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

To directly study the biological properties of purified hematopoietic colony-forming cell precursors,cells with a CD34+ CD45RAlo CD71lo phenotype were purified from human bone marrow using density separation and fluorescence-activated cell sorting,and were cultured in serum-free culture medium supplemented with various cytokines. In the presence of interleukin 3 (IL-3),IL-6,erythropoietin,and mast cell growth factor (a c-kit ligand),cell numbers increased approximately 10(6)-fold over a period of 4 wk,and the percentage of cells that expressed transferrin receptors (CD71) increased from less than 0.1% at day 0 to greater than 99% at day 14. Interestingly,the absolute number of CD34+ CD71lo cells did not change during culture. When CD34+ CD71lo cells were sorted from expanded cultures and recultured,extensive cell production was repeated,again without significant changes in the absolute number of cells with the CD34+ CD71lo phenotype that were used to initiate the (sub)cultures. These results document that primitive hematopoietic cells can generate progeny without an apparent decrease in the size of a precursor cell pool. View Publication

Human pluripotent stem cells (hPSCs) constitute a promising resource for use in cell-based therapies and a valuable in vitro model for studying early human development and disease. Despite significant advancements in the derivation of specific fates from hPSCs,the generation of skeletal muscle remains challenging and is mostly dependent on transgene expression. Here,we describe a method based on the use of a small-molecule GSK3?? inhibitor to derive skeletal muscle from several hPSC lines. We show that early GSK3?? inhibition is sufficient to create the conditions necessary for highly effective derivation of muscle cells. Moreover,we developed a strategy for stringent fluorescence-activated cell sorting-based purification of emerging PAX3+/PAX7+ muscle precursors that are able to differentiate in postsort cultures into mature myocytes. This transgene-free,efficient protocol provides an essential tool for producing myogenic cells for in vivo preclinical studies,in vitro screenings,and disease modeling. ?? 2013 The Authors. View Publication

Identification of prevalent specific markers is crucial to stem/progenitor cell purification. Determinants such as the surface antigens CD34 and CD38 are traditionally used to analyze and purify hematopoietic stem/progenitor cells (HSCs/HPCs). However,the variable expression of these membrane antigens poses some limitations to their use in HSC/HPC purification. Techniques based on drug/stain efflux through the ATP-binding cassette (ABC)G2 pump (side population [SP] phenotype) or on detection of aldehyde dehydrogenase (ALDH) activity have been independently developed and distinguish the SP and ALDH(Bright) (ALDH(Br)) cell subsets for their phenotype and proliferative capability. In this study,we developed a multiparametric flow cytometric method associating both SP and ALDH activities on human lineage negative (Lin(-)) bone marrow cells and sorted different cell fractions according to their SP/ALDH activity level. We find that Lin(-)CD34(+)CD38(Low/-) cells are found throughout the spectrum of ALDH expression and are enriched especially in ALDH(Br) cells when associated with SP functionality (SP/ALDH(Br) fraction). Furthermore,the SP marker identified G(0) cells in all ALDH fractions,allowing us to sort quiescent cells regardless of ALDH activity. Moreover,we show that,within the Lin(-)CD34(+)CD38(-)ALDH(Br) population,the SP marker identifies cells with higher primitive characteristics,in terms of stemness-related gene expression and in vitro and in vivo proliferative potential,than the Lin(-)CD34(+) CD38(-)ALDH(Br) main population cells. In conclusion,our study shows that the coexpression of SP and ALDH markers refines the Lin(-)CD34(+)CD38(-) hematopoietic compartment and identifies an SP/ALDH(Br) cell subset enriched in quiescent primitive HSCs/HPCs. View Publication

Williams syndrome is a genetic neurodevelopmental disorder characterized by an uncommon hypersociability and a mosaic of retained and compromised linguistic and cognitive abilities. Nearly all clinically diagnosed individuals with Williams syndrome lack precisely the same set of genes,with breakpoints in chromosome band 7q11.23 (refs 1-5). The contribution of specific genes to the neuroanatomical and functional alterations,leading to behavioural pathologies in humans,remains largely unexplored. Here we investigate neural progenitor cells and cortical neurons derived from Williams syndrome and typically developing induced pluripotent stem cells. Neural progenitor cells in Williams syndrome have an increased doubling time and apoptosis compared with typically developing neural progenitor cells. Using an individual with atypical Williams syndrome,we narrowed this cellular phenotype to a single gene candidate,frizzled 9 (FZD9). At the neuronal stage,layer V/VI cortical neurons derived from Williams syndrome were characterized by longer total dendrites,increased numbers of spines and synapses,aberrant calcium oscillation and altered network connectivity. Morphometric alterations observed in neurons from Williams syndrome were validated after Golgi staining of post-mortem layer V/VI cortical neurons. This model of human induced pluripotent stem cells fills the current knowledge gap in the cellular biology of Williams syndrome and could lead to further insights into the molecular mechanism underlying the disorder and the human social brain. View Publication

Regulated adhesion of T cells by the integrins LFA-1 (lymphocyte function-associated antigen-1) and VLA-4 (very late antigen-4) is essential for T-cell trafficking. The small GTPase Rap1 is a critical activator of both integrins in murine lymphocytes and T-cell lines. Here we examined the contribution of the Rap1 regulatory pathway in integrin activation in primary CD3(+) human T cells. We demonstrate that inactivation of Rap1 GTPase in human T cells by expression of SPA1 or Rap1GAP blocked stromal cell-derived factor-1alpha (SDF-1alpha)-stimulated LFA-1-ICAM-1 (intercellular adhesion molecule-1) interactions and LFA-1 affinity modulation but unexpectedly did not significantly affect binding of VLA-4 to its ligand VCAM-1 (vascular cell adhesion molecule 1). Importantly,silencing of the Rap1 guanine exchange factor CalDAG-GEFI inhibited SDF-1alpha- and phorbol 12-myristate 13-acetate (PMA)-induced adhesion to ICAM-1 while having no effect on adhesion to VCAM-1. Pharmacologic inhibition of Phospholipase C (PLC) blocked Rap1 activation and inhibited cell adhesion and polarization on ICAM-1 and VCAM-1. Protein kinase C (PKC) inhibition led to enhanced levels of active Rap1 concomitantly with increased T-cell binding to ICAM-1,whereas adhesion to VCAM-1 was reduced. Thus,PLC/CalDAG-GEFI regulation of Rap1 is selectively required for chemokine- and PMA-induced LFA-1 activation in human T cells,whereas alternate PLC- and PKC-dependent mechanisms are involved in the regulation of VLA-4. View Publication

Induced pluripotent stem cells (iPSCs) hold promise for the treatment of motoneuron diseases because of their distinct features including pluripotency,self-derivation and potential ability to differentiate into motoneurons. However,it is still unknown whether human iPSC-derived motoneurons can functionally innervate target muscles in vivo,which is the definitive sign of successful cell therapy for motoneuron diseases. In the present study,we demonstrated that human iPSCs derived from mesenchymal cells of the umbilical cord possessed a high yield in neural differentiation. Using a chemically-defined in vitro system,human iPSCs efficiently differentiated into motoneurons which displayed typical morphology,expressed specific molecules,and generated repetitive trains of action potentials. When transplanted into the injured musculocutaneous nerve of rats,they survived robustly,extended axons along the nerve,and formed functional connections with the target muscle (biceps brachii),thereby protecting the muscle from atrophy. Our study provides evidence for the first time that human iPSC-derived motoneurons are truly functional not only in vitro but also in vivo,and they have potential for stem cell-based therapies for motoneuron diseases. textcopyright 2013 Elsevier B.V. View Publication

The demonstration that the small synthetic molecule reversine [2-(4-morpholinoanilino)-N6-cyclohexyladenine] promotes the dedifferentiation of committed cells into multipotent progenitor-type cells has raised hopes on the exploitation of this small chemical tool for the generation of stem cells. Here,we show that reversine causes a failure in cytokinesis and induces polyploidization. These effects of reversine are due to the inhibition of Aurora A and B,two related kinases that are implicated in several aspects of mitosis and that are frequently amplified and overexpressed in human tumors. Reversine inhibits the phosphorylation of histone H3,a direct downstream target of Aurora kinases. Similarly to the Aurora kinase inhibitor VX-680,which has recently entered phase II clinical trials for cancer treatment,reversine inhibited colony formation of leukemic cells from patients with acute myeloid leukemia but was significantly less toxic than VX-680 on cells from healthy donors. The crystal structure of the reversine-Aurora B kinase complex shows that reversine is a novel class of ATP-competitive Aurora kinase inhibitors. Thus,although our studies raise serious doubts on the application of reversine in regenerative medicine,they support the paradigm that reversine might be a useful agent in cancer chemotherapy. View Publication

Human induced pluripotent stem cells (hiPSCs) have potential for personalized and regenerative medicine. While most of the methods using these cells have focused on deriving homogenous populations of specialized cells,there has been modest success in producing hiPSC-derived organotypic tissues or organoids. Here we present a novel approach for generating and then co-differentiating hiPSC-derived progenitors. With a genetically engineered pulse of GATA-binding protein 6 (GATA6) expression,we initiate rapid emergence of all three germ layers as a complex function of GATA6 expression levels and tissue context. Within 2 weeks we obtain a complex tissue that recapitulates early developmental processes and exhibits a liver bud-like phenotype,including haematopoietic and stromal cells as well as a neuronal niche. Collectively,our approach demonstrates derivation of complex tissues from hiPSCs using a single autologous hiPSCs as source and generates a range of stromal cells that co-develop with parenchymal cells to form tissues. View Publication

Genome instability is a potential limitation to the research and therapeutic application of induced pluripotent stem cells (iPSCs). Observed genomic variations reflect the combined activities of DNA damage,cellular DNA damage response (DDR),and selection pressure in culture. To understand the contribution of DDR on the distribution of copy number variations (CNVs) in iPSCs,we mapped CNVs of iPSCs with mutations in the central DDR gene ATM onto genome organization landscapes defined by genome-wide replication timing profiles. We show that following reprogramming the early and late replicating genome is differentially affected by CNVs in ATM deficient iPSCs relative to wild type iPSCs. Specifically,the early replicating regions had increased CNV losses during retroviral reprogramming. This differential CNV distribution was not present after later passage or after episomal reprogramming. Comparison of different reprogramming methods in the setting of defective DNA damage response reveals unique vulnerability of early replicating open chromatin to retroviral vectors. View Publication

The vertebrate retina is a highly multilayered nervous tissue with a large diversity of cellular components. With the development of stem cell technologies,human retinas can be generated in three-dimensional (3-D) culture in vitro. However,understanding the factors modulating key productive processes and the way that they influence development are far from clear. Oxygen,as the most essential element participating in metabolism,is a critical factor regulating organic development. In this study,using 3-D culture of human stem cells,we examined the effect of intermittent high oxygen treatment (40% O2) on the formation and cellular behavior of neural retinas (NR) in the embryonic body (EB). The volume of EB and number of proliferating cells increased significantly under 40% O2 on day 38,50,and 62. Additionally,the ratio of PAX6+ cells within NR was significantly increased. The neural rosettes could only develop with correct apical-basal polarity under 40% O2. In addition,the generation,migration and maturation of retinal ganglion cells were enhanced under 40% O2. All of these results illustrated that 40% O2 strengthened the formation of NR in EB with characteristics similar to the in vivo state,suggesting that the hyperoxic state facilitated the retinal development in vitro. View Publication