Orientadores: Nicola Amanda Conran Zorzetto, Fernando Ferreira Costa / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-25T05:42:46Z (GMT). No. of bitstreams: 1 Dominical_VeninaMarcela_D.pdf: 4297524 bytes, checksum: 86e7e426a479616f71a78d95e3333914 (MD5) Previous issue date: 2014 / Resumo: A anemia falciforme (AF) é uma hemoglobinopatia hereditária que resulta de uma mutação no gene da globina beta. Essa mutação leva a formação de uma hemoglobina (Hb) com propriedades físico-químicas anormais, denominada HbS. A vaso-oclusão é a principal complicação aguda e a principal causa de morbidade da doença falciforme, compreendendo um processo multicelular que parece ser iniciado pela adesão de hemácias e leucócitos ao endotélio ativado, causando a obstrução vascular e isquemia tecidual. A adesão de hemácias ao endotélio contribui para a redução do fluxo sanguíneo na AF, entretanto, leucócitos também parecem exercer um papel fundamental neste processo, pois são células maiores, menos flexíveis e seu recrutamento para a microvasculatura e subsequente interação com as células circulantes sanguíneas promove a redução do fluxo sanguíneo nos vasos. Assim, investigações na dinâmica de interações heterocelulares são áreas potencialmente atrativas para pesquisa, pois elas podem contribuir para melhorar o entendimento de mecanismos de inflamação vascular e para o desenvolvimento de novos alvos terapêuticos para doenças como a AF. O objetivo deste projeto foi estudar as interações heterotípicas dos neutrófilos a plaquetas, células vermelhas e células endoteliais em células de pacientes com AF e as moléculas de adesão celular envolvidas nestas interações, utilizando uma plataforma microfluidica (quantifica adesão celular em fluxo em biochips com canais paralelos), citometria de fluxo com imagem (imagem simultânea das células obtidas pelo citômetro) e o desenvolvimento de um biochip para estudo dos processos vaso-oclusivos (para utilização na plataforma microfluídica). Sangue periférico de indivíduos saudáveis (controles) e pacientes com anemia falciforme (em uso ou não da terapia de hidroxiureia ¿ HU) foi coletado e os experimentos realizados. Observamos que células vermelhas de pacientes AF sem uso da HU aderem mais, quando em fluxo, à laminina e interagem mais aos neutrófilos autólogos aderidos ao endotélio ativado. Quando avaliada a participação das principais moléculas de adesão expressas no endotélio, E-selectina e ICAM-1, na promoção das interações de eritrócitos a neutrófilos aderidos, observamos que a duração destas interações heterotípicas, em células provenientes dos pacientes AF, é mais prolongada na presença do ligante E-selectina. Neutrófilos de pacientes com AF também circulam mais em agregados a plaquetas ou células vermelhas no sangue periférico, comparados aos neutrófilos de indivíduos saudáveis. Os reticulócitos demonstraram ser o principal tipo de eritrócito envolvido nos agregados de neutrófilos circulantes e os níveis de hemoglobina fetal correlacionaram-se inversamente à porcentagem encontrada de agregados de neutrófilo-reticulócito no sangue periférico destes pacientes. As plaquetas demonstraram papel de destaque na formação e participação nos agregados circulantes de neutrófilos a células vermelhas e experimentos utilizando anticorpos bloqueadores ou inibidor, indicaram que as moléculas de adesão P-selectina, na plaqueta, Mac-1 no neutrófilo, VLA-4 nos reticulócitos e ICAM-4 nas hemácias podem ser as responsáveis pela interação dos neutrófilos a estas células. Neutrófilos de pacientes AF também obstruíram significativamente mais os microcanais com diâmetros de 25 a 40µm do biochip desenvolvido por nós para estudar os processos vaso-oclusivos, comparados aos neutrófilos de indivíduos controle. Quando misturamos suspensões de neutrófilos a eritrócitos, observamos uma obstrução ainda maior destes microcanais. Diante destes resultados, é possível concluir que neutrófilos de pacientes AF interagem significativamente mais às células vermelhas quando aderidos ao endotélio, circulam agregados a eritrócitos e plaquetas no sangue, além de possuírem maior capacidade de obstrução in vitro em microcanais que mimetizam vênulas de pequeno calibre. A terapia com HU parece afetar apenas as interações de neutrófilo na presença do endotélio vascular. Terapias que visem à inibição das moléculas de adesão Mac-1 e P-selectina na patologia da anemia falciforme parecem ser promissoras / Abstract: Sickle cell anemia (SCA) is a hereditary hemoglobinopathy that results from a mutation in the beta globin gene. This mutation leads to the formation of an abnormal hemoglobin (Hb), known as HbS. Vaso-occlusion is the major acute complication and the major cause of morbidity in SCA; it comprises a multicellular process that appears to be initiated by the adhesion of red blood cells (RBCs) and leukocytes to the activated endothelium, causing vascular obstruction and tissue ischemia. The adhesion of sickle RBCs to the endothelium contributes to decrease blood flow; however, leukocytes also seem to play a key role in this process as these cells are bigger, less flexible and their recruitment to the microvasculature and subsequent interaction with circulating blood cells promotes reduced blood flow in vessels. Research into the dynamics of heterocellular interactions is a potentially attractive area of research, since such data may improve our understanding of the mechanisms involved in vascular inflammation and contribute to the development of new therapeutic targets in diseases such as SCA. The aim of this project was to study the heterotypic interactions of neutrophils with platelets, red cells and endothelial cells in cells from SCA individuals and the possible adhesion molecules involved in these interactions, using microfluidic techniques (cell adhesion flow in biochips with parallel channels), imaging flow cytometry (simultaneous imagery of cells acquired by flow cytometry) and the development of a biochip for the study of vaso-occlusive processes (for use in conjunction with the microfluidic platform). Peripheral blood from healthy individuals (controls) and sickle cell anemia patients (with or without hydroxyurea therapy - HU) were collected and the experiments were performed. RBCs from SCA patients without HU were observed to adhere more, under flow, to laminin-coated biochips and they interact more with autologous neutrophils previously adhered to an activated endothelium. When evaluating the participation of the two main adhesion molecules expressed on activated endothelium, E- selectin and ICAM-1, in promoting interactions of RBCs to adherent neutrophils, we found that the duration of these heterotypic interactions for cells from SCA patients was longer in the presence of E-selectin ligand. Neutrophils from SCA patients also circulate aggregated to platelets or RBCs in the peripheral blood significantly more than the neutrophils of healthy individuals. Reticulocytes were the main RBC type involved in these neutrophil-RBC aggregates and the levels of fetal hemoglobin were inversely correlated to the percentage of the neutrophil- reticulocyte aggregates found in the peripheral blood of these patients. Platelets demonstrated a prominent role in the formation of the circulating neutrophil-RBCs aggregates, and function-blocking antibodies or inhibitors indicated that the adhesion molecules P-selectin, on platelets, Mac-1, on neutrophils, VLA-4, on reticulocytes, and ICAM-4, on mature erythrocytes, may be responsible for the interactions of neutrophils with these cells. Neutrophils from SCA patients also demonstrated a significant capacity to obstruct microchannels with diameters of between 25 and 40?m, of the biochip developed by us to study vaso-occlusive processes, compared to the cells from control subjects. When mixed suspensions of neutrophils and autologous RBCs were applied to the chips, we observed an even greater obstruction of these microchannels. In summary, we conclude that SCA neutrophils interact significantly more with red cells when adhered to endothelial cells, circulate aggregated to erythrocytes in the peripheral blood of these patients, and present a greater capacity to obstruct microchannels that mimic small venules in vitro. HU therapy appears to affect only neutrophil interactions in the presence of the vascular endothelium. Therapies that target molecules such Mac-1 and P-selectin in sickle cell disease seem to be promising strategies / Doutorado / Fisiopatologia Médica / Doutora em Ciências

Background: Between 2005 and 2015 the number of new cancer cases per year in Canada rose by 29% and this number is projected to increase to 277,000 cases per year. Ionizing radiation is used as therapy in the majority of cancer cases; however, it can have long-term detrimental effects on the hematopoietic system. Recent work from our lab, in a preclinical model of radiation damage, demonstrated that endurance exercise training can enhance hematopoietic recovery, while obesity can impair it. Extracellular vesicles (EVs) are a mode of cellular communication that has been implicated in regulating hematopoiesis acutely following radiation exposure. However, the long-term, radiation-induced changes to EVs, and the role of exercise and/or obesity at modulating marrow EVs remains unknown. Thus, the purpose of this project was to determine the extent to which obesity and exercise influence the regenerative potential of bone marrow-EVs following radiation. Method: Mice were randomly divided into control (n=20; CON) or high fat diet (n=20; HF) groups, then subdivided into exercise-trained (EX, n=10) or sedentary (SED, n=10). Mice underwent whole-body exposure to a 3 Gy dose of gamma-radiation at age 13 weeks of age followed by bone marrow collection at 20 weeks of age. EVs were then isolated from the bone marrow by ExoQuick and ultracentrifugation. A non-irradiated, sedentary, control diet group (n=10) was used to determine the effects of radiation alone. Data was evaluated using repeated-measures three-factor (diet, exercise, time) and two-factor ANOVA. Results: High fat diet-induced changes in body weight and composition and altered food consumption (p<0.05). Isolated EVs measured between 78 and 195 nm and western blot confirmed the presence of EV protein markers Alix, TSG101, and Flotillin. No size difference was observed between the groups. The concentration of EVs in irradiated mice was significantly lower compared to EVs from control mice (p<0.01). Radiation, obesity, exercise, or their combination had no significant effect on hematopoietic stem progenitor cells (HSPC) content in co-culture assays. Conversely, EVs from irradiated mice significantly increased the number of CFU-GEMM, CFU-G, and the TOTAL number of colonies compared to EVs from non-irradiated mice (p<0.01). However, EVs from the CON+SED, CON+EX, HF+SED, and HF+EX groups did not have a significant effect on colony formation. Conclusion: Our findings demonstrate that ionizing radiation can diminish the concentration of bone marrow-EVs and that irradiated bone marrow-EVs can increase the total number of myeloid colonies formed in vitro. These results suggest that radiation induces myelopoiesis via a mechanism that includes EVs; however, exercise and obesity induce their effects via a different mechanism.

No description available.

Gap junctions are highly-conserved communicating junctions composed of the connexin family of proteins. In addition to this channel function, gap junctions mediate adhesive contacts at extracellular domains, and are host to a variety of signalling metabolites at intracellular surfaces. In this thesis, I explore the emerging theme of the connexin interactome. Starting with a non-biased proteomic approach, I identified endogenous protein interactions with the predominant liver and oligodendrocyte connexin, connexin32 (Cx32). Here, I identified novel mitochondrial protein interactions suggesting that Cx32 might localize to mitochondrial membranes, as has been reported for cardiac Cx43. Following proteomic quantitation of WT and Cx32 KO membranes, I determined that loss of Cx32 specifically induces mitochondrial protein expression. Bioenergetic analysis of isolated mitochondria then confirmed that oxygen consumption and rates of reactive oxygen species (ROS) generation were elevated in Cx32 KO mitochondria. In addition to novel intracellular connexin protein interactions, we hypothesized that connexin-mediated glial cell:cell interactions were responsible for mediating fate decisions in the complex hippocampal neurogenic niche environment. We identified that Cx32-mediated glial cell:cell interactions exert significant proliferative and fate specifying pressures on hippocampal progenitor cell types, wherein the loss of Cx32 enables improved histological and functional regeneration following excitotoxic injury. Together, this thesis identifies novel connexin-mediated signalling pathways that provide mechanistic insight into both intracellular and extracellular interactomedependent functions for Cx32, and outlines a potentially transformative avenue for brain repair.

Dorsal root ganglia (DRG) cell preparations are commonly used to study the properties of sensory neurons in relation to nociception. A typical DRG cell preparation contains both neurons and glial cells, and in addition to a conventional supportive role of glial cells, an increasing volume of literature has reported interactions between neurons and accompanying glial cells. A typical mixed DRG cell preparation can be separated into a neuron-enriched cell fraction and a preparation of purified glial cells. Using these purified cell fractions, we can study the relative contributions and interactions between neurons and glial cells in regulating neurite outgrowth and adenylyl cyclase-dependent cell signalling activity in vitro. / From our previous studies, pretreating DRG cell cultures with pertussis toxin (PTx) caused neurite retraction over a period of 2 h following the initial stimulus of removal from incubator. The purpose of the current study was to investigate whether this PIx-dependent response was specific to anyone of the three subpopulations of DRG neurons. Interestingly, no neurite retraction response was observed in enriched DRG cultures, including cultures enriched with isolectin B4 (IB4)-positive neurons or IB4-negative neurons. Addition of glial cells or conditioned medium from glial cells to IB4-negative cultures was necessary to restore the PTx-dependent neurite retraction response, which was then only observed in large diameter proprioceptive neurons. To conclude, glial cells constitutively release factor/s that stimulate neurite retraction in larger diameter neurons, and is counterbalanced by neuroprotective Gilo protein signalling pathway. / From our studies, we have provided evidence of bidirectional interactions between neurons and glial cells, with glial cells regulating neurite outgrowth and neurons regulating adenylyl cyclase activity in glial cells. These findings reveal the properties of glial cells in regulating neurite outgrowth and in producing prostanoid-stimulated responses. Moreover, our fmdings provide foundation to understand complex neuron-glia interactions in vivo which will eventually help to overcome obstacles in promoting neurite regeneration and in controlling pain. / In a parallel study, we proved that hyperalgesic agents such as prostaglandin E2 (PGE2) and the prostacyclin (PGI2) mimetic (cicaprost) stimulate cAMP production in DRG cell culture via EP4 and IP receptors, respectively. These prostanoids were presumed to act only on the neurons in typical mixed cell cultures, but since we had acquired purified glial cell preparation, we tested for involvement of glial cells in measurement of agonist-stimulated cAMP production. Interestingly, a purified glial cell cultures also produced EP4 and IP-dependent responses. The expression of EP4 and IP receptors by DRG glia was further confirmed by the detection of EP4 and IP-like immunoreactivity and mRNA. Moreover, these agonist-stimulated responses were greatest in the glial cell preparation, and surprisingly weakest in the neuron-enriched cell cultures. Furthermore, the presence of neurons significantly inhibited both EP4 and IP receptor-dependent signalling in glial cells, but was without effect on forskolin (agonist-independent) stimulation of adenylyl cyclase. In order to characterize this neuron-glia interaction, we tested the adenylyl cyclase activities in glial cell cultures which were treated with conditioned medium derived from neurons or were separated from physical contact with neurons plated on transwell membrane. These studies further suggest that the neuron-glia interactions were dependent on both soluble factors and cell-cell contact. / Ng, Kai Yu. / Adviser: Helen Wise. / Source: Dissertation Abstracts International, Volume: 73-04, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 152-172). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Nuclear hormone receptors (NHRs) are ligand-activated transcriptions factors which transduce the effects of various hormones as well as nutritional and other environmental signals. They thus function to maintain physiological homeostasis by integrating the tissue expression of specific target genes to regulate a wealth of biological processes including reproduction, development, metabolism and environmental adaptation. Mounting evidence indicates NHRs are the target of endocrine disrupting compounds (EDCs), exogenous chemicals, often of anthropogenic origin, which disrupt NHRs and thus the processes under their control. EDCs can interfere with NHR signalling by activating receptors (agonists), by inhibiting the actions of the receptor (antagonists), or by disrupting endogenous hormone synthesis, secretion, transport or metabolism. Much of the focus to date has been on the risk of EDCs to reproductive functions, via estrogen and androgen NHRs in humans, and also in aquatic organisms. However environmental pollutants also have the potential to interact with other NHRs, particularly in aquatic environments, and cause dysregulation of other critical physiological processes, including energy homeostasis, immune functions and the stress response. To address this possibility a reporter gene assay was developed, allowing the high-throughput screening of pollutants for their interactions with piscine NHRs with critical roles in energy homeostasis, stress reponse and immune functions, namely the peroxisome proliferator-activated receptors (PPARs) and corticosteroid receptors (CRs) from European plaice (Pleuronectes platessa) and European flounder (Platichthys flesus), respectively. Complementary DNA (cDNA) sequences encoding the ligand-binding domains of PPARs and CRs, critical for receptor-ligand interactions and receptor activation, were ligated to the DNA-binding domain (DBD) of the yeast Gal4 transcription activator protein to create experimental expression plasmid constructs. Co-transfection of these expression plasmids into the fathead minnow (FHM) cell line with an upstream-activating sequence (UAS)-firefly luciferase reporter gene plasmid increased luciferase expression in the presence of known PPAR and CR ligands. Several aquatic pollutants including pharmaceuticals, industrial by-products and biocides were tested for their potential to disrupt PPAR and CR functions by interacting with these receptors in an agonistic or antagonistic manner. Several fibrates, a group of pharmaceutical compounds used to treat dyslipidemia in humans by targeting the PPARs, were able to activate plaice Gal4-PPARα and Gal4-PPARβ in the reporter gene assay, indicative of an interaction with PPAR receptors in non-target species. Fibrates which did not activate Gal4-PPARα were able to inhibit the activation of Gal4-PPARα by the PPARα-specific agonist, Wy14643, suggesting differential effects of fibrates on human and flounder PPARs. In addition some metabolites of widespread phthalate ester pollutants were also agonists of the Gal4-PPARα and Gal4-PPARβ constructs. The Gal4-PPARγ construct was unresponsive to almost all the compounds tested, including the mammalian PPARγ agonist, rosiglitazone. The exception to this was the phthalate metabolite monobenzylphthalate, which induced a small increase in firefly luciferase in Gal4-PPARγ transfected cells. All of the above effects required concentrations of at least 10 µM, which are unlikely to be encountered in the aquatic environment. In contrast bis(tributyltin) oxide (TBTO), a notorious environmental pollutant, inhibited Gal4-PPARα and Gal4-CR constructs at concentrations as low as 1 nM and 100 nM, respectively. These concentrations are lower than those reported in aquatic environments, or in fish tissues, making TBTO a candidate endocrine disruptor in fish by inhibiting PPARα and CR signalling. A European flounder cDNA microarray was used to investigate the trasnscriptional responses of flounder hepatocytes to TBTO (10 nM) exposure. Exposure to TBTO and Wy14643, both alone and in combination, indicated a TBTO-driven downregulation of several potential PPARα-target genes with functions in the immune system, the proteasome, and lipid metabolism, although, based on mammalian comparisons, some potential PPARα-target genes were also upregulated, indicating differences in mammalian and fish PPAR-target genes or reflecting the complexity of organisms at a higher organisational level than cell-based assay systems. However, the microarray-based approach was useful in formulating further hypotheses about the effects of TBTO on PPARα signalling. Overall, these results indicate that exogenous chemicals entering the aquatic environment can interfere with NHRs with functions in energy homeostasis, immune functions and stress, in non-target organisms. The cell-based reporter gene assay is a useful tool for identifying potential endocrine disruptors which target PPARs and CRs and would be a useful method in a first tier testing approach, limiting the use of live animal models and enabling investigation into specific receptors which are targets of endocrine disrupting compounds. Although more work is required to confirm the physiological consequences of TBTO inhibition of PPARα, the results presented here indicate that organisms inhabiting TBTO-polluted environments may experience suppression of the immune system, an increase in non-functional or misfolded proteins through suppression of genes involved in the ubiquitin/proteasome system and a disruption in lipid homeostasis.

Glial cells represent the most abundant cell population in the central nervous system (CNS), and yet, have historically been thought of as merely support cells for neurons. Over the past few decades, however, the number of identified roles that glial cells play in the CNS has expanded at an exponential rate, revealing new and exciting functions in neuron-glial communication. At synapses, astrocytes are now recognized as part of a "tripartite" complex with pre- and postsynaptic structures and can modulate synaptic transmission and plasticity. Accumulating evidence has also revealed new roles for oligodendrocytes in regulating axon diameter and integrity, and ion channel clustering. Despite our knowledge of the physiological connections between neurons and glia, relatively little is known about the morphological interplay of these cells during development and in the mature brain. The results presented in this thesis reveal the extent and time-course of rapid remodelling of astrocytes and oligodendrocytes in close proximity to dendritic spines and axons respectively. These findings provide further evidence that glia play an important role in regulating the structural plasticity of the brain. The methodology developed also provides a powerful system for the study of neuron-glial structural dynamics and may contribute to the development of novel therapeutic strategies for diseases affecting the central nervous system.

Orientador: Ailton Akira Shinoda / Banca: Sérgio Azevedo de Oliveira / Banca: Carlos Dias Maciel / Resumo: Neste trabalho é revisada a literatura sobre o funcionamento de um sistema de telefonia celular e apresentadas propostas de aplicações de processamento distribuído, baseada em Algoritmos Genéticos na resolução do problema de alocação de canais para o sistema celular. O estudo realizado para a apresentação desta dissertação descreve o modelamento da rede celular em termos de dois operadores genéticos, além disso, são propostas duas técnicas para o problema de alocação de canais em uma rede de telefonia celular. Uma das técnicas trabalha com a compatibilidade eletromagnética, já a outra, trabalha com a mínima relação sinal interferência (SIR). Os resultados das duas técnicas são obtidos de dois algoritmos de processamento distribuído, desenvolvidos em linguagem C e com a biblioteca de programação distribuída (Message Passing Interface - MPI). Os algoritmos propostos, através de uma função objetivo, calculam a alocação sem conflito de canais entre as células, na primeira abordagem satisfazendo a compatibilidade eletromagnética e exigências da demanda de tráfego, e na segunda abordagem satisfazendo a mínima SIR e exigências da demanda de tráfego, ambos otimizando a alocação de canais / Abstract: The literature about the cell phone system functioning and proposals of the distributed processing applications based on Genetic Algorithms in the assigning channels problems resolutions are presented in this study. This dissertation describes the cell phone problems modeling by two genetic operators and proposes two techniques for the telephone network allocation channels problems. One of the techniques works with the electromagnetic compatibility and the other with minimal signal interference ratio (SIR). The results of the two techniques are obtained by two algorithms distributed processing, developed in C language and Message Passing Interface (MPI). The algorithms proposed, by an objective function, calculate the allocation without channels conflict. At first, satisfying the electromagnetic compatibility and traffic demand requirements and then satisfying the minimum SIR and traffic demand requirements, both optimizing the channels allocation / Mestre

Made available in DSpace on 2014-06-11T19:22:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-06-01Bitstream added on 2014-06-13T19:28:00Z : No. of bitstreams: 1 albuquerque_lct_me_ilha.pdf: 1335297 bytes, checksum: 58c32f83ffe9cb091c553528e64dc780 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Neste trabalho é revisada a literatura sobre o funcionamento de um sistema de telefonia celular e apresentadas propostas de aplicações de processamento distribuído, baseada em Algoritmos Genéticos na resolução do problema de alocação de canais para o sistema celular. O estudo realizado para a apresentação desta dissertação descreve o modelamento da rede celular em termos de dois operadores genéticos, além disso, são propostas duas técnicas para o problema de alocação de canais em uma rede de telefonia celular. Uma das técnicas trabalha com a compatibilidade eletromagnética, já a outra, trabalha com a mínima relação sinal interferência (SIR). Os resultados das duas técnicas são obtidos de dois algoritmos de processamento distribuído, desenvolvidos em linguagem C e com a biblioteca de programação distribuída (Message Passing Interface – MPI). Os algoritmos propostos, através de uma função objetivo, calculam a alocação sem conflito de canais entre as células, na primeira abordagem satisfazendo a compatibilidade eletromagnética e exigências da demanda de tráfego, e na segunda abordagem satisfazendo a mínima SIR e exigências da demanda de tráfego, ambos otimizando a alocação de canais / The literature about the cell phone system functioning and proposals of the distributed processing applications based on Genetic Algorithms in the assigning channels problems resolutions are presented in this study. This dissertation describes the cell phone problems modeling by two genetic operators and proposes two techniques for the telephone network allocation channels problems. One of the techniques works with the electromagnetic compatibility and the other with minimal signal interference ratio (SIR). The results of the two techniques are obtained by two algorithms distributed processing, developed in C language and Message Passing Interface (MPI). The algorithms proposed, by an objective function, calculate the allocation without channels conflict. At first, satisfying the electromagnetic compatibility and traffic demand requirements and then satisfying the minimum SIR and traffic demand requirements, both optimizing the channels allocation

Au début de ma thèse, je me suis intéressé aux processus qui sous-tendent la communication cellulaire et plus spécifiquement les interactions cellule-cellule. Pourquoi une cellule établit-elle un contact spécifique avec une autre cellule ? Comment les cellules répondent-elles à cette interaction et quels en sont les effets ? J'ai utilisé comme modèle d'étude l'interaction entre les cellules souches/stromales mésenchymateuses (CSM) et des lignées de cancer du sein. L'objectif de mon travail a été d'analyser les mécanismes de ces interactions entre CSM et cellules cancéreuses et d'en évaluer les effets sur les fonctions des cellules cancéreuses. En effet, des mécanismes de recrutement des CSM aux sites tumoraux ont été décrits avec des effets sur la progression tumorale, ce qui ouvre par ailleurs des perspectives pour de nouvelles approches thérapeutiques. J'ai tout d'abord développé un système expérimental de microscopie confocale en temps réel pour observer le type d'interaction qui est produit entre les CSM humaines et les cellules de carcinomes mammaires MDA-MB-231 et MCF7. J'ai constaté la formation dynamique de structures tubulaires entre les deux types cellulaires et, de façon surprenante, le passage des mitochondries des CSM vers les cellules cancéreuses. En un deuxième temps, j'ai utilisé un système d'invasion dans une matrice 3D de collagène, que nous avons adapté à la coculture, afin d'observer les effets de l'interaction des MDA-MB-231 avec les CSM. En accord avec la littérature, nous avons constaté une augmentation du pouvoir invasif des cellules cancéreuses, effet qui pouvait être lié au transfert des mitochondries provenant des CSM. Pour répondre à cette question, j'ai mis au point un protocole pour transférer spécifiquement des mitochondries, isolées à partir de cellules, vers d'autres cellules. Ce protocole, exploité dans ce manuscrit pour le transfert de mitochondries de CSM vers les cellules cancéreuses MDA-MB-231, peut être transposé à d'autres types cellulaires et fait l'objet d'une demande de brevet. Nos données indiquent que l'acquisition de mitochondries de CSM par les cellules cancéreuses modifie leurs propriétés fonctionnelles et augmente leur capacité de prolifération et d'invasion. Concernant leur activité métabolique, on observe une augmentation de leur respiration mitochondriale et de leur production d'ATP. Nos données préliminaires suggèrent aussi une augmentation de l'expression transcriptionnelle d'enzymes impliquées dans la synthèse des lipides et l'oxydation des acides gras. Ces données, générées grâce au protocole de transfert artificiel de mitochondries mis au point, montrent pour la première fois que les mitochondries des CSM peuvent majorer certaines propriétés cellulaires liées à la progression tumorale, comme la prolifération et l'invasion, et contribuer à une reprogrammation métabolique des cellules cancéreuses. Elles s'intègrent au rôle proposé par la communauté scientifique pour les CSM dans le microenvironnement tumoral. La technique de transfert artificiel de mitochondries nous permettra de répondre à d'autres questions restées ouvertes, comme le rôle possible des mitochondries des CSM dans les résistances développées par les tumeurs vis-à-vis des agents anti-cancéreux. Le protocole de transfert de mitochondries développé au laboratoire constitue une technique de choix et offre de nombreux avantages comparativement à d'autres techniques comme la micro-injection et la génération des hybrides cytoplasmiques. Sa mise en œuvre est en effet simple et reproductible et permet de traiter une grande quantité de cellules. Cette méthode permet d'envisager de nombreuses perspectives et applications dans le domaine de la reprogrammation métabolique, comme par exemple de restaurer les capacités d'une cellule dysfonctionnelle par le transfert de mitochondries issues d'une cellule saine et « métaboliquement active ». / At the beginning of my thesis, I was interested in the process involved in cell communication, more specifically in cell-to-cell interactions. Why does a cell specifically establish contacts with another one, how do cells respond to these interactions and what are the effects? As a model to answer these questions, I studied the interactions between MSCs and two breast cancer cell lines. The study of the communications between MSCs and tumor cells is an alternative to explore and understand tumor progression. MSC recruitment to the tumor is shown to favor the progression of the disease. The mechanisms of this dialogue are multiple and are the object of a great number of studies that aim at finding new therapeutic approaches. The objective of this work was to analyze the interactions between MSCs and cancer cells and evaluate the potential effects of this communication in tumor progression. First, I developed an experimental system of real time confocal microscopy in order to observe the interaction produced between MSCs and the breast carcinoma MDA-MB-231 and MCF-7 cells. I noticed the dynamic formation of tubular structures between the two different cell types and, surprisingly, the passage of mitochondria from MSCs to the cancer cells. Second, we used a 3D system of cell invasion in a collagen matrix, which we adapted for the coculture, in order to observe the effects of the interactions between the MDA-MB-231 and MSCs. In agreement with the literature, we observed an increase in the migratory potential of the cancer cells, an effect that could be linked to the transfer of mitochondria from MSCs to the cancer cells. To answer this question, I set up a protocol to specifically transfer to the cancer cells mitochondria isolated from the MSCs and test directly the functional consequences for the cancer cells. This protocol can be used to transfer mitochondria, not only from MSCs but also from other cells. This method is currently submitted to a patent process. Our results show that the transfer of MSC mitochondria to the cancer cells modifies cancer cells functional properties and increase their invasive and proliferative capacities. Concerning the metabolic activity, we noticed an increase in mitochondrial respiration and ATP production. We also observed an increase in the transcription level of enzymes related to the lipid synthesis and fatty acid oxidation. The results generated with this new protocol of mitochondria transfer show, for the first time, that mitochondria originating from MSCs can improve cellular capacities linked to the tumor progression. The role proposed by the scientific community for the interactions of MSCs with the tumor cells fits with the data generated in our work. Several questions remain open. In particular, could the transfer of mitochondria from MSCs to the cancer cells contribute to the acquisition of resistance to anti-cancer agents observed in patients? The protocol of transfer of mitochondria that we developed in the laboratory is a technique of choice and offers many advantages over other techniques such as microinjection and cytoplasmic hybrids; its implementation is simple and reproducible and can target large numbers of cells. This method opens numerous perspectives and potential applications such as the study of metabolic reprogramming. Thus, we could consider restoring the activity of dysfunctional cells by transferring mitochondria from “metabolically active” or healthy cells. In the long term, one of the applications could be transferring healthy or genetically modified mitochondria to zygotes carrying mitochondrial DNA mutations, in order to treat pathologies like infertility, neuro-degenerative diseases, cancer and premature aging.