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Barrett TF, Patel B, Khan SM, Mullins RDZ, Yim AKY, Pugazenthi S, Mahlokozera T, Zipfel GJ, Herzog JA, Chicoine MR, Wick CC, Durakovic N, Osbun JW, Shew M, Sweeney AD, Patel AJ, Buchman CA, Petti AA, Puram SV, Kim AH. Single-cell multi-omic analysis of the vestibular schwannoma ecosystem uncovers a nerve injury-like state. Nat Commun 2024; 15:478. [PMID: 38216553 PMCID: PMC10786875 DOI: 10.1038/s41467-023-42762-w] [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: 11/03/2022] [Accepted: 10/10/2023] [Indexed: 01/14/2024] Open
Abstract
Vestibular schwannomas (VS) are benign tumors that lead to significant neurologic and otologic morbidity. How VS heterogeneity and the tumor microenvironment (TME) contribute to VS pathogenesis remains poorly understood. In this study, we perform scRNA-seq on 15 VS, with paired scATAC-seq (n = 6) and exome sequencing (n = 12). We identify diverse Schwann cell (SC), stromal, and immune populations in the VS TME and find that repair-like and MHC-II antigen-presenting SCs are associated with myeloid cell infiltrate, implicating a nerve injury-like process. Deconvolution analysis of RNA-expression data from 175 tumors reveals Injury-like tumors are associated with larger tumor size, and scATAC-seq identifies transcription factors associated with nerve repair SCs from Injury-like tumors. Ligand-receptor analysis and in vitro experiments suggest that Injury-like VS-SCs recruit myeloid cells via CSF1 signaling. Our study indicates that Injury-like SCs may cause tumor growth via myeloid cell recruitment and identifies molecular pathways that may be therapeutically targeted.
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Affiliation(s)
- Thomas F Barrett
- Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine, St. Louis, MO, USA
| | - Bhuvic Patel
- Department of Neurological Surgery, Washington University School of Medicine, St. Louis, MO, USA
| | - Saad M Khan
- Department of Neurosurgery, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Brain Tumor Immunology and Immunotherapy Program, Department of Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Riley D Z Mullins
- Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine, St. Louis, MO, USA
- Department of Genetics, Washington University School of Medicine, St. Louis, MO, USA
| | - Aldrin K Y Yim
- Department of Genetics, Washington University School of Medicine, St. Louis, MO, USA
| | - Sangami Pugazenthi
- Department of Neurological Surgery, Washington University School of Medicine, St. Louis, MO, USA
| | - Tatenda Mahlokozera
- Department of Neurological Surgery, Washington University School of Medicine, St. Louis, MO, USA
| | - Gregory J Zipfel
- Department of Neurological Surgery, Washington University School of Medicine, St. Louis, MO, USA
- Brain Tumor Center, Washington University School of Medicine/Siteman Cancer Center, St. Louis, MO, USA
| | - Jacques A Herzog
- Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine, St. Louis, MO, USA
- Brain Tumor Center, Washington University School of Medicine/Siteman Cancer Center, St. Louis, MO, USA
| | - Michael R Chicoine
- Department of Neurological Surgery, University of Missouri School of Medicine, Columbia, MO, USA
| | - Cameron C Wick
- Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine, St. Louis, MO, USA
- Brain Tumor Center, Washington University School of Medicine/Siteman Cancer Center, St. Louis, MO, USA
| | - Nedim Durakovic
- Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine, St. Louis, MO, USA
- Brain Tumor Center, Washington University School of Medicine/Siteman Cancer Center, St. Louis, MO, USA
| | - Joshua W Osbun
- Department of Neurological Surgery, Washington University School of Medicine, St. Louis, MO, USA
| | - Matthew Shew
- Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine, St. Louis, MO, USA
- Brain Tumor Center, Washington University School of Medicine/Siteman Cancer Center, St. Louis, MO, USA
| | - Alex D Sweeney
- Department of Otolaryngology-Head and Neck Surgery, Baylor College of Medicine, Houston, TX, USA
| | - Akash J Patel
- Department of Otolaryngology-Head and Neck Surgery, Baylor College of Medicine, Houston, TX, USA
- Department of Neurosurgery, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Craig A Buchman
- Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine, St. Louis, MO, USA
- Brain Tumor Center, Washington University School of Medicine/Siteman Cancer Center, St. Louis, MO, USA
| | - Allegra A Petti
- Department of Neurosurgery, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
- Brain Tumor Immunology and Immunotherapy Program, Department of Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
| | - Sidharth V Puram
- Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine, St. Louis, MO, USA.
- Department of Genetics, Washington University School of Medicine, St. Louis, MO, USA.
- Siteman Cancer Center, Washington University in St. Louis, St. Louis, MO, USA.
| | - Albert H Kim
- Department of Neurological Surgery, Washington University School of Medicine, St. Louis, MO, USA.
- Department of Genetics, Washington University School of Medicine, St. Louis, MO, USA.
- Brain Tumor Center, Washington University School of Medicine/Siteman Cancer Center, St. Louis, MO, USA.
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Four Seasons for Schwann Cell Biology, Revisiting Key Periods: Development, Homeostasis, Repair, and Aging. Biomolecules 2021; 11:biom11121887. [PMID: 34944531 PMCID: PMC8699407 DOI: 10.3390/biom11121887] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 12/08/2021] [Accepted: 12/10/2021] [Indexed: 01/28/2023] Open
Abstract
Like the seasons of the year, all natural things happen in stages, going through adaptations when challenged, and Schwann cells are a great example of that. During maturation, these cells regulate several steps in peripheral nervous system development. The Spring of the cell means the rise and bloom through organized stages defined by time-dependent regulation of factors and microenvironmental influences. Once matured, the Summer of the cell begins: a high energy stage focused on maintaining adult homeostasis. The Schwann cell provides many neuron-glia communications resulting in the maintenance of synapses. In the peripheral nervous system, Schwann cells are pivotal after injuries, balancing degeneration and regeneration, similarly to when Autumn comes. Their ability to acquire a repair phenotype brings the potential to reconnect axons to targets and regain function. Finally, Schwann cells age, not only by growing old, but also by imposed environmental cues, like loss of function induced by pathologies. The Winter of the cell presents as reduced activity, especially regarding their role in repair; this reflects on the regenerative potential of older/less healthy individuals. This review gathers essential information about Schwann cells in different stages, summarizing important participation of this intriguing cell in many functions throughout its lifetime.
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Quintá HR. Intraspinal Administration of Netrin-1 Promotes Locomotor Recovery after Complete Spinal Cord Transection. J Neurotrauma 2021; 38:2084-2102. [PMID: 33599152 DOI: 10.1089/neu.2020.7571] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Complete spinal cord lesions interrupt the connection of all axonal projections with their neuronal targets below and above the lesion site. In particular, the interruption of connections with the neurons at lumbar segments after thoracic injuries impairs voluntary body control below the injury. The failure of spontaneous regrowth of transected axons across the lesion prevents the reconnection and reinnervation of the neuronal targets. At present, the only treatment in humans that has proven to promote some degree of locomotor recovery is physical therapy. The success of these strategies, however, depends greatly on the type of lesion and the level of preservation of neural tissue in the spinal cord after injury. That is the reason it is key to design strategies to promote axonal regrowth and neuronal reconnection. Here, we test the use of a developmental axon guidance molecule as a biological agent to promote axonal regrowth, axonal reconnection, and recovery of locomotor activity after spinal cord injury (SCI). This molecule, netrin-1, guides the growth of the corticospinal tract (CST) during the development of the central nervous system. To assess the potential of this molecule, we used a model of complete spinal cord transection in rats, at thoracic level 10-11. We show that in situ delivery of netrin-1 at the epicenter of the lesion: (1) promotes regrowth of CST through the lesion and prevents CST dieback, (2) promotes synaptic reconnection of regenerated motor and sensory axons, and (3) preserves the polymerization of the neurofilaments in the sciatic nerve axons. These anatomical findings correlate with a significant recovery of locomotor function. Our work identifies netrin-1 as a biological agent with the capacity to promote the functional repair and recovery of locomotor function after SCI. These findings support the use of netrin-1 as a therapeutic intervention to be tested in humans.
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Affiliation(s)
- Héctor R Quintá
- Consejo Nacional de Investigaciones Científicas y Técnicas-CONICET, Buenos Aires, Argentina
- Laboratorio de Medicina Experimental "Dr. Jorge E. Toblli," Hospital Alemán. CABA, Buenos Aires, Argentina
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Khodabakhsh P, Pournajaf S, Mohaghegh Shalmani L, Ahmadiani A, Dargahi L. Insulin Promotes Schwann-Like Cell Differentiation of Rat Epidermal Neural Crest Stem Cells. Mol Neurobiol 2021; 58:5327-5337. [PMID: 34297315 DOI: 10.1007/s12035-021-02423-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 05/05/2021] [Indexed: 10/20/2022]
Abstract
Schwann cells (SCs) are considered potentially attractive candidates for transplantation therapies in neurodegenerative diseases. However, problems arising from the isolation and expansion of the SCs restrict their clinical applications. Establishing an alternative Schwann-like cell type is a prerequisite. Epidermal neural crest stem cells (EPI-NCSCs) are well studied for their autologous accessibility, along with the ability to produce major neural crest derivatives and neurotrophic factors. In the current study, we explored insulin influence, a well-known growth factor, on directing EPI-NCSCs into the Schwann cell (SC) lineage. EPI-NCSCs were isolated from rat hair bulge explants. The viability of cells treated with a range of insulin concentrations (0.05-100 μg/ml) was defined by MTT assay at 24, 48, and 72 h. The gene expression profiles of neurotrophic factors (BDNF, FGF-2, and IL-6), key regulators involved in the development of SC (EGR-1, SOX-10, c-JUN, GFAP, OCT-6, EGR-2, and MBP), and oligodendrocyte (PDGFR-α and NG-2) were quantified 1 and 9 days post-treatment with 0.05 and 5 μg/ml insulin. Furthermore, the protein expression of nestin (stemness marker), SOX-10, PDGFR-α, and MBP was analyzed following the long-term insulin treatment. Insulin downregulated the early-stage SC differentiation marker (EGR-1) and increased neurotrophins (BDNF and IL-6) and pro-myelinating genes, including OCT-6, SOX-10, EGR-2, and MBP, as well as oligodendrocyte differentiation markers, upon exposure for 9 days. Insulin can promote EPI-NCSC differentiation toward SC lineage and possibly oligodendrocytes. Thus, employing insulin might enhance the EPI-NCSCs efficiency in cell transplantation strategies.
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Affiliation(s)
- Pariya Khodabakhsh
- Department of Pharmacology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Safura Pournajaf
- Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Leila Mohaghegh Shalmani
- Pharmacology and Toxicology Department, Faculty of Pharmacy and Pharmaceutical Sciences, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran
| | - Abolhassan Ahmadiani
- Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Leila Dargahi
- Neurobiology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
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Chen CZ, Neumann B, Förster S, Franklin RJM. Schwann cell remyelination of the central nervous system: why does it happen and what are the benefits? Open Biol 2021; 11:200352. [PMID: 33497588 PMCID: PMC7881176 DOI: 10.1098/rsob.200352] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Myelin sheaths, by supporting axonal integrity and allowing rapid saltatory impulse conduction, are of fundamental importance for neuronal function. In response to demyelinating injuries in the central nervous system (CNS), oligodendrocyte progenitor cells (OPCs) migrate to the lesion area, proliferate and differentiate into new oligodendrocytes that make new myelin sheaths. This process is termed remyelination. Under specific conditions, demyelinated axons in the CNS can also be remyelinated by Schwann cells (SCs), the myelinating cell of the peripheral nervous system. OPCs can be a major source of these CNS-resident SCs—a surprising finding given the distinct embryonic origins, and physiological compartmentalization of the peripheral and central nervous system. Although the mechanisms and cues governing OPC-to-SC differentiation remain largely undiscovered, it might nevertheless be an attractive target for promoting endogenous remyelination. This article will (i) review current knowledge on the origins of SCs in the CNS, with a particular focus on OPC to SC differentiation, (ii) discuss the necessary criteria for SC myelination in the CNS and (iii) highlight the potential of using SCs for myelin regeneration in the CNS.
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Affiliation(s)
- Civia Z Chen
- Wellcome-Medical Research Council Cambridge Stem Cell Institute, University of Cambridge, Cambridge Biomedical Campus, Cambridge CB2 0AH, UK
| | - Björn Neumann
- Wellcome-Medical Research Council Cambridge Stem Cell Institute, University of Cambridge, Cambridge Biomedical Campus, Cambridge CB2 0AH, UK
| | - Sarah Förster
- Wellcome-Medical Research Council Cambridge Stem Cell Institute, University of Cambridge, Cambridge Biomedical Campus, Cambridge CB2 0AH, UK
| | - Robin J M Franklin
- Wellcome-Medical Research Council Cambridge Stem Cell Institute, University of Cambridge, Cambridge Biomedical Campus, Cambridge CB2 0AH, UK
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Garcia-Diaz B, Baron-Van Evercooren A. Schwann cells: Rescuers of central demyelination. Glia 2020; 68:1945-1956. [PMID: 32027054 DOI: 10.1002/glia.23788] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 01/15/2020] [Accepted: 01/23/2020] [Indexed: 12/31/2022]
Abstract
The presence of peripheral myelinating cells in the central nervous system (CNS) has gained the neurobiologist attention over the years. Despite the confirmed presence of Schwann cells in the CNS in pathological conditions, and the long list of their beneficial effects on central remyelination, the cues that impede or allow Schwann cells to successfully conquer and remyelinate central axons remain partially undiscovered. A better knowledge of these factors stands out as crucial to foresee a rational therapeutic approach for the use of Schwann cells in CNS repair. Here, we review the diverse origins of Schwann cells into the CNS, both peripheral and central, as well as the CNS components that inhibit Schwann survival and migration into the central parenchyma. Namely, we analyze the astrocyte- and the myelin-derived components that restrict Schwann cells into the CNS. Finally, we highlight the unveiled mode of invasion of these peripheral cells through the central environment, using blood vessels as scaffolds to pave their ways toward demyelinated lesions. In short, this review presents the so far uncovered knowledge of this complex CNS-peripheral nervous system (PNS) relationship.
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Affiliation(s)
- Beatriz Garcia-Diaz
- Unidad de Gestión Clínica de Neurociencias, IBIMA, Hospital Regional Universitario de Málaga, Universidad de Málaga, Málaga, Spain.,Institut du Cerveau et de la Moelle Epinière-Groupe Hospitalier Pitié-Salpêtrière, INSERM, U1127, CNRS, Paris, France.,Sorbonne Universités, Université Pierre et Marie Curie Paris 06, Paris, France
| | - Anne Baron-Van Evercooren
- Institut du Cerveau et de la Moelle Epinière-Groupe Hospitalier Pitié-Salpêtrière, INSERM, U1127, CNRS, Paris, France.,Sorbonne Universités, Université Pierre et Marie Curie Paris 06, Paris, France
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7
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Alves CJ, Maximino JR, Chadi G. Dysregulated expression of death, stress and mitochondrion related genes in the sciatic nerve of presymptomatic SOD1(G93A) mouse model of Amyotrophic Lateral Sclerosis. Front Cell Neurosci 2015; 9:332. [PMID: 26339226 PMCID: PMC4555015 DOI: 10.3389/fncel.2015.00332] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 08/10/2015] [Indexed: 12/11/2022] Open
Abstract
Schwann cells are the main source of paracrine support to motor neurons. Oxidative stress and mitochondrial dysfunction have been correlated to motor neuron death in Amyotrophic Lateral Sclerosis (ALS). Despite the involvement of Schwann cells in early neuromuscular disruption in ALS, detailed molecular events of a dying-back triggering are unknown. Sciatic nerves of presymptomatic (60-day-old) SOD1(G93A) mice were submitted to a high-density oligonucleotide microarray analysis. DAVID demonstrated the deregulated genes related to death, stress and mitochondrion, which allowed the identification of Cell cycle, ErbB signaling, Tryptophan metabolism and Rig-I-like receptor signaling as the most representative KEGG pathways. The protein-protein interaction networks based upon deregulated genes have identified the top hubs (TRAF2, H2AFX, E2F1, FOXO3, MSH2, NGFR, TGFBR1) and bottlenecks (TRAF2, E2F1, CDKN1B, TWIST1, FOXO3). Schwann cells were enriched from the sciatic nerve of presymptomatic mice using flow cytometry cell sorting. qPCR showed the up regulated (Ngfr, Cdnkn1b, E2f1, Traf2 and Erbb3, H2afx, Cdkn1a, Hspa1, Prdx, Mapk10) and down-regulated (Foxo3, Mtor) genes in the enriched Schwann cells. In conclusion, molecular analyses in the presymptomatic sciatic nerve demonstrated the involvement of death, oxidative stress, and mitochondrial pathways in the Schwann cell non-autonomous mechanisms in the early stages of ALS.
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Affiliation(s)
- Chrystian J Alves
- Department of Neurology, Neuroregeneration Center, University of São Paulo School of Medicine São Paulo, Brazil
| | - Jessica R Maximino
- Department of Neurology, Neuroregeneration Center, University of São Paulo School of Medicine São Paulo, Brazil
| | - Gerson Chadi
- Department of Neurology, Neuroregeneration Center, University of São Paulo School of Medicine São Paulo, Brazil
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Kanno H, Pearse DD, Ozawa H, Itoi E, Bunge MB. Schwann cell transplantation for spinal cord injury repair: its significant therapeutic potential and prospectus. Rev Neurosci 2015; 26:121-8. [DOI: 10.1515/revneuro-2014-0068] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Accepted: 10/16/2014] [Indexed: 11/15/2022]
Abstract
AbstractTransplantation of Schwann cells (SCs) is a promising therapeutic strategy for spinal cord repair. The introduction of SCs into the injured spinal cord has been shown to reduce tissue loss, promote axonal regeneration, and facilitate myelination of axons for improved sensorimotor function. The pathology of spinal cord injury (SCI) comprises multiple processes characterized by extensive cell death, development of a milieu inhibitory to growth, and glial scar formation, which together limits axonal regeneration. Many studies have suggested that significant functional recovery following SCI will not be possible with a single therapeutic strategy. The use of additional approaches with SC transplantation may be needed for successful axonal regeneration and sufficient functional recovery after SCI. An example of such a combination strategy with SC transplantation has been the complementary administration of neuroprotective agents/growth factors, which improves the effect of SCs after SCI. Suspension of SCs in bioactive matrices can also enhance transplanted SC survival and increase their capacity for supporting axonal regeneration in the injured spinal cord. Inhibition of glial scar formation produces a more permissive interface between the SC transplant and host spinal cord for axonal growth. Co-transplantation of SCs and other types of cells such as olfactory ensheathing cells, bone marrow mesenchymal stromal cells, and neural stem cells can be a more effective therapy than transplantation of SCs alone following SCI. This article reviews some of the evidence supporting the combination of SC transplantation with additional strategies for SCI repair and presents a prospectus for achieving better outcomes for persons with SCI.
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Beaud ML, Rouiller E, Bloch J, Mir A, Schwab M, Wannier T, Schmidlin E. Invasion of lesion territory by regenerating fibers after spinal cord injury in adult macaque monkeys. Neuroscience 2012; 227:271-82. [DOI: 10.1016/j.neuroscience.2012.09.052] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Revised: 09/21/2012] [Accepted: 09/22/2012] [Indexed: 11/26/2022]
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Nagoshi N, Shibata S, Hamanoue M, Mabuchi Y, Matsuzaki Y, Toyama Y, Nakamura M, Okano H. Schwann cell plasticity after spinal cord injury shown by neural crest lineage tracing. Glia 2011; 59:771-84. [PMID: 21351159 DOI: 10.1002/glia.21150] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2010] [Accepted: 12/22/2010] [Indexed: 01/10/2023]
Abstract
After spinal cord injury (SCI), various cell types are recruited to the lesion site, including Schwann cells, which originate in the neural crest and normally myelinate axons in the peripheral nervous system. Here, we investigated the differentiation states, migration patterns, and roles of neural crest derivatives following SCI, using two transgenic mouse lines carrying neural crest-specific reporters, P0-Cre/Floxed-EGFP and Wnt1-Cre/Floxed-EGFP. In these mice, EGFP is expressed only in the neural crest cell lineage. Immunohistochemical analysis revealed that most of the EGFP(+) cells that infiltrated the lesion site after SCI were Schwann cells. Seven days after SCI, the P0-positive, mature Schwann cells residing at the nerve roots had dedifferentiated into P0(-)/p75(+) immature Schwann cells, which proliferated and began migrating into the lesion site. The dedifferentiation of the Schwann cells was corroborated by their expression of phosphorylated c-Jun, which promotes dedifferentiation and inhibits the expression of myelin-associated genes in the peripheral nerves. Thereafter, the number of EGFP(+)/p75(+) immature Schwann cells decreased and that of EGFP(+)/P0(+) mature cells increased gradually, indicating that the cells redifferentiated into mature Schwann cells within the lesion site. This study draws on the advantages offered by transgenic mouse lines bearing a genetic cell-lineage marker and extends previous work by describing the origins and behavior of the neural crest-derived cells that contribute to endogenous repair after SCI. This process, involving Schwann cell plasticity, is a novel repair mechanism for the lesioned mammalian spinal cord.
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Affiliation(s)
- Narihito Nagoshi
- Department of Physiology, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo, Japan
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Combinatorial strategies with Schwann cell transplantation to improve repair of the injured spinal cord. Neurosci Lett 2009; 456:124-32. [PMID: 19429147 DOI: 10.1016/j.neulet.2008.08.092] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2008] [Revised: 07/29/2008] [Accepted: 08/04/2008] [Indexed: 12/11/2022]
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Deumens R, Joosten EAJ, Waxman SG, Hains BC. Locomotor dysfunction and pain: the scylla and charybdis of fiber sprouting after spinal cord injury. Mol Neurobiol 2008; 37:52-63. [PMID: 18415034 DOI: 10.1007/s12035-008-8016-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2007] [Accepted: 03/19/2008] [Indexed: 10/22/2022]
Abstract
Injury to the spinal cord (SCI) can produce a constellation of problems including chronic pain, autonomic dysreflexia, and motor dysfunction. Neuroplasticity in the form of fiber sprouting or the lack thereof is an important phenomenon that can contribute to the deleterious effects of SCI. Aberrant sprouting of primary afferent fibers and synaptogenesis within incorrect dorsal horn laminae leads to the development and maintenance of chronic pain as well as autonomic dysreflexia. At the same time, interruption of connections between supraspinal motor control centers and spinal cord output cells, due to lack of successful regenerative sprouting of injured descending fiber tracts, contributes to motor deficits. Similarities in the molecular control of axonal growth of motor and sensory fibers have made the development of cogent therapies difficult. In this study, we discuss recent findings related to the degradation of inhibitory barriers and promotion of sprouting of motor fibers as a strategy for the restoration of motor function and note that this may induce primary afferent fiber sprouting that can contribute to chronic pain. We highlight the importance of careful attentiveness to off-target molecular- and circuit-level modulation of nociceptive processing while moving forward with the development of therapies that will restore motor function after SCI.
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Affiliation(s)
- Ronald Deumens
- Pain Management and Research Center, Department of Anesthesiology, Maastricht University Hospital, P. Debyelaan 25, P.O. Box 5800, 6200 AZ, Maastricht, The Netherlands
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Boyd JG, Doucette R, Kawaja MD. Defining the role of olfactory ensheathing cells in facilitating axon remyelination following damage to the spinal cord. FASEB J 2005; 19:694-703. [PMID: 15857884 DOI: 10.1096/fj.04-2833rev] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Olfactory ensheathing cells (OECs) are unique cells that are responsible for the successful regeneration of olfactory axons throughout the life of adult mammals. More than a decade of research has shown that implantation of OECs may be a promising therapy for damage to the nervous system, including spinal cord injury. Based on this research, several clinical trials worldwide have been initiated that use autologous transplantation of olfactory tissue containing OECs into the damaged spinal cord of humans. However, research from several laboratories has challenged the widely held belief that OECs are directly responsible for myelinating axons and promoting axon regeneration. The purpose of this review is to provide a working hypothesis that integrates several current ideas regarding the mechanisms of the beneficial effects of OECs. Specifically, OECs promote axon regeneration and functional recovery indirectly by augmenting the endogenous capacity of host Schwann cells to invade the damaged spinal cord. Together with Schwann cells, OECs create a 3-dimensional matrix that provides a permissive microenvironment for successful axon regeneration in the adult mammalian central nervous system.
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Affiliation(s)
- J Gordon Boyd
- Department of Anatomy and Cell Biology, Queen's University, Room 926, Botterell Hall, Kingston, ON, Canada K7L 3N6.
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Calancie B, Alexeeva N, Broton JG, Molano MR. Interlimb reflex activity after spinal cord injury in man: strengthening response patterns are consistent with ongoing synaptic plasticity. Clin Neurophysiol 2005; 116:75-86. [PMID: 15589186 DOI: 10.1016/j.clinph.2004.07.018] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/09/2004] [Indexed: 11/20/2022]
Abstract
OBJECTIVE Previous reports from our laboratory have described short-latency contractions in muscles of the distal upper limb following stimulation of lower limb nerves or skin in persons with injury to the cervical spinal cord. It takes 6 or more months for interlimb reflexes (ILR) to appear following acute spinal cord injury (SCI), suggesting they might be due to new synaptic interconnections between lower limb sensory afferents and motoneurons in the cervical enlargement. In this study, we asked if once formed, the strength of these synaptic connections increased over time, a finding that would be consistent with the above hypothesis. METHODS We studied persons with sub-acute and/or chronic cervical SCI. ILR were elicited by brief trains of electrical pulses applied to the skin overlying the tibial nerve at the back of the knee. Responses were quantified based on their presence or absence in different upper limb muscles. We also generated peri-stimulus time histograms for single motor unit response latency, probability, and peak duration. Comparisons of these parameters were made in subjects at sub-acute versus chronic stages post-injury. RESULTS In persons with sub-acute SCI, the probability of seeing ILR in a given muscle of the forearm or hand was low at first, but increased substantially over the next 1-2 years. Motor unit responses at this sub-acute stage had a prolonged and variable latency, with a lower absolute response probability, compared to findings from subjects with chronic (i.e. stable) SCI. CONCLUSIONS Our findings demonstrate that interlimb reflex activity, once established after SCI, shows signs of strengthening synaptic contacts between afferent and efferent components, consistent with ongoing synaptic plasticity. SIGNIFICANCE Neurons within the adult human spinal cord caudal to a lesion site are not static, but appear to be capable of developing novel-yet highly efficacious-synaptic contacts following trauma-induced partial denervation. In this case, such contacts between ascending afferents and cervical motoneurons do not appear to provide any functional benefit to the subject. In fact their presence may limit the regenerative effort of supraspinal pathways which originally innervated these motoneurons, should effort in animal models to promote regeneration across the lesion epicenter be successfully translated to humans with chronic SCI.
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Affiliation(s)
- Blair Calancie
- Department of Neurosurgery, SUNY Upstate Medical University, 750 E. Adams St, IHP #1213, Syracuse, NY 13210, USA.
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15
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Woerly S, Doan VD, Sosa N, de Vellis J, Espinosa-Jeffrey A. Prevention of gliotic scar formation by NeuroGel? allows partial endogenous repair of transected cat spinal cord. J Neurosci Res 2004; 75:262-272. [PMID: 14705147 DOI: 10.1002/jnr.10774] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Spinal cords of adult cats were transected and subsequently reconnected with the biocompatible porous poly (N-[2-hydroxypropyl] methacrylamide) hydrogel, NeuroGel. Tissue repair was examined at various time points from 6-21 months post reconstructive surgery. We examined two typical phenomena, astrogliosis and scar formation, in spines reconstructed with the gel and compared them to those from transected non-reconstructed spines. Confocal examination with double immunostaining for glial fibrillary acidic protein (GFAP) and myelin basic protein (MBP) showed that the interface formed between the hydrogel and the spine stumps did prevent scar formation and only a moderate gliosis was observed. The gel implant provided an adequate environment for growth of myelinated fibers and we saw angiogenesis within the gel. Electron microscopy showed that regenerating axons were myelinated by Schwann cells rather than oligodendrocytes. Moreover, the presence of the gel implant lead to a considerable reduction in damage to distal caudal portions of the spine as assessed by the presence of more intact myelinated fibers and a reduction of myelin degradation. Neurologic assessments of hindlimb movement at various times confirmed that spinal cord reconstruction was not only structural but also functional. We conclude that NeuroGel lead to functional recovery by providing a favorable substrate for regeneration of transected spinal cord, reducing glial scar formation and allowing angiogenesis.
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Affiliation(s)
| | | | - Norma Sosa
- Mental Retardation Research Center, Neuropsychiatric Institute, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Jean de Vellis
- Mental Retardation Research Center, Neuropsychiatric Institute, David Geffen School of Medicine at UCLA, Los Angeles, California
| | - Araceli Espinosa-Jeffrey
- Mental Retardation Research Center, Neuropsychiatric Institute, David Geffen School of Medicine at UCLA, Los Angeles, California
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Wall JT, Xu J, Wang X. Human brain plasticity: an emerging view of the multiple substrates and mechanisms that cause cortical changes and related sensory dysfunctions after injuries of sensory inputs from the body. BRAIN RESEARCH. BRAIN RESEARCH REVIEWS 2002; 39:181-215. [PMID: 12423766 DOI: 10.1016/s0165-0173(02)00192-3] [Citation(s) in RCA: 166] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Injuries of peripheral inputs from the body cause sensory dysfunctions that are thought to be attributable to functional changes in cerebral cortical maps of the body. Prevalent theories propose that these cortical changes are explained by mechanisms that preeminently operate within cortex. This paper reviews findings from humans and other primates that point to a very different explanation, i.e. that injury triggers an immediately initiated, and subsequently continuing, progression of mechanisms that alter substrates at multiple subcortical as well as cortical locations. As part of this progression, peripheral injuries cause surprisingly rapid neurochemical/molecular, functional, and structural changes in peripheral, spinal, and brainstem substrates. Moreover, recent comparisons of extents of subcortical and cortical map changes indicate that initial subcortical changes can be more extensive than cortical changes, and that over time cortical and subcortical extents of change reach new balances. Mechanisms for these changes are ubiquitous in subcortical and cortical substrates and include neurochemical/molecular changes that cause functional alterations of normal excitation and inhibition, atrophy and degeneration of normal substrates, and sprouting of new connections. The result is that injuries that begin in the body become rapidly further embodied in reorganizational make-overs of the entire core of the somatosensory brain, from peripheral sensory neurons to cortex. We suggest that sensory dysfunctions after nerve, root, dorsal column (spinal), and amputation injuries can be viewed as diseases of reorganization in this core.
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Affiliation(s)
- J T Wall
- Cellular and Molecular Neurobiology Program, Medical College of Ohio, Toledo 43614-5804, USA.
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Calancie B, Molano MR, Broton JG. Interlimb reflexes and synaptic plasticity become evident months after human spinal cord injury. Brain 2002; 125:1150-61. [PMID: 11960903 DOI: 10.1093/brain/awf114] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Persons with long-standing injury to the cervical spinal cord resulting in complete or partial paralysis typically develop a wide spectrum of involuntary movements in muscles receiving innervation caudal to the level of injury. We have previously shown that these movements include brief and discrete contraction of muscles in the hand and forearm in response to innocuous sensory stimulation to the feet and legs, but we have been unable to replicate these interlimb reflexes in able- bodied subjects. Properties of these muscle responses indicate that the synaptic contacts between ascending sensory fibres and motor neurones of the cervical enlargement are more efficacious than normal. If these connections are present at all times, and require the more rostrally-placed spinal cord injury to allow their emergence, one might expect their appearance relatively soon following injury, as has been shown for studies of 'latent' synapses. Conversely, delayed appearance of these interlimb reflexes would suggest either the development of new synaptic connections or a profound strengthening of existing circuits in the cervical spinal cord due to a combination of afferent target loss and motor neurone denervation from motor tracts originating rostral to the injury site. In this study, we used repeated examinations of persons with acute injury to the cervical spinal cord to examine the time post-injury at which interlimb reflexes are first seen. Using tibial nerve stimulation at the knee as a screening test, a total of 24 subjects were found to develop interlimb reflexes following spinal cord injury. Latencies between stimulation and EMG were as brief as 32 ms for muscles of the forearm and 44 ms for muscles in the hand. These minimal delays all but rule out a supraspinal route for these interlimb reflexes. Interlimb reflexes first became evident no sooner than approximately 6 months following injury, and in some individuals were not seen until well over 1 year post-injury. Enhanced lower limb segmental excitability had emerged in nearly all of these subjects weeks or months prior to the first appearance of interlimb reflexes, arguing against a manifestation of traditional post-traumatic spasticity as a basis for this activity. This prolonged delay between time of injury and emergence of interlimb reflex activity lends support to the hypothesis that this activity represents an example of plasticity-and perhaps 'regenerative sprouting'-in the human spinal cord following traumatic injury.
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Affiliation(s)
- Blair Calancie
- The Miami Project to Cure Paralysis and Department of Neurological Surgery, University of Miami School of Medicine, Miami, FL 33136, USA.
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Woerly S, Doan VD, Evans-Martin F, Paramore CG, Peduzzi JD. Spinal cord reconstruction using NeuroGel implants and functional recovery after chronic injury. J Neurosci Res 2001; 66:1187-97. [PMID: 11746452 DOI: 10.1002/jnr.1255] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
There is currently a lack of effective ways to achieve functional tissue repair of the chronically injured spinal cord. We investigated the potential of using NeuroGel, a biocompatible polymer hydrogel, to induce a reconstruction of the rat spinal cord after chronic compression-produced injury. NeuroGel was inserted 3 months after a severe injury into the post-traumatic lesion cavity. Rats were placed in an enriched environment and the functional deficits were measured using the BBB rating scale. A significant improvement in the mean BBB scores was observed. Rats without enriched environment and severely injured rats with an enriched environment alone showed no improvement; however, 7 months after reconstructive surgery using NeuroGel, a reparative neural tissue had formed within the polymer gel that included myelinated axons and dendro-dendritic contacts. NeuroGel implantation into a chronic spinal cord injury therefore resulted in tissue reconstruction and functional improvement, suggesting that such an approach may have therapeutic value in the repair of focal lesions in humans.
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Affiliation(s)
- S Woerly
- Organogel Canada Ltée, 1400 Parc Technologique Blvd., Québec City, Québec G1P 4R7, Canada.
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Brook GA, Lawrence JM, Raisman G. Columns of Schwann cells extruded into the CNS induce in-growth of astrocytes to form organized new glial pathways. Glia 2001; 33:118-30. [PMID: 11180509 DOI: 10.1002/1098-1136(200102)33:2<118::aid-glia1011>3.0.co;2-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Our previous work showed that stereotaxic microextrusion of columns of purified peripheral nerve-derived Schwann cells into the thalamus of syngeneic adult rats induces host axons to grow into the column and form a new fiber tract. Here we describe the time course of cellular events that lead to the formation of this new tract. At 2 h postoperation, numerous OX42-positive microglia accumulated at the graft-host interface, after which donor columns became progressively and heavily infiltrated by microglia/macrophages that took on an elongated morphology in parallel with the highly orientated processes of the donor Schwann cells. The penetration of host astrocytic processes into the Schwann cell columns was substantially slower in onset, being first detected at 4 days postoperation. This event was contemporaneous with the in-growth of host thalamic axons. Between 7 and 14 days postoperation, GFAP-positive astrocytes became fully incorporated into the transplants, where they too adopted an elongated form, orientated in parallel with the longitudinal axis of the graft. Thus, the columns became a mosaic of elongated and highly orientated donor Schwann cells intimately mingled with host microglia, astrocytes, and numerous, largely unbranched 200-kDa neurofilament-positive axons from the adjacent thalamus. Electron microscopy demonstrated that the processes of donor Schwann cells and host astrocytes within the column formed tightly packed bundles that were surrounded by a partial or complete basal lamina. Control columns, formed by extruding freeze-thaw-killed Schwann cells or purified peripheral nerve fibroblasts induced a reactive injury response by the adjacent host microglia and astrocytes, but neither host astrocytes nor neurofilament-positive axons were incorporated into the columns. A better understanding of the mechanisms that regulate the interactions between donor and host glia should facilitate improved integration of such grafts and enhance their potential for inducing tissue repair.
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Affiliation(s)
- G A Brook
- Department of Neurology, Aachen University Medical School, Pauwelsstrasse 30, D-52057 Aachen, Germany.
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King VR, Bradbury EJ, McMahon SB, Priestley JV. Changes in truncated trkB and p75 receptor expression in the rat spinal cord following spinal cord hemisection and spinal cord hemisection plus neurotrophin treatment. Exp Neurol 2000; 165:327-41. [PMID: 10993692 DOI: 10.1006/exnr.2000.7480] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Although numerous studies have examined the effects of neurotrophin treatment following spinal cord injury, few have examined the changes that occur in the neurotrophin receptors following either such damage or neurotrophin treatment. To determine what changes occur in neurotrophin receptor expression following spinal cord damage, adult rats received a midthoracic spinal cord hemisection alone or in combination with intrathecal application of brain-derived neurotrophic factor (BDNF) or neurotrophin-3 (NT-3). Using immunohistochemical and in situ hybridization techniques, p75, trkA, trkB, and trkC receptor expression was examined throughout the spinal cord. Results showed that trkA, full-length trkB, and trkC receptors were not present in the lesion site but had a normal expression pattern in uninjured parts of the spinal cord. In contrast, p75 receptor expression occurred on Schwann cells throughout the lesion site. BDNF and NT-3 (but not saline) applied to the lesion site increased this expression. In addition, the truncated trkB receptor was expressed in the border between the lesion and intact spinal cord. Truncated trkB receptor expression was also increased throughout the white matter ipsilateral to the lesion and BDNF (but not NT-3 or saline) prevented this increase. The study is the first to show changes in truncated trkB receptor expression that extend beyond the site of a spinal cord lesion and is one of the first to show that BDNF and NT-3 affect Schwann cells and/or p75 expression following spinal cord damage. These results indicate that changes in neurotrophin receptor expression following spinal cord injury could influence the availability of neurotrophins at the lesion site. In addition, neurotrophins may affect their own availability to damaged neurons by altering the expression of the p75 and truncated trkB receptor.
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Affiliation(s)
- V R King
- Neuroscience Section, Division of Biomedical Sciences, Queen Mary and Westfield College, Mile End Road, London, E1 4NS, United Kingdom
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Bruce JH, Norenberg MD, Kraydieh S, Puckett W, Marcillo A, Dietrich D. Schwannosis: role of gliosis and proteoglycan in human spinal cord injury. J Neurotrauma 2000; 17:781-8. [PMID: 11011818 DOI: 10.1089/neu.2000.17.781] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Schwannosis (aberrant proliferation of Schwann cells and nerve fibers) has been reported following spinal cord injury (SCI). In this study, we examined the incidence of schwannosis following human SCI, and investigated its relationship to gliosis. We found evidence of schwannosis in 32 out of 65 cases (48%) of human SCI that survived 24 h to 24 years after injury; this incidence rose to 82% in those patients who survived for more than 4 months. Schwannosis was not observed in cases that survived less than 4 months after injury. In affected cases, it was generally noted in areas that had low immunoreactivity for glial fibrillary acidic protein (GFAP), suggesting that reduced gliosis might have contributed to the aberrant proliferation of Schwann cells following SCI. Since chondroitin sulfate proteoglycan (CSPG) has been proposed to play a role in Schwann cell/glial interaction, we performed immunohistochemical staining for CSPG to investigate its potential relationship with schwannosis. CSPG in the injured cord was generally associated with the blood vessel walls, but was also sometimes noted in reactive astrocytes. In SCI with schwannosis, CSPG staining was more prominent and confined largely to the extracellular matrix and basal lamina of proliferating Schwann cells. Our study suggests that Schwann cells, which may have been displaced from spinal roots and introduced into the injured cord through a break in the pial surface, are capable of proliferating and producing CSPG, particularly in the setting of reduced gliosis. Since CSPG has been associated with inhibition of neurite outgrowth, its increased production by aberrant Schwann cells may impair spinal cord regeneration after injury.
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Affiliation(s)
- J H Bruce
- Department of Pathology, University of Miami School of Medicine, and Miami Project to Cure Paralysis, Florida 33101,USA.
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Brook GA, Houweling DA, Gieling RG, Hermanns T, Joosten EA, Bär DP, Gispen WH, Schmitt AB, Leprince P, Noth J, Nacimiento W. Attempted endogenous tissue repair following experimental spinal cord injury in the rat: involvement of cell adhesion molecules L1 and NCAM? Eur J Neurosci 2000; 12:3224-38. [PMID: 10998106 DOI: 10.1046/j.1460-9568.2000.00228.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
It is widely accepted that the devastating consequences of spinal cord injury are due to the failure of lesioned CNS axons to regenerate. The current study of the spontaneous tissue repair processes following dorsal hemisection of the adult rat spinal cord demonstrates a phase of rapid and substantial nerve fibre in-growth into the lesion that was derived largely from both rostral and caudal spinal tissues. The response was characterized by increasing numbers of axons traversing the clearly defined interface between the lesion and the adjacent intact spinal cord, beginning by 5 days post operation (p.o.). Having penetrated the lesion, axons became associated with a framework of NGFr-positive non-neuronal cells (Schwann cells and leptomeningeal cells). Surprisingly few of these axons were derived from CGRP- or SP-immunoreactive dorsal root ganglion neurons. At the longest survival time (56 days p.o.), there was a marked shift in the overall orientation of fibres from a largely rostro-caudal to a dorso-ventral axis. Attempts to identify which recognition molecules may be important for these re-organizational processes during attempted tissue repair demonstrated the widespread and intense expression of the cell adhesion molecules (CAM) L1 and N-CAM. Double immunofluorescence suggested that both Schwann cells and leptomeningeal cells contributed to the pattern of CAM expression associated with the cellular framework within the lesion.
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Affiliation(s)
- G A Brook
- Department of Neurology, Aachen University Medical School, Pauwelsstrabetae 30, D-52057 Aachen, Germany.
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Haninec P, Dubový P, Houst'ava L, Stejskal L. Acellular nerve graft re-seeded by Schwann cells migrating from the nerve stump can stimulate spinal motoneurons for functional reinnervation of the rat muscle. Ann Anat 2000; 182:123-31. [PMID: 10755179 DOI: 10.1016/s0940-9602(00)80069-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The acellular nerve graft was utilised to restore a functional reinnervation of the biceps brachii muscle from the motoneuron pool of the cervical spinal cord. The musculocutaneous nerve stump was sutured to an acellular nerve graft, the opposite end of which was inserted into the cervical spinal cord cranial to the avulsed C5 ventral root. The acellular nerve graft was repopulated by Schwann cells heavily immunostained for NGFr within 90 days. The Schwann cells migrating from the nerve stump reached the spinal cord grey matter, where they stimulated the motoneurons to send axonal sprouts. The functional reinnervation of the biceps brachii muscle was assessed by means of the behavioural (grooming) test and EMG, the presence of myelinated and unmyelinated axons was demonstrated by light and electron microscopy. The axonal reconnection of the musculocutaneous nerve stump was verified by horseradish peroxidase retrograde labelling of the spinal motoneurons. Moreover, the motoneurons on the operated side of the C5 spinal segment displayed increased immunostaining for GAP-43 in comparison to the contralateral side, whereas the pattern of AChE histochemical reaction was similar on both the operated and contralateral side, of the C5 segment 150 days after acellular graft implantation. The regenerated axons bridged a 4-cm long originally acellular nerve graft to reach and reinnervate the biceps brachii muscle. The reinnervation of the neuromuscular junctions was morphologically determined by immunofluorescence for neurofilaments. The number of myelinated axons in the acellular nerve graft was significantly higher than those growing over the cellular graft, but their diameter was smaller. The results of experiments presented here demonstrate functional recovery of the biceps muscle reinnervation through the acellular nerve graft repopulated by migrating Schwann cells. The process of reinnervation by acellular nerve graft is however delayed and worse in comparison with the cellular graft.
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Affiliation(s)
- P Haninec
- Division of Neurosurgery, 3rd Faculty of Medicine, Charles University, Prague, Czech Republic
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