搜索结果: 'methocult media formulations for mouse hematopoietic cells serum containing'

Diminishing homeostatic proliferation of memory T cells is essential for improving the efficacy of lymphoablation in transplant recipients. Our previous studies in a mouse heart transplantation model established that B lymphocytes secreting proinflammatory cytokines are critical for T cell recovery after lymphoablation. The goal of the current study was to identify mediators of B cell activation following lymphoablation in allograft recipients. Transcriptome analysis revealed that macrophage-inducible C-type lectin (Mincle,Clec4e) expression is up-regulated in B cells from heart allograft recipients treated with murine anti-thymocyte globulin (mATG). Recipient Mincle deficiency diminishes B cell production of pro-inflammatory cytokines and impairs T lymphocyte reconstitution. Mixed bone marrow chimeras lacking Mincle only in B lymphocytes have similar defects in T cell recovery. Conversely,treatment with a synthetic Mincle ligand enhances T cell reconstitution after lymphoablation in non-transplanted mice. Treatment with agonistic CD40 mAb facilitates T cell reconstitution in CD4 T cell-depleted,but not in Mincle-deficient,recipients indicating that CD40 signaling induces T cell proliferation via a Mincle-dependent pathway. These findings are the first to identify an important function of B cell Mincle as a sensor of damage-associated molecular patterns released by the graft and demonstrate its role in clinically relevant settings of organ transplantation. View Publication

One of the key consequences of exposure of human cells to genotoxic agents is the activation of DNA damage responses (DDR). While the mechanisms underpinning DDR in fully differentiated somatic human cells have been studied extensively,molecular signaling events and pathways involved in DDR in pluripotent human embryonic stem cells (hESC) remain largely unexplored. We studied changes in the human genome-wide transcriptome of H9 hESC line following exposures to 1Gy of gamma-radiation at 2h and 16h post-irradiation. Quantitative real-time PCR was performed to verify the expression data for a subset of genes. In parallel,the cell growth,DDR kinetics,and expression of pluripotency markers in irradiated hESC were monitored. The changes in gene expression in hESC after exposure to ionizing radiation (IR) are substantially different from those observed in somatic human cell lines. Gene expression patterns at 2h post-IR showed almost an exclusively p53-dependent,predominantly pro-apoptotic,signature with a total of only 30 up-regulated genes. In contrast,the gene expression patterns at 16h post-IR showed 354 differentially expressed genes,mostly involved in pro-survival pathways,such as increased expression of metallothioneins,ubiquitin cycle,and general metabolism signaling. Cell growth data paralleled trends in gene expression changes. DDR in hESC followed the kinetics reported for human somatic differentiated cells. The expression of pluripotency markers characteristic of undifferentiated hESC was not affected by exposure to IR during the time course of our analysis. Our data on dynamics of transcriptome response of irradiated hESCs may provide a valuable tool to screen for markers of IR exposure of human cells in their most naive state; thus unmasking the key elements of DDR; at the same time,avoiding the complexity of interpreting distinct cell type-dependent genotoxic stress responses of terminally differentiated cells. View Publication

Induced pluripotent stem cells (iPSCs) are obtained from adult cells through overexpression of pluripotency factors. iPSCs share many features with embryonic stem cells (ESCs),circumventing ethical issues,and,noteworthy,match donor's genotype. iPSCs represent therefore a valuable tool for regenerative medicine. Cardiac differentiation of ESCs can be enhanced via microRNAs (miRNAs) and small chemical compounds,which probably act as chromatin remodelers. Cardiomyogenic potential of iPSCs is currently intensely investigated for cell therapy or in vitro drug screening and disease modeling. However,influences of small compounds on iPSC-related cardiomyogenesis have not yet been investigated in details. Here,we compared the effects of two small molecules,bis-peroxo-vanadium (bpV) and sulfonyl-hydrazone-1 (SHZ) at varying concentrations,during cardiac differentiation of murine iPSCs. SHZ (5 µM) enhanced specific marker expression and cardiomyocyte yield,without loss of cell viability. In contrast,bpV showed negligible effects on cardiac differentiation rate and appeared to induce Casp3-dependent apoptosis in differentiating iPSCs. Furthermore,SHZ-treated iPSCs were able to increase beating foci rate and upregulate early and late cardiomyogenic miRNA expression (miR-1,miR-133a,and miR-208a). Thus,our results demonstrate that small chemical compounds,such as SHZ,can constitute a novel and clinically feasible strategy to improve iPSC-derived cardiac differentiation. View Publication

UNLABELLED Epigenetic mechanisms play critical roles in stem cell biology by maintaining pluripotency of stem cells and promoting differentiation of more mature derivatives. If similar mechanisms are relevant for the cancer stem cell (CSC) model,then epigenetic modulation might enrich the CSC population,thereby facilitating CSC isolation and rigorous evaluation. To test this hypothesis,primary human cancer cells and liver cancer cell lines were treated with zebularine (ZEB),a potent DNA methyltransferase-1 inhibitor,and putative CSCs were isolated using the side population (SP) approach. The CSC properties of ZEB-treated and untreated subpopulations were tested using standard in vitro and in vivo assays. Whole transcriptome profiling of isolated CSCs was performed to generate CSC signatures. Clinical relevance of the CSC signatures was evaluated in diverse primary human cancers. Epigenetic modulation increased frequency of cells with CSC properties in the SP fraction isolated from human cancer cells as judged by self-renewal,superior tumor-initiating capacity in serial transplantations,and direct cell tracking experiments. Integrative transcriptome analysis revealed common traits enriched for stemness-associated genes,although each individual CSC gene expression signature exhibited activation of different oncogenic pathways (e.g.,EGFR,SRC,and MYC). The common CSC signature was associated with malignant progression,which is enriched in poorly differentiated tumors,and was highly predictive of prognosis in liver and other cancers. CONCLUSION Epigenetic modulation may provide a tool for prospective isolation and in-depth analysis of CSC. The liver CSC gene signatures are defined by a pernicious interaction of unique oncogene-specific and common stemness traits. These data should facilitate the identifications of therapeutic tools targeting both unique and common features of CSCs. View Publication

Cancer stem cells (CSCs) or tumor initiating cells (TICs) make up only a small fraction of total tumor cell population,but recent evidence suggests that they are responsible for tumor initiation and the maintenance of tumor growth. Whether CSCs/TICs originate from normal stem cells or result from the dedifferentiation of terminally differentiated cells remains unknown. Here we provide evidence that sustained expression of the proinflammatory protein tissue transglutaminase (TG2) confers stem cell like properties in non-transformed and transformed mammary epithelial cells. Sustained expression of TG2 was associated with increase in CD44(high)/CD24(low/-) subpopulation,increased ability of cells to form mammospheres,and acquisition of self-renewal ability. Mammospheres derived from TG2-transfected mammary epithelial cells (MCF10A) differentiated into complex secondary structures when grown in Matrigel cultures. Cells in these secondary structures differentiated into Muc1-positive (luminal marker) and integrin α6-positive (basal marker) cells in response to prolactin treatment. Highly aggressive MDA-231 and drug-resistant MCF-7/RT breast cancer cells,which express high basal levels of TG2,shared many traits with TG2-transfected MCF10A stem cells but unlike MCF10A-derived stem cells they failed to form the secondary structures and to differentiate into Muc1-positive luminal cells when grown in Matrigel culture. Downregulation of TG2 attenuated stem cell properties in both non-transformed and transformed mammary epithelial cells. Taken together,these results suggested a new function for TG2 and revealed a novel mechanism responsible for promoting the stem cell characteristics in adult mammary epithelial cells. View Publication

Cancer stem cells (CSC) are resistant to radiation and chemotherapy and play a significant role in cancer recurrence and metastatic disease. It is therefore important to identify alternative strategies,such as immunotherapies that can be used to control this refractory population. A CD44(+)CD24(-/low) subpopulation of cells within the B6 PyMT-MMTV transgenic mouse-derived AT-3 mammary carcinoma cell line was identified,which had CSC-like characteristics,including pluripotency and a resistance to chemo- and radiotherapy. Therefore,unlike xenograph models that require immunocompromised settings,this novel system may provide a means to study immune-mediated responses against CSC-like cells. The immunobiology of the AT-3 CSC-like cell population was studied by their surface molecule expression profile and their sensitivity to specified cell death pathways. Comparable levels of Rae-1,CD155,CD54 and higher levels of Fas and DR5 were expressed on the AT-3 CSC-like cells compared to non-CSC-like tumor cells. Expression correlated with an in vitro sensitivity to cell death by NK cells or through the ligation of the death receptors (Fas or DR5),by their ligands or anti-Fas and anti-DR5 mAbs. Indeed,compared to the rest of the AT-3 tumor cells,the CD44(+)CD24(-/low) subpopulation of cells were more sensitive to both Fas- and TRAIL-mediated cell death pathways. Therefore,despite the refractory nature of CSC to other conventional therapies,these CSC-like cells were not inherently resistant to specified forms of immune-mediated cell death. These results encourage the continued investigation into immunotherapeutic strategies as a means of controlling breast CSC,particularly through their cell death pathways. View Publication

Aberrant reactivation of Gli signaling has been described in a wide variety of human cancers and rapamycin can down-regulate Gli pathway in some solid tumors. In this study,we attempt to define the cytotoxic effect of Gli inhibitor on AML cells. And the regulation action of rapamycin on Gli in AML cells also has been assessed. Gli inhibitor GANT61 caused growth arrest and apoptosis in AML cells. Rapamycin decreased not only the Gli protein and mRNA expressions but also expression of the Gli-luciferase reporter in AML cells. Synergism effect between GANT61 and rapamycin was found in Kasumi-1,HL-60 and U937 cell lines. The results suggest that aberrant Gli activation is a feature of some myeloid leukemic cells and Gli activiation can be down-regulated by rapamycin. View Publication

To identify early populations of committed progenitors derived from human embryonic stem cells (hESCs),we screened self-renewing,BMP4-treated and retinoic acid-treated cultures with >400 antibodies recognizing cell-surface antigens. Sorting of >30 subpopulations followed by transcriptional analysis of developmental genes identified four distinct candidate progenitor groups. Subsets detected in self-renewing cultures,including CXCR4(+) cells,expressed primitive endoderm genes. Expression of Cxcr4 in primitive endoderm was confirmed in visceral endoderm of mouse embryos. BMP4-induced progenitors exhibited gene signatures of mesoderm,trophoblast and vascular endothelium,suggesting correspondence to gastrulation-stage primitive streak,chorion and allantois precursors,respectively. Functional studies in vitro and in vivo confirmed that ROR2(+) cells produce mesoderm progeny,APA(+) cells generate syncytiotrophoblasts and CD87(+) cells give rise to vasculature. The same progenitor classes emerged during the differentiation of human induced pluripotent stem cells (hiPSCs). These markers and progenitors provide tools for purifying human tissue-regenerating progenitors and for studying the commitment of pluripotent stem cells to lineage progenitors. View Publication

Human pluripotent stem cells (hPSCs) offer the potential to generate large numbers of functional cardiomyocytes from clonal and patient-specific cell sources. Here we show that temporal modulation of Wnt signaling is both essential and sufficient for efficient cardiac induction in hPSCs under defined,growth factor-free conditions. shRNA knockdown of β-catenin during the initial stage of hPSC differentiation fully blocked cardiomyocyte specification,whereas glycogen synthase kinase 3 inhibition at this point enhanced cardiomyocyte generation. Furthermore,sequential treatment of hPSCs with glycogen synthase kinase 3 inhibitors followed by inducible expression of β-catenin shRNA or chemical inhibitors of Wnt signaling produced a high yield of virtually (up to 98%) pure functional human cardiomyocytes from multiple hPSC lines. The robust ability to generate functional cardiomyocytes under defined,growth factor-free conditions solely by genetic or chemically mediated manipulation of a single developmental pathway should facilitate scalable production of cardiac cells suitable for research and regenerative applications. View Publication

In mice and humans,it has been shown that embryonic and adult fibroblasts can be reprogrammed into pluripotency by introducing 4 transcription factors,Oct3/4,Klf4,Sox2,and c-Myc (OKSM). Here,we report the derivation of induced pluripotent stem cells (iPSCs) from adult canine fibroblasts by retroviral OKSM transduction. The isolated canine iPSCs (ciPSCs) were expanded in 3 different culture media [fibroblast growth factor 2 (FGF2),leukemia inhibitory factor (LIF),or FGF2 plus LIF]. Cells cultured in both FGF2 and LIF expressed pluripotency markers [POU5F1 (OCT4),SOX2,NANOG,and LIN28] and embryonic stem cell (ESC)-specific genes (PODXL,DPPA5,FGF5,REX1,and LAMP1) and showed strong levels of alkaline phosphatase expression. In vitro differentiation by formation of embryoid bodies and by directed differentiation generated cell derivatives of all 3 germ layers as confirmed by mRNA and protein expression. In vivo,the ciPSCs created solid tumors,which failed to reach epithelial structure formation,but expressed markers for all 3 germ layers. Array comparative genomic hybridization and chromosomal fluorescence in situ hybridization analyses revealed that while retroviral transduction per se did not result in significant DNA copy number imbalance,there was evidence for the emergence of low-level aneuploidy during prolonged culture or tumor formation. In summary,we were able to derive ciPSCs from adult fibroblasts by using 4 transcription factors. The isolated iPSCs have similar characteristics to ESCs from other species,but the exact cellular mechanisms behind their unique co-dependency on both FGF2 and LIF are still unknown. View Publication