AF-MSCs fate can be regulated by culture conditions

Human mesenchymal stem cells (hMSCs) represent a population of multipotent adherent cells able to differentiate into many lineages. In our previous studies, we isolated and expanded fetal MSCs from second-trimester amniotic fluid (AF) and characterized them based on their phenotype, pluripotency and proteomic profile. In the present study, we investigated the plasticity of these cells based on their differentiation, dedifferentiation and transdifferentiation potential in vitro. To this end, adipocyte-like cells (AL cells) derived from AF-MSCs can regain, under certain culture conditions, a more primitive phenotype through the process of dedifferentiation. Dedifferentiated AL cells derived from AF-MSCs (DAF-MSCs), gradually lost the expression of adipogenic markers and obtained similar morphology and differentiation potential to AF-MSCs, together with regaining the pluripotency marker expression. Moreover, a comparative proteomic analysis of AF-MSCs, AL cells and DAF-MSCs revealed 31 differentially expressed proteins among the three cell populations. Proteins, such as vimentin, galectin-1 and prohibitin that have a significant role in stem cell regulatory mechanisms, were expressed in higher levels in AF-MSCs and DAF-MSCs compared with AL cells. We next investigated whether AL cells could transdifferentiate into hepatocyte-like cells (HL cells) directly or through a dedifferentiation step. AL cells were cultured in hepatogenic medium and 4 days later they obtained a phenotype similar to AF-MSCs, and were termed as transdifferentiated AF-MSCs (TRAF-MSCs). This finding, together with the increase in pluripotency marker expression, indicated the adaption of a more primitive phenotype before transdifferentiation. Additionally, we observed that AF-, DAF- and TRAF-MSCs displayed similar clonogenic potential, secretome and proteome profile. Considering the easy access to this fetal cell source, the plasticity of AF-MSCs and their potential to dedifferentiate and transdifferentiate, AF may provide a valuable tool for cell therapy and tissue engineering applications

Role of environmental chemicals, processed food derivatives, and nutrients in the induction of carcinogenesis

In recent years it has been hypothesized that cancer stem cells (CSCs) are the actual driving force of tumor formation, highlighting the need to specifically target CSCs to successfully eradicate cancer growth and recurrence. Particularly, the deregulation of physiological signaling pathways controlling stem cell proliferation, self-renewal, differentiation, and metabolism is currently considered as one of the leading determinants of cancer formation. Given their peculiar, slow-dividing phenotype and their ability to respond to multiple microenvironmental stimuli, stem cells appear to be more susceptible to genetic and epigenetic carcinogens, possibly undergoing mutations resulting in tumor formation. In particular, some animal-derived bioactive nutrients and metabolites known to affect the hormonal milieu, and also chemicals derived from food processing and cooking, have been described as possible carcinogenic factors. Here, we review most recent literature in this field, highlighting how some environmental toxicants, some specific nutrients and their secondary products can induce carcinogenesis, possibly impacting stem cells and their niches, thus causing tumor growt

Expression of Eph receptor tyrosine kinases and their ligands in human Granulosa lutein cells and human umbilical vein endothelial cells

Corpus luteum development is regulated by gonadotropins and accompanied by extremely rapid vascularization of the avascular granulosa cell compartiment by endothelial cells (EC). The proliferation of Granulosa cells (GC) and EC is a complex interplay and takes place in a spatially and temporarily coordinated manner. The erythropoietin-producing hepatoma amplified sequence (Eph) receptors and their ligands-the ephrins- are a recently detected family of membrane located protein tyrosine kinases which play a crucial role in the growth and development of nerve and blood vessel network. We report about the mRNA expression pattern of Ephs and their ligands in human GC, in human EC, and in carcinoma cell lines OvCar-3 and Hela. The mRNA of EphA4, EphA7, ephrinA4, ephrinB1 and ephrinB2 was detected in GC and EC, while EphA2 was expressed only in CC. The expression of various Ephs and ephrins did not change in GC after stimulation with human chorion gonadotropin. Our study analyzes for the first time the expression of the complete human Eph/ephriny-system in GC and in EC. The remarkable similarity between these two cell types supports the theory of a functional relationship of EC and GC. In addition, it was shown that hCG is not a major determinant of Eph/ephrin regulation in GC. © J. A. Barth Verlag in Georg Thieme Verlag KG

Role of environmental chemicals, processed food derivatives, and nutrients in the induction of carcinogenesis

In recent years it has been hypothesized that cancer stem cells (CSCs) are the actual driving force of tumor formation, highlighting the need to specifically target CSCs to successfully eradicate cancer growth and recurrence. Particularly, the deregulation of physiological signaling pathways controlling stem cell proliferation, self-renewal, differentiation, and metabolism is currently considered as one of the leading determinants of cancer formation. Given their peculiar, slow-dividing phenotype and their ability to respond to multiple microenvironmental stimuli, stem cells appear to be more susceptible to genetic and epigenetic carcinogens, possibly undergoing mutations resulting in tumor formation. In particular, some animal-derived bioactive nutrients and metabolites known to affect the hormonal milieu, and also chemicals derived from food processing and cooking, have been described as possible carcinogenic factors. Here, we review most recent literature in this field, highlighting how some environmental toxicants, some specific nutrients and their secondary products can induce carcinogenesis, possibly impacting stem cells and their niches, thus causing tumor growt

Role of environmental chemicals, processed food derivatives, and nutrients in the induction of carcinogenesis

In recent years it has been hypothesized that cancer stem cells (CSCs) are the actual driving force of tumor formation, highlighting the need to specifically target CSCs to successfully eradicate cancer growth and recurrence. Particularly, the deregulation of physiological signaling pathways controlling stem cell proliferation, self-renewal, differentiation, and metabolism is currently considered as one of the leading determinants of cancer formation. Given their peculiar, slow-dividing phenotype and their ability to respond to multiple microenvironmental stimuli, stem cells appear to be more susceptible to genetic and epigenetic carcinogens, possibly undergoing mutations resulting in tumor formation. In particular, some animal-derived bioactive nutrients and metabolites known to affect the hormonal milieu, and also chemicals derived from food processing and cooking, have been described as possible carcinogenic factors. Here, we review most recent literature in this field, highlighting how some environmental toxicants, some specific nutrients and their secondary products can induce carcinogenesis, possibly impacting stem cells and their niches, thus causing tumor growth. © Mary Ann Liebert, Inc. 2015

Regenerative toxicology: the role of stem cells in the development of chronic toxicities

Introduction: Human stem cell lines and their derivatives, as alternatives to the use of animal cells or cancer cell lines, have been widely discussed as cellular models in predictive toxicology. However, the role of stem cells in the development of long-term toxicities and carcinogenesis has not received great attention so far, despite growing evidence indicating the relationship of stem cell damage to adverse effects later in life. However, testing this in vitro is a scientific/technical challenge in particular due to the complex interplay of factors existing under physiological conditions. Current major research programs in stem cell toxicity are not aiming to demonstrate that stem cells can be targeted by toxicants. Therefore, this knowledge gap needs to be addressed in additional research activities developing technical solutions and defining appropriate experimental designs. Areas covered: The current review describes selected examples of the role of stem cells in the development of long-term toxicities in the brain, heart or liver and in the development of cancer. Expert opinion: The presented examples illustrate the need to analyze the contribution of stem cells to chronic toxicity in order to make a final conclusion whether stem cell toxicities are an underestimated risk in mechanism-based safety assessments. This requires the development of predictive in vitro models allowing the assessment of adverse effects to stem cells on chronic toxicity and carcinogenicity

Sox2 suppression by miR-21 governs human mesenchymal stem cell properties

MicroRNAs (miRNAs) have recently been shown to act as regulatory signals for maintaining stemness and for determining the fate of adult and fetal stem cells, such as human mesenchymal stem cells (hMSCs). hMSCs constitute a population of multipotent stem cells that can be expanded easily in culture and are able to differentiate into many lineages. We have isolated two subpopulations of fetal mesenchymal stem cells (MSCs) from amniotic fluid (AF) known as spindle-shaped (SS) and roundshaped (RS) cells and characterized them on the basis of their phenotypes, pluripotency, proliferation rates, and differentiation potentials. In this study, we analyzed the miRNA profile of MSCs derived from AF, bone marrow (BM), and umbilical cord blood (UCB). We initially identified 67 different miRNAs that were expressed in all three types ofMSCs but at different levels, depending on the source. A more detailed analysis revealed that miR-21 was expressed at higher levels in RS-AF-MSCs and BMMSCs compared with SS-AF-MSCs. We further demonstrated for the first time a direct interaction betweenmiR-21 and the pluripotencymarker Sox2. The induction of miR-21 strongly inhibited Sox2 expression in SS-AF-MSCs, resulting in reduced clonogenic and proliferative potential and cell cycle arrest. Strikingly, the opposite effect was observed upon miR-21 inhibition in RS-AF-MSCs and BMMSCs, which led to an enhanced proliferation rate. Finally, miR-21 induction accelerated osteogenesis and impaired adipogenesis and chondrogenesis in SS-AF-MSCs. Therefore, these findings suggest that miR-21 might specifically function by regulating Sox2 expression in human MSCs and might also act as a key molecule determining MSC proliferation and differentiation. © AlphaMed Press 2014

miR-26a Mediates Adipogenesis of Amniotic Fluid Mesenchymal Stem/Stromal Cells via PTEN, Cyclin E1, and CDK6

Recent findings indicate that microRNAs (miRNAs) are critical for the regulatory network of adipogenesis in human mesenchymal stem/stromal cells (MSCs). Fetal MSCs derived from amniotic fluid (AF-MSCs) represent a population of multipotent stem cells characterized by a wide range of differentiation properties that can be applied in cell-based therapies. In this study, miRNA microarray analysis was performed to assess miRNA expression in terminal differentiated AF-MSCs into adipocyte-like cells (AL cells). MiR-26a was identified in high expression levels in AL cells indicating a critical role in the process of adipogenesis. Overexpression of miR-26a in AF-MSCs led to significant induction of their adipogenic differentiation properties that were altered after miR-26a inhibition. We have demonstrated that miR-26a regulates adipogenesis through direct inhibition of PTEN, which in turn promotes activation of Akt pathway. Also, miR-26a modulates cell cycle during adipogenesis by interacting with Cyclin E1 and CDK6. These results point to the regulatory role of miR-26a and its target genes PTEN, Cyclin E1, and CDK6 in adipogenic differentiation of AF-MSCs, providing a basis for understanding the mechanisms of fat cell development and obesity

Molecular and proteomic characterization of human mesenchymal stem cells derived from amniotic fluid: Comparison to bone marrow mesenchymal stem cells

Human mesenchymal stem cells (hMSCs) constitute a population of multipotent adherent cells able to give rise to multiple mesenchymal lineages such as osteoblasts, adipocytes, or chondrocytes. So far, the most common source of MSCs has been the bone marrow (BM); however BM-MSC harvesting and processing exhibits major drawbacks and limitations. Thus, identification and characterization of alternative sources of MSCs are of great importance. In the present study, we isolated and expanded fetal MSCs from second-trimester amniotic fluid (AF). We documented that these cells are of embryonic origin, can differentiate under appropriate conditions into cell types derived from all three germ layers, and express the pluripotency marker Oct-4, the human Nanog protein, and the stage-specific embryonic antigen-4 (SSEA-4). Furthermore, we systematically tested the immunophenotype of cultured MSCs by flow cytometry analysis using a wide variety of markers. Direct comparison of this phenotype to the one derived from cultured BM-MSCs demonstrated that cultured MSCs from both sources exhibit similar expression patterns. Using the two-dimensional gel electrophoresis and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) approach, we have generated for the first time the protein map of cultured AF-MSCs by identifying 261 proteins, and we compared it directly to that of cultured BM-MSCs. The functional pattern of the identified proteins from both sources was similar. However, cultured AF-MSCs displayed a number of unique proteins related to proliferation and primitive phenotype, which may confer to the distinct features of the two types. Considering the easy access to this new cell source and the yield of expanded MSCs for stem cell research, AF may provide an excellent source of MSCs both for basic research and for potential therapeutic applications. © 2007 Mary Ann Liebert, Inc

Human amniotic fluid-derived mesenchymal stem cells as therapeutic vehicles: A novel approach for the treatment of bladder cancer

Recent studies support cell-based therapies for cancer treatment. An advantageous cell type for such therapeutic schemes are the mesenchymal stem cells (MSCs) that can be easily propagated in culture, genetically modified to express therapeutic proteins, and exhibit an innate tropism to solid tumors in vivo. Recently, we successfully isolated and expanded MSCs from second-trimester amniotic fluid (AF-MSCs). The main characteristic of AF-MSCs is their efficient and rapid expansion in vitro. Herein, we investigated the AF-MSCs tropism and capability to transport interferon beta (IFNβ) to the region of neoplasia in a bladder tumor model. To this end, we used the T24M bladder cancer cell line, previously generated from our studies, and developed a disease progression model in immunosuppressed mice, that can recapitulate the molecular events of bladder carcinogenesis. Our results documented that AF-MSCs exhibited high motility, when migrated either to T24M cells or to T24M-conditioned medium, and we further identified and studied the secreted factors which may trigger these enhanced migratory properties. Further, lentivirus-transduced AF-MSCs, expressing green fluorescent protein (GFP) or IFNβ, were intravenously administered to T24M tumor-bearing animals at multiple doses to examine their therapeutic effect. GFP- and IFNβ-AF-MSCs successfully migrated and colonized at the tumor site. Notably, significant inhibition of tumor growth as well as prolonged survival of mice were observed in the presence of IFNβ-AF-MSCs. Collectively, these results document the great potential of AF-MSCs as anti-cancer vehicles, implemented by the targeting of the tumor site and further facilitated by their high proliferation rate and expansion efficiency in culture. © Copyright 2012, Mary Ann Liebert, Inc