Amniotic Fluid Stem Cells: Future Perspectives

The existence of stem cells in human amniotic fluid was reported for the first time almost ten years ago. Since this discovery, the knowledge about these cells has increased dramatically. Today, amniotic fluid stem (AFS) cells are widely accepted as a new powerful tool for basic research as well as for the establishment of new stem-cell-based therapy concepts. It is possible to generate monoclonal genomically stable AFS cell lines harboring high proliferative potential without raising ethical issues. Many different groups have demonstrated that AFS cells can be differentiated into all three germ layer lineages, what is of relevance for both, the scientific and therapeutical usage of these cells. Of special importance for the latter is the fact that AFS cells are less tumorigenic than other pluripotent stem cell types. In this paper, we have summarized the current knowledge about this relatively young scientific field. Furthermore, we discuss the relevant future perspectives of this promising area of stem cell research focusing on the next important questions, which need to be answered

Activation of the human anaphase-promoting complex by proteins of the CDC20/Fizzy family

AbstractThe initiation of anaphase and exit from mitosis depend on the activation of the cyclosome/anaphase-promoting complex (APC) that ubiquitinates regulatory proteins such as anaphase inhibitors and mitotic cyclins [1–4]. Genetic experiments have demonstrated that two related WD40-repeat proteins – called Cdc20p and Hct1p/Cdh1p in budding yeast and Fizzy and Fizzy-related in Drosophila – are essential for APC-dependent proteolysis [5–11]. Human orthologs of these proteins – hCDC20/p55CDC[12] and hCDH1 – have recently been found to associate with APC in a cell-cycle-dependent manner [13,14]. Here, we show that the amount of hCDC20 and hCDH1 bound to APC correlates with a high ubiquitination activity of APC and that binding of recombinant hCDC20 and hCDH1 can activate APC in vitro. Our results suggest that the association between hCDH1 and APC is regulated by post-translational mechanisms, whereas the amount of hCDC20 bound to APC may in addition be controlled by hCDC20 synthesis and destruction [15]. The temporally distinct association of hCDC20 and hCDH1 with APC suggests that these proteins are, respectively, mitosis-specific and G1-specific activating subunits of APC

The first trimester human trophoblast cell line ACH-3P: A novel tool to study autocrine/paracrine regulatory loops of human trophoblast subpopulations – TNF-α stimulates MMP15 expression

<p>Abstract</p> <p>Background</p> <p>The trophoblast compartment of the placenta comprises various subpopulations with distinct functions. They interact among each other by secreted signals thus forming autocrine or paracrine regulatory loops. We established a first trimester trophoblast cell line (ACH-3P) by fusion of primary human first trimester trophoblasts (week 12 of gestation) with a human choriocarcinoma cell line (AC1-1).</p> <p>Results</p> <p>Expression of trophoblast markers (cytokeratin-7, integrins, matrix metalloproteinases), invasion abilities and transcriptome of ACH-3P closely resembled primary trophoblasts. Morphology, cytogenetics and doubling time was similar to the parental AC1-1 cells. The different subpopulations of trophoblasts e.g., villous and extravillous trophoblasts also exist in ACH-3P cells and can be immuno-separated by HLA-G surface expression. HLA-G positive ACH-3P display pseudopodia and a stronger expression of extravillous trophoblast markers. Higher expression of insulin-like growth factor II receptor and human chorionic gonadotropin represents the basis for the known autocrine stimulation of extravillous trophoblasts.</p> <p>Conclusion</p> <p>We conclude that ACH-3P represent a tool to investigate interaction of syngeneic trophoblast subpopulations. These cells are particularly suited for studies into autocrine and paracrine regulation of various aspects of trophoblast function. As an example a novel effect of TNF-α on matrix metalloproteinase 15 in HLA-G positive ACH-3P and explants was found.</p

Stromal fibroblasts shape the myeloid phenotype in normal colon and colorectal cancer and induce CD163 and CCL2 expression in macrophages

Colorectal cancer (CRC) accounts for about 10% of cancer deaths worldwide. Colon carcinogenesis is critically influenced by the tumor microenvironment. Cancer associated fibroblasts (CAFs) and tumor associated macrophages (TAMs) represent the major components of the tumor microenvironment. TAMs promote tumor progression, angiogenesis and tissue remodeling. However, the impact of the molecular crosstalk of tumor cells (TCs) with CAFs and macrophages on monocyte recruitment and their phenotypic conversion is not known in detail so far. In a 3D human organotypic CRC model, we show that CAFs and normal colonic fibroblasts are critically involved in monocyte recruitment and for the establishment of a macrophage phenotype, characterized by high CD163 expression. This is in line with the steady recruitment and differentiation of monocytes to immunosuppressive macrophages in the normal colon. Cytokine profiling revealed that CAFs produce M-CSF, and IL6, IL8, HGF and CCL2 secretion was specifically induced by CAFs in co-cultures with macrophages. Moreover, macrophage/CAF/TCs co-cultures increased TC invasion. We demonstrate that CAFs and macrophages are the major producers of CCL2 and, upon co-culture, increase their CCL2 production twofold and 40-fold, respectively. CAFs and macrophages expressing high CCL2 were also found in vivo in CRC, strongly supporting our findings. CCL2, CCR2, CSF1R and CD163 expression in macrophages was dependent on active MCSFR signaling as shown by M-CSFR inhibition. These results indicate that colon fibroblasts and not TCs are the major cellular component, recruiting and dictating the fate of infiltrated monocytes towards a specific macrophage population, characterized by high CD163 expression and CCL2 production

mTORC1 is essential for early steps during Schwann cell differentiation of amniotic fluid stem cells and regulates lipogenic gene expression.

Schwann cell development is hallmarked by the induction of a lipogenic profile. Here we used amniotic fluid stem (AFS) cells and focused on the mechanisms occurring during early steps of differentiation along the Schwann cell lineage. Therefore, we initiated Schwann cell differentiation in AFS cells and monitored as well as modulated the activity of the mechanistic target of rapamycin (mTOR) pathway, the major regulator of anabolic processes. Our results show that mTOR complex 1 (mTORC1) activity is essential for glial marker expression and expression of Sterol Regulatory Element-Binding Protein (SREBP) target genes. Moreover, SREBP target gene activation by statin treatment promoted lipogenic gene expression, induced mTORC1 activation and stimulated Schwann cell differentiation. To investigate mTORC1 downstream signaling we expressed a mutant S6K1, which subsequently induced the expression of the Schwann cell marker S100b, but did not affect lipogenic gene expression. This suggests that S6K1 dependent and independent pathways downstream of mTORC1 drive AFS cells to early Schwann cell differentiation and lipogenic gene expression. In conclusion our results propose that future strategies for peripheral nervous system regeneration will depend on ways to efficiently induce the mTORC1 pathway

Premature aging in genetic diseases: what conclusions can be drawn for physiological aging

According to current views the major hallmarks of physiological aging may be subdivided into three categories, primary causes of cellular damage (genomic instability, telomere attrition, loss of proteostasis, epigenetic alterations and compromised macroautophagy), antagonistic hallmarks that represent response to damage (deregulated nutrient sensing, cellular senescence, mitochondrial dysfunction) and integrative hallmarks that represent culprits of the phenotype (stem cell exhaustion, altered intercellular communication, chronic inflammation, dysbiosis). In contrast to physiological aging, premature aging diseases are driven by one or two distinct primary causes of aging, such as genomic instability in the case of Werner syndrome (WS), each displaying other hallmarks of aging to a variable extent. In this review we will focus on primary causes of well-investigated premature aging diseases Hutchinson-Gilford progeria syndrome (HGPS), WS, and Cockayne syndrome (CS) and for each provide an overview of reported aging hallmarks to elucidate resemblance to physiological aging on the mechanistic level and in the context of characteristic age-related diseases. Ubiquitous and tissue specific animal models of premature aging diseases will be discussed as useful tools to decipher fundamental aging-related mechanisms and develop intervention strategies to combat premature aging and age-related diseases