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

Non-viral gene delivery into human embryonic stem cells (hESCs)is an important tool for controlling cell fate. However,the delivery efficiency remains low due in part to the tight colony structure of the cells which prevents effective exposure towards delivery vectors. We herein report a novel approach to enhance non-viral gene delivery to hESCs by transiently altering the cell and colony structure. (R)-(+)-trans-4-(1-aminoethyl)-N-(4-pyridyl)cyclohexanecarboxamide (Y-27632),a small molecule that inhibits the rho-associated protein kinase pathway,is utilized to induce transient colony spreading which leads to increased transfection efficiency by 1.5 to 2 folds in a spectrum of non-viral transfection reagents including Lipofectamine 2000 and Fugene HD. After removal of Y-27632 post-transfection,cells can revert back to its normal state and do not show alteration of pluripotency. This approach provides a simple,effective tool to enhance non-viral gene delivery into adherent hESCs for genetic manipulation. View Publication

The vertebrae mesoderm is a source of cells that forms a variety of tissues,including the heart,vasculature,and blood. Consequently,the derivation of various mesoderm-specific cell types from human embryonic stem cells (hESCs) has attracted the interest of many investigators owing to their therapeutic potential in clinical applications. However,the need for efficient and reliable methods of differentiation into mesoderm lineage cell types remains a significant challenge. Here,we demonstrated that inhibition of glycogen synthase kinase-3 (GSK-3) is an essential first step toward efficient generation of the mesoderm. Under chemically defined conditions without additional growth factors/cytokines,short-term GSK inhibitor (GSKi) treatment effectively drives differentiation of hESCs into the primitive streak (PS),which can potentially commit toward the mesoderm when further supplemented with bone morphogenetic protein 4. Further analysis confirmed that the PS-like cells derived from GSKi treatment are bipotential,being able to specify toward the endoderm as well. Our findings suggest that the bipotential,PS/mesendoderm-like cell population exists only at the initial stages of GSK-3 inhibition,whereas long-term inhibition results in an endodermal fate. Lastly,we demonstrated that our differentiation approach could efficiently generate lateral plate (CD34(+)KDR(+)) and paraxial (CD34(-)PDGFRα(+)) mesoderm subsets that can be further differentiated along the endothelial and smooth muscle lineages,respectively. In conclusion,our study presents a unique approach for generating early mesoderm progenitors in a chemically directed fashion through the use of small-molecule GSK-3 inhibitor,which may be useful for future applications in regenerative medicine. View Publication

BACKGROUND Human rhinoviruses (HRVs) are a major trigger of asthma exacerbations,with the bronchial epithelium being the major site of HRV infection and replication. Mast cells (MCs) play a key role in asthma where their numbers are increased in the bronchial epithelium with increasing disease severity. OBJECTIVE In view of the emerging role of MCs in innate immunity and increased localization to the asthmatic bronchial epithelium,we investigated whether HRV infection of MCs generated innate immune responses which were protective against infection. METHODS The LAD2 MC line or primary human cord blood-derived MCs (CBMCs) were infected with HRV or UV-irradiated HRV at increasing multiplicities of infection (MOI) without or with IFN-β or IFN-λ. After 24 h,innate immune responses were assessed by RT-qPCR and IFN protein release by ELISA. Viral replication was determined by RT-qPCR and virion release by TCID50 assay. RESULTS HRV infection of LAD2 MCs induced expression of IFN-β,IFN-λ and IFN-stimulated genes. However,LAD2 MCs were permissive for HRV replication and release of infectious HRV particles. Similar findings were observed with CBMCs. Neutralization of the type I IFN receptor had minimal effects on viral shedding,suggesting that endogenous type I IFN signalling offered limited protection against HRV. However,augmentation of these responses by exogenous IFN-β,but not IFN-λ,protected MCs against HRV infection. CONCLUSION AND CLINICAL RELEVANCE MCs are permissive for the replication and release of HRV,which is prevented by exogenous IFN-β treatment. Taken together,these findings suggest a novel mechanism whereby MCs may contribute to HRV-induced asthma exacerbations. View Publication

Gene therapy for a wide variety of disorders would be greatly enhanced by the development of vectors that could be targeted for gene delivery to specific populations of cells. We describe here high-efficiency targeted transduction based on a novel targeting strategy that exploits the ability of retroviruses to incorporate host cell proteins into the surface of the viral particle as they bud through the plasma membrane. Ecotropic retroviral particles produced in cells engineered to express the membrane-bound form of stem cell factor (mbSCF) transduce both human cell lines and primary cells with high efficiency in a strictly c-kit (SCF receptor)-dependent fashion. The availability of efficient targeted vectors provides a platform for the development of a new generation of therapies using in vivo gene delivery. View Publication

High levels of aldehyde dehydrogenase (ALDH) activity have been proposed to be a common feature of stem cells. Adult hematopoietic,neural,and cancer stem cells have all been reported to have high ALDH activity,detected using Aldefluor,a fluorogenic substrate for ALDH. This activity has been attributed to Aldh1a1,an enzyme that is expressed at high levels in stem cells and that has been suggested to regulate stem cell function. Nonetheless,Aldh1a1 function in stem cells has never been tested genetically. We observed that Aldh1a1 was preferentially expressed in mouse hematopoietic stem cells (HSCs) and expression increased with age. Hematopoietic cells from Aldh1a1-deficient mice exhibited increased sensitivity to cyclophosphamide in a non-cell-autonomous manner,consistent with its role in cyclophosphamide metabolism in the liver. However,Aldh1a1 deficiency did not affect hematopoiesis,HSC function,or the capacity to reconstitute irradiated recipients in young or old adult mice. Aldh1a1 deficiency also did not affect Aldefluor staining of hematopoietic cells. Finally,Aldh1a1 deficiency did not affect the function of stem cells from the adult central or peripheral nervous systems. Aldh1a1 is not a critical regulator of adult stem cell function or Aldefluor staining in mice. View Publication

The small number of hematopoietic stem and progenitor cells in cord blood units limits their widespread use in human transplant protocols. We identified a family of chemically related small molecules that stimulates the expansion ex vivo of human cord blood cells capable of reconstituting human hematopoiesis for at least 6 months in immunocompromised mice. The potent activity of these newly identified compounds,UM171 being the prototype,is independent of suppression of the aryl hydrocarbon receptor,which targets cells with more-limited regenerative potential. The properties of UM171 make it a potential candidate for hematopoietic stem cell transplantation and gene therapy. View Publication

BACKGROUND: Serum-free cultures supplemented with stem cell factor (SCF) and IL-6 is reported to support the extensive growth of less functional human cord blood-derived mast cells. OBJECTIVE: To obtain more functional mast cells from cord blood,we developed a culture system combining a serum-free condition for 0-8 weeks of culture,and followed by a serum-supplemented culture condition and examined the function of the cells compared to the cells cultured continuously in serum-free condition. METHODS: Human cord blood progenitors were purified with anti-CD133 antibody. They were cultured in a serum-free medium StemSpan supplemented with SCF at 100 ng/ml and IL-6 at 50 ng/ml for 8 weeks. Then,an aliquot of the cultured cells were cultured in the above condition but further supplemented with 10% fetal calf serum (FCS). RESULTS: The addition of FCS after 8 weeks of culture significantly increased the amount of histamine per mast cell (3.8 pg/cell) when compared to the serum-free condition (0.7 pg/cell). The cells cultured with FCS after 8 weeks expressed more FcvarepsilonRI alpha and released textgreater30% of the histamine content upon anti-IgE stimulation than those cultured without serum. CONCLUSION: It is uncertain why FCS enhanced the functional maturation of mast cells when added after week 8 of culture but suppressed mast cell development when added at day 0 of culture. Yet,the present method combining a serum-free culture system with a serum-supplemented culture system seems to be beneficial for most of the laboratories to obtain functional human mast cells. View Publication

Human pluripotent stem cell (hPSC)-derived endothelial lineage cells constitutes a promising source for therapeutic revascularization,but progress in this arena has been hampered by a lack of clinically-scalable differentiation protocols and inefficient formation of a functional vessel network integrating with the host circulation upon transplantation. Using a human embryonic stem cell reporter cell line,where green fluorescent protein expression is driven by an endothelial cell-specific VE-cadherin (VEC) promoter,we screened for textgreater 60 bioactive small molecules that would promote endothelial differentiation,and found that administration of BMP4 and a GSK-3β inhibitor in an early phase and treatment with VEGF-A and inhibition of the Notch signaling pathway in a later phase led to efficient differentiation of hPSCs to the endothelial lineage within six days. This sequential approach generated textgreater 50% conversion of hPSCs to endothelial cells (ECs),specifically VEC(+)CD31(+)CD34(+)CD14(-)KDR(high) endothelial progenitors (EPs) that exhibited higher angiogenic and clonogenic proliferation potential among endothelial lineage cells. Pharmaceutical inhibition or genetical knockdown of Notch signaling,in combination with VEGF-A treatment,resulted in efficient formation of EPs via KDR(+) mesodermal precursors and blockade of the conversion of EPs to mature ECs. The generated EPs successfully formed functional capillary vessels in vivo with anastomosis to the host vessels when transplanted into immunocompromised mice. Manipulation of this VEGF-A-Notch signaling circuit in our protocol leads to rapid large-scale production of the hPSC-derived EPs by 12- to 20-fold vs current methods,which may serve as an attractive cell population for regenerative vascularization with superior vessel forming capability compared to mature ECs. View Publication

Improvement of methods to produce endoderm-derived cells from pluripotent stem cells is important to realize high-efficient induction of endodermal tissues such as pancreas and hepatocyte. Difficulties hampering such efforts include the low efficiency of definitive endoderm cell induction and establishing appropriate defined culture conditions to ensure a safe cell source for human transplantation. Based on previous studies,we revised the experimental condition of definitive endoderm induction in feeder- and serum-free culture. Our results suggested that CHIR99021 is more effective than Wnt3A ligand in feeder- and serum-free conditions. In addition,keeping cell density low during endoderm induction is important for the efficiency. On the other hand,we showed that overtreatment with CHIR99021 converted the cells into BRACHYURY-expressing posterior mesoderm cells rather than endoderm,indicating strict CHIR99021 treatment requirements for endoderm differentiation. Nevertheless,these results should enable better control in the production of definitive endoderm-derived cells. View Publication

C1q modulates the differentiation and function of cells committed to the monocyte-derived dendritic cell (DC) lineage. Because the two C1q receptors found on the DC surface - gC1qR and cC1qR - lack a direct conduit into intracellular elements,we postulated that the receptors must form complexes with transmembrane partners. Here we show that DC-SIGN,a C-type lectin expressed on DCs,binds directly to C1q,as assessed by ELISA,flow cytometry and immuno-precipitation experiments. Surface plasmon resonance analysis revealed that the interaction was specific,and intact C1q,as well as the globular portion of C1q,bound to DC-SIGN. While IgG significantly reduced the binding; the Arg residues (162-163) of the C1q-A-chain,considered to contribute to C1q-IgG interaction,were not required for C1q binding to DC-SIGN. Binding was significantly reduced in the absence of Ca(2+) and by pre-incubation of DC-SIGN with mannan,suggesting that C1q binds to DC-SIGN at its principal Ca(2+)-binding pocket,which has increased affinity for mannose residues. Antigen-capture ELISA and immunofluorescence microscopy revealed that C1q and gC1qR associate with DC-SIGN on blood DC precursors and immature DCs. Thus the data suggest that C1q/gC1qR may regulate DC differentiation and function through DC-SIGN-mediated induction of cell signaling pathways. View Publication

Neutrophils are critical for host defense against fungi. However,the short life span and lack of genetic tractability of primary human neutrophils has limited in vitro analysis of neutrophil-fungal interactions. Human induced pluripotent stem cell (iPSC)-derived neutrophils (iNeutrophils) are a genetically tractable alternative to primary human neutrophils. Here,we show that deletion of the transcription factor GATA1 from human iPSCs results in iNeutrophils with improved antifungal activity against Aspergillus fumigatus. GATA1 knockout (KO) iNeutrophils have increased maturation,antifungal pattern recognition receptor expression and more readily execute neutrophil effector functions compared to wild-type iNeutrophils. iNeutrophils also show a shift in their metabolism following stimulation with fungal ?-glucan,including an upregulation of the pentose phosphate pathway (PPP),similar to primary human neutrophils in vitro. Furthermore,we show that deletion of the integrin CD18 attenuates the ability of GATA1-KO iNeutrophils to kill A. fumigatus but is not necessary for the upregulation of PPP. Collectively,these findings support iNeutrophils as a robust system to study human neutrophil antifungal immunity and has identified specific roles for CD18 in the defense response. Author SummaryNeutrophils are important first responders to fungal infections,and understanding their antifungal functions is essential to better elucidating disease dynamics. Primary human neutrophils are short lived and do not permit genetic manipulation,limiting their use to study neutrophil-fungal interactions in vitro. Human induced pluripotent stem cell (iPSC)-derived neutrophils (iNeutrophils) are a genetically tractable alternative to primary human neutrophils for in vitro analyses. In this report we show that GATA1-deficient iPSCs generate neutrophils (iNeutrophils) that are more mature than wild-type iNeutrophils and display increased antifungal activity against the human fungal pathogen Aspergillus fumigatus. We also show that GATA1-deficient iNeutrophils have increased expression of antifungal receptors than wild-type cells and shift their metabolism and execute neutrophil antifungal functions at levels comparable to primary human neutrophils. Deletion of the integrin CD18 blocks the ability of GATA1-deficient iNeutrophils to kill and control the growth of A. fumigatus,demonstrating an important role for this integrin in iNeutrophil antifungal activity. Collectively,these findings support the use of iNeutrophils as a model to study neutrophil antifungal immunity. View Publication

How BMP signaling integrates into and destabilizes the pluripotency circuitry of human pluripotent stem cells (hPSCs) to initiate differentiation into individual germ layers is a long-standing puzzle. Here we report muscle segment homeobox 2 (MSX2),a homeobox transcription factor of msh family,as a direct target gene of BMP signaling and a master mediator of hPSCs' differentiation to mesendoderm. Enforced expression of MSX2 suffices to abolish pluripotency and induce directed mesendoderm differentiation of hPSCs,while MSX2 depletion impairs mesendoderm induction. MSX2 is a direct target gene of the BMP pathway in hPSCs,and can be synergistically activated by Wnt signals via LEF1 during mesendoderm induction. Furthermore,MSX2 destabilizes the pluripotency circuitry through direct binding to the SOX2 promoter and repression of SOX2 transcription,while MSX2 controls mesendoderm lineage commitment by simultaneous suppression of SOX2 and induction of NODAL expression through direct binding and activation of the Nodal promoter. Interestingly,SOX2 can promote the degradation of MSX2 protein,suggesting a mutual antagonism between the two lineage-specifying factors in the control of stem cell fate. Together,our findings reveal crucial new mechanisms of destabilizing pluripotency and directing lineage commitment in hPSCs. View Publication