Current Issue : October - December Volume : 2016 Issue Number : 4 Articles : 5 Articles
Background: Microenvironment is being increasingly recognized as a critical determinant in tumor progression and\nmetastasis. However, the appropriate regulatory mechanism to maintain the normal balance between differentiation\nand self-renewal of the cancer cell in microenvironment is not well known.\nMethods: 4T1 breast cancer cells were treated with embryonic stem (ES) cell conditioned medium which was\ncollected from mouse ES cells. Inhibition of tumor cell growth was based on the reduction of cell proliferation and\nviability, and inhibition of aggressive properties of tumor cells were examined using the wound-healing and\nmammosphere assays. The expression of stem cell-associated genes was detected by quantitative RT-PCR.\nResults: We used a real-time imaging system to investigate the effect of the mouse ES cell microenvironment on\naggressive breast cancer cells in vitro and in vivo. Exposure of breast cancer cells in mouse ES cell conditioned medium\nresulted in inhibition of growth, migration, metastasis, and angiogenesis of cancer cells. For many tumors, aggressive\nproperties were tightly related to Stat3 signaling activation. We specifically discovered that the ES cell\nmicroenvironment sufficiently suppressed Stat3 signaling pathway activation in aggressive tumor cells, leading to a\nreduction in tumorigenesis and invasiveness.\nConclusions: We identified important functions of Stat3 and their implications for antitumor effects of ES cell\nconditioned medium. Some factors secreted by ES cells could efficiently suppress Stat3 pathway activation in breast\ncancer cells, and were then involved in cancer cell growth, survival, invasion, and migration. This study may act as a\nplatform to understand tumor cell plasticity and may offer new therapeutic strategies to inhibit breast cancer\nprogression....
Background: Diabetes mellitus is a devastating metabolic disease. Generation of insulin-producing cells (IPCs) from\nstem cells, especially from Whartonâ��s jelly mesenchymal stem cells (WJ-MSCs), has sparked much interest recently.\nExendin-4 has several beneficial effects on MSCs and �² cells. However, its effects on generation of IPCs from WJ-MSCs\nspecifically have not been studied adequately. The purpose of this study was therefore to investigate how exendin-4\ncould affect the differentiation outcome of WJ-MSCs into IPCs, and to investigate the role played by exendin-4 in this\ndifferentiation process.\nMethods: WJ-MSCs were isolated, characterized and then induced to differentiate into IPCs using two differentiation\nprotocols: protocol A, without exendin-4; and protocol B, with exendin-4. Differentiated IPCs were assessed by\nthe expression of various �²-cell-related markers using quantitative RT-PCR, and functionally by measuring glucosestimulated\ninsulin secretion.\nResults: The differentiation protocol B incorporating exendin-4 significantly boosted the expression levels of\n�²-cell-related genes Pdx-1, Nkx2.2, Isl-1 and MafA. Moreover, IPCs generated by protocol B showed much better\nresponse to variable glucose concentrations as compared with those derived from protocol A, which totally\nlacked such response. Furthermore, exendin-4 alone induced early differentiation markers such as Pdx-1 and\nNkx2.2 but not Isl-1, besides inducing late markers such as MafA. In addition, exendin-4 showed a synergistic\neffect with nicotinamide and �²-mercaptoethanol in the induction of these markers.\nConclusions: Exendin-4 profoundly improves the differentiation outcome of WJ-MSCs into IPCs, possibly through the\nability to induce the expression of �²-cell markers....
Background: Induced pluripotent mesenchymal stem cells (iPMSCs) are novel candidates for drug screening,\nregenerative medicine, and cell therapy. However, introduction of transcription factor encoding genes for induced\npluripotent stem cell (iPSC) generation which could be used to generate mesenchymal stem cells is accompanied\nby the risk of insertional mutations in the target cell genome.\nMethods: We demonstrate a novel method using an inactivated viral particle to package and deliver four purified\nrecombinant Yamanaka transcription factors (Sox2, Oct4, Klf4, and c-Myc) resulting in reprogramming of human\nprimary fibroblasts. Whole genome bisulfite sequencing was used to analyze genome-wide CpG methylation of\nhuman iPMSCs. Western blot, quantitative PCR, immunofluorescence, and in-vitro differentiation were used to\nassess the pluripotency of iPMSCs.\nResults: The resulting reprogrammed fibroblasts show high-level expression of stem cell markers. The human\nfibroblast-derived iPMSC genome showed gains in DNA methylation in low to medium methylated regions and\nconcurrent loss of methylation in previously hypermethylated regions. Most of the differentially methylated regions\nare close to transcription start sites and many of these genes are pluripotent pathway associated. We found that\nDNA methylation of these genes is regulated by the four iPSC transcription factors, which functions as an\nepigenetic switch during somatic reprogramming as reported previously. These iPMSCs successfully differentiate\ninto three embryonic germ layer cells, both in vitro and in vivo. Following multipotency induction in our study, the\ndelivered transcription factors were degraded, leading to an improved efficiency of subsequent programmed\ndifferentiation.\nConclusion: Recombinant transcription factor based reprogramming and derivatization of iPMSC offers a novel\nhigh-efficiency approach for regenerative medicine from patient-derived cells....
Background: Acute myocardial infarction (MI) leads to an irreversible loss of proper cardiac function. Application of\nstem cell therapy is an attractive option for MI treatment. Adipose tissue has proven to serve as a rich source of stem\ncells (ADSCs). Taking into account the different morphogenesis, anatomy, and physiology of adipose tissue, we\nhypothesized that ADSCs from different adipose tissue depots may exert a diverse multipotency and cardiogenic\npotential.\nMethods: The omental, pericardial, and epicardial adipose tissue samples were obtained from organ donors and\npatients undergoing heart transplantation at our institution. Human foreskin fibroblasts were used as the control group.\nIsolated ADSCs were analyzed for adipogenic and osteogenic differentiation capacity and proliferation potential. The\nimmunophenotype and constitutive gene expression of alkaline phosphatase (ALP), GATA4, Nanog, and OCT4 were\nanalyzed. DNA methylation inhibitor 5-azacytidine was exposed to the cells to stimulate the cardiogenesis. Finally,\nreprogramming towards cardiomyocytes was initiated with exogenous overexpression of seven transcription factors\n(ESRRG, GATA4, MEF2C, MESP1, MYOCD, TBX5, ZFPM2) previously applied successfully for fibroblast transdifferentiation\ntoward cardiomyocytes. Expression of cardiac troponin T (cTNT) and alpha-actinin (Actn2) was analyzed 3 weeks after\ninitiation of the cardiac differentiation.\nResults: The multipotent properties of isolated plastic adherent cells were confirmed with expression of CD29, CD44,\nCD90, and CD105, as well as successful differentiation toward adipocytes and osteocytes; with the highest osteogenic\nand adipogenic potential for the epicardial and omental ADSCs, respectively. Epicardial ADSCs demonstrated a lower\ndoubling time as compared with the pericardium and omentum-derived cells. Furthermore, epicardial ADSCs revealed\nhigher constitutive expression of ALP and GATA4. Increased Actn2 and cTNT expression was observed after the\ntransduction of seven reprogramming factors, with the highest expression in the epicardial ADSCs, as compared with\nthe other ADSC subtypes and fibroblasts.\nConclusions: Human epicardial ADSCs revealed a higher cardiomyogenic potential as compared with the pericardial\nand omental ADSC subtypes as well as the fibroblast counterparts. Epicardial ADSCs may thus serve as the valuable\nsubject for further studies on more effective methods of adult stem cell differentiation toward cardiomyocytes....
Background: Endothelial progenitor cell (EPC) transplantation is a promising therapy for ischemic diseases such as\nischemic myocardial infarction and hindlimb ischemia. However, limitation of EPC sources remains a major obstacle.\nDirect reprogramming has become a powerful tool to produce EPCs from fibroblasts. Some recent efforts successfully\ndirectly reprogrammed human fibroblasts into functional EPCs; however, the procedure efficacy was low. This study\ntherefore aimed to improve the efficacy of direct reprogramming of human fibroblasts to functional EPCs.\nMethods: Human fibroblasts isolated from foreskin were directly reprogrammed into EPCs by viral ETV2 transduction.\nReprogramming efficacy was improved by culturing transduced fibroblasts in hypoxia conditions (5 % oxygen).\nPhenotype analyses confirmed that single-factor ETV2 transduction successfully reprogrammed dermal fibroblasts\ninto functional EPCs.\nResults: Hypoxia treatment during the reprogramming procedure increased the efficacy of reprogramming from\n1.21 �± 0.61 % in normoxia conditions to 7.52 �± 2.31 % in hypoxia conditions. Induced EPCs in hypoxia conditions\nexhibited functional EPC phenotypes similar to those in normoxia conditions, such as expression of CD31 and\nVEGFR2, and expressed endothelial gene profiles similar to human umbilical vascular endothelial cells. These cells\nalso formed capillary-like networks in vitro.\nConclusion: Our study demonstrates a new simple method to increase the reprogramming efficacy of human\nfibroblasts to EPCs using ETV2 and hypoxia...
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