First insights for targeted therapies in odontogenic myxoma.

OBJECTIVE: Odontogenic myxoma (OM) occasionally responds poorly to surgical treatment. The MAPK pathway is constitutively activated in several neoplasms and we aimed to test if the MAPK pathway is activated in OM, in order to pave the way for an alternative therapy for aggressive and recurrent cases. MATERIALS AND METHODS: The immunoexpression of phosphorylated ERK1/2 (pERK1/2) was assessed in OM. We established a 3D organotypic culture model for the in vitro study and patient-derived xenografts (PDX) in mice for the in vivo study. The MEK inhibitor U0126 was used to inhibit phosphorylation of ERK1/2 in the in vitro and in vivo models. RESULTS: All OM showed strong pERK1/2 immunoexpression, consistent with MAPK pathway activation. Treatment of the 3D culture with U0126 resulted in a reduced pERK1/2/ERK1/2 ratio. Consistent with the in vitro results, all PDX of animals treated with U0126 showed a decreased volume fold change compared with controls. CONCLUSIONS: The MAPK pathway is activated in OM and its inhibition leads to tumor shrinkage in PDX and cell culture models. CLINICAL RELEVANCE: Our results offer a pre-clinical frame for OM-targeted therapy. Further work is needed to determine if this initial finding holds clinical promise.

Bringing benign ectomesenchymal odontogenic tumours to the lab: An in vitro study using an organotypic culture model.

BACKGROUND: Benign neoplasms exhibit most of the cellular phenomena considered hallmarks of cancer, except the capacity to metastasize. Thus, the elucidation of the mechanisms associated with the progression of benign neoplasms may complement and clarify the mechanisms involved in carcinogenesis. Benign odontogenic tumours often result in facial deformities and morbidities, and have complex pathogenesis, mainly due to the diversity of interactions between the odontogenic epithelium and the ectomesenchyme. Primary cell culture of such tumours is not only difficult to be established and maintained, but also tumour cells lose characteristic cellular morphology. Considering gene expression, growth, migration, proliferation and cellular morphology are controlled by cell-cell interactions and cell-extracellular matrix interactions, cell culture in 3D substrates has gained space as a way to overcome some of the limitations of traditional monolayer cell culture systems. METHODS: In this study, fragments obtained from mesenchymal odontogenic tumours were cultured in type I collagen scaffolds. Invasion tests were performed in these models, as well as phenotypic characterization of the cultured tumours. RESULTS: The results obtained for the odontogenic myxoma and the cemento-ossifying fibroma demonstrate a good reproduction of the growth pattern of these tumours under ex vivo conditions. Microscopic evaluation showed maintenance of cell viability in the explants for more than 30 days, without the presence of necrosis. CONCLUSION: This is the first study involving long-term 3D primary cultures of benign odontogenic tumours, which is expected to support complex approaches to cell and molecular biology, and to serve as an experimental model for testing molecular therapies.

Repulsive Guidance Molecules a, b and c Are Skeletal Muscle Proteins, and Repulsive Guidance Molecule a Promotes Cellular Hypertrophy and Is Necessary for Myotube Fusion.

Repulsive guidance molecules (RGMs) compose a family of glycosylphosphatidylinositol (GPI)-anchored axon guidance molecules and perform several functions during neural development. New evidence has suggested possible new roles for these axon guidance molecules during skeletal muscle development, which has not been investigated thus far. In the present study, we show that RGMa, RGMb and RGMc are all induced during skeletal muscle differentiation in vitro. Immunolocalization performed on adult skeletal muscle cells revealed that RGMa, RGMb and RGMc are sarcolemmal proteins. Additionally, RGMa was found to be a sarcoplasmic protein with a surprisingly striated pattern. RGMa colocalization with known sarcoplasmic proteins suggested that this axon guidance molecule is a skeletal muscle sarcoplasmic protein. Western blot analysis revealed two RGMa fragments of 60 and 33 kDa, respectively, in adult skeletal muscle samples. RGMa phenotypes in skeletal muscle cells (C2C12 and primary myoblasts) were also investigated. RGMa overexpression produced hypertrophic cells, whereas RGMa knockdown resulted in the opposite phenotype. RGMa knockdown also blocked myotube formation in both skeletal muscle cell types. Our results are the first to show an axon guidance molecule as a skeletal muscle sarcoplasmic protein and to include RGMa in a system that regulates skeletal muscle cell size and differentiation.

Collagen XVIII and fibronectin involvement in bullous scleroderma.

BACKGROUND: Endostatin, an anti-angiogenic C-terminal fragment of collagen XVIII, has been recently reported to play a role in scleroderma pathogenesis, but collagen XVIII immunohistochemistry in scleroderma skin has still not been performed. Bullous scleroderma, a rare form of scleroderma, may have altered angiogenic and lymphangiogenic characteristics. OBJECTIVE: Our aim is to report a rare case of bullous scleroderma, studying the presence of fibronectin and collagens type I, III and XVIII in sclerodermic skin. METHODS: We describe the progression of bullous scleroderma in a 67-year-old patient since the first symptoms. Histological and immunohistochemical aspects of skin biopsies are compared to normal skin from a patient without scleroderma and are correlated with the pathogenesis of the disease. Indirect immunofluorescence measured by laser confocal microscopy allows quantitative determination of fibronectin and collagens type I, III and XVIII. RESULTS AND CONCLUSIONS: Dermo-epidermal cleavage, fibrosis and inflammation are the main histological findings. The dermal distribution and amounts of collagens and in the scleroderma patient are similar to normal skin. Conversely, both fibronectin and collagen XVIII are increased in scleroderma skin, suggesting their involvement in the pathogenesis of bullous scleroderma.

Mesenchymal stem cells in the dental tissues: perspectives for tissue regeneration.

In recent years, stem cell research has grown exponentially owing to the recognition that stem cell-based therapies have the potential to improve the life of patients with conditions that range from Alzheimer's disease to cardiac ischemia and regenerative medicine, like bone or tooth loss. Based on their ability to rescue and/or repair injured tissue and partially restore organ function, multiple types of stem/progenitor cells have been speculated. Growing evidence demonstrates that stem cells are primarily found in niches and that certain tissues contain more stem cells than others. Among these tissues, the dental tissues are considered a rich source of mesenchymal stem cells that are suitable for tissue engineering applications. It is known that these stem cells have the potential to differentiate into several cell types, including odontoblasts, neural progenitors, osteoblasts, chondrocytes, and adipocytes. In dentistry, stem cell biology and tissue engineering are of great interest since may provide an innovative for generation of clinical material and/or tissue regeneration. Mesenchymal stem cells were demonstrated in dental tissues, including dental pulp, periodontal ligament, dental papilla, and dental follicle. These stem cells can be isolated and grown under defined tissue culture conditions, and are potential cells for use in tissue engineering, including, dental tissue, nerves and bone regeneration. More recently, another source of stem cell has been successfully generated from human somatic cells into a pluripotent stage, the induced pluripotent stem cells (iPS cells), allowing creation of patient- and disease-specific stem cells. Collectively, the multipotency, high proliferation rates, and accessibility make the dental stem cell an attractive source of mesenchymal stem cells for tissue regeneration. This review describes new findings in the field of dental stem cell research and on their potential use in the tissue regeneration.

Mesenchymal stem cells in the dental tissues: perspectives for tissue regeneration

In recent years, stem cell research has grown exponentially owing to the recognition that stem cell-based therapies have the potential to improve the life of patients with conditions that range from Alzheimer’s disease to cardiac ischemia and regenerative medicine, like bone or tooth loss. Based on their ability to rescue and/or repair injured tissue and partially restore organ function, multiple types of stem/progenitor cells have been speculated. Growing evidence demonstrates that stem cells are primarily found in niches and that certain tissues contain more stem cells than others. Among these tissues, the dental tissues are considered a rich source of mesenchymal stem cells that are suitable for tissue engineering applications. It is known that these stem cells have the potential to differentiate into several cell types, including odontoblasts, neural progenitors, osteoblasts, chondrocytes, and adipocytes. In dentistry, stem cell biology and tissue engineering are of great interest since may provide an innovative for generation of clinical material and/or tissue regeneration. Mesenchymal stem cells were demonstrated in dental tissues, including dental pulp, periodontal ligament, dental papilla, and dental follicle. These stem cells can be isolated and grown under defined tissue culture conditions, and are potential cells for use in tissue engineering, including, dental tissue, nerves and bone regeneration. More recently, another source of stem cell has been successfully generated from human somatic cells into a pluripotent stage, the induced pluripotent stem cells (iPS cells), allowing creation of patient- and disease-specific stem cells. Collectively, the multipotency, high proliferation rates, and accessibility make the dental stem cell an attractive source of mesenchymal stem cells for tissue regeneration. This review describes new findings in the field of dental stem cell research and on their potential use in the tissue regeneration.

Nos últimos anos, as pesquisas com células tronco têm aumentado exponencialmente devido ao reconhecimento de que seu potencial terapêutico pode melhorar a qualidade de vida de pacientes com diversas doenças, como a doença de Alzheimer, isquemias cardíacas e, até mesmo, nas pesquisas de medicina regenerativa que visa uma possível substituição de órgão perdidos, como por exemplo, os dentes. Baseado em habilidades de reparar tecidos injuriados e restaurar parcialmente as funções de um órgão, diversos tipos de células-tronco têm sido estudadas. Recentes evidências demonstram que as células-tronco são primariamente encontradas em nichos e que certos tecidos apresentam mais células-tronco que outros. Entre estes, os tecidos dentais são considerados como uma fonte rica de células-tronco mesenquimais adequado para aplicações em engenharia tecidual. Sabe-se que estas células têm o potencial de diferenciarem-se em diversos tipos celulares, incluindo osteoblastos, células progenitoras de neurônios, osteoblastos, condrócitos e adipósitos. Na odontologia, a biologia celular e a engenharia tecidual são de grande interesse, pois fornecem inovações na geração de novos materiais clínicos e ou na regeneração tecidual. Estas podem ser isoladas e crescidas em diversos meios de cultura apresentando grande potencial para ser usada na engenharia tecidual, incluindo regeneração de tecidos dentais, nervos e ossos. Recentemente, outra fonte de células tronco tem sido geradas a partir de células somáticas de humanos a um estágio de pluripotência, chamados de células-tronco pluripotente induzida (iPS) levando à criação de células-tronco específicas. Coletivamente, a multipotencialidade, altas taxas de proliferação e acessibilidade, faz das células-tronco dentárias uma fonte atrativa de células-tronco mesenquimais para regeneração tecidual. Esta revisão descreve novos achados no campo da pesquisa com células-tronco dentais e seu potencial uso na regeneração tecidual.