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UNLABELLED Basal-like breast cancer (BLBC) is an aggressive subtype of breast cancer which is often enriched with cancer stem cells (CSC),but the underlying molecular basis for this connection remains elusive. We hypothesized that BLBC cells are able to establish a niche permissive to the maintenance of CSCs and found that tumor cell-derived periostin (POSTN),a component of the extracellular matrix,as well as a corresponding cognate receptor,integrin $$(v)$$(3),are highly expressed in a subset of BLBC cell lines as well as in CSC-enriched populations. Furthermore,we demonstrated that an intact periostin-integrin $$3 signaling axis is required for the maintenance of breast CSCs. POSTN activates the ERK signaling pathway and regulates NF-$$B-mediated transcription of key cytokines,namely IL6 and IL8,which in turn control downstream activation of STAT3. In summary,these findings suggest that BLBC cells have an innate ability to establish a microenvironmental niche supportive of CSCs. IMPLICATIONS The findings reported here indicate that POSTN produced by CSCs acts to reinforce the stem cell state through the activation of integrin receptors and the production of key cytokines. View Publication

Mesenchymal stem/stromal cells (MSCs) have great clinical potential in modulating inflammation and promoting tissue repair. Human embryonic stem cells (hESCs) have recently emerged as a potentially superior cell source for MSCs. However,the generation methods reported so far vary greatly in quality and efficiency. Here,we describe a novel method to rapidly and efficiently produce MSCs from hESCs via a trophoblast-like intermediate stage in approximately 11-16 days. We term these cells T-MSCs" and show that T-MSCs express a phenotype and differentiation potential minimally required to define MSCs. T-MSCs exhibit potent immunomodulatory activity in vitro as they can remarkably inhibit proliferation of cocultured T and B lymphocytes. Unlike bone marrow MSCs� View Publication

The prevalence and specificity of unique fusion oncogenes are high in a number of soft tissue sarcomas (STSs). The close relationship between fusion genes and clinicopathological features suggests that a correlation may exist between the function of fusion proteins and cellular context of the cell-of-origin of each tumor. However,most STSs are origin-unknown tumors and this issue has not yet been investigated in detail. In the present study,we examined the effects of the cellular context on the function of the synovial sarcoma (SS)-specific fusion protein,SS18-SSX,using human pluripotent stem cells (hPSCs) containing the drug-inducible SS18-SSX gene. We selected the neural crest cell (NCC) lineage for the first trial of this system,induced SS18-SSX at various differentiation stages from PSCs to NCC-derived mesenchymal stromal cells (MSCs),and compared its biological effects on each cell type. We found that the expression of FZD10,identified as an SS-specific gene,was induced by SS18-SSX at the PSC and NCC stages,but not at the MSC stage. This stage-specific induction of FZD10 correlated with stage-specific changes in histone marks associated with the FZD10 locus and also with the loss of the BAF47 protein,a member of the SWI/SNF chromatin-remodeling complex. Furthermore,the global gene expression profile of hPSC-derived NCCs was the closest to that of SS cell lines after the induction of SS18-SSX. These results clearly demonstrated that the cellular context is an important factor in the function of SS18-SSX as an epigenetic modifier. View Publication

Induced pluripotent stem cells hold great potential in regenerative medicine as it enables to generate pluripotent stem cells from any available cell types. Ectopic expression of four transcription factors (Oct4,Sox2,Klf4,and c-Myc) can reprogram fibroblasts directly to pluripotency as shown in multiple species. Here,we describe detailed protocols for generation of iPSCs from adult canine fibroblasts. Robust canine iPSCs will provide powerful tools not only to study human diseases,but also for the development of therapeutic approaches. View Publication

Human monocytes are a heterogeneous cell population classified into three different subsets: Classical CD14++CD16-,intermediate CD14++CD16+,and non-classical CD14+CD16++ monocytes. These subsets are distinguished by their differential expression of CD14 and CD16,and unique gene expression profile. So far,the variation in inter-cellular gene expression within the monocyte subsets is largely unknown. In this study,the cellular variation within each human monocyte subset from a single healthy donor was described by using a novel single-cell PCR gene-expression analysis tool. We investigated 86 different genes mainly encoding cell surface markers,and proteins involved in immune regulation. Within the three human monocyte subsets,our descriptive findings show multimodal expression of key immune response genes,such as CD40,NFⱪB1,RELA,TLR4,TLR8 and TLR9. Furthermore,we discovered one subgroup of cells within the classical monocytes,which showed alterations of 22 genes e.g. IRF8,CD40,CSF1R,NFⱪB1,RELA and TNF. Additionally one subgroup within the intermediate and non-classical monocytes also displayed distinct gene signatures by altered expression of 8 and 6 genes,respectively. Hence the three monocyte subsets can be further subdivided according to activation status and differentiation,independently of the traditional classification based on cell surface markers. Demonstrating the use and the ability to discover cell heterogeneity within defined populations of human monocytes is of great importance,and can be useful in unravelling inter-cellular variation in leukocyte populations,identifying subpopulations involved in disease pathogenesis and help tailor new therapies. View Publication

Expression of genes associated with inflammation was analyzed during differentiation of human pluripotent stem cells (PSCs) to hepatic cells. Messenger RNA transcript profiles of differentiated endoderm (day 5),hepatoblast (day 15) and hepatocyte-like cells (day 21) were obtained by RNA sequencing analysis. When compared to endoderm cells an immature cell type,the hepatic cells (days 15 and 21) had significantly higher expression of acute phase protein genes including complement factors,coagulation factors,serum amyloid A and serpins. Furthermore,hepatic phase of cells expressed proinflammatory cytokines IL18 and IL32 as well as cytokine receptors IL18R1,IL1R1,IL1RAP,IL2RG,IL6R,IL6ST and IL10RB. These cells also produced CCL14,CCL15,and CXCL- 1,2,3,16 and 17 chemokines. Endoderm cells had higher levels of chemokine receptors,CXCR4 and CXCR7,than that of hepatic cells. Sirtuin family of genes involved in aging,inflammation and metabolism were differentially regulated in endoderm and hepatic phase cells. Ligands and receptors of the tumor necrosis factor (TNF) family as well as downstream signaling factors TRAF2,TRAF4,FADD,NFKB1 and NFKBIB were differentially expressed during hepatic differentiation. View Publication

Human adipose-derived stem cells (hASCs) become an appealing source for regenerative medicine. However,with the multi-passage or cryopreservation for large-scale growth procedures in terms of preclinical and clinical purposes,hASCs often reveal defective cell viability,which is a major obstacle for cell therapy. In our study,the effects of induced pluripotent stem cells-derived conditioned medium (iPS-CM) on the proliferation and anti-apoptosis in hASCs were investigated. hASCs at passage 1 were identified by the analysis of typical surface antigens with flow cytometry assay and adipogenic and osteogenic differentiation. The effect of iPS-CM on the proliferation in hASCs was analyzed by cell cycle assay and Ki67/P27 quantitative polymerase chain reaction analysis. The effect of iPS-CM on the anti-apoptosis of hASCs irradiated by 468 J/m(2) of ultraviolet C was investigated by annexin v/propidium iodide analysis,mitochondrial membrane potential assay,intracellular reactive oxygen species assay,Western blotting and caspase activity assays. The effect of iPS-CM on the surface antigen expressions of hASCs was analyzed using flow cytometry assay. The levels of Activin A and bFGF in culture supernatant of hASCs with different treatments were also detected by enzyme-linked immunosorbent assay. iPS-CM promoted proliferation and inhibited apoptosis of hASCs. This discovery demonstrates that iPS-CM might be used as one of the available means to overcome the propagation obstacle for hASCs and make for large-scale growth procedures in terms of preclinical and clinical purposes. View Publication

Chromatin structure affects the extent of DNA damage and repair. Thus,it has been shown that heterochromatin is more protective against DNA double strand breaks (DSB) formation by ionizing radiation (IR); and that DNA DSB repair may proceed differently in hetero- and euchromatin regions. Human embryonic stem cells (hESC) have a more open chromatin structure than differentiated cells. Here,we study the effect of chromatin structure in hESC on initial DSB formation and subsequent DSB repair. DSB were scored by comet assay; and DSB repair was assessed by repair foci formation via 53BP1 antibody staining. We found that in hESC,heterochromatin is confined to distinct regions,while in differentiated cells it is distributed more evenly within the nuclei. The same dose of ionizing radiation produced considerably more DSB in hESC than in differentiated derivatives,normal human fibroblasts; and one cancer cell line. At the same time,the number of DNA repair foci were not statistically different among these cells. We showed that in hESC,DNA repair foci localized almost exclusively outside the heterochromatin regions. We also noticed that exposure to ionizing radiation resulted in an increase in heterochromatin marker H3K9me3 in cancer HT1080 cells,and to a lesser extent in IMR90 normal fibroblasts,but not in hESCs. These results demonstrate the importance of chromatin conformation for DNA protection and DNA damage repair; and indicate the difference of these processes in hESC. View Publication

Type II diabetes mellitus (T2D) is a chronic metabolic disorder that results from defects in both insulin secretion and insulin action. The deficit and dysfunction of insulin secreting $\$-cell are signature symptom for T2D. Additionally,in pancreatic $\$-cell,a small group of genes which are abundantly expressed in most other tissues are highly selectively repressed. Lactate dehydrogenase A (LDHA) is one of such genes. Upregulation of LDHA is found in both human T2D and rodent T2D models. In this study,we identified a LDHA-suppressing microRNA (hsa-miR-590-3p) and used it together with human embryonic stem cell (hESC) derived pancreatic endoderm (PE) transplantation into a high-fat diet induced T2D mouse model. The procedure significantly improved glucose metabolism and other symptoms of T2D. Our findings support the potential T2D treatment using the combination of microRNA and hESC-differentiated PE cells. View Publication

STUDY HYPOTHESIS Does a preferential X chromosome inactivation (XCI) pattern exist in female human pluripotent stem cells (hPSCs) and does the pattern change during long-term culture or upon differentiation? STUDY FINDING We identified two independent phenomena that lead to aberrant XCI patterns in female hPSC: a rapid loss of histone H3 lysine 27 trimethylation (H3K27me3) and long non-coding X-inactive specific transcript (XIST) expression during culture,often accompanied by erosion of XCI-specific methylation,and a frequent loss of random XCI in the cultures. WHAT IS KNOWN ALREADY Variable XCI patterns have been reported in female hPSC,not only between different hPSC lines,but also between sub-passages of the same cell line,however the reasons for this variability remain unknown. Moreover,while non-random XCI-linked DNA methylation patterns have been previously reported,their origin and extent have not been investigated. STUDY DESIGN,SAMPLES/MATERIALS,METHODS We investigated the XCI patterns in 23 human pluripotent stem cell (hPSC) lines,during long-term culture and after differentiation,by gene expression analysis,histone modification assessment and study of DNA methylation. The presence and location of H3K27me3 was studied by immunofluorescence,XIST expression by real-time PCR,and mono- or bi-allelic expression of X-linked genes was studied by sequencing of cDNA. XCI-specific DNA methylation was analysed using methylation-sensitive restriction and PCR,and more in depth by massive parallel bisulphite sequencing. MAIN RESULTS AND THE ROLE OF CHANCE All hPSC lines showed XCI,but we found a rapid loss of XCI marks during the early stages of in vitro culture. While this loss of XCI marks was accompanied in several cases by an extensive erosion of XCI-specific methylation,it did not result in X chromosome reactivation. Moreover,lines without strong erosion of methylation frequently displayed non-random DNA methylation,which occurred independently from the loss of XCI marks. This bias in X chromosome DNA methylation did not appear as a passenger event driven by clonal culture take-over of chromosome abnormalities and was independent of the parental origin of the X chromosome. Therefore,we suggest that a culture advantage conferred by alleles on the X chromosome or by XCI-related mechanisms may be at the basis of this phenomenon. Finally,differentiated populations inherited the aberrant XCI patterns from the undifferentiated cells they were derived from. LIMITATIONS,REASONS FOR CAUTION All hPSC lines in this study were cultured in highly similar conditions. Our results may therefore be specific for these conditions and alternative culture conditions might lead to different findings. Our findings are only a first step towards elucidating the molecular events leading to the phenomena we observed. WIDER IMPLICATIONS OF THE FINDINGS Our results highlight the significant extent of aberrant XCI in female hPSC. The fact that these aberrations are inherited by the differentiated progeny may have a significant impact on downstream research and clinical uses of hPSC. In order to achieve the full potential of hPSC,more insight into the XCI status and its stability in hPSC and its effect on the properties of the differentiated progeny is needed. LARGE SCALE DATA Not applicable. STUDY FUNDING AND COMPETING INTERESTS Our research is supported by grants from the Research Foundation - Flanders (FWO-Vlaanderen,grant 1502512N),Generalitat de Catalunya (2014SGR-005214) and the Methusalem grant of the Research Council of the Vrije Universiteit Brussel,on name of K.S. L.V.H. is funded by EMBO (ALTF 701-2013). The authors declare no potential conflict of interest. View Publication

Fluorescence in situ hybridization (FISH) is superior to routine chromosome analysis (RCA) in detecting important prognostic genetic abnormalities in plasma cell dyscrasia (PCD); however,its sensitivity is hampered due to paucity of plasma cells (PC) in whole bone marrow (BM). Studies showed that the abnormality detection rate in enriched plasma cells (EPC) is greater than unselected plasma cells (UPC),but purification techniques are limiting to only FISH when sample volumes are inadequate. Not performing RCA may compromise patient care since RCA is equally important for detecting non-PC related abnormalities when the diagnosis is undefined. To resolve this critical issue,we designed a study where an immuno-magnetic CD138 enriched positive selection was used for FISH while the negative fraction (NF) was used to retrieve other myeloid elements for RCA. Parallel FISH studies were performed using UPC and CD138 EPC,while karyotyping was achieved using whole BM and discarded myeloid elements from the NF. Results showed that the abnormality rate of EPC was doubled compared to UPC for FISH,and CA displayed 100% success rate using the NF. PCD related chromosome abnormalities were confined to whole BM while non-PCD related abnormalities were found in both whole BM and NF. Our results demonstrate the feasibility of using the NF for RCA. View Publication

Resveratrol (trans-3,5,4'-trihydroxystilbene) (RSV) is a natural polyphenol with protective effects over cardiac tissues and can affect cell survival and differentiation in cardiac stem cells transplantation. However,whether this agent can affect cardiomyocytes (CMs) differentiation of induced pluripotent stem cells (iPSCs) is not yet clear. This study explored whether RSV can affect CMs differentiation of human iPSCs. Under embryoid bodies (EBs) condition,the effect of RSV on the change of pluripotent markers,endoderm markers,mesoderm markers,and ectoderm markers was measured using qRT-PCR. Under CM differentiation culture,the effect of RSV on CM specific markers was also measured. The regulative role of RSV over canonical Wnt signal pathway and serum response factor- (SRF-) miR-1 axis and the functions of these two axes were further studied. Results showed that RSV had no effect on the self-renewal of human iPSCs but could promote mesoderm differentiation. Under CM differentiation culture,RSV could promote CM differentiation of human iPSCs through suppressing canonical Wnt signal pathway and enhancing SRF-miR-1 axis. View Publication