FGF-2, TGFβ-1, PDGF-A and respective receptors expression in pleomorphic adenoma myoepithelial cells: an in vivo and in vitro study

Myoepithelial cells have an important role in salivary gland tumor development, contributing to a low grade of aggressiveness of these tumors. Normal myoepithelial cells are known by their suppressor function presenting increased expression of extracellular matrix genes and protease inhibitors. The importance of stromal cells and growth factors during tumor initiation and progression has been highlighted by recent literature. Many tumors result from the alteration of paracrine growth factors pathways. Growth factors mediate a wide variety of biological processes such as development, tissue repair and tumorigenesis, and also contribute to cellular proliferation and transformation in neoplastic cells. OBJECTIVES: This study evaluated the expression of fibroblast growth factor-2 (FGF-2), transforming growth factor β-1 (TGFβ-1), platelet-derived growth factor-A (PDGF-A) and their respective receptors (FGFR-1, FGFR-2, TGFβR-II and PDGFR-α) in myoepithelial cells from pleomorphic adenomas (PA) by in vivo and in vitro experiments. MATERIAL AND METHODS: Serial sections were obtained from paraffin-embedded PA samples obtained from the school's files. Myoepithelial cells were obtained from explants of PA tumors provided by surgery from different donors. Immunohistochemistry, cell culture and immunofluorescence assays were used to evaluate growth factor expression. RESULTS: The present findings demonstrated that myoepithelial cells from PA were mainly positive to FGF-2 and FGFR-1 by immunohistochemistry and immunofluorescence. PDGF-A and PDGFR-α had moderate expression by immunohistochemistry and presented punctated deposits throughout cytoplasm of myoepithelial cells. FGFR-2, TGFβ-1 and TGFβR-II were negative in all samples. CONCLUSIONS: These data suggested that FGF-2 compared to the other studied growth factors has an important role in PA benign myoepithelial cells, probably contributing to proliferation of these cells through the FGFR-1

Mesenchymal stem cells: Isolation and characterization of populations derived from human dental alveolus and identification and characterization of populations from mouse dental pulp

Há um grande interesse no estudo de células-tronco em função de sua capacidade de auto-renovação e plasticidade. Estas características capacitam as células-tronco a produzirem células de diferentes linhagens que participam ativamente do processo de homeostase, da resposta à injúria e da regeneração e reparação tecidual. A polpa dental é o tecido mais estudado na Odontologia em relação a células-tronco, mas diversos estudos já mostraram a presença dessas células também na região periodontal. É importante salientar, que dependendo de sua origem, as células-tronco apresentam comportamentos diversos, especialmente no que tange ao transplante in vivo. Além disso, os microambientes onde as células-tronco residem (nichos), têm um papel fundamental no comportamento das mesmas, pois controlam aspectos essenciais como o estado de indiferenciação e a auto-renovação. Esse projeto de pesquisa teve como objetivos duas análises distintas. Na primeira, verificar se existem células-tronco mesenquimais derivadas da curetagem do alvéolo dental humano após extrações dentais. Na segunda, analisar o nicho de células-tronco nas polpas dentais de camundongos. Em comum, as duas análises se basearam no uso de marcadores previamente utilizados na literatura para o estudo de células-tronco. Como não existem marcadores únicos e específicos para a identificação dessas células, diferentes combinações desses marcadores entre si e de técnicas laboratoriais foram empregadas. No primeiro estudo, após o isolamento das células, deu-se especial atenção à sua caracterização, que foi realizada através de ensaios que avaliaram propriedades e comportamentos que sabidamente ocorrem em células-tronco. Já na segunda parte desse estudo, utilizamos a polpa dental de camundongos para a análise in vivo de nichos. Em camundongos, a localização do nicho responsável pelo crescimento continuo dos incisivos é conhecida. De uma maneira geral, nossos resultados demonstram que: 1) É possível isolar células-tronco/progenitoras a partir de tecidos curetados de alvéolo dental após extrações dentárias. Esse fato é inédito e abre novas perspectivas em termos de oportunidade de coleta e futura aplicação clínica. 2) É possível observar a diversidade populacional nas células que formam o nicho de células-tronco em polpa dental de camundongos, e através de uma organização hierárquica, propusemos um modelo para este nicho. Esse modelo servirá de base para estudos subsequentes que visem avaliar o comportamento das células que formam o nicho, quando isoladas das demais, e abrirá possibilidade para análises em outros tecidos dentais e não dentais.There is great interest in the study of stem cells due to their ability to produce mature cells of different lineages that participate actively in the process of homeostasis, injury response, regeneration and tissue repair. The dental pulp is the most studied tissue in dentistry, but several studies have shown the presence of these cells in the periodontal tissue region. It is important to note that depending on their origin, these cells exhibit different behaviours, especially in regard to in vivo transplantation. Furthermore, the microenvironment in which these cells are found (niches) have an essential role in their behaviour as they control important aspects such as differentiation and self-renewal. This research project aimed for two distinct analyses. The first was to verify if there are mesenchymal stem cells derived from human dental socket curettage after dental extractions. The second, to analyse the stem cell niche in mouse dental pulp. In common, the two analyses were based on the use of markers previously used in the literature for the study of stem cells. As there are no specific and unique markers to identify these cells, an extensive combination of these markers among themselves, and laboratory techniques were performed. In the first study, after the isolation of the cells, special attention was given to their characterization by combining assays to evaluate stem cells properties and behaviours. In the second part of this study, we used the mouse dental pulp model for in vivo analysis of stem cell niches. In mice, the location of the niche responsible for the incisors continuous growth is known. In general our results showed that: 1) It is possible to isolate progenitor/stem cells from tissue curettage of the alveolus after tooth extractions. This fact is unprecedented and opens new perspectives for the obtention of stem cells for future clinical applications. 2) It is possible to observe the cells population diversity of the mouse dental pulp niche and through a hierarchical organization, we proposed a model for this niche. This model will provide basis for further studies aimed at evaluating the behavior of cells that form the niche, when isolated from the others, and opens the possibility for the analysis of the niche structure in other dental and non-dental tissues

Can porous polymeric scaffolds be functionalized by stem cells leading to osteogenic differentiation? a systematic review of in vitro studies

The aim of this study was to analyze the influence of nanoporous structure of polymeric biomaterials on the in vitro osteogenic induction of human stem cells. An electronic search in three databases (MEDLINE, SCOPUS, and Web of Science) was performed for articles that were published before May 2018. In vitro studies were included if they met the following criteria: (1) the use of polymeric scaffolds (natural or synthetic); (2) the co-culture of human stem cells with the scaffold; and (3) cell viability, proliferation, and osteogenic differentiation assays. The main characteristics of the published studies were summarized, and a quality assessment tool was used to analyze methodological features. Eighty-eight potential articles were firstly retrieved. Thirteen were eligible for qualitative analysis. Only three studies characterized cell stemness. Nanostructure of the scaffolds showed a significant influence on viability, proliferation, and osteogenic differentiation of human stem cells. Combination of porosity between 72 and 93% and a large range diameter between 50 and 224 μm resulted in more remarkable cellular proliferation and differentiation. Porous polymeric scaffolds can be functionalized by stem cells leading to osteogenic induction. High standards of laboratory practice and accurate methodological reporting are essential for the credibility of the results157571576

Anticancer Activities of the Quinone-Methide Triterpenes Maytenin and 22-β-hydroxymaytenin Obtained from Cultivated Maytenus ilicifolia Roots Associated with Down-Regulation of miRNA-27a and miR-20a/miR-17-5p

Natural triterpenes exhibit a wide range of biological activities. Since this group of secondary metabolites is structurally diverse, effects may vary due to distinct biochemical interactions within biological systems. In this work, we investigated the anticancer-related activities of the quinone-methide triterpene maytenin and its derivative compound 22-β-hydroxymaytenin, obtained from Maytenus ilicifolia roots cultivated in vitro. Their antiproliferative and pro-apoptotic activities were evaluated in monolayer and three-dimensional cultures of immortalized cell lines. Additionally, we investigated the toxicity of maytenin in SCID mice harboring tumors derived from a squamous cell carcinoma cell line. Both isolated molecules presented pronounced pro-apoptotic activities in four cell lines derived from head and neck squamous cell carcinomas, including a metastasis-derived cell line. The molecules also induced reactive oxygen species (ROS) and down-regulated microRNA-27a and microRNA-20a/miR-17-5p, corroborating with the literature data for triterpenoids. Intraperitoneal administration of maytenin to tumor-bearing mice did not lead to pronounced histopathological changes in kidney tissue, suggesting low nephrotoxicity. The wide-ranging activity of maytenin and 22-β-hydroxymaytenin in head and neck cancer cells indicates that these molecules should be further explored in plant biochemistry and biotechnology for therapeutic applications

Monitoring the Establishment of VOC Gamma in Minas Gerais, Brazil: A Retrospective Epidemiological and Genomic Surveillance Study

Since its first identification in Brazil, the variant of concern (VOC) Gamma has been associated with increased infection and transmission rates, hospitalizations, and deaths. Minas Gerais (MG), the second-largest populated Brazilian state with more than 20 million inhabitants, observed a peak of cases and deaths in March–April 2021. We conducted a surveillance study in 1240 COVID-19-positive samples from 305 municipalities distributed across MG’s 28 Regional Health Units (RHU) between 1 March to 27 April 2021. The most common variant was the VOC Gamma (71.2%), followed by the variant of interest (VOI) zeta (12.4%) and VOC alpha (9.6%). Although the predominance of Gamma was found in most of the RHUs, clusters of Zeta and Alpha variants were observed. One Alpha-clustered RHU has a history of high human mobility from countries with Alpha predominance. Other less frequent lineages, such as P.4, P.5, and P.7, were also identified. With our genomic characterization approach, we estimated the introduction of Gamma on 7 January 2021, at RHU Belo Horizonte. Differences in mortality between the Zeta, Gamma and Alpha variants were not observed. We reinforce the importance of vaccination programs to prevent severe cases and deaths during transmission peaks