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Transplante de células olfativas (olfactory ensheating cells). Mudança de paradigma no tratamento de lesões medulares?
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As lesões traumáticas da medula espinhal são atualmente um problema de saúde importante, nomeadamente por afetar muitos indivíduos durante a sua vida ativa, condicionando uma redução drástica da sua qualidade de vida. Quando ocorre uma lesão medular, há uma diminuição da transmissão do sinal elétrico através das vias medulares ascendentes e descentes, devido a uma interrupção física dos feixes neuronais, mas também devido ao microambiente que se forma no local de lesão, altamente inibitório da regeneração neuronal. Esta diminuição parcial ou total da transmissão do sinal eléctrico manifesta-se clinicamente por uma redução ou abolição das capacidades sensitiva e motora abaixo do nível de lesão. As terapêuticas para as lesões medulares traumáticas oferecidas pela medicina atual são muito limitadas quer em diversidade, quer em eficácia. Assim, urge a necessidade de novas terapêuticas capazes de mudar o paradigma da abordagem a esta situação clínica.
O sistema nervoso olfativo (SNO) possui uma capacidade regenerativa inata, visto estar em contacto com o meio externo, onde existem partículas nocivas como gases e poeiras, que danificam o SNO. Para que o indivíduo mantenha o seu olfato intacto, é necessário que este sistema regenere, razão pela qual o SNO adquiriu essa capacidade ao longo de milhões de anos de evolução. As células embainhantes olfativas (Olfactory Ensheating Cells – OECs) são células da glia que existem apenas no SNO, onde desempenham funções essenciais ao desenvolvimento e regeneração neuronais, existindo evidência de que poderão contribuir para a regeneração da medula espinhal.
Foram realizados diversos estudos, quer em modelos animais, quer em humanos para investigar a eficácia do transplante de OECs em contexto de lesão da medula espinhal, com resultados promissores.
Traumatic spinal cord injury is currently an important health problem, particularly as it affects many individuals during their active lives, resulting in a drastic reduction in their quality of life. When a spinal cord injury occurs, there is a decrease in electrical signal transmission through ascending and descending spinal cord pathways, due to a physical interruption of the neural bundles, but also due to the microenvironment that forms at the site of injury, highly inhibitory to neuronal regeneration. This partial or total decrease in electrical signal transmission is clinically manifested by a reduction or abolition of sensory and motor capacities below the level of injury. The therapies for traumatic spinal cord injuries offered by current medicine are very limited in both diversity and efficacy. Thus, there is an urgent the need for new therapies capable of changing the paradigm of the approach to this clinical situation. The olfactory nervous system (ONS) has an innate regenerative capacity, since it is in contact with the external environment, where there are noxious particles such as gases and dust, which persistently damage the ONS. In order for the individual to keep his sense of smell intact, this system needs to regenerate, which is why the ONS has acquired this ability over millions of years of evolution. Olfactory Ensheating Cells (OECs) are glial cells that exist only in the ONS, where they play essential roles in the neural development and regeneration, and are believed to contribute to regeneration of the spinal cord. Several studies have been conducted, both in animal models and in humans to investigate the efficacy of transplantation of OECs in the context of spinal cord injury, with promising results.
Traumatic spinal cord injury is currently an important health problem, particularly as it affects many individuals during their active lives, resulting in a drastic reduction in their quality of life. When a spinal cord injury occurs, there is a decrease in electrical signal transmission through ascending and descending spinal cord pathways, due to a physical interruption of the neural bundles, but also due to the microenvironment that forms at the site of injury, highly inhibitory to neuronal regeneration. This partial or total decrease in electrical signal transmission is clinically manifested by a reduction or abolition of sensory and motor capacities below the level of injury. The therapies for traumatic spinal cord injuries offered by current medicine are very limited in both diversity and efficacy. Thus, there is an urgent the need for new therapies capable of changing the paradigm of the approach to this clinical situation. The olfactory nervous system (ONS) has an innate regenerative capacity, since it is in contact with the external environment, where there are noxious particles such as gases and dust, which persistently damage the ONS. In order for the individual to keep his sense of smell intact, this system needs to regenerate, which is why the ONS has acquired this ability over millions of years of evolution. Olfactory Ensheating Cells (OECs) are glial cells that exist only in the ONS, where they play essential roles in the neural development and regeneration, and are believed to contribute to regeneration of the spinal cord. Several studies have been conducted, both in animal models and in humans to investigate the efficacy of transplantation of OECs in the context of spinal cord injury, with promising results.
Descrição
Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2018
Palavras-chave
Células embainhantes dos axónios olfativos Mucosa olfativa Bulbo olfativo Sistema nervoso olfativo Transplante celular Otorrinolaringologia