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

Human GWAS have shown that obesogenic FTO polymorphisms correlate with lean mass,but the mechanisms have remained unclear. It is counterintuitive because lean mass is inversely correlated with obesity and metabolic diseases. Here,we use CRISPR to knock-in FTOrs9939609-A into hESC-derived tissue models,to elucidate potentially hidden roles of FTO during development. We find that among human tissues,FTOrs9939609-A most robustly affect human muscle progenitors’ proliferation,differentiation,senescence,thereby accelerating muscle developmental and metabolic aging. An edited FTOrs9939609-A allele over-stimulates insulin/IGF signaling via increased muscle-specific enhancer H3K27ac,FTO expression and m6A demethylation of H19 lncRNA and IGF2 mRNA,with excessive insulin/IGF signaling leading to insulin resistance upon replicative aging or exposure to high fat diet. This FTO-m6A-H19/IGF2 circuit may explain paradoxical GWAS findings linking FTOrs9939609-A to both leanness and obesity. Our results provide a proof-of-principle that CRISPR-hESC-tissue platforms can be harnessed to resolve puzzles in human metabolism. Human GWAS paradoxically linked FTO SNPs to both lean mass and sarcopenia/obesity. Here,Guang et al used CRISPR-edited stem cells to reveal that an obesogenic FTO SNP accelerates both muscle development and aging,by increasing RNA m6A demethylation. View Publication

Smith-Lemli-Opitz syndrome (SLOS) is a malformation disorder caused by mutations in DHCR7,which impair the reduction of 7-dehydrocholesterol (7DHC) to cholesterol. SLOS results in cognitive impairment,behavioral abnormalities and nervous system defects,though neither affected cell types nor impaired signaling pathways are fully understood. Whether 7DHC accumulation or cholesterol loss is primarily responsible for disease pathogenesis is also unclear. Using induced pluripotent stem cells (iPSCs) from subjects with SLOS,we identified cellular defects that lead to precocious neuronal specification within SLOS derived neural progenitors. We also demonstrated that 7DHC accumulation,not cholesterol deficiency,is critical for SLOS-associated defects. We further identified downregulation of Wnt/$$-catenin signaling as a key initiator of aberrant SLOS iPSC differentiation through the direct inhibitory effects of 7DHC on the formation of an active Wnt receptor complex. Activation of canonical Wnt signaling prevented the neural phenotypes observed in SLOS iPSCs,suggesting that Wnt signaling may be a promising therapeutic target for SLOS. View Publication

The mutagenic enzyme activation-induced cytidine deaminase (AID) is required for immunoglobulin class switch recombination (CSR) and somatic hypermutation (SHM) in germinal center (GC) B cells. Deregulated expression of AID is associated with various B-cell malignancies and,currently,it remains unclear how AID activity is extinguished to avoid illegitimate mutations. AID has also been shown to be alternatively spliced in malignant B cells,and there is limited evidence that this also occurs in normal blood B cells. The functional significance of these splice variants remains unknown. Here we show that normal GC human B cells and blood memory B cells similarly express AID splice variants and show for the first time that AID splicing variants are singly expressed in individual normal B cells as well as malignant B cells from chronic lymphocytic leukemia patients. We further demonstrate that the alternative AID splice variants display different activities ranging from inactivation of CSR to inactivation or heightened SHM activity. Our data therefore suggest that CSR and SHM are differentially switched off by varying the expression of splicing products of AID at the individual cell level. Most importantly,our findings suggest a novel tumor suppression mechanism by which unnecessary AID mutagenic activities are promptly contained for GC B cells. View Publication

To determine the effects and immunological mechanisms of low-dose interleukin-2 (IL-2) in a murine model of chronic cardiac allograft rejection (BALB/c to C57BL/6) after costimulatory blockade consisting of MR1 (250??$\mu$g/ip day 0) and CTLA4-Ig (200??$\mu$g/ip day 2),we administered low-dose IL-2 (2000??IU/day) starting on posttransplant day 14 for 3??weeks. T regulatory (Treg) cell infiltration of the grafts was determined by immunohistochemistry; circulating exosomes by western blot and aldehyde bead flow cytometry; antibodies to donor MHC by immunofluorescent staining of donor cells; and antibodies to cardiac self-antigens (myosin,vimentin) by ELISA. We demonstrated that costimulation blockade after allogeneic heart transplantation induced circulating exosomes containing cardiac self-antigens and antibodies to both donor MHC and self-antigens,leading to chronic rejection by day 45. Treatment with low-dose IL-2 prolonged allograft survival (>100??days),prevented chronic rejection,and induced splenic and graft-infiltrating CD4+ CD25+ Foxp3 Treg cells by day 45 and circulating exosomes (Foxp3+) with PD-L1 and CD73. MicroRNA 142,associated with the TGF$\beta$ pathway,was significantly downregulated in exosomes from IL-2-treated mice. In conclusion,low-dose IL-2 delays rejection in a murine model of chronic cardiac allograft rejection and also induces graft-infiltrating Tregs and circulating exosomes with immunoregulatory molecules. View Publication

A human cell-based in vitro model that can accurately predict drug penetration into the brain as well as metrics to assess these in vitro models are valuable for the development of new therapeutics. Here,human induced pluripotent stem cells (hPSCs) are differentiated into a polarized monolayer that express blood-brain barrier (BBB)-specific proteins and have transendothelial electrical resistance (TEER) values greater than 2500 Ωtextperiodcenteredcm(2). By assessing the permeabilities of several known drugs,a benchmarking system to evaluate brain permeability of drugs was established. Furthermore,relationships between TEER and permeability to both small and large molecules were established,demonstrating that different minimum TEER thresholds must be achieved to study the brain transport of these two classes of drugs. This work demonstrates that this hPSC-derived BBB model exhibits an in vivo-like phenotype,and the benchmarks established here are useful for assessing functionality of other in vitro BBB models. View Publication

Cancer stem cells (CSCs) have recently been identified in leukaemia and solid tumours; however,the role of CSCs in metastasis remains poorly understood. This dearth of knowledge about CSCs and metastasis is due largely to technical challenges associated with the use of primary human cancer cells in pre-clinical models of metastasis. Therefore,the objective of this study was to develop suitable pre-clinical model systems for studying stem-like cells in breast cancer metastasis,and to test the hypothesis that stem-like cells play a key role in metastatic behaviour. We assessed four different human breast cancer cell lines (MDA-MB-435,MDA-MB-231,MDA-MB-468,MCF-7) for expression of prospective CSC markers CD44/CD24 and CD133,and for functional activity of aldehyde dehydrogenase (ALDH),an enzyme involved in stem cell self-protection. We then used fluorescence-activated cell sorting and functional assays to characterize differences in malignant/metastatic behaviour in vitro (proliferation,colony-forming ability,adhesion,migration,invasion) and in vivo (tumorigenicity and metastasis). Sub-populations of cells demonstrating stem-cell-like characteristics (high expression of CSC markers and/or high ALDH) were identified in all cell lines except MCF-7. When isolated and compared to ALDH(low)CD44(low/-) cells,ALDH(hi)CD44(+)CD24(-) (MDA-MB-231) and ALDH(hi)CD44(+)CD133(+) (MDA-MB-468) cells demonstrated increased growth (P textless 0.05),colony formation (P textless 0.05),adhesion (P textless 0.001),migration (P textless 0.001) and invasion (P textless 0.001). Furthermore,following tail vein or mammary fat pad injection of NOD/SCID/IL2gamma receptor null mice,ALDH(hi)CD44(+)CD24(-) and ALDH(hi)CD44(+)CD133(+) cells showed enhanced tumorigenicity and metastasis relative to ALDH(low)CD44(low/-) cells (P textless 0.05). These novel results suggest that stem-like ALDH(hi)CD44(+)CD24(-) and ALDH(hi)CD44(+)CD133(+) cells may be important mediators of breast cancer metastasis. View Publication

Tissue engineering strategies,based on solid/porous scaffolds,suffer from several limitations,such as ineffective vascularization,poor cell distribution and organization within scaffold,in addition to low final cell density,among others. Therefore,the search for other tissue engineering approaches constitutes an active area of investigation. Decellularized matrices (DM) present major advantages compared to solid scaffolds,such as ideal chemical composition,the preservation of vascularization structure and perfect three-dimensional structure. In the present study,we aimed to characterize and investigate murine heart decellularized matrices as biomaterials for regular and whole organ tissue engineering. Heart decellularized matrices were characterized according to: 1. DNA content,through DNA quantificationo and PCR of isolated genomic DNA; 2. Histological structure,assessed after Hematoxylin and Eosin,as well as Masson's Trichrome stainings; 3. Surface nanostructure analysis,performed,using SEM. Those essays allowed us to conclude that DM was indeed decellularized,with preserved extracellular matrix structure. Following characterization,decellularized heart slices were seeded with induced Pluripotent Stem cells (iPS). As expected,but - to the best of our knowledge - never shown before,decellularization of murine heart matrices maintained matrix biocompatibility,as iPS cells rapidly attached to the surface of the material and proliferated. Strikingly though,heart DM presented a differentiation induction effect over those cells,which lost their pluripotency markers after 7 days of culture in the DM. Such loss of differentiation markers was observed,even though bFGF containing media mTSR was used during such period. Gene expression of iPS cells cultured on DM will be further analyzed,in order to assess the effects of culturing pluripotent stem cells in decellularized heart matrices. View Publication

Transplantation of genetically corrected autologous hematopoietic stem cells is an attractive approach for the cure of sickle-cell disease and beta-thalassemia. Here,we infected human cord blood cells with a self-inactivating lentiviral vector encoding an anti-sickling betaA-T87Q-globin transgene and analyzed the transduced progeny produced over a 6-month period after transplantation of the infected cells directly into sublethally irradiated NOD/LtSz-scid/scid mice. Approximately half of the human erythroid and myeloid progenitors regenerated in the mice containing the transgene,and erythroid cells derived in vitro from these in vivo-regenerated cells produced high levels of betaA-T87Q-globin protein. Linker-mediated PCR analysis identified multiple transgene-positive clones in all mice analyzed with 2.1 +/- 0.1 integrated proviral copies per cell. Genomic sequencing of vector-containing fragments showed that 86% of the proviral inserts had occurred within genes,including several genes implicated in human leukemia. These findings indicate effective transduction of very primitive human cord blood cells with a candidate therapeutic lentiviral vector resulting in the long-term and robust,erythroid-specific production of therapeutically relevant levels of beta-globin protein. However,the frequency of proviral integration within genes that regulate hematopoiesis points to a need for additional safety modifications. View Publication

Although there is evidence that endothelial cells are important targets for human pathogenic Bartonella species,the primary niche of infection is unknown. Here we elucidated whether human CD34+ hematopoietic progenitor cells (HPCs) internalize B. henselae and may serve as a potential niche of the pathogen. We showed that B. henselae does not adhere to or invade human erythrocytes. In contrast,B. henselae invades and persists in HPCs as shown by gentamicin protection assays,confocal laser scanning microscopy (CLSM),and electron microscopy (EM). Fluorescence-activated cell sorting (FACS) analysis of glycophorin A expression revealed that erythroid differentiation of HPCs was unaffected following infection with B. henselae. The number of intracellular B. henselae continuously increased over a 13-day period. When HPCs were infected with B. henselae immediately after isolation,intracellular bacteria were subsequently detectable in differentiated erythroid cells on day 9 and day 13 after infection,as shown by CLSM,EM,and FACS analysis. Our data provide,for the first time,evidence that a bacterial pathogen is able to infect and persist in differentiating HPCs,and suggest that HPCs might serve as a potential primary niche in Bartonella infections. View Publication

Much attention is focused on characterizing the contribution of bone marrow (BM)-derived cells to regenerating skeletal muscle,fuelled by hopes for stem cell-mediated therapy of muscle degenerative diseases. Though physical integration of BM stem cells has been well documented,little evidence of functional commitment to myotube phenotype has been reported. This is due to the innate difficulty in distinguishing gene products derived from donor versus host nuclei. Here,we demonstrate that BM-derived stem cells contribute via gene expression following incorporation to skeletal myotubes. By co-culturing human BM-derived mesenchymal stem cells (MSC) with mouse skeletal myoblasts,physical incorporation was observed by genetic lineage tracing and species-specific immunofluorescence. We used a human-specific antibody against the intermediate filament protein nestin,a marker of regenerating skeletal muscle,to identify functional contribution of MSC to myotube formation. Although nestin expression was never detected in MSC,human-specific expression was detected in myotubes that also contained MSC-derived nuclei. This induction of gene expression following myotube integration suggests that bone marrow-derived stem cells can reprogram and functionally contribute to the muscle cell phenotype. We propose that this model of myogenic commitment may provide the means to further characterize functional reprogramming of MSC to skeletal muscle. View Publication

Current neural induction protocols for human embryonic stem (hES) cells rely on embryoid body formation,stromal feeder co-culture or selective survival conditions. Each strategy has considerable drawbacks,such as poorly defined culture conditions,protracted differentiation and low yield. Here we report that the synergistic action of two inhibitors of SMAD signaling,Noggin and SB431542,is sufficient to induce rapid and complete neural conversion of textgreater80% of hES cells under adherent culture conditions. Temporal fate analysis reveals the appearance of a transient FGF5(+) epiblast-like stage followed by PAX6(+) neural cells competent to form rosettes. Initial cell density determines the ratio of central nervous system and neural crest progeny. Directed differentiation of human induced pluripotent stem (hiPS) cells into midbrain dopamine and spinal motoneurons confirms the robustness and general applicability of the induction protocol. Noggin/SB431542-based neural induction should facilitate the use of hES and hiPS cells in regenerative medicine and disease modeling and obviate the need for protocols based on stromal feeders or embryoid bodies. View Publication

BACKGROUND: Human tonsils are a rich source of B lymphocytes exhibiting a variety of phenotypes and activation states. Existing methods of purification are time consuming or costly. The aim of the present study was to optimize conditions to isolate large numbers of highly purified primary B lymphocytes from tonsils in a short and cost-effective single step,using a commercially available reagent designed for purifying cells from whole blood (RosetteSep). This technique relies on the presence of the large excess of red blood cells in whole blood for the formation of immunorosettes,whereas single cell suspensions from tonsils contain relatively few red blood cells. RESULTS: B cell enrichment from tonsils was achieved using RosetteSep with no modification to the whole blood procedure; however,the degree of purity depended on the extent of red blood cell contamination of the starting tonsil cell suspension. Addition of a 50-fold excess of allogeneic human red blood cells,but not sheep red blood cells,reproducibly resulted in high levels of purity. Depletion of mononuclear cells from the donor red blood cells eliminated potential contamination with allogeneic B cells. CONCLUSION: RosetteSep reagent can be used in combination with allogeneic human red blood cells to reproducibly isolate tonsil B lymphocytes to high levels of purity with no change in phenotype or loss of cells. This method provides considerable time and cost savings compared to other methods. View Publication