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

The site-directed recombinase Cre can be employed to delete or express genes in cell lines or animals. Clearly,the ability to control remotely the activity of this enzyme would be highly desirable. To this end we have constructed expression vectors for fusion proteins consisting of the Cre recombinase and a mutated hormone-binding domain of the murine oestrogen receptor. The latter still binds the anti-oestrogen drug tamoxifen but no longer 17 beta-oestradiol. We show here that in embryonic stem cells expressing such fusion proteins,tamoxifen can efficiently induce Cre-mediated recombination,thereby activating a stably integrated LacZ reporter gene. In the presence of either 10 microM tamoxifen or 800 nM 4-hydroxy-tamoxifen,recombination of the LacZ gene is complete within 3-4 days. By placing a tamoxifen-binding domain on both ends of the Cre protein,the enzymatic activity of Cre can be even more tightly controlled. Transgenic mice expressing such an tamoxifen-inducible Cre enzyme may thus provide a new and useful genetic tool to mutate or delete genes at specific times during development or in adult animals. View Publication

Hematopoietic stem cells (HSCs) develop from a specialized subpopulation of endothelial cells known as hemogenic endothelium (HE). Although the HE origin of HSCs is now well established in different species,the signaling pathways that control this transition remain poorly understood. Here,we show that activation of retinoic acid (RA) signaling in aorta-gonad-mesonephros-derived HE ex vivo dramatically enhanced its HSC potential,whereas conditional inactivation of the RA metabolizing enzyme retinal dehydrogenase 2 in VE-cadherin expressing endothelial cells in vivo abrogated HSC development. Wnt signaling completely blocked the HSC inductive effects of RA modulators,whereas inhibition of the pathway promoted the development of HSCs in the absence of RA signaling. Collectively,these findings position RA and Wnt signaling as key regulators of HSC development and in doing so provide molecular insights that will aid in developing strategies for their generation from pluripotent stem cells. View Publication

MED1/TRAP220,a subunit of the transcriptional Mediator/TRAP complex,is crucial for various biological events through its interaction with distinct activators,such as nuclear receptors and GATA family activators. In hematopoiesis,MED1 plays a pivotal role in optimal nuclear receptor-mediated myelomonopoiesis and GATA-1-induced erythropoiesis. In this study,we present evidence that MED1 in stromal cells is involved in supporting hematopoietic stem and/or progenitor cells (HSPCs) through osteopontin (OPN) expression. We found that the proliferation of bone marrow (BM) cells cocultured with MED1 knockout (Med1(-/-)) mouse embryonic fibroblasts (MEFs) was significantly suppressed compared to the control. Furthermore,the number of long-term culture-initiating cells (LTC-ICs) was attenuated for BM cells cocultured with Med1(-/-) MEFs. The vitamin D receptor (VDR)- and Runx2-mediated expression of OPN,as well as Mediator recruitment to the Opn promoter,was specifically attenuated in the Med1(-/-) MEFs. Addition of OPN to these MEFs restored the growth of cocultured BM cells and the number of LTC-ICs,both of which were attenuated by the addition of the anti-OPN antibody to Med1(+/+) MEFs and to BM stromal cells. Consequently,MED1 in niche appears to play an important role in supporting HSPCs by upregulating VDR- and Runx2-mediated transcription on the Opn promoter. View Publication

Mouse embryonic stem (mES) cells have short duration of their cell cycle and are capable of proliferating in the absence of growth factors. To find out which signaling pathways contribute to the regulation of the mES cell cycle,we used pharmacological inhibitors of MAP and PI3 kinase cascades. The MAP kinase inhibitors as well as serum withdrawal did not affect mES cell cycle distribution,whereas the inhibitor of PI3K activity,LY294002,induced accumulation of cells in G(1) phase followed by apoptotic cell death. Serum withdrawal also causes apoptosis,but it does not change the content and activity of cell cycle regulators. In contrast,in mES cells treated with LY294002,the activities of Cdk2 and E2F were significantly decreased. Interestingly,LY294002had a much stronger effect on cell cycle distribution in low serum conditions,implying that serum can promote G(1)--textgreaterS transition of mES cells by a LY294002-resistant mechanism. Thus,proliferation of mES cells is maintained by at least two separate mechanisms: a LY294002-sensitive pathway,which is active even in the absence of serum,and LY294002-resistant,but serum-dependent,pathway. View Publication

Natural killer T (NKT) cells are innate-like lymphocytes that recognize lipid antigens and have been shown to enhance B-cell activation and antibody production. B cells typically recruit T-cell help by presenting internalized antigens recognized by their surface antigen receptor. Here,we demonstrate a highly efficient means whereby human B cells present lipid antigens to NKT cells,capturing the antigen using apolipoprotein E (apoE) and the low-density lipoprotein receptor (LDL-R). ApoE dramatically enhances B-cell presentation of alpha-galactosylceramide (alphaGalCer),an exogenous CD1d presented antigen,inducing activation of NKT cells and the subsequent activation of B cells. B cells express the LDL-R on activation,and the activation of NKT cells by B cells is completely LDL-R dependent,as shown by blocking experiments and the complete lack of presentation when using apoE2,an isoform of apoE incapable of LDL-R binding. The dependence on apoE and the LDL-R is much more pronounced in B cells than we had previously seen in dendritic cells,which can apparently use alternate pathways of lipid antigen uptake. Thus,B cells use an apolipoprotein-mediated pathway of lipid antigen presentation,which constitutes a form of innate help for B cells by NKT cells. View Publication

BCR-ABL and v-ABL are oncogenic forms of the Abl tyrosine kinase that can cause leukemias in mice and humans. ABL oncogenes trigger multiple signaling pathways whose contribution to transformation varies among cell types. Activation of phosphoinositide 3-kinase (PI3K) is essential for ABL-dependent proliferation and survival in some cell types,and global PI3K inhibitors can enhance the antileukemia effects of the Abl kinase inhibitor imatinib. Although a significant fraction of BCR-ABL-induced human leukemias are of B-cell origin,little is known about PI3K signaling mechanisms in B-lineage cells transformed by ABL oncogenes. Here we show that activation of class I(A) PI3K and downstream inactivation of FOXO transcription factors are essential for survival of murine pro/pre-B cells transformed by v-ABL or BCR-ABL. In addition,analysis of mice lacking individual PI3K genes indicates that products of the Pik3r1 gene contribute to transformation efficiency by BCR-ABL. These findings establish a role for PI3K signaling in B-lineage transformation by ABL oncogenes. View Publication

Niches in the bone marrow regulate hematopoietic stem and progenitor cell (HSPC) fate and behavior through cell-cell interactions and soluble factor secretion. The niche-HSPC crosstalk is a very complex process not completely elucidated yet. To aid further investigation of this crosstalk,a functional in vitro 3D model that closely represents the main supportive compartments of the bone marrow is developed. Different combinations of human stromal cells and hydrogels are tested for their potential to maintain CD34+ HSPCs. Cell viability,clonogenic hematopoietic potential,and surface marker expression are assessed over time. Optimal HSPC support is obtained in presence of adipogenic and osteogenic cells,together with progenitor derived endothelial cells. When cultured in a bioactive hydrogel,the supportive cells self-assemble into a hypoxic stromal network,stimulating CD34+ CD38+ cell formation,while maintaining the pool of CD34+ 38- HSPCs. HSPC clusters colocalize with the stromal networks,in close proximity to sinusoidal clusters of CD31+ endothelial cells. Importantly,the primary in vitro niche model supports HSPCs with no cytokine addition. Overall,the engineered primary 3D bone marrow environment provides an easy and reliable model to further investigate interactions between HSPCs and their endosteal and perivascular niches,in the context of normal hematopoiesis or blood-related diseases. View Publication

Emerging evidence has shown that resting quiescent hematopoietic stem cells (HSCs) prefer to utilize anaerobic glycolysis rather than mitochondrial respiration for energy production. Compelling evidence has also revealed that altered metabolic energetics in HSCs underlies the onset of certain blood diseases; however,the mechanisms responsible for energetic reprogramming remain elusive. We recently found that Fanconi anemia (FA) HSCs in their resting state are more dependent on mitochondrial respiration for energy metabolism than on glycolysis. In the present study,we investigated the role of deficient glycolysis in FA HSC maintenance. We observed significantly reduced glucose consumption,lactate production,and ATP production in HSCs but not in the less primitive multipotent progenitors or restricted hematopoietic progenitors of Fanca-/- and Fancc-/- mice compared with that of wild-type mice,which was associated with an overactivated p53 and TP53-induced glycolysis regulator,the TIGAR-mediated metabolic axis. We utilized Fanca-/- HSCs deficient for p53 to show that the p53-TIGAR axis suppressed glycolysis in FA HSCs,leading to enhanced pentose phosphate pathway and cellular antioxidant function and,consequently,reduced DNA damage and attenuated HSC exhaustion. Furthermore,by using Fanca-/- HSCs carrying the separation-of-function mutant p53R172P transgene that selectively impairs the p53 function in apoptosis but not cell-cycle control,we demonstrated that the cell-cycle function of p53 was not required for glycolytic suppression in FA HSCs. Finally,ectopic expression of the glycolytic rate-limiting enzyme PFKFB3 specifically antagonized p53-TIGAR-mediated metabolic reprogramming in FA HSCs. Together,our results suggest that p53-TIGAR metabolic axis-mediated glycolytic suppression may play a compensatory role in attenuating DNA damage and proliferative exhaustion in FA HSCs. Stem Cells 2019;37:937-947. View Publication

AIMS The aim of this study was to improve a method that induce cartilage differentiation of human embryoid stem cells (hESCs) in vitro,and test the effect of in vivo environments on the further maturation of hESCs derived cells. MAIN METHODS Embryoid bodies (EBs) formed from hESCs,with serum-free KSR-based medium and mesodermal specification related factors,CHIR,and Noggin for first 8days. Then cells were digested and cultured as micropellets in serum-free KSR-based chondrogenic medium that was supplemented with PDGF-BB,TGF β3,BMP4 in sequence for 24days. The morphology,FACS,histological staining as well as the expression of chondrogenic specific genes were detected in each stage,and further in vivo experiments,cell injections and tissue transplantations,further verified the formation of chondrocytes. KEY FINDINGS We were able to obtain chondrocyte/cartilage from hESCs using serum-free KSR-based conditioned medium. qPCR analysis showed that expression of the chondroprogenitor genes and the chondrocyte/cartilage matrix genes. Morphology analysis demonstrated we got PG+COL2+COL1-particles. It indicated we obtained hyaline cartilage-like particles. 32-Day differential cells were injected subcutaneous. Staining results showed grafts developed further mature in vivo. But when transplanted in subrenal capsule,their effect was not good as in subcutaneous. Microenvironment might affect the cartilage formation. SIGNIFICANCE The results of this study provide an absolute serum-free and efficient approach for generation of hESC-derived chondrocytes,and cells will become further maturation in vivo. It provides evidence and technology for the hypothesis that hESCs may be a promising therapy for the treatment of cartilage disease. View Publication

AIMS Contradictory outcomes from recent clinical trials investigating the transplantation of autologous bone marrow mononuclear cell (BM-MNC) fraction containing stem/progenitor cells to damaged myocardium,following acute myocardial infarction,may be,in part,due to the different cell isolation protocols used. We compared total BM-MNC numbers and its cellular subsets obtained following isolation using Ficoll-Paque and Lymphoprep - two different density gradient media used in the clinical trials. MATERIALS & METHODS Bone marrow samples were taken from patients entered into the REGENERATE-IHD clinical trial after 5 days of subcutaneous granulocyte colony-stimulating factor injections. Each sample was divided equally for BM-MNC isolation using Ficoll-Paque and Lymphoprep,keeping all other procedural steps constant. Isolated fractions were characterized for hematopoietic stem cells,endothelial progenitor cells,T lymphocytes,B lymphocytes and NK cells using cell surface markers CD34(+),CD133(+)VEGFR2(+),CD45(+)CD3(+),CD45(+)CD19(+) and CD45(+)CD16(+)CD56(+),respectively. There were no significant differences in the absolute numbers and percentage cell recovery of various mononuclear cell types recovered following separation using either density gradient media. Cell viability and the proportion of various cell phenotypes investigated were similar between the two media. They were also equally efficient in excluding unwanted red blood cells,granulocytes and platelets from the final cell products. CONCLUSION We demonstrated that the composition and quantity of cell types found within therapeutic BM-MNC preparations for use in clinical trials of cardiac stem cell transplantation are not influenced by the type of density gradient media used when comparing Ficoll-Paque and Lymphoprep. View Publication

Innate lymphoid cells (ILCs) are a heterogeneous family of lymphocytes that populate barrier and non-barrier tissues. ILCs regulate immune responses to pathogens and commensals but also sustain metabolic homeostasis,tissue remodeling after injury and establish dialogue with the nervous system. ILCs rapidly become activated in the absence of adaptive antigen receptors by responding to signaling molecules provided by hematopoietic or non-hematopoietic cells. Here we provide protocols designed for processing the lung,liver,small intestine,bone marrow,mediastinal and mesenteric lymph nodes in order to obtain a purified leukocyte fraction of cells,in which ILC2 enrichment is optimized. In addition,we describe in detail the methodologies used to activate ILC2s and the assays necessary for the detection of their effector cytokines. We highlight the differences in ILC2 characterization within distinct tissues that we have recently identified. {\textcopyright} 2019 by John Wiley Sons,Inc. View Publication