O exercício físico pode atenuar os efeitos do envelhecimento sobre o sistema nervoso central, por meio do aumento da expressão de neurotrofinas, tais como fator neurotrófico derivado do cérebro (BDNF), o qual promove a ramificação dendrítica e melhora da maquinaria sináptica, pela interação com seu receptor TrkB. Receptores TrkB são produzidos no corpo da célula e transportados aos terminais axonais, por meio de SLP1, CRMP2, Rab27B e Sortilina onde são ancorados para realizar seu papel fisiológico. Sabendo que a relação entre o tráfego de receptores de neurotrofinas e o treinamento físico ainda é pouco conhecida, o objetivo do presente trabalho é analisar os níveis do receptor TrkB, bem como de seus transportadores anterógrados e retrógrados, no sistema nervoso central de ratos idosos, modelos de neurodegeneração, expostos a diferentes protocolos de treinamento físico moderado. Os ratos do primeiro grupo experimental foram expostos a 1mg/kg/dia de Rotenona ou DMSO durante 4 semanas, depois, juntamente com a exposição à rotenona, realizaram treinamento físico moderado em esteira, 5 vezes por semana, durante 40 minutos; ou permaneceram em repouso. Os ratos do segundo grupo experimental realizaram 6 semanas de treinamento, sendo em seguida expostos à rotenona por 4 semanas, e subdividos em dois grupos, um que continuou o exercício e outro que ficou sedentário. Os resultados encontrados sugerem que o treinamento físico parece reverter ou prevenir de maneira geral os danos presentes na neurodegeneração considerando as proteínas do tráfego de BDNF e seu receptor, e ainda, que a magnitude e direção destas alterações está diretamente relacionada ao protocolo de treinamento físico, bem como, a região do sistema nervoso central analisada / Physical exercise can attenuate the effects of aging on the central nervous system by increasing the expression of neurotrophins such as brain-derived neurotrophic factor (BDNF), which promotes dendritic branching and enhances synaptic machinery, through interaction with its receptor TrkB. TrkB receptors are synthesized in the cell body and are transported to the axonal terminals, through SLP1, CRMP2, Sortilin and Rab27B, to where receptors are anchored to perform its physiological role. However, the aspects of the neurotrophin receptors traffic after physical training is still a matter of investigation. Thus, the present study aims to analyze the expression levels of TrkB receptor and their anterograde carriers in aged Lewis rats, model of neurodegeneration, and its relationship with moderate exercise training. Rats from the first experimental group were exposed to 1mg/kg/day of Rotenone (ROT) or DMSO for 4 weeks, and then subjected or not to moderate exercise running on treadmill, five days a week, 40 minutes a day, combined with the drug. Rats from the second experimental group were trained for 6 weeks, followed by exposure to rotenone during 4 weeks, rats were then subdivided into two groups, one that continued the exercise and the other became sedentary. Results suggest that exercise training appears to reverse or prevent the impairment related to neurodegeneration considering the proteins involved in BDNF signaling, and also that the magnitude and direction of these changes in directly related to the physical training protocol, as well as the area of the central nervous system analyzed

INTRODUÇÃO: A degeneração do disco intervertebral (DIV) é um processo crônico e apontado como o maior causador de cervicalgia e lombalgia. Esse processo geralmente conta com a degradação da matriz extracelular, expressão de citocinas inflamatórias e fatores angiogênicos e axonogênicos. Entretanto, muito pouco se sabe sobre esse processo em DIVs assintomáticos durante o envelhecimento, principalmente no segmento cervical. O objetivo desse estudo foi de delinear o perfil de moléculas relacionadas à degeneração discal em DIVs cervicais e lombares. MÉTODOS: Discos intervertebrais humanos cervicais e lombares (C4-C6 e L4-S1) foram coletados em autópsia de 30 indivíduos presumivelmente assintomáticos e divididos em grupos jovem (GJ < 35 anos, n=60) e idoso (GI > 65 anos, n=60). O nível de degeneração foi constatado pela escala de Thompson, e foi correlacionado com a detecção imuno-histoquímica das moléculas de MMP-1, -2, -3, TIMP-1, IL-1beta, TNF-alfa, VEGF, NGF-beta e BDNF. RESULTADOS: Todos os DIVs mostraram algum grau de degeneração, embora mais acentuadas no GI. As moléculas empenhadas no estudo foram identificadas em ambos grupos. A detecção imuno-histoquímica foi prevalente no citoplasma das células nativas do DIV e na região de interseção entre a placa vertebral e o arranjo fibro-colágeno. O envelhecimento propiciou, no disco cervical, maior expressão de MMP-2, -3, VEGF, NGF-beta e BDNF, enquanto que no disco lombar, a maior expressão foi de MMP-1, -2 -3, TIMP-1, TNF-alfa, VEGF e NGF-beta. DISCUSSÃO: O envelhecimento de DIVs cervicais e lombares caracterizou-se por exibir um processo catabólico e extensivo remodelamento da matriz extracelular, os quais podem ser interpretados como eventos que antecipam a doença degenerativa discal. Esse processo é capaz de levar a angiogênese e axonogênese de modo a ampliar o metabolismo aeróbio do DIV e captar informação nociceptiva como forma de defesa, uma vez que até nos discos lombares de indivíduos jovens essa última característica pôde ser observada. Discos assintomáticos também exibem moléculas relacionadas à doença degenerativa discal e talvez a inibição de parte dessas possa resultar em terapia preventiva / INTRODUCTION: Degeneration of the intervertebral disc (DIV) is a chronic process that pointed as a major cause of neck and low back pain. This process generally includes an extracellular matrix degradation, expression of inflammatory cytokines, angiogenesis and axonogenesis factors. However, there is a little known about this process in asymptomatic DIVs during aging, especially in the cervical region. The aim of this study was to delineate the profile of molecules related to disc degeneration in the cervical and lumbar discs. METHODS: Human cervical and lumbar intervertebral discs (C4-C6 e L4-S1) were harvested at autopsy from 30 asymptomatic individuals, and divided according to age with young (GJ < 35 years old, n=60) and elderly (GI > 65 years old, n=60) groups. Gross degeneration was graded according to the Thompson scale and this was correlated to the immunohistochemical detection of molecules of MMP-1, -2, -3, TIMP-1, IL-1beta, TNF-alfa, VEGF, NGF-beta e BDNF. RESULTS: Discs from GJ were significantly less degenerated than those of GI. The molecules involved in the study were identified in both groups. The immunohistochemical detection was prevalent in the cytoplasm of native disc cells and the region between the vertebral plate and fibrous collagen arrangement (intersection). Aging provided in cervical disc, increased expression of MMP-2, -3, VEGF, NGF and BDNF-beta, whereas in the lumbar disc the highest expression of MMP-1, -2, -3, TIMP-1, TNF-alfa, VEGF and NGF-beta was seen. DISCUSSION: The aging of cervical and lumbar DIV was marked by catabolic process and a extensive remodeling on extracellular matrix which can be interpreted as a predict event of the degenerative disc disease. This process can lead to angiogenesis and axonogenesis in order to expand the aerobic metabolism of the DIV and get nociceptive information as a defense, since even in the lumbar discs of young individuals this last feature can be observed. Asymptomatic discs also exhibit molecules related to degenerative disc disease and perhaps the inhibition some of these can result in preventive therapy

O objetivo deste estudo foi avaliar a imunolocalização do fator de crescimento BMP- 2 em enxerto ósseo autógeno em bloco recoberto ou não por membrana de PTFE-e na fase inicial da reparação óssea. MATERIAL E MÉTODOS: Quarenta e oito ratos \"wistar\" foram divididos em dois grupos de estudo, um que recebeu somente o enxerto ósseo autógeno (E) e o outro que recebeu o enxerto ósseo autógeno recoberto por membrana (ME). Os períodos de avaliação foram: 0 hora, 3, 7, 14, 21 e 45 dias. Os cortes foram submetidos à reação imunoistoquímica. Foram realizadas as análises, qualitativa e quantitativa: contagem de células com marcação intracitoplasmática nas estruturas bordo, enxerto, tecido conjuntivo superior ao enxerto, interface e leito. RESULTADOS: No leito o maior número de células marcadas foi observado em 3 dias nos grupos (E) e (ME). A região de bordo apresentou maior número de células marcadas em 7 dias no grupo (E) e em 14 dias no grupo (ME), onde a marcação foi predominante em osteoblastos e células osteoprogenitoras em áreas de remodelação óssea. No tecido conjuntivo superior ao enxerto a maior proporção de marcação no grupo (E) ocorreu em 7 dias e no grupo (ME) em 21 dias, no entanto, neste último, ainda havia marcação em células osteoprogenitoras ao final dos 45 dias. Na interface, o maior número de células marcadas ocorreu entre 7 e 21 dias, considerando os grupos (E) e (ME), quando células osteoprogenitoras apresentaram-se positivas nas áreas de pontes de osso imaturo entre o leito e o enxerto. A maior proporção de marcação no enxerto foi variável entre os períodos de 3 dias no grupo (E) e 21 dias no grupo (ME), mas esta foi considerada de menor proporção quando comparada às marcações observadas nas outras estruturas. CONCLUSÕES: Os dados observados mostram que as estruturas de maiores proporções de marcação são aquelas relacionadas à intensa revascularização e osteogênese. Células osteoprogenitoras, osteoblastos e osteócitos apresentaram marcação intracitoplasmática, independentemente do período ou da estrutura analisada. À exceção da interface, o grupo (ME) apresentou marcação mais tardia quando comparado ao grupo (E) para as estruturas bordo e tecido conjuntivo superior ao enxerto. / The aim of this study was to evaluate the immunolocalization of the BMP-2 growth factor in an autogenous block graft covered or not with an e-PTFE membrane on the early phases of bone repair. MATERIAL AND METHODS: Forty-eigth wistar male rats had their mandibles augmented by either an autogenous bone block graft (B) or an autogenous bone block graft covered with an e-PTFE membrane (MB). The specimens were evaluated at baseline, 3, 7, 14, 21 and 45 days after surgery by immunohistochemistry. Qualitative and quantitative analysis were performed. RESULTS: On the receptor bed the greatest number of staining cells was observed within three days on groups (B) and (MB). The border region has shown a largest number of staining cells in seven days on (B) group and in fourteen days on (MB) group, where the staining was prominent in osteoblasts and osteoprogenitor cells in bone remodeling areas. On the connective tissue above the graft, the greatest staining proportion occurred on (B) group within seven days and on (MB) group in twenty one days. However, there was still staining in osteoprogenitor cells in the end of the experiment, (at fourty-five day period). On the interface, the greatest number of staining cells occurred between seven and twenty one days for groups (B) and (MB) respectively, when osteoprogenitor cells were positive in woven bone edges between the receptor bed and the graft. The greatest proportion of staining on the graft was variable among tree days on group (B) and twenty one days on group (MB), but this was considered a smaller proportion when compared to other structures staining. CONCLUSIONS: The data suggest that the greatest staining proportions structures are related to intense revascularization and osteogenesis. Osteoprogenitor cells, osteoblasts and osteocytes showed intracitoplasmatic staining, independently of the period or structure analyzed. Except for the interface, the (MB) group has shown later staining compared to group (MB) for border and connective tissue above the graft.

Dissialogangliosídios, como GD3 e derivados são marcadores da progressão de melanomas. Para avaliar as possíveis funções desta molécula, transfectamos células de melanócitos com o gene da enzima ST8Sia I, que converte GM3 em GD3. Mostramos que GD3 não interfere na capacidade proliferativa dessas células, porém a expressão de GD3 mostrou-se associada à sobrevivência celular. Melanomas adquirem autonomia quanto às vias dependentes do fator de crescimento de fibroblastos (FGF-1 e -2). A expressão de GD3 não interfere na resposta proliferativa a estes fatores, porém GD3 e outros glicoesfingolipídios de membrana modulam a resposta migratória induzida por FGF-2. A expressão de GD3 sensibiliza as células à morte celular induzida por diferentes quimioterápicos, como cisplatina e vimblastina; porém, torna as células resistentes ao tratamento com temozolamida. A sensibilização ao tratamento com vimblastina, mas não às outras drogas, depende da presença de GD3, como observado por ensaios de depleção metabólica / Disialoganglioside GD3 and its derivatives are melanoma progression markers. To evaluate the possible roles of these molecules along melanoma progression, we have transfected the GD3 synthase gene (ST8Sia I) in a melanocyte cell line. Accumulation of GD3 did not confer any proliferative advantage to melanocytes. However, GD3 expression was associated with cell survival. The autonomic growth of melanomas is in part related to a constitutive activation of fibroblast growth factor dependent pathways. GD3 expression did not alter the proliferative response to either FGF-1 or FGF-2. However, GD3 and other membrane glycospingolipids modulate the motogenic activity of FGF-2. GD3 expression sensitizes melanocytes to chemotherapeutic agent-induced cell death, as cisplatin and vimblastin. On the other hand, GD3 turned melanocytes more resistant to temozolomide. Chemosensitization to vimblastin, but not to the other drugs, was dependent on the presence of GD3 within the cells, as shown by metabolic depletion of glycosphingolipids

Le diabète gestationnel (DG) est un trouble de la tolérance glucidique de gravité variable, survenant ou diagnostiqué pour la première fois pendant la grossesse, quel que soit le traitement nécessaire et son évolution après l’accouchement. Il est associé, à court et à long terme, à un ensemble de complications ou pathologies tant chez la mère que chez l’enfant. Nous avons étudié le rôle des cytokines, des adipokines, du statut anti-oxydant et des facteurs de croissance au cours du diabète gestationnel et de la macrosomie. Notre étude a montré que le diabète gestationnel et la macrosomie sont associés à une perturbation du métabolisme lipidique et une altération des statuts antioxydant et immunitaire. Le DG était lié à une diminution de l’adiponectine et des cytokines Th1 et une augmentation de la leptine et des cytokines inflammatoires alors que la macrosomie est associée à une augmentation des cytokines Th1 et une diminution de toutes ces hormones relatives à l’obésité (IL-6, TNF-α, leptine et adiponectine). Plusieurs altérations observées à la naissance dans le métabolisme des carbohydrates et des lipides chez les enfants issus de mères diabétiques persistent encore à l’âge adulte. Il semble que la programmation in utero au cours du diabète gestationnel crée une ‘‘mémoire métabolique’’ qui est responsable de l’obésité et des altérations chez les nouveau-nés macrosomiques. Selon les régressions linéaires multiples incrémentielles que nous avons établies, il semble que les facteurs de croissance qui influencent l’augmentation du poids fœtal sont : PDGF du côté maternel et FGF2 des deux côté maternel et fœtal. / Gestational diabetes mellitus (GDM) is defined as ‘carbohydrate intolerance of variable severity with onset or first recognition during pregnancy’, irrespective to necessary treatment and its evolution in the post partum. GDM is associated with a number of complications/ pathologies both in mother and in their newborns, with short and long-term. In this study, we investigated the role of cytokines, adipokines and antioxidant status during GDM and macrosomia. Our study has demonstrated that these pathologies are associated with a perturbation in lipid metabolism, and antioxidant and immune status. GDM is linked to the down-regulation of adiponectin along with Th1 cytokines and upregulation of leptin and inflammatory cytokines whereas macrosomia was associated with the up-regulation of Th1 cytokines and the down-regulation of the obesity-related agents (IL-6, TNF-α, leptin and adiponectin). Several alterations observed at birth in carbohydrates and lipids metabolism in the children born to diabetic mothers, still persist at the adulthood. It seems that in utero programming during diabetic pregnancy creates a ‘‘metabolic memory’’ which is responsible for the development of obesity and physiological anomalies in macrosomic offspring. According to multiple linear regressions incremental that we established, it appears that growth factors that influence the increase of foetal weight are: PDGF in mother's side and FGF2 in maternal and foetal side.

Background: Different types of cardiomyopathies are associated with variable hypertrophic response. <p>A number of growth factors are thought to play a role in pathologic cardiac remodeling. <p>Aims: We compared the modulation of the TGF-ƒÒ superfamily and IGF-1 signaling pathways and their target genes, the cell cycle regulatory proteins in tachycardia-induced dilated cardiomyopathy, a model with no detectable hypertrophy and in ischemic cardiomyopathy, a model with a marked hypertrophic reaction. <p>Methods: In the first study, endomyocardial biopsies were obtained weekly in 15 dogs, during the development of tachycardiomyopaty. Genes involved in the myostatin-TGF-ƒÒ-Activin-A/Smad signaling pathway, p21 and cyclin D were quantified and correlated to echocardiographic measures of hypertrophy. In the second study, myocardial tissue samples were obtained in 8 dogs with a healed myocardial infarction, in 8 dogs with heart failure induced by overpacing and in 7 healthy dogs. We measured gene expression of IGF-1, its receptor (IGF-1R) and cyclins A, B, D1, D2, D3 and E and correlated them to the level of hypertrophy. <p>Results: Tachycardiomyopathy was characterized by chambers dilation with no identifiable hypertrophy. Ischemic cardiomyopathy was characterized by eccentric hypertrophy. In tachycardiomyopathy, Activin-A mRNA was 4-fold higher than at baseline. Smad7 was overexpressed in severe heart failure; p21, a direct target gene of the Smad pathway was upregulated 8-fold and cyclin D1 was down-regulated. In that model, IGF-1 was overexpressed but neither IGF-1R nor any of the cyclins studied.<p> In ischemic cardiomyopathy, IGF-1, IGF-R, and cyclins B, D1, D3 and E gene expression were upregulated.<p> In tachycardiomyopathy, Activin-A and p21 were inversely correlated to the thickness of the interventricular septum. In normal dogs and in the both models of cardiomyopathy, IGF-1R was correlated to the thickness of the interventricular septum and to cyclins. <p>Conclusions: Taken together, these results agree with the notion that Activin-A, IGF and cyclins are involved in the modulation of hypertrophic response observed in cardiomyopathies. <p> / Doctorat en Sciences médicales / info:eu-repo/semantics/nonPublished

Le diabète est une maladie qui touche 347 millions de personnes dans le monde (90% ayant un diabète de type 2) (OMS, septembre 2012). Elle se définit par une perturbation de la régulation de l’homéostasie glucidique avec un déficit dans la fonction des cellules ß du pancréas. Dans le diabète de type 1, ce déficit est provoqué par une destruction autoimmune. Dans le diabète de type 2, il est dû à une insulino-résistance périphérique conduisant à un épuisement des cellules ß qui ne peuvent plus maintenir leur fonction. Une stratégie pour restaurer une masse fonctionnelle de cellules ß est, soit d’induire la prolifération de ces cellules in vitro avant de les greffer, soit d’induire leur prolifération in vivo. Cependant, ceci implique une meilleure compréhension des mécanismes moléculaires impliqués dans le cycle cellulaire des cellules ß pancréatiques humaines. L’objectif de ma thèse a été de disséquer ces mécanismes. Pour cela, nous disposons au laboratoire d’un outil unique, deux lignées de cellules ß pancréatiques humaines. Dans l’une d’elle, les transgènes immortalisant peuvent être délétés. Les cellules arrêtent alors de proliférer donnant des cellules ß pseudo-primaires. En comparant l’expression des régulateurs du cycle cellulaire de la lignée de cellules ß humaine immortalisées aux cellules ß humaine pseudo-primaires, nous avons pu montrer que le cycle de ces cellules était bloqué en phase G1. L’absence de plusieurs protéines responsables de la progression du cycle cellulaire en aval de cette phase a été confirmée dans les îlots humains. Nous avons également observé une diminution du temps de doublement des cellules ß humaines suite à leur traitement avec de la GH et de l’EPO. Suite à ce traitement nous observons également une activation du facteur de transcription STAT5 connue pour son implication dans la prolifération cellulaire des cellules ß de rongeurs. Enfin nous avons étudié l’effet que provoquait un apport nutritif sur la fonction et la prolifération des cellules ß humaines. Nous avons ainsi pu voir que les cellules répondaient mieux à la fonction ß avec un temps de doublement du nombre de cellules plus court dans un milieu enrichi en nutriment. De plus, dans ces conditions, l’autophagie, préexistante avant l’apport de nutriments et vraisemblablement due à un manque en énergie cellulaire, disparait. Ces résultats nous permettent de mieux comprendre les mécanismes contrôlant la prolifération des cellules ß pancréatiques humaines et d’envisager de nouvelles thérapies du diabète. / Diabetes is a disease that affects 347 million people worldwide (90% with type 2 diabetes) (WHO, September 2012). It is defined by a disturbance in the regulation of glucose homeostasis with a deficit in function of pancreatic beta cells. In type 1 diabetes, this deficit is caused by autoimmune destruction. In type 2 diabetes, it is due to peripheral insulin resistance leading to a depletion of beta cells that can no longer maintain their function. A strategy to restore a functional beta cell mass is, or of inducing proliferation of these cells in vitro prior to transplant, or to induce proliferation in vivo. However, this implies a better understanding of the molecular mechanisms involved in the cell cycle of human pancreatic beta cells. The aim of my thesis was to dissect these mechanisms. For this, we have a unique laboratory tool, two lines of human pancreatic beta cells. In one of them, immortalizing transgenes may be deleted. Then, the cells stop to proliferate giving pseudo- primary beta-cells. By comparing the expression of cell cycle regulators of the lineage of human beta cells immortalized pseudo- primary human beta- cells, we could show that the cycle of these cells was blocked in the G1 phase. The lack of several proteins responsible for cell cycle progression downstream of this phase has been confirmed in human islets. We also observed a decrease in the doubling time of human beta cells following treatment with GH and EPO. Following this treatment we also observe an activation of the transcription factor STAT5 known for its involvement in cell proliferation of rodent beta cells. Finally, we studied the effect that caused a nutrient supply on the function and proliferation of human beta cells. We have seen that the cells responded better to beta function with a doubling time shorter amount of cells in a nutrient enriched environment. In addition, under these conditions, autophagy, existing before the supply of nutrients and likely due to a lack of cellular energy, disappears. These results allow us to better understand the mechanisms controlling proliferation of human pancreatic ß and consider new diabetes therapies cells.

Periodontitis is a chronic inflammatory disease caused by exaggerated host immune responses to dysregulated microbiota in dental biofilms leading to degradation of tissues and alveolar bone loss. Porphyromonas gingivalis is a major periodontal pathogen and expresses several potent virulence factors. Among these factors, arginine and lysine gingipains are of special importance, both for the bacterial survival/proliferation and the pathological outcome. The major aim of this thesis was to develop and test novel methods for diagnosis and prevention of P. gingivalis infection and periodontitis. In study I, anti-P. gingivalis antibodies were developed in vitro for immunodetection of bacteria in clinical samples using a surface plasmon resonance (SPR)-based biosensor. Specific binding of the antibodies to P. gingivalis was demonstrated in samples of patients with periodontitis and the results were validated using real-time PCR and DNA-DNA checkerboard analysis. In study II, we elucidated the properties and antimicrobial effects of different lactobacillus species and the two-peptide bacteriocin PLNC8 αβ on P. gingivalis. L. plantarum NC8 and 44048 effectively inhibited P. gingivalis growth and pure PLNC8 αβ induced bacterial lysis by damaging P. gingivalis membrane. In study III, we demonstrated that PLNC8 αβ dose-dependently induces proliferation and release of growth factors in gingival epithelial cells (GECs). Furthermore, PLNC8 αβ decreased P. gingivalis-induced cytotoxic effects in GECs but did not alter the effect of gingipains on cytokine expression. In study IV, we elucidated the effects of anti-P. gingivalis antibodies and PLNC8 αβ in regulating cellular responses during P. gingivalis infection. Both antibodies and PLNC8 αβ modulated P. gingivalis-induced expression of growth factors in GECs, however, their effects were diminished when used in combination. The results of this thesis demonstrate a possible role of anti-P. gingivalis antibodies and PLNC8 αβ in prevention and treatment of P. gingivalis infection and periodontitis with no cytotoxic effects on human cells.

La dégénérescence discale lombaire (DDL) est caractérisée par un vieillissement prématuré du disque intervertébral (DIV) et une déshydratation progressive du nucleus pulposus (NP) entrainant in fine des lombalgies. L'objectif général de ce travail est d'établir des données précliniques afin de régénérer le DIV en cas de DDL modérée. Dans un premier chapitre, nous avons déterminé une association de facteur de croissance et un mode de culture visant à obtenir une prédifférentiation nucléopulpogénique de cellules stromales mésenchymateuses (CSMs) humaines issues de la moelle osseuse. Nos résultats montrent que la culture tridimensionnelle des CSMs en billes d'alginate en présence de TGF-β3, GDF-5 et BMP-7 les oriente vers un phénotype cartilagineux. Dans un deuxième chapitre, nous avons élaboré un modèle porcin de DDL induite par cryolésion et nous l'avons comparé aux techniques de référence. L'évaluation de l'importance de la DDL a été effectuée par scanner, IRM et histologiquement. Un score histologique de DDL porcine a été décrit et validé. La cryolésion a permis d'obtenir une DDL plus importante que les autres techniques. Dans un troisième chapitre, nous avons injecté les CSMs préorientées dans les DIV lésés. L'analyse IRM a montré une amélioration de l'intensité du signal et de la surface du NP après injection des cellules. L'analyse immunohistologique a montré une survie des CSMs dans les DIV porcins à 2 mois. Dans un quatrième chapitre, nous avons comparé les taux de fusion et de complication pour la RhBMP-2 et la greffe spongieuse autologue dans les arthrodèses lombaires par voie antérieure dans une même cohorte de patients. La RhBMP-2 était associée à un taux de fusion inférieur et un taux de complications radiologiques supérieur à l'autogreffe spongieuse. / Degenerative disc disease (DDD) is characterized by premature aging of the intervertebral disc (IVD) and gradual dehydration of the nucleus pulposus (NP), ultimately causing back pain. The general objective of this work is to establish preclinical data to regenerate the IVD in moderate DDD. In the first chapter, we have identified a growth factor association and a culture method to achieve nucleopulpogenic prédifférentiation of mesenchymal stromal cells (MSCs) derived from human bone marrow. Our results show that the three-dimensional culture of MSCs in alginate beads in the presence of TGF-β3, GDF-5 and BMP-7 directs them to a cartilaginous phenotype. In the second chapter, we developed a porcine model of DDD, induced by cryoinjury, and compared it to reference techniques. Assessing the importance of DDD was performed by CT, MRI and histologically. A histological score of porcine DDD has been described and validated. Cryoinjury yielded a higher DDD that other techniques. In a third chapter, we injected preoriented MSCs in cryo-injured IVDs. MRI analysis showed an improvement in the signal intensity and the surface of the NP after the injection. The immunohistological analysis showed a survival of the MSCs in the porcine IVD 2 months after injection. In a fourth chapter, we compared the rate of fusion and complication for rhBMP-2 and autologous cancellous graft in the anterior lumbar interbody fusion, in the same cohort of patients. RhBMP-2 was associated with a lower fusion rate and a higher rate of radiological complications than the cancellous autograft.

Les "Bone Morphogenetic Proteins" (BMPs) jouent un rôle clef dans la régulation de cellules précurseurs du muscle prénatal et de cellules souches musculaires adultes dénommées "cellules satellites". Les objectifs principaux de ma thèse étaient d'une part de déterminer si la signalisation BMP joue un rôle pendant la phase de croissance du muscle postnatale/juvénile dépendante des cellules satellites, et d'autre part d'investiguer si cette voie est impliquée dans la maintenance de la masse musculaire squelettique adulte. J'ai trouvé que les composants de cette voie de signalisation sont exprimés dans les cellules satellites de souris néonatales, juvéniles et adultes. Par ailleurs, j'ai utilisé des lignées de souris transgéniques pour surexprimer, de manière conditionnelle, l'inhibiteur Smad6 de la cascade de signalisation BMP dans les cellules satellites ou dans le muscle squelettique. J'ai pu ainsi démontrer que cette signalisation est requise pour une prolifération correcte des cellules satellites et pour leur différentiation en myonuclei, assurant que les fibres musculaires en croissance atteignent une taille finale normale. Par ailleurs, mes travaux révèlent que le nombre final de cellules satellites est établis pendant la phase de croissance postnatale/juvénile et que celle-ci dépend de la cascade de signalisation BMP. Enfin, je fournis des preuves montrant que la signalisation BMP est un puissant signal hypertrophique dans le muscle squelettique adulte et que sa présence est indispensable pour le maintien du tissu musculaire. En résumé, mes résultats de recherche démontrent que les BMPs sont des facteurs de croissance essentiels pour le muscle squelettique postnatal. / Bone Morphogenetic Proteins (BMPs), a subfamily of TGF-β growth factors, have been shown to be key signals that regulate embryonic and fetal muscle precursors during prenatal myogenesis, as well as the stem cells of adult muscle, termed ‘satellite cells’, when activated during muscle regeneration. The main aims of my thesis were to elucidate whether BMP signaling plays a role during postnatal/juvenile satellite cell-dependent muscle growth as well as for maintenance of adult muscle mass. I found that components of BMP signaling pathway are expressed in muscle satellite cells of neonatal, juvenile and adult mice. I used transgenic mouse lines to conditionally overexpress the BMP signaling cascade inhibitor Smad6 in muscle satellite cells and in differentiated skeletal muscle. I show that BMP signaling is required for correct proliferation of muscle satellite cells and their differentiation into myonuclei, thereby ensuring that the growing muscle fibers reach the correct final size. Moreover, I demonstrated that the final number of muscle stem cells is established during the postnatal/juvenile growth phase and this also depends on the BMP signaling cascade. Finally, I provide evidence that BMP signaling is a strong hypertrophic signal for the adult skeletal muscle and its presence is indispensable for muscle tissue maintenance. In summary, my findings demonstrate that BMPs are essential growth factors for postnatal skeletal muscle.