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

The enteric nervous system (ENS) of the gastrointestinal tract controls many diverse functions,including motility and epithelial permeability. Perturbations in ENS development or function are common,yet there is no human model for studying ENS-intestinal biology and disease. We used a tissue-engineering approach with embryonic and induced pluripotent stem cells (PSCs) to generate human intestinal tissue containing a functional ENS. We recapitulated normal intestinal ENS development by combining human-PSC-derived neural crest cells (NCCs) and developing human intestinal organoids (HIOs). NCCs recombined with HIOs in vitro migrated into the mesenchyme,differentiated into neurons and glial cells and showed neuronal activity,as measured by rhythmic waves of calcium transients. ENS-containing HIOs grown in vivo formed neuroglial structures similar to a myenteric and submucosal plexus,had functional interstitial cells of Cajal and had an electromechanical coupling that regulated waves of propagating contraction. Finally,we used this system to investigate the cellular and molecular basis for Hirschsprung's disease caused by a mutation in the gene PHOX2B. This is,to the best of our knowledge,the first demonstration of human-PSC-derived intestinal tissue with a functional ENS and how this system can be used to study motility disorders of the human gastrointestinal tract. View Publication

The glycoprotein hormone erythropoietin regulates the level of oxygen in the blood by modulating the number of circulating erythrocytes,and is produced in the kidney or liver of adult and the liver of fetal or neonatal mammals. Neither the precise cell types that produce erythropoietin nor the mechanisms by which the same or different cells measure the circulating oxygen concentration and consequently regulate erythropoietin production are known. Cells responsive to erythropoietin have been identified in the adult bone marrow,fetal liver or adult spleen. In cultures of erythropoietic progenitors,erythropoietin stimulates proliferation and differentiation to more mature red blood cells. Detailed molecular studies have been hampered,however,by the impurity and heterogeneity of target cell populations and the difficulty of obtaining significant quantities of the purified hormone. Highly purified erythropoietin may be useful in the treatment of various forms of anaemia,particularly in chronic renal failure. Here we describe the cloning of the human erythropoietin gene and the expression of an erythropoietin cDNA clone in a transient mammalian expression system to yield a secreted product with biological activity. View Publication

Transplantation of Defined Populations of Differentiated Human Neural Stem Cell Progeny View Publication

Given their self-renewing and pluripotent capabilities,human embryonic stem cells (hESCs) are well poised as a cellular source for tissue regeneration therapy. However,the host immune response against transplanted hESCs is not well characterized. In fact,controversy remains as to whether hESCs have immune-privileged properties. To address this issue,we used in vivo bioluminescent imaging to track the fate of transplanted hESCs stably transduced with a double-fusion reporter gene consisting of firefly luciferase and enhanced GFP. We show that survival after transplant is significantly limited in immunocompetent as opposed to immunodeficient mice. Repeated transplantation of hESCs into immunocompetent hosts results in accelerated hESC death,suggesting an adaptive donor-specific immune response. Our data demonstrate that transplanted hESCs trigger robust cellular and humoral immune responses,resulting in intragraft infiltration of inflammatory cells and subsequent hESC rejection. Moreover,we have found CD4(+) T cells to be an important modulator of hESC immune-mediated rejection. Finally,we show that immunosuppressive drug regimens can mitigate the anti-hESC immune response and that a regimen of combined tacrolimus and sirolimus therapies significantly prolongs survival of hESCs for up to 28 days. Taken together,these data suggest that hESCs are immunogenic,trigger both cellular and humoral-mediated pathways,and,as a result,are rapidly rejected in xenogeneic hosts. This process can be mitigated by a combined immunosuppressive regimen as assessed by molecular imaging approaches. View Publication

DNA methyltransferase inhibitors represent promising new drugs for cancer therapies. The first of these compounds (5-azacytidine,Vidaza) has recently been approved as an antitumor agent,and others are presently in various stages of their preclinical or clinical development. Most of the archetypal inhibitors have been established and characterized in different experimental systems,which has thus far precluded their direct comparison. We have now established defined experimental conditions that allowed a comparative analysis of the six most widely known DNA methyltransferase inhibitors: 5-azacytidine (5-aza-CR),5-aza-2'-deoxycytidine (5-aza-CdR),zebularine,procaine,(-)-epigallocatechin-3-gallate (EGCG),and RG108. Of these,5-aza-CR,5-aza-CdR,zebularine,and EGCG were found to exhibit significant cytotoxicity in human cancer cell lines. 5-aza-CdR and EGCG were also found to be genotoxic,as evidenced by the induction of micronuclei. In addition,5-aza-CR,5-aza-CdR,zebularine,and RG108 caused concentration-dependent demethylation of genomic DNA,whereas procaine and EGCG failed to induce significant effects. Finally,the experiments in cancer cell lines were complemented by a cell-free in vitro assay with purified recombinant DNA methyltransferase,which indicated that RG108 is the only drug capable of direct enzyme inhibition. These results show a substantial diversity in the molecular activities of DNA methyltransferase inhibitors and provide valuable insights into the developmental potential of individual drugs. View Publication

Monocytes and macrophages are often claimed to have limited potential for proliferation in vivo and in vitro although a human monocyte subset with increased potential to proliferate in culture,termed the proliferative monocyte (PM),has previously been identified. The response of the putatively less mature PM to conditions conducive to haematopoietic stem cell culture was determined. Co-culture of monocytes on a HUVEC monolayer induced up to four cell divisions in a 9 day period. The PM response to haematopoietic growth factors (Flt3L,SCF,IL-6,IL-3 and M-CSF) was determined. M-CSF induced the greatest proliferative response in PM; IL-3 and Flt3L reduced basal and M-CSF-induced proliferation. The inhibition of M-CSFR kinase activity by GW2580 indicated that the ligand(s) for this receptor was a potent inducer of proliferation of this subset; inhibitors of intracellular signalling pathways also reduced PM proliferation. View Publication

Rett syndrome (RTT) is a postnatal neurodevelopmental disorder that primarily affects girls. Mutations in the methyl-CpG-binding protein 2 (MECP2) gene account for approximately 95 % of all RTT cases. To model RTT in vitro,we generated induced pluripotent stem cells (iPSCs) from fibroblasts of two RTT patients with different mutations (MECP2 (R306C) and MECP2 (1155$$32)) in their MECP2 gene. We found that these iPSCs were capable of differentiating into functional neurons. Compared to control neurons,the RTT iPSC-derived cells had reduced soma size and a decreased amount of synaptic input,evident both as fewer Synapsin 1-positive puncta and a lower frequency of spontaneous excitatory postsynaptic currents. Supplementation of the culture media with choline rescued all of these defects. Choline supplementation may act through changes in the expression of choline acetyltransferase,an important enzyme in cholinergic signaling,and also through alterations in the lipid metabolite profiles of the RTT neurons. Our study elucidates the possible mechanistic pathways for the effect of choline on human RTT cell models,thereby illustrating the potential for using choline as a nutraceutical to treat RTT. View Publication

Photoreceptor degeneration due to retinitis pigmentosa (RP) is a primary cause of inherited retinal blindness. Photoreceptor cell-replacement may hold the potential for repair in a completely degenerate retina by reinstating light sensitive cells to form connections that relay information to downstream retinal layers. This study assessed the therapeutic potential of photoreceptor progenitors derived from human embryonic and induced pluripotent stem cells (ESCs and iPSCs) using a protocol that is suitable for future clinical trials. ESCs and iPSCs were cultured in four specific stages under defined conditions,resulting in generation of a near-homogeneous population of photoreceptor-like progenitors. Following transplantation into mice with end-stage retinal degeneration,these cells differentiated into photoreceptors and formed a cell layer connected with host retinal neurons. Visual function was partially restored in treated animals,as evidenced by two visual behavioral tests. Furthermore,the magnitude of functional improvement was positively correlated with the number of engrafted cells. Similar efficacy was observed using either ESCs or iPSCs as source material. These data validate the potential of human pluripotent stem cells for photoreceptor replacement therapies aimed at photoreceptor regeneration in retinal disease. View Publication

Human NK cell deficiencies are rare yet result in severe and often fatal disease,particularly as a result of viral susceptibility. NK cells develop from hematopoietic stem cells,and few monogenic errors that specifically interrupt NK cell development have been reported. Here we have described biallelic mutations in IRF8,which encodes an interferon regulatory factor,as a cause of familial NK cell deficiency that results in fatal and severe viral disease. Compound heterozygous or homozygous mutations in IRF8 in 3 unrelated families resulted in a paucity of mature CD56dim NK cells and an increase in the frequency of the immature CD56bright NK cells,and this impairment in terminal maturation was also observed in Irf8-/-,but not Irf8+/-,mice. We then determined that impaired maturation was NK cell intrinsic,and gene expression analysis of human NK cell developmental subsets showed that multiple genes were dysregulated by IRF8 mutation. The phenotype was accompanied by deficient NK cell function and was stable over time. Together,these data indicate that human NK cells require IRF8 for development and functional maturation and that dysregulation of this function results in severe human disease,thereby emphasizing a critical role for NK cells in human antiviral defense. View Publication

Using radioligand binding assays,we determined the equilibrium dissociation constants (KD's) for 37 antidepressants,three of their metabolites (desmethylcitalopram,desmethylsertraline,and norfluoxetine),some mood stabilizers,and assorted other compounds (some antiepileptics,Ca2+ channel antagonists,benzodiazepines,psychostimulants,antihistamines,and monoamines) for the human serotonin,norepinephrine,and dopamine transporters. Among the compounds that we tested,mazindol was the most potent at the human norepinephrine and dopamine transporters with KD's of 0.45 +/- 0.03 nM and 8.1 +/- 0.4 nM,respectively. Sertraline (KD = 25 +/- 2 nM) and nomifensine (56 +/- 3 nM) were the two most potent antidepressants at the human dopamine transporter. We showed significant correlations for antidepressant affinities at binding to serotonin (R = 0.93),norepinephrine (R = 0.97),and dopamine (R = 0.87) transporters in comparison to their respective values for inhibiting uptake of monoamines into rat brain synaptosomes. These data are useful in predicting some possible adverse effects and drug-drug interactions of antidepressants and related compounds. View Publication

In hereditary hemochromatosis,mutations in HFE lead to iron overload through abnormally low levels of hepcidin. In addition,HFE potentially modulates cellular iron uptake by interacting with transferrin receptor,a crucial protein during erythropoiesis. However,the role of HFE in this process was never explored. We hypothesize that HFE modulates erythropoiesis by affecting dietary iron absorption and erythroid iron intake. To investigate this,we used Hfe-KO mice in conditions of altered dietary iron and erythropoiesis. We show that Hfe-KO mice can overcome phlebotomy-induced anemia more rapidly than wild-type mice (even when iron loaded). Second,we evaluated mice combining the hemochromatosis and β-thalassemia phenotypes. Our results suggest that lack of Hfe is advantageous in conditions of increased erythropoietic activity because of augmented iron mobilization driven by deficient hepcidin response. Lastly,we demonstrate that Hfe is expressed in erythroid cells and impairs iron uptake,whereas its absence exclusively from the hematopoietic compartment is sufficient to accelerate recovery from phlebotomy. In summary,we demonstrate that Hfe influences erythropoiesis by 2 distinct mechanisms: limiting hepcidin expression under conditions of simultaneous iron overload and stress erythropoiesis,and impairing transferrin-bound iron uptake by erythroid cells. Moreover,our results provide novel suggestions to improve the treatment of hemochromatosis. View Publication

Autosomal recessive osteopetrosis (OP) is a rare,lethal disorder in which osteoclasts are absent or nonfunctional,resulting in a bone marrow cavity insufficient to support hematopoiesis. Because osteoclasts are derived from hematopoietic precursors,allogeneic hematopoietic cell transplantation can cure the bony manifestations of the disorder. However,high rates of graft failure have been observed in this population. It is not possible to harvest bone marrow from these patients for reinfusion should graft failure be observed. We report that 8 of 10 patients with OP had high numbers of circulating CD34(+) cells (3% +/- 0.9%). This increased proportion of peripheral CD34(+) cells made it possible to harvest 2 x 10(6) CD34(+) cells per kilogram with a total volume of blood ranging from 8.3 to 83.7 mL (1.3-11.6 mL/kg). In addition,colony-forming assays documented significantly more colony-forming unit-granulocyte-macrophage and burst-forming unit-erythroid in the blood of osteopetrotic patients compared with controls; the numbers of colony-forming units approximated those found in control marrow. We conclude that OP patients with high levels of circulating CD34(+) are candidates for peripheral blood autologous harvest by limited exchange transfusion. These cells are then available for reinfusion should graft failure be observed in patients for whom retransplantation is impractical. View Publication