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

The enteric pathogen Lawsonia intracellularis is one of the main causes of diarrhea and compromised weight gain in pigs worldwide. Traditional cell-line cultures have been used to study L. intracellularis pathogenesis. However,these systems fail to reproduce the epithelial changes observed in the intestines of L. intracellularis-infected pigs,specifically,the changes in intestinal cell constitution and gene expression. A more physiologically accurate and state-of-the-art model is provided by swine enteroids derived from stem cell-containing crypts from healthy pigs. The objective of this study was to verify the feasibility of two-dimensional swine enteroids as in vitro models for L. intracellularis infection. We established both three- and two-dimensional swine enteroid cultures derived from intestinal crypts. The two-dimensional swine enteroids were infected by L. intracellularis in four independent experiments. Enteroid-infected samples were collected 3 and 7 d postinfection for analysis using real-time quantitative PCR and L. intracellularis immunohistochemistry. In this study,we show that L. intracellularis is capable of infecting and replicating intracellularly in two-dimensional swine enteroids derived from ileum. View Publication

The study of induced pluripotency is complicated by the need for infection with high-titer retroviral vectors,which results in genetically heterogeneous cell populations. We generated genetically homogeneous 'secondary' somatic cells that carry the reprogramming factors as defined doxycycline (dox)-inducible transgenes. These cells were produced by infecting fibroblasts with dox-inducible lentiviruses,reprogramming by dox addition,selecting induced pluripotent stem cells and producing chimeric mice. Cells derived from these chimeras reprogram upon dox exposure without the need for viral infection with efficiencies 25- to 50-fold greater than those observed using direct infection and drug selection for pluripotency marker reactivation. We demonstrate that (i) various induction levels of the reprogramming factors can induce pluripotency,(ii) the duration of transgene activity directly correlates with reprogramming efficiency,(iii) cells from many somatic tissues can be reprogrammed and (iv) different cell types require different induction levels. This system facilitates the characterization of reprogramming and provides a tool for genetic or chemical screens to enhance reprogramming. View Publication

Tissue fibrosis is a major cause of death in SSc,but therapies that target selectively fibrosis are not yet available for routine clinical use. Recent pre-clinical studies suggest that selective tyrosine kinase inhibitors that target c-Abl,PDGF receptor or Src kinases might be promising targets for anti-fibrotic approaches. Dual inhibition of c-Abl and PDGF receptor by imatinib and nilotinib,and inhibition of Src kinases either selectively by SU6656 or in combination with c-Abl and PDGF by dasatinib exerted potent anti-fibrotic effects. Imatinib,nilotinib,dasatinib and SU6656 reduced dose-dependently the synthesis of extracellular matrix protein in human dermal fibroblasts in vitro and prevented fibrosis in the mouse model of bleomycin-induced skin fibrosis. Clinical data from patients with chronic myelogenous leukaemia suggest that imatinib,nilotinib and dasatinib are well tolerated. Based on the promising pre-clinical data,imatinib is currently evaluated in clinical trials for the treatment of fibrosis in SSc and trials with other tyrosine kinase inhibitors are in preparation. View Publication

The Hedgehog (Hh) signaling pathway controls growth,cell fate decisions,and morphogenesis during development. Damage to Hh transduction machinery can lead to birth defects and cancer. The transmembrane protein Smoothened (Smo) relays the Hh signal and is an important drug target in cancer. Smo enrichment in primary cilia is thought to drive activation of target genes. Using small-molecule agonists and antagonists to dissect Smo function,we find that Smo enrichment in cilia is not sufficient for signaling and a distinct second step is required for full activation. This 2-step mechanism--localization followed by activation--has direct implications for the design and use of anticancer therapeutics targeted against Smo. View Publication

Extracts of the resin of the guggul tree (Commiphora mukul) lower LDL (low-density lipoprotein) cholesterol levels in humans. The plant sterol guggulsterone [4,17(20)-pregnadiene-3,16-dione] is the active agent in this extract. We show that guggulsterone is a highly efficacious antagonist of the farnesoid X receptor (FXR),a nuclear hormone receptor that is activated by bile acids. Guggulsterone treatment decreases hepatic cholesterol in wild-type mice fed a high-cholesterol diet but is not effective in FXR-null mice. Thus,we propose that inhibition of FXR activation is the basis for the cholesterol-lowering activity of guggulsterone. Other natural products with specific biologic effects may modulate the activity of FXR or other relatively promiscuous nuclear hormone receptors. View Publication

Thrombopoietin (TPO) is a potent regulator of megakaryopoiesis and stimulates megakaryocyte (MK) progenitor expansion and MK differentiation. In this study,we show that TPO induces activation of the mammalian target of rapamycin (mTOR) signaling pathway,which plays a central role in translational regulation and is required for proliferation of MO7e cells and primary human MK progenitors. Treatment of MO7e cells,human CD34+,and primary MK cells with the mTOR inhibitor rapamycin inhibits TPO-induced cell cycling by reducing cells in S phase and blocking cells in G0/G1. Rapamycin markedly inhibits the clonogenic growth of MK progenitors with high proliferative capacity but does not reduce the formation of small MK colonies. Addition of rapamycin to MK suspension cultures reduces the number of MK cells,but inhibition of mTOR does not significantly affect expression of glycoproteins IIb/IIIa (CD41) and glycoprotein Ib (CD42),nuclear polyploidization levels,cell size,or cell survival. The downstream effectors of mTOR,p70 S6 kinase (S6K) and 4E-binding protein 1 (4E-BP1),are phosphorylated by TPO in a rapamycin- and LY294002-sensitive manner. Part of the effect of the phosphatidyl inositol 3-kinase pathway in regulating megakaryopoiesis may be mediated by the mTOR/S6K/4E-BP1 pathway. In conclusion,these data demonstrate that the mTOR pathway is activated by TPO and plays a critical role in regulating proliferation of MK progenitors,without affecting differentiation or cell survival. View Publication