Les lésions spinales conduisent à des altérations majeures des fonctions sensorimotrices. Les récupérations fonctionnelles consécutives à ces atteintes sont très limitées, notamment en raison des capacités réduites de réparation des tissus endommagés dans le SNC. En outre, ces récupérations dépendent notamment de plusieurs processus cellulaires tels que l'activation astrogliale qui conduit à la formation de la cicatrice gliale, ou encore l'inflammation dont les cellules microgliales et les mastocytes sont les effecteurs les plus précoces. Cette inflammation est connue pour exacerber les dommages tissulaires et restreindre les possibilités de récupération. Cependant, des études récentes chez l'animal et chez l'Homme montrent que l'inflammation pourrait également avoir des effets favorisant les processus de récupération. Le but de cette thèse était de mieux comprendre les liens qui existent entre neuroinflammation, neuroplasticité et récupérations fonctionnelles après lésion spinale. L’objectif expérimental visait à examiner les réactivités microgliales, mastocytaires et astrocytaires post-lésionnelles, en parallèle avec des restaurations fonctionnelles. Dans ce contexte nous nous sommes plus particulièrement intéressés à l'influence d'une cytokine pro-inflammatoire, le Granulocyte-Macrophage Colony Stimulating Factor (GM-CSF) sur ces processus inflammatoires et la plasticité fonctionnelle après une hémisection C4-C5 chez le rat adulte. L’ensemble de nos travaux suggère que le GM-CSF pourrait agir par l’intermédiaire de plusieurs événements cellulaires et moléculaires, en favorisant des phénomènes de plasticité adaptatifs et la récupération partielle de fonctions altérées. / Spinal cord injuries are mostly of traumatic origin and result in major sensorimotor deficits. Postlesion functional recovery is limited, especially because of the reduced capacity of repairing damaged tissues. Moreover, this recovery depends specifically on several cellular processes such as astroglial activation conducting to glial scar formation, or inflammation for which microglial and mast cells are the earliest effectors. This inflammation is known to exacerbate tissue damages and restrain the capacity to recover. However, recent studies in animals and humans show that inflammation may also have beneficial aeffects on recovery processes. The studies conducted during my doctoral research were intended to better understand the links between neuroinflammation, neuroplasticity and functional recovery following spinal cord injury. We aimed at examining microglial, mast cells and astroglial reactivities after the injury, in relation with functional recovery of somatosensory and motor functions. In this context, we were particularly interested in the influence of Granulocyte Macrophage-Colony Stimulating Factor (GM-CSF) on inflammatory and plasticity mechanisms after a C4-C5 hemisection in the adult rat. Our doctoral research suggests that GM-CSF could act through several cellular and molecular events promoting adaptive plasticity phenomena underlying partial recovery of impaired functions.

A lesão medular traumática é uma patologia incapacitante, ainda sem tratamento eficaz. As terapias celulares representam uma nova estratégia para o tratamento destas lesões. As células-tronco adultas são fontes potenciais para o transplante celular com o objetivo de minimizar a lesão e promover a recuperação de tecidos lesados, como a medula espinhal. O objetivo desta tese foi avaliar a eficácia do transplante de células-tronco adultas na recuperação funcional e regeneração da lesão medular traumática em modelo experimental de lesão medular contusa em ratas fêmeas Wistar. Os principais objetivos foram: a) comparar os efeitos do transplante da fração mononuclear de sangue de cordão umbilical humano e de células-tronco mesenquimais dos vasos da parede do cordão umbilical humano; b) determinar a janela terapêutica deste tipo de intervenção, comparando os implantes de células- tronco realizados 1 hora, 24 horas e 9 dias após a lesão; c) demonstrar a possível diferenciação das células-tronco implantadas, bem como sua integração no tecido lesado. Os resultados obtidos demonstraram que o transplante de células foi mais eficaz para a recuperação funcional da lesão medular em ratas Wistar quando realizado pela via de administração local 1h após a lesão, quando comparado com a administração na cisterna magna e a aplicação 9 dias a lesão. O tratamento com a fração de células mononucleares ou com as células-tronco mesenquimais do sangue do cordão umbilical 24h após a lesão, não apresentou resultado funcional significativo.Observou-se a neuroproteção do tecido medular quando foi realizado o transplante de células-tronco mesenquimais 1h após a lesão medular. As células humanas transplantadas migraram e sobreviveram no local da lesão quando administradas na cisterna magna ou quando administradas diretamente no local da lesão, porém não se diferenciaram em células gliais ou neurônios. Concluímos que o transplante de células-tronco adultas promoveu a recuperação funcional após a lesão medular contusa, principalmente quando realizado 1h após a lesão diretamente no local da lesão. Apesar das células transplantadas sobreviverem na área da lesão, não foi evidenciada diferenciação celular. / Spinal cord injury is a debilitating disease and yet no effective treatment is available. In this framework cell therapy represents a new strategy to treat this condition. Adult stem cells are potential sources for cell transplantation in order to minimize injury and promote the recovery of damaged tissues, such as the spinal cord. The purpose of this Thesis was to evaluate the action of adult stem cells in the regeneration and functional recovery of spinal cord injury in experimental contusion spinal cord injury in female Wistar rats. Main goals were: a) to compare the effects of transplantation of the mononuclear cells of human umbilical cord blood and mesenchymal stem cells of the vessel wall of human umbilical cord; b) to determine the therapeutic window of this type of intervention, comparing the stem cell implants performed 1 hour, 24 hours and 9 days after injury; c) to demonstrate the possible differentiation of cells implanted, as well as their integration into the damaged tissue. Results reported demonstrate that the transplantation of stem cells was more effective for functional recovery of spinal cord injury when performed into the site of the lesion 1 h after injury, as compared with administration in the cisterna magna 9 days after injury. Treatment with mononuclear cells and mesenchymal cells from umbilical cord blood 24 hours after injury, not showed functional outcome. Neuroprotection was observed when mesenchymal stem cells were transplanted 1 hour after spinal cord injury. The transplanted human cells survived and migrated to the site of injury either when administered in the cisterna magna or directly onto the injury site, but did not differentiated into glial cells or neurons. It is suggested that the transplantation of adult stem cells promotes functional recovery after spinal cord injury when performed 1 hour after injury directly at the injury site, however differentiation of transplanted cells was not detected.

A lesão medular traumática é uma patologia incapacitante, ainda sem tratamento eficaz. As terapias celulares representam uma nova estratégia para o tratamento destas lesões. As células-tronco adultas são fontes potenciais para o transplante celular com o objetivo de minimizar a lesão e promover a recuperação de tecidos lesados, como a medula espinhal. O objetivo desta tese foi avaliar a eficácia do transplante de células-tronco adultas na recuperação funcional e regeneração da lesão medular traumática em modelo experimental de lesão medular contusa em ratas fêmeas Wistar. Os principais objetivos foram: a) comparar os efeitos do transplante da fração mononuclear de sangue de cordão umbilical humano e de células-tronco mesenquimais dos vasos da parede do cordão umbilical humano; b) determinar a janela terapêutica deste tipo de intervenção, comparando os implantes de células- tronco realizados 1 hora, 24 horas e 9 dias após a lesão; c) demonstrar a possível diferenciação das células-tronco implantadas, bem como sua integração no tecido lesado. Os resultados obtidos demonstraram que o transplante de células foi mais eficaz para a recuperação funcional da lesão medular em ratas Wistar quando realizado pela via de administração local 1h após a lesão, quando comparado com a administração na cisterna magna e a aplicação 9 dias a lesão. O tratamento com a fração de células mononucleares ou com as células-tronco mesenquimais do sangue do cordão umbilical 24h após a lesão, não apresentou resultado funcional significativo.Observou-se a neuroproteção do tecido medular quando foi realizado o transplante de células-tronco mesenquimais 1h após a lesão medular. As células humanas transplantadas migraram e sobreviveram no local da lesão quando administradas na cisterna magna ou quando administradas diretamente no local da lesão, porém não se diferenciaram em células gliais ou neurônios. Concluímos que o transplante de células-tronco adultas promoveu a recuperação funcional após a lesão medular contusa, principalmente quando realizado 1h após a lesão diretamente no local da lesão. Apesar das células transplantadas sobreviverem na área da lesão, não foi evidenciada diferenciação celular. / Spinal cord injury is a debilitating disease and yet no effective treatment is available. In this framework cell therapy represents a new strategy to treat this condition. Adult stem cells are potential sources for cell transplantation in order to minimize injury and promote the recovery of damaged tissues, such as the spinal cord. The purpose of this Thesis was to evaluate the action of adult stem cells in the regeneration and functional recovery of spinal cord injury in experimental contusion spinal cord injury in female Wistar rats. Main goals were: a) to compare the effects of transplantation of the mononuclear cells of human umbilical cord blood and mesenchymal stem cells of the vessel wall of human umbilical cord; b) to determine the therapeutic window of this type of intervention, comparing the stem cell implants performed 1 hour, 24 hours and 9 days after injury; c) to demonstrate the possible differentiation of cells implanted, as well as their integration into the damaged tissue. Results reported demonstrate that the transplantation of stem cells was more effective for functional recovery of spinal cord injury when performed into the site of the lesion 1 h after injury, as compared with administration in the cisterna magna 9 days after injury. Treatment with mononuclear cells and mesenchymal cells from umbilical cord blood 24 hours after injury, not showed functional outcome. Neuroprotection was observed when mesenchymal stem cells were transplanted 1 hour after spinal cord injury. The transplanted human cells survived and migrated to the site of injury either when administered in the cisterna magna or directly onto the injury site, but did not differentiated into glial cells or neurons. It is suggested that the transplantation of adult stem cells promotes functional recovery after spinal cord injury when performed 1 hour after injury directly at the injury site, however differentiation of transplanted cells was not detected.

A lesão medular traumática é uma patologia incapacitante, ainda sem tratamento eficaz. As terapias celulares representam uma nova estratégia para o tratamento destas lesões. As células-tronco adultas são fontes potenciais para o transplante celular com o objetivo de minimizar a lesão e promover a recuperação de tecidos lesados, como a medula espinhal. O objetivo desta tese foi avaliar a eficácia do transplante de células-tronco adultas na recuperação funcional e regeneração da lesão medular traumática em modelo experimental de lesão medular contusa em ratas fêmeas Wistar. Os principais objetivos foram: a) comparar os efeitos do transplante da fração mononuclear de sangue de cordão umbilical humano e de células-tronco mesenquimais dos vasos da parede do cordão umbilical humano; b) determinar a janela terapêutica deste tipo de intervenção, comparando os implantes de células- tronco realizados 1 hora, 24 horas e 9 dias após a lesão; c) demonstrar a possível diferenciação das células-tronco implantadas, bem como sua integração no tecido lesado. Os resultados obtidos demonstraram que o transplante de células foi mais eficaz para a recuperação funcional da lesão medular em ratas Wistar quando realizado pela via de administração local 1h após a lesão, quando comparado com a administração na cisterna magna e a aplicação 9 dias a lesão. O tratamento com a fração de células mononucleares ou com as células-tronco mesenquimais do sangue do cordão umbilical 24h após a lesão, não apresentou resultado funcional significativo.Observou-se a neuroproteção do tecido medular quando foi realizado o transplante de células-tronco mesenquimais 1h após a lesão medular. As células humanas transplantadas migraram e sobreviveram no local da lesão quando administradas na cisterna magna ou quando administradas diretamente no local da lesão, porém não se diferenciaram em células gliais ou neurônios. Concluímos que o transplante de células-tronco adultas promoveu a recuperação funcional após a lesão medular contusa, principalmente quando realizado 1h após a lesão diretamente no local da lesão. Apesar das células transplantadas sobreviverem na área da lesão, não foi evidenciada diferenciação celular. / Spinal cord injury is a debilitating disease and yet no effective treatment is available. In this framework cell therapy represents a new strategy to treat this condition. Adult stem cells are potential sources for cell transplantation in order to minimize injury and promote the recovery of damaged tissues, such as the spinal cord. The purpose of this Thesis was to evaluate the action of adult stem cells in the regeneration and functional recovery of spinal cord injury in experimental contusion spinal cord injury in female Wistar rats. Main goals were: a) to compare the effects of transplantation of the mononuclear cells of human umbilical cord blood and mesenchymal stem cells of the vessel wall of human umbilical cord; b) to determine the therapeutic window of this type of intervention, comparing the stem cell implants performed 1 hour, 24 hours and 9 days after injury; c) to demonstrate the possible differentiation of cells implanted, as well as their integration into the damaged tissue. Results reported demonstrate that the transplantation of stem cells was more effective for functional recovery of spinal cord injury when performed into the site of the lesion 1 h after injury, as compared with administration in the cisterna magna 9 days after injury. Treatment with mononuclear cells and mesenchymal cells from umbilical cord blood 24 hours after injury, not showed functional outcome. Neuroprotection was observed when mesenchymal stem cells were transplanted 1 hour after spinal cord injury. The transplanted human cells survived and migrated to the site of injury either when administered in the cisterna magna or directly onto the injury site, but did not differentiated into glial cells or neurons. It is suggested that the transplantation of adult stem cells promotes functional recovery after spinal cord injury when performed 1 hour after injury directly at the injury site, however differentiation of transplanted cells was not detected.

Lorsque le système nerveux central des mammifères est lésé, un ensemble de réactions secondaires impliquant l’inflammation et une gliose réactive conduit à la formation d’une cicatrice gliale qui inhibe la régénération axonale. Dans le cas d’une lésion de la moelle épinière l’absence de réparation efficace des réseaux axonaux lésés peut conduire à la paraplégie ou à la tétraplégie. Aujourd’hui on estime à plus de 2,5 millions le nombre d’individus dans le monde souffrant de ces handicaps et il n’existe à ce jour aucun traitement validé pour améliorer la situation des patients. Cependant, certaines approches de thérapie moléculaire, cellulaire, et de réadaptation semblent toutefois prometteuses sur modèle animal. La dégradation des chondroitines sulfates protéoglycanes (CSPGs), principales protéines inhibitrices de la cicatrice gliale, par clivage des coeurs protéiques et ou des chaînes latérales glycosaminoglycanes favorise la régénération axonale et entraîne une récupération fonctionnelle. Des études ont montré que la métalloprotéase matricielle MMP‐2 est capable de dégrader le coeur protéique de ces CSPGs. Par ailleurs, les cellules engainantes de la muqueuse olfactive (CEOs) occupent une place privilégiée parmi les types cellulaires proposés dans la thérapie cellulaire en favorisant la croissance axonale et la récupérationfonctionnelle après lésion de la moelle épinière. Cependant, les mécanismes qui sous‐tendent les propriétés régénératrices des CEOs restent essentiellement inconnus. Dans notre Thèse, nous présentons nos travaux en trois parties. Dans la première, nous montrons in vitro que : i) les CEOs en culture primaire secrètent des taux élevés de MMP‐2, au moins en partie active ; ii) les gélatinases MMP‐2 et MMP‐9 présentent une sécrétion vésiculaire golgi‐dépendante; iii) la distribution des vésicules contenant les MMPs est liée à celle du cytosquelette et des moteurs moléculaires qui participent probablement à une sécrétion focalisée de ces molécules en fonction d’interactions entre le milieu extracellulaire et le cytosquelette ; iv) les MMPs peuvent avoir une distribution nucléaire dans les CEOs ; v) MMP‐2 jouerait un rôle dans la migration des CEOs, un processus important dans leurs capacités à réparer le tissu nerveux. Dans la seconde partie de notre thèse, nous avons développé un modèle de cicatrice gliale in vitro et nous montrons que : i) la migration des cellules astrocytaires de la cicatrice gliale in vitro est sensible aux effets des inhibiteurs des MMPs, contrairement aux cellules microgliales ; ii) les CEOs lèvent l’inhibition de croissance axonale due aux cellules astro‐microgiales ; iii) le potentiel des CEOs à créer un environnement permissif à la croissance axonale serait lié aux gélatinases sécrétées par ces cellules, en particulier MMP‐2. Dans la troisième partie de notre Thèse, nous avons évalué in vivo si MMP‐2 contribuait aux effets bénéfiques des CEOs. Nous montrons pour la première fois, dans un model animal d’hémisection de la moelle épinière, et en utilisant des approches anatomiques, électrophysiologiques et d’analyse de la locomotion, qu’une administration chronique de MMP‐2 recombinante : i) augmente le nombre et le diamètre des axones du coté distal du site de lésion ; ii) restaure la réponse évoquée du reflexe‐H distal au site de lésion ; iii) améliore la réponse respiratoire à la fatigue musculaire induite électriquement et, iv) le plus important, améliore la récupération de la locomotion. L’ensemble de notre travail suggère que MMP‐2 sécrétée par les CEOs jouerait un rôle important des les propriétés bénéfiques de ces cellules lorsqu’elles sont transplantées dans des sites de lésions de la ME, et que cette MMP présente un réel potentiel thérapeutique qui reste à explorer. / When the mammalian central nervous system is injured, a set of secondary reactions involving inflammation and reactive gliosis leads to the formation of a glial scar that inhibits axonal regeneration. In the case of a spinal cord lesion, the lack of effective repair of injured axonal networks can lead to paraplegia or quadriplegia. Today it is estimated that more than 2.5 million people are suffering from these handicaps worldwide, and there is as yet no validated treatment to improve the situation of patients. However, based on animal models, some molecular, cellular, and rehabilitation therapy approaches seem promising. Degradation of chondroitin sulfate proteoglycan (CSPG), the main inhibitory protein of the glial scar, by cleavage of either the protein core or side chains glycosaminoglycans, promotes axonal regeneration and leads to functional recovery. Studies have shown that the matrix metalloproteinase MMP-2 is capable of degrading the core protein of the CSPG. In addition, olfactory mucosa ensheathing cells (OECs) represent the most promising cell type for promoting axonal growth and functional recovery after spinal cord injury. However, the mechanisms underlying the regenerative properties of OECs remain essentially unknown. Here, we present our work in 2 parts. First, we show in vitro that: i) OECs in primary culture secrete high levels of active MMP-2; ii) both gelatinases, MMP-2 and MMP-9, have a vesicular Golgi-dependent secretion; iii) the distribution of vesicles containing the MMPs is linked to cytoskeleton and molecular motors distribution, which are probably involved in focused secretion of these molecules; iv) MMPs may have a nuclear distribution in OECs; v) MMP-2 plays a role in the migration of EOCs, an important process in their ability to repair nerve tissue. In the second part of my work, we evaluated whether the MMP-2 contributed to the beneficial effects of EOCs. We used an in vivo approach and we show for the first time, in an animal model of hemisection of the spinal cord, and using anatomical, electrophysiological analysis of locomotion approaches, that a chronic administration of recombinant MMP-2: i) increases the number and diameter of axons in the distal side of the site of injury; ii) restores the response-evoked H-reflex distal to the lesion site, iii) enhances the respiratory response to electrically-induced muscle fatigue, and iv) most importantly, improves the recovery of locomotion. All our work suggests that MMP-2, secreted by the EOCs, plays an important role in the recovery properties of these cells, when transplanted into spinal cord lesions, and that this MMP has a real therapeutic potential that remains to be explored.

L’accident vasculaire cérébral (AVC) est un problème majeur de santé publique car les troubles fonctionnels associés ont des répercussions délétères sur la qualité de vie des patients. Deux axes de recherche portant sur l’ischémie cérébrale chez le rat sont abordés. Pour le premier, il s’agira d’étudier les modifications de la régulation des réflexes somatiques qui peuvent contribuer à expliquer en partie les déficits fonctionnels. Nos résultats montrent une fatigue précoce au cours d’un exercice isométrique du triceps brachial et une perturbation de l’inhibition du réflexe-H post-exercice. Nous avons précisé que la perturbation de l’activité des voies réflexes est associée à une modification de l’action inhibitrice des afférences musculaires des groupes III et IV pouvant expliquer la fatigue précoce observée. L’axe 2 concerne l’optimisation de l’entrainement d’endurance, stratégie prometteuse pour traiter les déficits. L’objectif est de définir la stratégie d’endurance la plus appropriée en nous focalisant sur l’intensité de l’exercice. Pour cela, les effets des exercices d’intensité modérée (classiquement recommandés) ont été confrontés avec ceux des exercices intermittents de haute intensité (HIT) en analysant la récupération fonctionnelle et la neuroplasticité cérébrale. Nos résultats montrent que l’intensité de travail, déterminée à partir du seuil lactique, est un paramètre crucial car les HIT se révèlent être plus efficaces en termes de récupération de la force, d’aptitude aérobie et de neuroplasticité. Ces travaux ouvrent de nombreuses perspectives où ces 2 axes pourraient se rejoindre en approfondissant les effets des HIT au niveau cérébral et spinal. / Stroke is a major public health issue because associated functional disorders have detrimental impacts on life quality and independence of patients as well as on economic state. This thesis work is focused on 2-research axis concerning cerebral ischemia in rat. The aim of the first axis is to study plasticity at spinal level by investigating the alteration of somatic reflex regulation that could contribute to partially explain functional deficits. Ours results show early fatigue of triceps brachii during an isometric contraction and H-reflex inhibition perturbation post-exercise. We also observed that the disturbance of reflex pathway activity is associated with a decrease of the inhibitory effect induced by muscular metabosensitive afferents that might explain early fatigue and observed functional deficits. The second axis treats about endurance training that is a promising strategy to reduce stroke-induced disorders but remains to improve. In that way, the purpose is to determine which endurance strategy is the most suitable by focusing on exercise intensity. In order to ensure this, the effects of moderate intensity exercise (classically recommended) have been compared to high intensity interval training (HIT) by analysing the functional recovery and cerebral neuroplasticity. Our data show that work intensity, based on lactic threshold, is a critical parameter. Indeed, HIT is more effective for increasing grip strength recovery, aerobic capacity as well as promoting neuroplasticity. The results of these 2 lines of research could be now associated by deepening the HIT effects at cerebral and spinal level that lead to numerous perspectives.

No description available.

Une lésion médullaire traumatique (LMT) a des conséquences neurologiques importantes, dont l’altération de la capacité à marcher. Prédire précocement cette capacité suite au traumatisme a inspiré le développement de multiples règles de prédiction. Simples et précises, elles prédisent la marche intérieure sur de courtes distances, sans considérer la qualité de la marche. L’utilité et la valeur ajoutée de ces règles n’ont jamais été évaluées comparativement au jugement non structuré des cliniciens à qui elles sont dédiées. L’objectif était d’identifier des éléments de l’évaluation aiguë standardisée ISNCSCI (International Standards for Neurological Classification of Spinal Cord Injury) permettant de développer une règle de prédiction clinique pour la marche communautaire extérieure indépendante un an après une LMT, tout en assurant une bonne validité externe et une utilité clinique lorsque comparée au jugement des cliniciens. La force segmentaire du membre inférieur le plus fort et la préservation de la sensibilité au toucher léger sont de meilleurs prédicteurs d’une marche indépendante. Une règle de prédiction clinique a également pu être développée : elle est pertinente; généralisable; simple; tient compte de la qualité de la marche; et est axée sur la vie communautaire, la participation sociale et la qualité de vie. La performance d’une règle de prédiction de la marche intérieure est statistiquement similaire à celle de cliniciens utilisant leur jugement non structuré, mais peut varier. Cette recherche recommande l’utilisation de règles de prédiction clinique comme aide à la décision chez les patients après une LMT, dont celle développée pour la marche communautaire indépendante. / Traumatic spinal cord injury (TSCI) has important neurological consequences including impaired walking ability. Predicting early the ability to walk again after the trauma has inspired the development of multiple clinical prediction rules. Simple and accurate, they do predict walking on short indoor distances but do not consider the quality of walking. Moreover, the usefulness and added value of these rules have never been evaluated and compared to the unstructured clinical judgment of the physicians for whom they are intended. The objective of this thesis was to identify elements of the acute INSCSCI (International Standards for Neurological Classification of Spinal Cord Injury) standardized evaluation that would allow the development of a clinical prediction rule for outdoor independent community walking one year after a TSCI, ensuring good internal and external validity as well as clinical usefulness when compared to clinical judgment. The strength of the strongest lower limb and preserved light touch sensation are the best predictors of independent walking. A clinical prediction rule was developed to meet the objective: this rule is relevant; generalizable; simple; takes into consideration the quality of walking; and is focused on community living, social participation and quality of life. The performance of a clinical prediction rule for indoor walking is statistically similar to that of clinicians using their unstructured judgment, but can vary depending on different factors. This research recommends the use of clinical prediction rules as a decision aid in patients who have undergone a TSCI, including the one developed for independent functional community walking.

Les traumatismes spinaux (TS) touchent environ 17 810 personnes chaque année en Amérique du Nord. À la suite de ces lésions, la plupart des individus atteints vont perdre l’habilité à effectuer des mouvements simples et certains peuvent présenter des paralysies d’un ou plusieurs membres. Également, ces patients vont souffrir de troubles du sommeil, de détresse émotionnelle (anxiété et dépression) et de déficits cognitifs (mémoire). L’occurrence d’un traumatisme crânien (TC) concomitant est sous-estimée et sous-diagnostiquée dans 12.4 à 74% des patients TS, pouvant affecter considérablement la réhabilitation post-traumatisme. Bien que les soins prodigués actuellement permettent une certaine récupération après TS ou TC, il semble nécessaire de développer des thérapies adaptées dans le cadre des TS-TC concomitants. Afin de combler ce manque de connaissances après TS-TC concomitant, nous avons développé un nouveau modèle animal de TS-TC concomitant. En utilisant des approches comportementales et électrophysiologiques, nous avons examiné l’impact d’un TS-TC concomitant sur les fonctions motrices, le sommeil, l’état émotionnel et les capacités cognitives. Un groupe de rats recevant un TS-TC concomitant a été comparé avec un groupe ne recevant qu’un TS seul et un groupe contrôle (SHAM), recevant une laminectomie et une craniotomie sans TS et TC. La locomotion globale et le sommeil ont été évalués à chaque semaine pendant un mois par le test de session en arène ouverte et par électroencéphalographie pour évaluer l’architecture du sommeil, l’analyse spectrale des états de vigilance, incluant spécifiquement la dynamique de l’activité delta en sommeil sans mouvement rapide des yeux (sommeil NREM). L’état émotionnel et les capacités cognitives ont été testés 6 semaines post-traumatisme. L’anxiété et la dépression ont été testées en arène ouverte et par le test de préférence au sucrose respectivement. La mémoire de travail et la mémoire spatiale ont été testées par le test du labyrinthe en Y et par le test de reconnaissance spatiale d’objets respectivement. Le TS-TC et le TS seul ont induit des déficits moteurs en comparaison au groupe SHAM. La durée et la qualité de l’éveil et du sommeil n’ont pas été affectées par le TS seul ou le TS-TC concomitant, malgré une tendance à la hause de l’activité spectrale et de la dynamique de l’activité delta en sommeil NREM après TS-TC. Ni le TS-TC ou le TS seul n’a affecté l’état émotionnel. Seule la mémoire de travail a été affectée après TS-TC en comparaison aux groupes SHAM et TS seul. Les résultats obtenus suggèrent que la mémoire de travail pourrait être considérée comme un potentiel biomarqueur de lésion concomitante de la moelle épinière et du cerveau. De plus amples expériences seront nécessaires afin de décrire complétement ce nouveau modèle animal de TS-TC concomitant comme d’une part, la réalisation de mesures comportementales spécifiques dans les phases aigue et chronique post-traumatisme et d’autre part, une mesure de la neuro-inflammation et de la plasticité par immunohistochimie au niveau de l’hippocampe. Le développement de ce nouveau modèle animal va permettre la création et l’adaptation d’outils diagnostiques et thérapeutiques pour les patients présentant des TS-TC concomitants. / Spinal cord injuries (SCI) affect 17,810 people in North America every year. In this condition, most individuals will lose the ability to perform simple motor actions and will additionally suffer from sleep disturbances, emotional distress (anxiety and depression) and cognitive impairments (memory). The occurrence of traumatic brain injury (TBI) in SCI population is underestimated and missed-diagnosed in 12.4 to 74% of SCI patients, impeding the implementation of optimal rehabilitation strategies and drug therapies. Although specialized care is critically needed to improve rehabilitation outcomes in these patients, specialized dual diagnosis care and evidence-based approaches for treatment are currently lacking. To address this knowledge gap, we developed and characterized a novel rodent model of concomitant TBI and SCI. Using a combination of behavioral and electrophysiological techniques, we examined the impact of concomitant TBI and SCI on motor function, sleep, emotional state, and cognition. A group of rats receiving concomitant TBI and SCI were compared with control groups that received SCI only or surgical procedures without injuries (SHAM group). Global locomotion and sleep were evaluated each week for one month by using the open-field test and electroencephalography to evaluate sleep architecture, the spectral composition of vigilance states, including delta activity during non-rapid eye movement (NREM) sleep. Emotional states and cognition were assessed at 6 weeks after surgery. Anxiety and depression were tested using the open-filed and sucrose preference tests, respectively. Working memory and spatial memory were evaluated by Y Maze test and spatial object recognition test, respectively. We found that concomitant TBI-SCI and SCI alone both impacted locomotor abilities, by comparison to the intact state. The duration and quality of wakefulness and sleep were not significantly affected by SCI or TBI-SCI, despite spectral analysis showing a tendency for TBI-SCI to increase NREM sleep delta activity. Neither concomitant TBI SCI nor SCI significantly impacted anxiety and depressive-like behaviors in comparison to the SHAM group. By contrast, working memory was significantly impaired after TBI-SCI but was preserved in SHAM and SCI groups. This result suggests that working memory could potentially be used as a biomarker of these concomitant injuries. Further experiments are needed to fully characterize this novel animal model. This includes performing more specific behavioral tests in the acute and chronic stages after injury. Also, immunochemistry experiments directed on molecular markers of neuro-inflammation and plasticity are needed. This novel animal model will be useful to create and adapted diagnosis and therapeutic tools for TBI-SCI patients.

A lesão medular (LM) é uma patologia incapacitante que resulta em déficits sensoriais e motores. No Brasil, a incidência anual é de 30 novos casos de lesão medular a cada 1 milhão de indivíduos e, infelizmente, a LM permanece sem um tratamento eficaz. Células-tronco derivadas do dente decíduo humano estão entre as potenciais fontes de células-tronco para transplante após a lesão medular, cujo objetivo é de promover a proteção ou a recuperação da lesão na medula espinal. Buscou-se nesta tese avaliar os efeitos do transplante, uma hora após a lesão, das células tronco de dente decíduo humano (SHED) no período agudo, subagudo e crônico sobre a neuroproteção, proteção tecidual e recuperação funcional em ratos Wistar submetidos à lesão medular por contusão. Os principais objetivos foram: a) investigar os efeitos do transplante das SHED sobre a recuperação funcional, volume da lesão e morte neuronal; b) verificar os efeitos do transplante sobre as células progenitoras, formação da cicatriz glial e modificações astrocitárias após o modelo de contusão medular Observou-se a melhora na recuperação funcional, redução do volume da lesão e morte neuronal na medula espinal dos animais que receberam o transplante de SHED após a lesão medular. As SHED aumentam o número de células precursoras na medula espinal, no período subagudo, reduzem a expressão da proteína fibrilar glial ácida (GFAP) e aumentam a expressão do canal retificador de influxo de potássio 4.1, ambas proteínas astrocitárias. Concluímos que o transplante de células-tronco derivadas do dente decíduo humano após a lesão medular promove a recuperação funcional a partir do efeito neuroprotetor iniciado na fase aguda, confirmado pelo maior número de neurônios motores presentes seis semanas após a contusão. As SHED são capazes de aumentar o número de células precursoras e de produzir modificações astrocitárias na medula espinal de ratos lesados na fase subaguda, reduzindo a formação da cicatriz glial. / Spinal cord injury (SCI) is a disabling condition that results in sensory and motor deficits. The estimated annual incidence in Brazil is of 30 new cases of spinal cord injury per 1 million of individuals; unfortunately SCI remains without an effective treatment. Stem cells from human exfoliated deciduous teeth (SHED) are one among potential sources of stem cells for transplantation after spinal cord injury in order to promote protection or tissue and functional recovery after spinal cord injury. The aim of this Thesis was to evaluate the effects of stem cells from human exfoliated deciduous teeth (SHED) transplantation, one hour after lesion, in the acute, subacute and chronic phases on neuroprotection, tissue protection and functional recovery in Wistar rats submitted to spinal cord injury by contusion The main goals were: a) to investigate the effects of SHED transplantation on functional recovery, lesion volume, and neuronal death; b) to verify the effects of the transplantation on the progenitor cells number, glial scar formation and astrocytic modifications after spinal cord contusion. Improvement of functional recovery, reduction of lesion volume and neuronal death were observed in the spinal cord of animals submitted to spinal cord injury and SHED transplantation. SHEDs increased the number of precursor cells in the spinal cord in the subacute period, reduced the expression of glial fibrillary acidic protein (GFAP) and increased the expression of the potassium influx rectifier channel 4.1, both astrocyte proteins. We conclude that transplantation of stem cells from human exfoliated deciduous teeth after spinal cord injury promotes functional recovery from the neuroprotection effect, which starts in the acute phase and is confirmed six weeks after the contusion with a higher number of motor neurons in the ventral horn of spinal cord. SHEDs are able to increase the number of precursor cells and produce astrocyte modifications in the spinal cord of injured rats in the subacute phase, reducing glial scar formation.