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

The production of red blood cells is tightly regulated by erythropoietin (Epo). The phosphoinositide 3-kinase (PI 3-kinase) pathway was previously shown to be activated in response to Epo. We studied the role of this pathway in the control of Epo-induced survival and proliferation of primary human erythroid progenitors. We show that phosphoinositide 3 (PI 3)-kinase associates with 4 tyrosine-phosphorylated proteins in primary human erythroid progenitors,namely insulin receptor substrate-2 (IRS2),Src homology 2 domain-containing inositol 5'-phosphatase (SHIP),Grb2-associated binder-1 (Gab1),and the Epo receptor (EpoR). Using different in vitro systems,we demonstrate that 3 alternative pathways independently lead to Epo-induced activation of PI 3-kinase and phosphorylation of its downstream effectors,Akt,FKHRL1,and P70S6 kinase: through direct association of PI 3-kinase with the last tyrosine residue (Tyr479) of the Epo receptor (EpoR),through recruitment and phosphorylation of Gab proteins via either Tyr343 or Tyr401 of the EpoR,or through phosphorylation of IRS2 adaptor protein. The mitogen-activated protein (MAP) kinase pathway was also activated by Epo in erythroid progenitors,but we found that this process is independent of PI 3-kinase activation. In erythroid progenitors,the functional role of PI 3-kinase was both to prevent apoptosis and to stimulate cell proliferation in response to Epo stimulation. Finally,our results show that PI 3-kinase-mediated proliferation of erythroid progenitors in response to Epo occurs mainly through modulation of the E3 ligase SCF(SKP2),which,in turn,down-regulates p27(Kip1) cyclin-dependent kinase (CDK) inhibitor via proteasome degradation. View Publication

Efficient delivery of therapeutics across the neuroprotective blood-brain barrier (BBB) remains a formidable challenge for central nervous system drug development. High-fidelity in vitro models of the BBB could facilitate effective early screening of drug candidates targeting the brain. In this study,we developed a microfluidic BBB model that is capable of mimicking in vivo BBB characteristics for a prolonged period and allows for reliable in vitro drug permeability studies under recirculating perfusion. We derived brain microvascular endothelial cells (BMECs) from human induced pluripotent stem cells (hiPSCs) and cocultured them with rat primary astrocytes on the two sides of a porous membrane on a pumpless microfluidic platform for up to 10 days. The microfluidic system was designed based on the blood residence time in human brain tissues,allowing for medium recirculation at physiologically relevant perfusion rates with no pumps or external tubing,meanwhile minimizing wall shear stress to test whether shear stress is required for in vivo-like barrier properties in a microfluidic BBB model. This BBB-on-a-chip model achieved significant barrier integrity as evident by continuous tight junction formation and in vivo-like values of trans-endothelial electrical resistance (TEER). The TEER levels peaked above 4000 $$ textperiodcentered cm(2) on day 3 on chip and were sustained above 2000 $$ textperiodcentered cm(2) up to 10 days,which are the highest sustained TEER values reported in a microfluidic model. We evaluated the capacity of our microfluidic BBB model to be used for drug permeability studies using large molecules (FITC-dextrans) and model drugs (caffeine,cimetidine,and doxorubicin). Our analyses demonstrated that the permeability coefficients measured using our model were comparable to in vivo values. Our BBB-on-a-chip model closely mimics physiological BBB barrier functions and will be a valuable tool for screening of drug candidates. The residence time-based design of a microfluidic platform will enable integration with other organ modules to simulate multi-organ interactions on drug response. Biotechnol. Bioeng. 2016;9999: 1-11. textcopyright 2016 Wiley Periodicals,Inc. View Publication

Modeling tissues and organs using conventional 2D cell cultures is problematic as the cells rapidly lose their in vivo phenotype. In microfluidic bioreactors the cells reside in microstructures that are continuously perfused with cell culture medium to provide a dynamic environment mimicking the cells natural habitat. These micro scale bioreactors are sometimes referred to as organs-on-chips and are developed in order to improve and extend cell culture experiments. Here,we describe the two manufacturing techniques photolithography and soft lithography that are used in order to easily produce microfluidic bioreactors. The use of these bioreactors is exemplified by a toxicity assessment on 3D clustered human pluripotent stem cells (hPSC)-derived cardiomyocytes by beating frequency imaging. View Publication

Retroviral vectors with long terminal repeats (LTRs),which contain strong enhancer/promoter sequences at both ends of their genome,are widely used for stable gene transfer into hematopoietic cells. However,recent clinical data and mouse models point to insertional activation of cellular proto-oncogenes as a dose-limiting side effect of retroviral gene delivery that potentially induces leukemia. Self-inactivating (SIN) retroviral vectors do not contain the terminal repetition of the enhancer/promoter,theoretically attenuating the interaction with neighboring cellular genes. With a new assay based on in vitro expansion of primary murine hematopoietic cells and selection in limiting dilution,we showed that SIN vectors using a strong internal retroviral enhancer/promoter may also transform cells by insertional mutagenesis. Most transformed clones,including those obtained after dose escalation of SIN vectors,showed insertions upstream of the third exon of Evi1 and in reverse orientation to its transcriptional orientation. Normalizing for the vector copy number,we found the transforming capacity of SIN vectors to be significantly reduced when compared with corresponding LTR vectors. Additional modifications of SIN vectors may further increase safety. Improved cell-culture assays will likely play an important role in the evaluation of insertional mutagenesis. View Publication

High purity chromosome sorting can be performed on instruments such as MoFlo MLS and BD influx,which are stream-in-air sorters equipped with water-cooled high power lasers. The FACSAria is a true fixed alignment,low laser powered instrument with a quartz flow cell gel-coupled to the collection optics. However,whether high purity mouse and human chromosomes can be obtained by sorting on the BD FACSAria(TM) Special Order Research Product (FACSAria SORP) remains to be determined. Here,we report that the high resolution flow karyotype of mouse lymphocytes and normal male human peripheral blood mononuclear cells (hPBMCs) can be obtained on the FACSAria SORP using laser power settings of 50 mW for 355 nm and 20 mW for 444 nm excitation. Furthermore,the use of Fluorescence in situ hybridization (FISH) confirmed that chromosome paints prepared from the sorted chromosomes demonstrated high purity and signal specificity. Notably,human chromosome 12 was separated from the chromosome 9-12 cluster in the flow karyotype,and its identity was confirmed using FISH in trisomy 12 human ES cell lines B2-C7 and B2-B8. In addition,multicolor FISH (mFISH) with human chromosome painting probes to 13,18,21,and sex chromosomes X and Y showed high signal specificity in hPBMCs. Taken together,our findings demonstrated that high resolution flow karyotype can be obtained using FACSAria SORP. Moreover,a FISH analysis confirmed high purity of the sorted chromosomes. Additionally,in contrast to centromeric satellite probes,chromosome painting probes with high specificity are more suitable for detection of chromosome aberrations,such as deletions and translocations,in prenatal diagnosis. textcopyright 2016 International Society for Advancement of Cytometry. View Publication

Disentangling the complex interactions that govern stem cell fate choices of self-renewal,differentiation,or death presents a formidable challenge. Image-based phenotype-driven screening meets this challenge by providing means for rapid testing of many small molecules simultaneously. Pluripotent embryonal carcinoma (EC) cells offer a convenient substitute for embryonic stem (ES) cells in such screens because they are simpler to maintain and control. The authors developed an image-based screening assay to identify compounds that affect survival or differentiation of the human EC stem cell line NTERA2 by measuring the effect on cell number and the proportion of cells expressing a pluripotency-associated marker SSEA3. A pilot screen of 80 kinase inhibitors identified several compounds that improved cell survival or induced differentiation. The survival compounds Y-27632,HA-1077,and H-8 all strongly inhibit the kinases ROCK and PRK2,highlighting the important role of these kinases in EC cell survival. Two molecules,GF109203x and rottlerin,induced EC differentiation. The effects of rottlerin were also investigated in human ES cells. Rottlerin inhibited the self-renewal ability of ES cells,caused the cell cycle arrest,and repressed the expression of pluripotency-associated genes. View Publication

Gaucher disease is caused by an inherited deficiency of glucocerebrosidase that manifests with storage of glycolipids in lysosomes,particularly in macrophages. Available cell lines modeling Gaucher disease do not demonstrate lysosomal storage of glycolipids; therefore,we set out to develop two macrophage models of Gaucher disease that exhibit appropriate substrate accumulation. We used these cellular models both to investigate altered macrophage biology in Gaucher disease and to evaluate candidate drugs for its treatment. We generated and characterized monocyte-derived macrophages from 20 patients carrying different Gaucher disease mutations. In addition,we created induced pluripotent stem cell (iPSC)-derived macrophages from five fibroblast lines taken from patients with type 1 or type 2 Gaucher disease. Macrophages derived from patient monocytes or iPSCs showed reduced glucocerebrosidase activity and increased storage of glucocerebroside and glucosylsphingosine in lysosomes. These macrophages showed efficient phagocytosis of bacteria but reduced production of intracellular reactive oxygen species and impaired chemotaxis. The disease phenotype was reversed with a noninhibitory small-molecule chaperone drug that enhanced glucocerebrosidase activity in the macrophages,reduced glycolipid storage,and normalized chemotaxis and production of reactive oxygen species. Macrophages differentiated from patient monocytes or patient-derived iPSCs provide cellular models that can be used to investigate disease pathogenesis and facilitate drug development. View Publication

We studied the suitability of collagen-based semisolid medium for assay of endogenous erythroid colony formation performed in myeloproliferative disorders. Bone marrow (BM) mononuclear cells (MNC) from 103 patients suspected of having polycythemia vera (PV,76 patients) or essential thrombocythemia (ET,27 patients) were grown in collagen-based,serum-free,cytokine-free semisolid medium. Colony analysis at day 8 or 10 showed that this collagen assay is specific,as endogenous growth of erythroid colonies was never observed in cultures of 16 healthy donors and 6 chronic myelogenous leukemia (CML) patients. Endogenous erythroid colony formation was observed in 53.3% of patients suspected of PV,with only 15.4% of positive cultures for patients with 1 minor PV criterion and 72% (p = 0.009) of positive cultures for patients with textgreater or =2 minor or 1 major PV criterion. Similarly,endogenous growth of erythroid colonies was found in 44.4% of patients suspected of ET,with 31.6% of positive cultures for patients with 1 ET criterion versus 75% for patients with textgreater or =2 ET criteria. In addition,we found that in collagen gels,tests of erythropoietin (EPO) hypersensitivity in the presence of 0.01 or 0.05 U/ml of EPO and tests of endogenous colony-forming units-megakaryocyte (CFU-MK) formation cannot be used to detect PV or ET,as these tests were positive for,respectively,21.4% and 50% of healthy donors and 83% and 50% of CML patients. A retrospective analysis suggests that collagen assays are more sensitive than methylcellulose assays to assess endogenous growth of erythroid colonies. In summary,serum-free collagen-based colony assays are simple and reliable assays of endogenous growth of erythroid colonies in myeloproliferative diseases. They also appear to be more sensitive than methylcellulose-based assays. View Publication

The cell-surface straight and branched repeats of N-acetyllactosamine (LacNAc) units,called poly-LacNAc chains,characterize the histo-blood group i and I antigens,respectively. The transition of straight to branched poly-LacNAc chain (i to I) is determined by the I locus,which expresses 3 IGnT transcripts,IGnTA,IGnTB,and IGnTC. Our previous investigation demonstrated that the i-to-I transition in erythroid differentiation is regulated by the transcription factor CCAAT/enhancer binding protein alpha (C/EBPalpha). In the present investigation,the K-562 cell line was used as a model to show that the i-to-I transition is determined by the phosphorylation status of the C/EBPalpha Ser-21 residue,with dephosphorylated C/EBPalpha Ser-21 stimulating the transcription of the IGnTC gene,consequently resulting in I branching. Results from studies using adult erythropoietic and granulopoietic progenitor cells agreed with those derived using the K-562 cell model,with lentiviral expression of C/EBPalpha in CD34(+) hematopoietic cells demonstrating that the dephosphorylated form of C/EBPalpha Ser-21 induced the expression of I antigen,granulocytic CD15,and also erythroid CD71 antigens. Taken together,these results demonstrate that the regulation of poly-LacNAc branching (I antigen) formation in erythropoiesis and granulopoiesis share a common mechanism,with dephosphorylation of the Ser-21 residue on C/EBPalpha playing the critical role. View Publication

In this study we dissected retinal organoid morphogenesis in human embryonic stem cell (hESC)-derived cultures and established a convenient method for isolating large quantities of retinal organoids for modeling human retinal development and disease. Epithelialized cysts were generated via floating culture of clumps of Matrigel/hESCs. Upon spontaneous attachment and spreading of the cysts,patterned retinal monolayers with tight junctions formed. Dispase-mediated detachment of the monolayers and subsequent floating culture led to self-formation of retinal organoids comprising patterned neuroretina,ciliary margin,and retinal pigment epithelium. Intercellular adhesion-dependent cell survival and ROCK-regulated actomyosin-driven forces are required for the self-organization. Our data supports a hypothesis that newly specified neuroretina progenitors form characteristic structures in equilibrium through minimization of cell surface tension. In long-term culture,the retinal organoids autonomously generated stratified retinal tissues,including photoreceptors with ultrastructure of outer segments. Our system requires minimal manual manipulation,has been validated in two lines of human pluripotent stem cells,and provides insight into optic cup invagination in vivo. View Publication