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      Schwann cell expression of an oligodendrocyte-like remyelinating pattern after ethidium bromide injection in the rat spinal cord Translated title: Expressão pelas células de Schwann de um padrão de remielinização semelhante ao oligodendroglial após injeção de brometo de etídio na medula espinhal de ratos

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          Abstract

          Schwann cells are recognized by their capacity of producing single internodes of myelin around axons of the peripheral nervous system. In the ethidium bromide (EB) model of primary demyelination in the brainstem, it is observed the entry of Schwann cells into the central nervous system in order to contribute to the myelin repair performed by the oligodendrocytes that survived to the EB gliotoxic action, being able to even remyelinate more than one axon at the same time, in a pattern of repair similar to the oligodendroglial one. The present study was developed in the spinal cord to observe if Schwann cells maintained this competence of attending simultaneously different internodes. It was noted that, on the contrary of the brainstem, Schwann cells were the most important myelinogenic cells in the demyelinated site and, although rare, also presented the capacity of producing more than one internode of myelin in distinct axons.

          Translated abstract

          As células de Schwann são reconhecidas por sua capacidade de produzir internodos de mielina únicos ao redor de axônios do sistema nervoso periférico. No modelo de desmielinização primária do brometo de etídio (BE) no tronco encefálico, tem sido observada a entrada destas células no sistema nervoso central. Isso pode contribuir para o reparo mielínico desempenhado pelos oligodendrócitos que sobreviveram à ação glitóxica do BE, chegando a remielinizar mais de um axônio ao mesmo tempo, em um padrão de reparo semelhante ao oligodendroglial. O presente estudo foi realizado na medula espinhal para observar se as células de Schwann mantinham esta competência de atender simultaneamente diferentes internodos. Foi observado que, ao contrário do tronco encefálico, as células de Schwann foram as células mielinogênicas mais importantes no sítio de desmielinização induzida pelo BE e, embora raro, também apresentaram a capacidade de produzir mais de um internodo de mielina em axônios distintos.

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          Most cited references28

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          Extracellular matrix of the central nervous system: from neglect to challenge.

          The basic concept, that specialized extracellular matrices rich in hyaluronan, chondroitin sulfate proteoglycans (aggrecan, versican, neurocan, brevican, phosphacan), link proteins and tenascins (Tn-R, Tn-C) can regulate cellular migration and axonal growth and thus, actively participate in the development and maturation of the nervous system, has in recent years gained rapidly expanding experimental support. The swift assembly and remodeling of these matrices have been associated with axonal guidance functions in the periphery and with the structural stabilization of myelinated fiber tracts and synaptic contacts in the maturating central nervous system. Particular interest has been focused on the putative role of chondroitin sulfate proteoglycans in suppressing central nervous system regeneration after lesions. The axon growth inhibitory properties of several of these chondroitin sulfate proteoglycans in vitro, and the partial recovery of structural plasticity in lesioned animals treated with chondroitin sulfate degrading enzymes in vivo have significantly contributed to the increased awareness of this long time neglected structure.
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            Schwann cell migration is integrin-dependent and inhibited by astrocyte-produced aggrecan.

            Schwann cells transplantation has considerable promise in spinal cord trauma to bridge the site of injury and for remyelination in demyelinating conditions. They support axonal regeneration and sprouting by secreting growth factors and providing a permissive surface and matrix molecules while shielding axons from the inhibitory environment of the central nervous system. However, following transplantation Schwann cells show limited migratory ability and they are unable to intermingle with the host astrocytes. This in turn leads to formation of a sharp boundary and an abrupt transition between the Schwann cell graft and the host tissue astrocytes, therefore preventing regenerating axons from exiting the graft. The objective of this study was to identify inhibitory elements on astrocytes involved in restricting Schwann cell migration. Using in vitro assays of cell migration, we show that aggrecan produced by astrocytes is involved in the inhibition of Schwann cell motility on astrocytic monolayers. Knockdown of this proteoglycan in astrocytes using RNAi or digestion of glycosaminglycan chains on aggrecan improves Schwann cell migration. We further show aggrecan mediates its effect by disruption of integrin function in Schwann cells, and that the inhibitory effects of aggrecan can overcome by activation of Schwann cell integrins.
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              ETHIDIUM BROMIDE INDUCED DEMYELINATION IN THE SPINAL CORD OF THE CAT

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                Author and article information

                Journal
                anp
                Arquivos de Neuro-Psiquiatria
                Arq. Neuro-Psiquiatr.
                Academia Brasileira de Neurologia - ABNEURO (São Paulo, SP, Brazil )
                0004-282X
                1678-4227
                October 2010
                : 68
                : 5
                : 783-787
                Affiliations
                [01] São Paulo SP orgnameUniversity Paulista orgdiv1Department of Immunopathology Brazil
                [02] Santa Maria RS orgnameFederal University of Santa Maria orgdiv1Departament of Pathology Brazil
                Article
                S0004-282X2010000500021 S0004-282X(10)06800521
                10.1590/S0004-282X2010000500021
                2d64647f-f971-4b2b-a530-76dd070877ea

                This work is licensed under a Creative Commons Attribution 4.0 International License.

                History
                : 23 March 2010
                : 05 April 2010
                : 15 November 2009
                Page count
                Figures: 0, Tables: 0, Equations: 0, References: 27, Pages: 5
                Product

                SciELO Brazil

                Categories
                Articles

                spinal cord,demyelination,ethidium bromide,remyelination,Schwann cells,brometo de etídio,células de Schwann,desmielinização,medula espinhal,remielinização

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