entitled ‘A revised model for estimating g-ratio from MRI’ (West et al., NeuroImage, 2015).
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36
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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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37
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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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