Epithelial–mesenchymal transdifferentiation and extracellular matrix gene expression in pleomorphic adenomas of the parotid salivary gland

Mesenchymal and epithelial cell differentiation are assumed to be dichotomic primary events in embryonic development. In this study, pleomorphic adenomas of the parotid gland were analysed as a model which shows morphological features of both epithelial and mesenchymal tissue types. Using matrix gene expression profiles as a supplementary criterion for the identification of cellular phenotypes, areas with unequivocal epithelial and mesenchymal differentiation could be demonstrated. Many areas displayed a transitional phenotype with cells showing both epithelial and mesenchymal features. The data provide evidence that epithelial–mesenchymal transitions represent the basic principle of the tisuse heterogeneity in pleomorphic adenomas. Thus, pleomorphic adenomas demonstrate the potential of adult (neoplastic) epithelial cells to transdifferentiate into mesenchymal cells in vivo. Copyright © 1998 John Wiley & Sons, Ltd.     

羊膜上皮细胞和羊膜间充质干细胞构建组织工程皮肤

背景：由于人胎盘来源的间充质干细胞具有多方面的优点,近年来已成为干细胞研究的热点。 目的：分析鉴定羊膜间充质干细胞和羊膜上皮细胞的生物学特性,探讨其作为皮肤种子细胞在三维气液培养构建组织工程皮肤中的应用情况。 方法：用胰酶胶原酶多步消化法获取羊膜间充质干细胞和羊膜上皮细胞,通过流式细胞术、反转录-聚合酶链反应和免疫荧光染色技术,鉴定两种细胞的表面分子标记、干细胞特性、与皮肤角质形成细胞的相似性,并利用两种细胞为种子细胞以鼠Ⅰ型胶原为基质进行三维气液培养。 结果与结论：①流式细胞术检测体外培养羊膜间充质干细胞和羊膜上皮细胞均高表达CD90、CD73、CD105,不表达造血干细胞标志CD34以及MHC-Ⅱ类分子HLA-DR。②反转录-聚合酶链反应检测到羊膜间充质干细胞表达干细胞特性基因CMCY和NANOG,羊膜上皮细胞表达干细胞特性基因CMCY和 KLF4,两种细胞均有干细胞特性。③反转录-聚合酶链反应检测羊膜间充质干细胞表达皮肤角质形成细胞特性基因K19、β1-integrin、K8,羊膜上皮细胞表达K19、β1-integrin、K5、K8,免疫荧光染色见羊膜上皮细胞表达与角质形成细胞增殖相关的的特性蛋白K14,说明羊膜上皮细胞与皮肤角质形成细胞更具相似性, 在特定条件下更易于分化为皮肤角质形成细胞。④利用两种细胞成功构建组织工程皮肤,苏木精-伊红染色切片显示其具有一定的皮肤结构,且羊膜上皮细胞发生了初步分化。以上结果说明羊膜间充质干细胞与羊膜上皮细胞通过三维培养构建人皮肤组织是可行的。     

Comparative study of the dynamics of focal contacts in live epithelial and mesenchymal cells

To further characterize the morphology and dynamics of focal contacts (FCs) in epithelial cells, we compared the size, number, localization, velocity, and turnover of FCs in epithelial and mesenchymal cell lines. Using immunocytochemistry, we found there were no significant differences between mesenchymal and epithelial cells in number and appearance whereas the location and size of FCs in each cell were different between mesenchymal and epithelial cells. FCs in mesenchymal cells localized at the cell periphery and cell center, but FCs were found only at the cell periphery in epithelial cells. The size of FCs in epithelial cells were significantly smaller than in mesenchymal cells. Next, we compared the dynamics of FCs in both mesenchymal and epithelial cells and found no significant difference between the two groups. Finally, we added inhibitors for the hemidesmosome (HD) proteins, α6 integrin and β4 integrin, to HaCat cell (epithelial) cultures and examined the number and size of FCs. Under these conditions, the size and localization of FCs in HaCat cells became comparable to that of mesenchymal cells. Therefore, we concluded the size and localization of FCs is regulated by the existence of HDs in epithelial cells.     

Metaplastic breast carcinoma with epithelial phenotype of pseudosarcomatous components

A case of metaplastic breast carcinoma was subjected to an immunohistochemical study to characterize its apparent fibrosarcomatous and chondrosarcomatous elements. Polyclonal and monoclonal antibodies against epithelial cell components such as keratin proteins, epithelial membrane antigen, membrane and cytoplasmic antigens of human mammary carcinoma cells, and carcinoembryonic antigen were used, as well as antibodies against the mesenchymal antigens, desmin, and vimentin. The cells with a mesenchymal appearance had an epithelial derivation, as shown by the presence of epithelial cell markers and absence of mesenchymal cell markers.     

Immunohistochemical analysis of extracellular matrix components in synovial sarcoma

Little attention has been paid to the composition of the extracellular matrix in synovial sarcoma, a tumour showing both epithelial and mesenchymal phenotypes. As extracellular matrix participates actively in interactions between epithelial and mesenchymal tissues, further knowledge of the pathogenesis of this tumour may be provided by the study of extracellular matrix components. Therefore, we have analysed the immunohistochemical distribution of type I, III, and IV collagen, fibronectin, laminin and tenascin in four cases of synovial sarcoma. The pattern of immunoreactivity for these molecules varied according to the tissue phenotype of the tumour. Mesenchymal tissue labelled mainly for type I and III interstitial collagen and fibronectin. The epithelial component was surrounded by a laminin and type IV collagen-positive basement membrane, but punctate pericellular reactivity for laminin and type IV collagen was also detected among some mesenchymal cells. Tenascin was strongly expressed in the mesenchymal tissue immediately around epithelial structures and weakly or not at all expressed in the monophasic tumours and in mesenchymal tissue distant from epithelial elements in the biphasic tumours. These results suggest some resemblances between synovial sarcoma and the embryonic development of epithelia from mesenchymal cells, providing further support for the concept of an epitheliogenesis from the mesenchyme in these tumours.     

Epithelial–mesenchymal transition in human lungs with usual interstitial pneumonia: Quantitative immunohistochemistry

Fibroblastic foci, a major histological feature of usual interstitial pneumonia (UIP), play a critical role in the development of UIP. The mechanisms involved in the formation of these foci, however, including cellular origin, remain unclear. Recent in vitro and animal studies suggested epithelial–mesenchymal transition (EMT) of alveolar epithelial cells during pulmonary fibrogenesis. The aim of the present study was to investigate the presence of EMT in patients with UIP on quantitative immunohistochemistry using pathological tissue sections. The study subjects were 13 patients with UIP pattern among 52 patients with interstitial pneumonia who underwent lung biopsy. Alveolar epithelial cells overlying fibroblastic foci expressed epithelial markers less frequently and mesenchymal markers more frequently compared with those in non-diseased control lung tissues ( n = 10). Moreover, double immunostaining showed that some epithelial cells stained for both epithelial and mesenchymal markers. Furthermore, significantly higher numbers of epithelial marker-positive fibroblastic cells were found in fibroblastic foci in UIP as well as in other non-UIP fibrosing diseases than in control lung tissues. The results showed that some epithelial cells overlying fibroblastic foci lose the epithelial phenotype and gain the mesenchymal phenotype, and that some fibroblastic cells in fibroblastic foci originate from epithelial cells. But this EMT may not be specific for UIP.     

Mesenchymal cells are required for functional development of thymic epithelial cells

Epithelial-mesenchymal interactions have essential roles in thymus organogenesis. Mesenchymal cells are known to be required for epithelial cell proliferation. However, the contribution of mesenchymal cells to thymic epithelial cell differentiation is still unclear. In the present study, we have investigated the roles of mesenchymal cells in functional development of epithelial cells in the thymus anlage in patch (ph) mutant mice, which have a primarily defect in mesenchymal cells caused by the absence of platelet-derived growth factor receptor alpha expression. In the ph/ph thymus anlage, T cell progenitors migrate normally among the epithelial cells, however, they are severely impaired to proliferate and differentiate to CD25-positive cells. Epithelial cells of the ph/ph thymus anlage show severely impaired proliferation and expression of functional molecules, such as SCF, Delta-like 4 and MHC class II, which have crucial roles in T cell development. Moreover, the cultured ph/ph thymus anlage fails to develop into a mature organ supporting full T cell development. Addition of intact thymic mesenchymal cells to organ culture induces development of the ph/ph thymus anlage. In the cultured lobes, added mesenchymal cells contribute to form not only the capsule but also the meshwork structure mingled with epithelial cells. Our present results strongly suggest the roles of mesenchymal cells in functional development of epithelial cells in thymus organogenesis. In addition, our data suggest that mesenchymal cells are required to create the thymic microenvironment and to maintain epithelial architecture and function.     

New insights into the pathogenesis and treatment of peritoneal fibrosis: A potential role of Wnt/β-catenin induced epithelial to mesenchymal transition and stem cells for therapy

Peritoneal fibrosis is a chronic, progressive progress, which is associated with ultrafiltration failure. In the development of peritoneal fibrosis, Epithelial to mesenchymal transition is an important cellular process whereby epithelial cells transform into mesenchymal cells under physiology and pathology conditions, along with change of cell morphology and expression of related genes. It plays an important role in embryogenesis and development of tissues and organs, as well as organ fibrosis and tumorigenesis. Several intracellular signal transduction pathways induce the process of Epithelial to mesenchymal transition. In recent researches, Wnt/β-catenin induced epithelial to mesenchymal transition was suggested to be an important reason for tissues and organs fibrosis. The following paper reviews the potential role of Wnt/β-catenin induced epithelial to mesenchymal transition in peritoneal fibrosis. New potential therapeutic interventions of peritoneal fibrosis are discussed.     

Expression of epithelial and extracellular matrix protein markers in meningiomas

In an attempt to characterize the dual mesenchymal and epithelial differentiating potential of meningiomas, cryostat sections from 50 meningiomas of diverse histological subtypes were examined immunohistochemically with a panel of markers for epithelial and mesenchymal differentiation. The overall positivities were: keratins 50%, epithelial membrane antigen 94%, human milk fat globules 38%, carcinoembryonic antigen 4% (secretory meningiomas only), desmoplakins 64%, collagen I 82%, procollagen I 96%, collagen III 74%, collagen IV 60%, laminin 54%, fibronectin 98% and vimentin 98%. Such production of keratins was not found in many previous immunohistochemical analyses of meningiomas with paraffin sections. The extracellular matrix proteins were present in a pericellular distribution suggestive of their being produced by the tumour cells. The potential of dual epithelial and mesenchymal differentiation in meningiomas was further examined in seven cases established on short-term cultures. Morphologically, subcultured tumour cells resembled fibroblasts and in five cases revealed similar epithelial and mesenchymal immunohistochemical profiles as for direct tumour immunostaining. In two cases, cells from the primary cultures revealed a fine skeleton of intercellular matrix proteins stainable by immunohistochemical methods, providing further proof that meningioma cells possess the capability to elaborate extracellular matrix proteins, a major mesenchymal function akin to that of fibroblasts.     

Reappraisal of histogenesis in the bursal lymphoid follicle of the chicken

The development of the bursal follicle and the appearance of the follicle-associated epithelial (FAE) cell and the reticuloepithelial (REp) cell were studied. The stadied. The stages of development of the bursal follicle were observed by light and electron microscopy; an anticytokeratin monoclonal antibody was also used. At the beginning of folicle development, a mesenchymal cell cluster is observed in the tunica propria; the cluster becomes wedged in a niche of the surface epithelium, and gradually it is completely surounded by the epithelium itself, which closes under the clump of mesenchymal cells. The epithelial cells lying upon the mesenchymal clump become necrotic, and anumber of mesenchymal cells bulge out, forming the FAE cells. The epithelial cells that hav closed under the mesenchymal nodule become stratified and form the REp cells; they become star-shaped because the mdedullarylymphoid cells grow between them. Finally, the cortex in formed, possibly as a result of the migration of medullary cells before they peripheralize. it is concluded that FAE cells are not specialized It is concluded that FAE cells are not specialized epithelial cells, as they do not react to an anticytokeratin monoclonal antibody; on the contrary, they are formed by mesenchymal stemcells that bulge into the lumen and change their character after moving into the epithelium. The REp cells appear in the follicular primordium shortly after the bursal follicle begins to develop; the pronounced reactivity of the REp cells to an anticytokeratin monoclonal antibody supports the hypothesis of their epithelial origin.     

Epithelial–mesenchymal transition in Crohn's disease

Crohn's disease (CD) is often accompanied by the complications of intestinal strictures and fistulas. These complications remain obstacles in CD treatment. In recent years, the importance of epithelial–mesenchymal transition in the pathogenesis of CD-associated fistulas and intestinal fibrosis has become apparent. Epithelial–mesenchymal transition refers to a dynamic change, wherein epithelial cells lose their polarity and adherence and acquire migratory function and fibroblast features. During formation of CD-associated fistulas, intestinal epithelial cells dislocate from the basement membrane and migrate to the lining of the fistula tracts, where they convert into transitional cells as a compensatory response under the insufficient wound healing condition. In CD-associated intestinal fibrosis, epithelial–mesenchymal transition may serve as a source of new fibroblasts and consequently lead to overproduction of extracellular matrix. In this review, we present current knowledge of epithelial–mesenchymal transition and its role in the pathogenesis of CD in order to highlight new therapy targets for the associated complications.     

Is sclerosing hemangioma of lung an alveolar mixed tumour?

A case of a peripheral lung tumour histologically categorized as a sclerosing hemangioma of the lung is presented. Ultrastructurally, the tumour is composed of a mixture of epithelial and mesenchymal elements in varying stages of differentiation. Type II pneumocytes are identified as one epithelial component, while primitive mesenchymal cells with a tendency to develop into pericytes are the predominant mesenchymal component. The tumour appears to differentiate along the line of the pulmonary alveolar septa, and should be designated as a 'pulmonary alveolar mixed tumour'.     

Desmoplastic ameloblastoma: a case report with fine-needle aspiration cytologic findings

A case of desmoplastic ameloblastoma of the maxilla in a 25-yr-old woman is presented. Smears prepared from fine-needle aspiration cytology showed two populations of cellular elements: cohesive epithelial clusters with basaloid morphology present, mostly in bidimensional, irregularly outlined clusters with ill-formed palisading of nuclei at the periphery in some, and a mesenchymal component represented by 1) a sparse chunk of moderate-sized tissue fragments made up of spindle- or ovoid-shaped nuclei entrapped in mesenchymal matrix, and 2) many dissociated naked oval-to-spindle-shaped nuclei. The presence of epithelial and mesenchymal components and their benign nature lead us to consider the possibility of benign odontogenic tumors 1) of epithelial origin, such as ameloblastma with a stromal component, e.g., desmoplastic ameloblastoma; 2) of mesenchymal origin, such as odontogenic fibroma; and 3) of mixed epithelial and mesenchymal origin, such as ameloblastic fibroma. Excision and histopathological examination of this lesion confirmed the diagnosis of desmoplastic ameloblastoma. In the given clinical setting and radiological examination, the above cytological features suggest a benign odontogenic tumor, rather than precisely diagnosing any of the entities mentioned above. However, it is important to distinguish between these, since the treatment varies accordingly. The differential diagnosis is discussed.     

Effective Differentiation of Induced Pluripotent Stem Cells Into Dental Cells

Background: A biotooth is defined as a complete living tooth, made in laboratory cultures from a spontaneous interplay between epithelial and mesenchymal cell-based frontal systems. A good solution to these problems is to use induced pluripotent stem cells (iPSCs). However, no one has yet formulated culture conditions that effectively differentiate iPSCs into dental epithelial and dental mesenchymal cells phenotypes analogous to those present in tooth development. Results: Here, we tried to induce differentiation methods for dental epithelial cells (DEC) and dental mesenchymal cells from iPSCs. For the DEC differentiation, the conditional media of SF2 DEC was adjusted to embryoid body. Moreover, we now report on a new cultivation protocol, supported by transwell membrane cell culture that make it possible to differentiate iPSCs into dental epithelial and mesenchymal cells with abilities to initiate the first stages in de novo tooth formation. Conclusions: Implementation of technical modifications to the protocol that maximize the number and rate of iPSC differentiation, into mesenchymal and epithelial cell layers, will be the next step toward growing an anatomically accurate biomimetic tooth organ. Developmental Dynamics 248:129–139, 2019. © 2018 Wiley Periodicals, Inc.     

Pulmonary blastoma. An immunohistochemical analysis with comparison with fetal lung in its pseudoglandular stage

Pulmonary blastomas are believed to be mixed epithelial and mesenchymal tumors that recapitulate the developing lung at 10-16 weeks gestation. The authors compared nine blastomas with ten fetal lungs in the pseudoglandular stage of development with a panel of antibodies to various lung antigens to evaluate immunophenotypic homology. Both blastomas and embryonal lungs showed expression of cytokeratin, epithelial membrane antigen, and carcinoembryonic antigen in their epithelial elements, and both contained scattered chromogranin-positive neuroendocrine cells. Rare surfactant-producing and Clara cell antigen-elaborating cells were identified in both groups. The mesenchymal components of blastomas and fetal lung showed smooth muscle, myofibroblastic, and blastematous differentiation. The blastematous elements demonstrated vimentin and keratin coexpression in four cases, providing some support for the contention that pluripotential blastema may give rise to the epithelial and mesenchymal elements of the distal lobule.     

犬脂肪间充质干细胞及其外泌体修复庆大霉素致犬肾小管上皮细胞损伤

文题释义：犬脂肪间充质干细胞：由犬皮下脂肪组织分离得到,是一类具有自我更新潜能、多向分化能力的成体多能干细胞,它能分泌多种细胞因子、趋化因子以及外泌体等活性物质,具有强大的组织修复作用,在宠物临床上有很大发展前景。外泌体：是活细胞分泌产生的胞外囊泡,大小为40-100  nm,含有多种蛋白质、mRNA和miRNAs,它通过这些生物分子的传递改变受体细胞的生化特征,是参与细胞间通讯的重要成分,而且在疾病诊断和治疗中也发挥着重要作用。  摘要背景：犬肾脏损伤的特点是肾小管上皮细胞凋亡坏死。最近研究表明间充质干细胞及其外泌体在人、大鼠、小鼠肾损伤治疗中显示出良好的效果,但对犬的研究甚少。目的：探讨犬脂肪间充质干细胞及其外泌体对庆大霉素致犬肾小管上皮细胞损伤的影响。方法：采用5 mmol/L硫酸庆大霉素处理犬肾小管上皮细胞,随后分别将犬脂肪间充质干细胞及其条件培养基和外泌体与受损犬肾小管上皮细胞共培养。在24 h及48 h后采用CCK-8法测定各组细胞增殖活力,流式细胞术检测各组细胞凋亡率,最后通过Q-PCR法检测PCNA、Bcl-2和Bax基因的表达。结果与结论：犬脂肪间充质干细胞及其条件培养基和外泌体均可显著促进受损犬肾小管上皮细胞增殖以及减少细胞凋亡(P < 0.05),其中犬脂肪间充质干细胞外泌体的效果最好,可显著提高受损犬肾小管上皮细胞PCNA、Bcl-2基因的表达(P < 0.05),对庆大霉素诱导的犬肾小管上皮细胞损伤发挥修复作用。 ORCID: 0000-0003-3613-2980(林嘉颖) 中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程     

Mesenchymal to epithelial transition in development and disease

Cellular plasticity is fundamental to embryonic development. The importance of cellular transitions in development is first apparent during gastrulation when the process of epithelial to mesenchymal transition transforms polarized epithelial cells into migratory mesenchymal cells that constitute the embryonic and extraembryonic mesoderm. It is now widely accepted that this developmental pathway is exploited in various disease states, including cancer progression. The loss of epithelial characteristics and the acquisition of a mesenchymal-like migratory phenotype are crucial to the development of invasive carcinoma and metastasis. However, given the morphological similarities between primary tumour and metastatic lesions, it is likely that tumour cells re-activate certain epithelial properties through a mesenchymal to epithelial transition (MET) at the secondary site, although this is yet to be proven. MET is also an essential developmental process and has been extensively studied in kidney organogenesis and somitogenesis. In this review we describe the process of MET, highlight important mediators, and discuss their implication in the context of cancer progression.     

体外诱导骨髓间充质干细胞向胆管上皮样细胞分化

背景：肝外胆管和胆囊上皮细胞的分离、纯化相对比较容易,但是胆管上皮细胞在体外易失去增殖能力,难以提供基础研究所需的细胞量,限制了胆管修复等基础研究的进程。虽然骨髓间充质干细胞可以转化为肝细胞,但是尚无体外培养骨髓间充质干细胞分化为胆管上皮细胞的报道。 目的：探讨体外诱导骨髓间充质干细胞分化为胆管上皮细胞的可行性。 方法：采取全骨髓贴壁筛选法体外分离并纯化大鼠骨髓间充质干细胞后,在第3代骨髓间充质干细胞培养基中加入肝细胞生长因子和表皮生长因子,倒置显微镜下观察骨髓间充质干细胞的形态学变化,免疫荧光检测不同时间CK19的表达情况。 结果与结论：在肝细胞生长因子和表皮生长因子的诱导下,骨髓间充质干细胞由梭形逐渐变为多边形、三角形;免疫荧光检查显示诱导第4周细胞膜开始表达CK19,诱导第6周CK19表达率明显提高。结果表明在两种细胞因子联合诱导下骨髓间充质干细胞能够转化为胆管上皮样细胞,从而为骨髓间充质干细胞修复损伤胆管提供了一个新思路。