>Magister Scientiae - MSc / Odontogenic myxoma (OM) is one of the rare odontogenic tumours that affect the maxilo-facial regions. Skeletal myxomas are more common than soft tissue types in the facial regions. Odontogenic myxomas (OM) are non metastasizing tumours and therefore are considered benign. These lesions are known for their distinctive infiltrative nature which makes complete surgical removal a challenging task.Since the tumour occurs inside the bone and can reach a considerable size with little or no clinical manifestation, the radiologic examination remains the main method to determine the size and the extension of the tumour preoperatively.Aim of the study To assess the different imaging techniques which are currently in use for the diagnosis of the odontogenic myxomas.Materials and methods The images were retrieved from the library of the Department of Diagnostics and Radiology at the Tygerberg Oral Health Centre.Initially each of the imaging modalities was assessed independently to describe the imaging features of odontogenic myxoma on conventional radiograph,Computed Tomography (CT) and Magnetic Resonance Image (MRI). Secondly the imaging features of the three techniques were correlated and contrasted to determine the most valuable imaging modality in the diagnosis of the tumour.Results In this study we found that MRI was superior to other modalities in the ability to show and determine the true extension of the tumours. Therefore, MRI distinguished the tumour tissue from the surrounding structures and soft tissues.Myxomas were found to display characteristic patterns of growth on MRI. These patterns include lobulations and/or budding, nodulation and crevices formation.Moreover T2 weighted images deduced the contents of the tumour by emitting different signal intensities from the various components of the tumours.Additionally, characteristic pattern of contrast uptake differentiated the myxomatous, collagenous parts and presumed the nature of the trabeculae whether it is bony or fibrous.CT also showed the tumour and determined the subtle extension of the tumour into the adjacent structures and bone. Expansion and status of the cortical margin were reliably detected on CT. It also determined the pattern of growth in all tumours whether it is lobulation and/or budding, crevices formation or combination of them. In the present study this feature seemed to be a characteristic finding for all the tumours on CT. Moreover CT was able to compare densities of the tumours to surrounding muscles.Conventional radiography (CR) showed great limitations with regard to diagnostic abilities. Although it displayed the existence of the abnormality in all cases,conventional radiograph failed to detect margins and extension in most of the lesions. Therefore conventional radiograph is not reliable for presurgical assessment of the tumour or in differentiation the tumour from other benign and some malignant tumour. Conclusion In spite of the many limitations and shortcomings, conventional radiography remains the preliminary step in the diagnosis process. However digital imaging techniques provide images of great diagnostic value which is especially helpful in the diagnosis of odontogenic myxoma.

Células-tronco adultas podem ser isoladas de vários tecidos, dentre eles a polpa dentária humana, tecido originado na papila dentária do dente em desenvolvimento. Estas linhagens multipotentes podem ser estudadas sob vários aspectos, como na elucidação da histogênese de tumores. O objetivo deste estudo foi inferir a histogênese do mixoma odontogênico, neoplasia odontogênica benigna, analisando a expressão de proteínas da matriz extracelular (MEC) e de metaloproteinases da matriz (MMPs) em células-tronco adultas de polpa dentária humana. Três linhagens diferentes de células-tronco originadas de polpas dentárias humanas IDPSCs (DL-1, DL-2 e DL4) foram utilizadas. As proteínas analisadas foram as mesmas expressas na neoplasia: vimentina, colágeno tipo I, fibronectina, tenascina, ácido hialurônico e MMPs (MMP-1, MMP-2 e MMP-9). Imunofluorescência e ensaios enzimáticos foram utilizados para analisar a presença de proteínas nas células cultivadas e no meio de cultura condicionado por estas células, respectivamente. Todas as linhagens celulares expressaram a vimentina e nenhuma expressou o ácido hialurônico. A linhagem celular DL-1 expressou todas as outras proteínas da matriz extracelular estudadas, enquanto que na linhagem DL-2 apenas não foi observada a expressão do colágeno tipo I. Fibronectina e tenascina não foram observados na linhagem DL-4. Todas as linhagens expressaram todas as MMPs, sendo que a produção de MMP-2 nas três linhagens foi significantemente maior que a de todas outras MMPs. Baseado nas condições deste estudo, é possível concluir que a expressão de proteínas da MEC e de MMPs em células-tronco de polpa dentária humana apresentaram perfil similar àquela apresentada no mixoma odontogênico, exceto pela ausência de marcação do ácido hialurônico em todas as linhagens. A ausência de secreção de ácido hialurônico pelas IDPSCs poderia indicar que o mixoma odontogênico deriva de uma célula mais diferenciada que as células-tronco. / Adult stem cells can be isolated from different tissues including the human dental pulp, a structure originated from the dental papillae. These cell lineages are of importance in a series of studies, as the analysis of tumors histogenesis. The aim of this study was to infer the histogenesis of odontogenic myxoma, a benign odontogenic neoplasia by analyzing the ECM and MMPs molecules expressed in human dental pulp stem cells. Three different lineages of immature dental pulp stem cells (IDPSCs) (DL-1, DL-2 and DL-4) were used. The proteins searched were those expressed by the tumoral cells: vimentin, type I collagen, fibronectin, tenascin and hialuronic acid (HA) and the matrix metalloproteinases (MMP-1, MMP-2 and MMP-9). Immunofluorecence and enzymatic assays were used for analyzing the presence of the proteins in the cells and in the culture media conditioned by the cells, respectively. All the lineages expressed vimentin; however none expressed HA. DL-1 lineage expressed all the other ECM proteins, and the expression of type I collagen was not observed in the DL-2 lineage. Fibronectin and tenascin were not observed in the DL-4 lineage. All the lineages expressed all the MMPs. The release of MMP-2 from all cell lineages was significantly higher than those of all other MMPs. Based on the conditions of this study its possible to conclude that the overall expression of MEC proteins and MMPs in the lineages of human dental pulp stem cells were similar to those found in the odontogenic myxoma, except for the absence of hyaluronic acid. The absence of HA secretion by the IDPSCs could indicate that the odontogenic myxoma tumoural cells derive from a cell more differentiated than the stem cells.

Made available in DSpace on 2014-12-17T15:32:22Z (GMT). No. of bitstreams: 1 CassianoFWN.pdf: 2062817 bytes, checksum: d3cc1231e84c63282116f5950923db98 (MD5) Previous issue date: 2006-02-23 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / The odontogenic myxoma shares cellular and structural aspects with dental papilla, which has been implicated as probable origin of this neoplasm. The aim of the present study was to perform a comparative immunohistochemical analysis for the expression of collagenase-1 (MMP-1) and gelatinases A (MMP-2) and B (MMP-9) in odontogenic myxomas and dental papilla of teeth germs. Twelve cases of odontogenic myxomas and eight specimens of teeth germs were selected. It was taken into consideration the presence or absence of immunoreactivity, the pattern of immunohistochemical distribution of proteases within extracellular matrix, as well as, the number of cells revealing immunostaining for matrix metalloproteinases (MMPs). It was verified a significant difference (p<0,05) in relation to MMP-2 immunoexpression, which was observed only within extracellular matrix of myxomas. Nevertheless, MMP-1 labeling was revealed by most of the cases of odontogenic myxoma, at levels close to those observed in dental papilla. In relation to the pattern of distribution, a significant difference was obtained between specimens (p<0,05), with neoplasms predominantly exhibiting a focal pattern for MMP-1. The quantitative analysis of neoplastic cells labeled for MMPs denoted a significant difference (p<0,05), demonstrating a higher proportion of MMP-1 in comparison to MMPs-2 and -9. It can be concluded that immunohistochemical expression of MMP-1 at levels comparable to those observed in dental papilla and quantitatively superior in relation to MMPs-2 and -9, suggest an implication of this protease on extracellular matrix degradation of odontogenic myxomas. Moreover, the possibility of interactions with receptors involved in cellular adhesion, particularly with integrins, suggests a plausible function on local invasiveness of such neoplasms. Additionally, the presence of a descent immunoexpression gradient for these MMPs on odontogenic myxomas, associated to substrate specificity inherent in each enzyme, suggest the existence of a coordinated mechanism between interstitial collagenase and gelatinases A and B in order to allow an efficient degradation of extracellular matrix and local invasion by neoplastic cells / O mixoma odontog?nico compartilha aspectos celulares e estruturais com a papila dent?ria, tendo-se implicado esta ?ltima como prov?vel origem deste neoplasma. O prop?sito desta pesquisa consistiu em analisar comparativamente a express?o imuno-histoqu?mica de colagenase-1 (MMP-1) e gelatinases A (MMP-2) e B (MMP-9) em mixomas odontog?nicos e papilas de germes dent?rios. Foram selecionados 12 casos de mixoma odontog?nico e 08 esp?cimes de germes dent?rios, para an?lise da presen?a ou aus?ncia de express?o imunohistoqu?mica e padr?o de distribui??o destas proteases em meio ? matriz extracelular, bem como, o n?mero de c?lulas positivamente marcadas para estas metaloproteinases de matriz (MMPs). Constatou-se diferen?a significativa (p<0,05) em rela??o ? imunorreatividade para MMP-2, apresentando-se expressa apenas em meio ? matriz extracelular dos mixomas. Para MMP-1 foi verificada imunorreatividade na maioria dos casos de mixomas, com propor??es semelhantes ?s constatadas nas papilas dent?rias. Em rela??o ao padr?o de distribui??o, evidenciou-se diferen?a significativa apenas para MMP-1 (p<0,05), com predomin?ncia do padr?o focal nos neoplasmas. Por sua vez, a quantidade de c?lulas imunorreativas ?s proteases, nos mixomas odontog?nicos, revelou diferen?as significativas (p<0,05), estando a MMP-1 presente em maiores propor??es, em compara??o com as MMPs-2 e -9. Concluiu-se que a express?o de MMP-1, em n?vel compar?vel ao constatado nas papilas de germes dent?rios e numericamente superior ?s MMPs-2 e -9, sugere a implica??o desta protease no processo de degrada??o da matriz extracelular nos mixomas odontog?nicos e, em decorr?ncia da possibilidade de associa??o das MMPs a receptores envolvidos no processo de ades?o celular, especialmente ?s integrinas, ainda um prov?vel papel na invasividade local destes neoplasmas. Adicionalmente, a evidencia??o de um gradiente descendente na express?o imuno-histoqu?mica das MMPs nos mixomas odontog?nicos, associada ? especificidade de substrato inerente a cada uma destas proteases, sugerem a exist?ncia de um mecanismo coordenado entre colagenase intersticial e gelatinases A e B, direcionado ? degrada??o eficiente da matriz extracelular e invas?o local por parte das c?lulas neopl?sicas

Células-tronco adultas podem ser isoladas de vários tecidos, dentre eles a polpa dentária humana, tecido originado na papila dentária do dente em desenvolvimento. Estas linhagens multipotentes podem ser estudadas sob vários aspectos, como na elucidação da histogênese de tumores. O objetivo deste estudo foi inferir a histogênese do mixoma odontogênico, neoplasia odontogênica benigna, analisando a expressão de proteínas da matriz extracelular (MEC) e de metaloproteinases da matriz (MMPs) em células-tronco adultas de polpa dentária humana. Três linhagens diferentes de células-tronco originadas de polpas dentárias humanas IDPSCs (DL-1, DL-2 e DL4) foram utilizadas. As proteínas analisadas foram as mesmas expressas na neoplasia: vimentina, colágeno tipo I, fibronectina, tenascina, ácido hialurônico e MMPs (MMP-1, MMP-2 e MMP-9). Imunofluorescência e ensaios enzimáticos foram utilizados para analisar a presença de proteínas nas células cultivadas e no meio de cultura condicionado por estas células, respectivamente. Todas as linhagens celulares expressaram a vimentina e nenhuma expressou o ácido hialurônico. A linhagem celular DL-1 expressou todas as outras proteínas da matriz extracelular estudadas, enquanto que na linhagem DL-2 apenas não foi observada a expressão do colágeno tipo I. Fibronectina e tenascina não foram observados na linhagem DL-4. Todas as linhagens expressaram todas as MMPs, sendo que a produção de MMP-2 nas três linhagens foi significantemente maior que a de todas outras MMPs. Baseado nas condições deste estudo, é possível concluir que a expressão de proteínas da MEC e de MMPs em células-tronco de polpa dentária humana apresentaram perfil similar àquela apresentada no mixoma odontogênico, exceto pela ausência de marcação do ácido hialurônico em todas as linhagens. A ausência de secreção de ácido hialurônico pelas IDPSCs poderia indicar que o mixoma odontogênico deriva de uma célula mais diferenciada que as células-tronco. / Adult stem cells can be isolated from different tissues including the human dental pulp, a structure originated from the dental papillae. These cell lineages are of importance in a series of studies, as the analysis of tumors histogenesis. The aim of this study was to infer the histogenesis of odontogenic myxoma, a benign odontogenic neoplasia by analyzing the ECM and MMPs molecules expressed in human dental pulp stem cells. Three different lineages of immature dental pulp stem cells (IDPSCs) (DL-1, DL-2 and DL-4) were used. The proteins searched were those expressed by the tumoral cells: vimentin, type I collagen, fibronectin, tenascin and hialuronic acid (HA) and the matrix metalloproteinases (MMP-1, MMP-2 and MMP-9). Immunofluorecence and enzymatic assays were used for analyzing the presence of the proteins in the cells and in the culture media conditioned by the cells, respectively. All the lineages expressed vimentin; however none expressed HA. DL-1 lineage expressed all the other ECM proteins, and the expression of type I collagen was not observed in the DL-2 lineage. Fibronectin and tenascin were not observed in the DL-4 lineage. All the lineages expressed all the MMPs. The release of MMP-2 from all cell lineages was significantly higher than those of all other MMPs. Based on the conditions of this study its possible to conclude that the overall expression of MEC proteins and MMPs in the lineages of human dental pulp stem cells were similar to those found in the odontogenic myxoma, except for the absence of hyaluronic acid. The absence of HA secretion by the IDPSCs could indicate that the odontogenic myxoma tumoural cells derive from a cell more differentiated than the stem cells.