The hepatic stem cell niche and paracrine signaling by mesenchymal cells in support of human hepatic stem cells

Paracrine signaling is important for tissues both during embryonic development and in regulation of the tissue's cell lineages in adults. In liver, the mesenchymal cells adjacent to hepatic parenchymal cells secret soluble factors as well as extracellular matrix (ECM) molecules that regulate hepatic parenchymal cells to grow and/or to differentiate in order to form a functional liver. Human hepatic stellate cells (hHpSTCs) with classic stellate cell markers (vitamin A+, desmin+ and [alpha]-smooth muscle actin+) and liver sinusoidal endothelial cells (VEGFr+, von Willebrand factor+ and CD31+) are two major mesenchymal cell types in the liver. They were found present in primary cultures of human hepatic stem cells (hHpSCs) derived from fetal livers and were found to be critical as "companion cells" for survival and expansion of the hHpSCs. Many of the markers are shared by hHpSCs and the other pluripotent hepatic progenitors in human livers, hepatoblasts (hHBs) including expression of albumin, epithelial cell adhesion molecule (EpCAM), cytokeratins 8, 18 and 19, hedgehog proteins, and telomerase but not hematopoietic markers (CD45, CD34, CD38) or mesenchymal markers (those of endothelia or HpSTCs). However, they can be distinquished in that hHpSCs express neuronal cell adhesion molecule (NCAM) and claudin 3 but are negative for intercellular adhesion molecule-1 (ICAM-1) and [alpha]-fetoprotein (AFP), whereas hHBs express intercellular cell adhesion molecule (ICAM-1), AFP, higher levels of albumin but not claudin 3 or NCAM. The hHpSCs behave differently depending on type of feeder cells are used. Feeders of angioblasts or endothelia resulted in maintenance of hHpSCs as stem cells; feeders replete with HpSTCs resulted in lineage restriction of hHpSCs to hepatoblasts; and STO feeders caused even more differentiation to both hepatoblasts and committed progenitors. Representative feeders of angioblasts/endothelia versus HpSTCs were characterized for expression of matrix genes and proteins; those matrix components identified were then tested as substrata for effects on the hHpSCs. The hHpSCs remained as stem cells on substrata of type III collagen or culture plastic; they differentiated into hepatoblasts on substrata of laminin or on top of collagen type IV; they differentiated into hepatoblasts and committed progenitors on the surface of type I collagen and into hepatocytes when embedded into type I collagen gel. STO feeder cells secret inflammatory cytokines and factors, many of them identified in other studies as being produced following liver injury. A number of the factors were induced to be secreted to higher levels by co-culture of STO cells with human hepatic progenitors. These included several members of the interleukin family (e.g. IL-4, IL-5, IL-6, IL-10, IL-11 and IL-13), eotaxin, transforming growth factor-[beta]1 (TGF-[beta]1), interferon-[gamma] (IFN-[gamma]), macrophage inflammatory protein-2 (MIP-2), and others. Some of these factors have been found in preliminary studies to have potent effects on human and rodent hepatic progenitors but have not yet been fully characterized. They are assumed to play complementary roles to those of the matrix components in regulating hHpSCs. Analyses of these role(s) will be part of future studies

Paracrine signals from mesenchymal cell populations govern the expansion and differentiation of human hepatic stem cells to adult liver fates

Differentiation of embryonic or determined stem cell populations to adult liver fates under known conditions yields cells with some but not other adult-specific genes, aberrant regulation of one or more genes, and variation in the results from experiment to experiment. We tested the hypothesis that sets of signals produced by freshly isolated, lineage-dependent mesenchymal cell populations would yield greater efficiency and reproducibility in driving differentiation of human hepatic stem cells (hHpSCs) to adult liver fates. Subpopulations of liver-derived mesenchymal cells, purified by immunoselection technologies, included 1) angioblasts; 2) mature endothelia; 3) hepatic stellate cell precursors; 4) mature stellate cells (pericytes) and 5) myofibroblasts. Freshly immunoselected cells of each of these subpopulations were established in primary cultures under wholly defined (serum-free) conditions that we developed for short-term cultures and used them as feeders with hHpSCs. Feeders of angioblasts yielded self-replication; stellate cell precursors caused lineage restriction to hepatoblasts; mature endothelia produced differentiation to hepatocytes; and mature stellate cells and/or myofibroblasts resulted in differentiation to cholangiocytes. Paracrine signals, produced by the different feeders, were identified by biochemical, immunohistochemical, and qRT-PCR analyses and then those signals were used to replace the feeders in monolayer and 3-D cultures to elicit the desired biological responses from the hHpSCs. The defined paracrine signals proved able to yield reproducible responses from the hHpSCs and to permit differentiation to fully mature and functional parenchymal cells

Human hepatic stem cells from fetal and postnatal donors

Human hepatic stem cells (hHpSCs), which are pluripotent precursors of hepatoblasts and thence of hepatocytic and biliary epithelia, are located in ductal plates in fetal livers and in Canals of Hering in adult livers. They can be isolated by immunoselection for epithelial cell adhesion molecule–positive (EpCAM+) cells, and they constitute ∼0.5–2.5% of liver parenchyma of all donor ages. The self-renewal capacity of hHpSCs is indicated by phenotypic stability after expansion for >150 population doublings in a serum-free, defined medium and with a doubling time of ∼36 h. Survival and proliferation of hHpSCs require paracrine signaling by hepatic stellate cells and/or angioblasts that coisolate with them. The hHpSCs are ∼9 μm in diameter, express cytokeratins 8, 18, and 19, CD133/1, telomerase, CD44H, claudin 3, and albumin (weakly). They are negative for α-fetoprotein (AFP), intercellular adhesion molecule (ICAM) 1, and for markers of adult liver cells (cytochrome P450s), hemopoietic cells (CD45), and mesenchymal cells (vascular endothelial growth factor receptor and desmin). If transferred to STO feeders, hHpSCs give rise to hepatoblasts, which are recognizable by cordlike colony morphology and up-regulation of AFP, P4503A7, and ICAM1. Transplantation of freshly isolated EpCAM+ cells or of hHpSCs expanded in culture into NOD/SCID mice results in mature liver tissue expressing human-specific proteins. The hHpSCs are candidates for liver cell therapies

The Use of Nanoscale Visible Light-Responsive Photocatalyst TiO2-Pt for the Elimination of Soil-Borne Pathogens

Exposure to the soil-borne pathogens Burkholderia pseudomallei and Burkholderia cenocepacia can lead to severe infections and even mortality. These pathogens exhibit a high resistance to antibiotic treatments. In addition, no licensed vaccine is currently available. A nanoscale platinum-containing titania photocatalyst (TiO2-Pt) has been shown to have a superior visible light-responsive photocatalytic ability to degrade chemical contaminants like nitrogen oxides. The antibacterial activity of the catalyst and its potential use in soil pathogen control were evaluated. Using the plating method, we found that TiO2-Pt exerts superior antibacterial performance against Escherichia coli compared to other commercially available and laboratory prepared ultraviolet/visible light-responsive titania photocatalysts. TiO2-Pt-mediated photocatalysis also affectively eliminates the soil-borne bacteria B. pseudomallei and B. cenocepacia. An air pouch infection mouse model further revealed that TiO2-Pt-mediated photocatalysis could reduce the pathogenicity of both strains of bacteria. Unexpectedly, water containing up to 10% w/v dissolved soil particles did not reduce the antibacterial potency of TiO2-Pt, suggesting that the TiO2-Pt photocatalyst is suitable for use in soil-contaminated environments. The TiO2-Pt photocatalyst exerted superior antibacterial activity against a broad spectrum of human pathogens, including B. pseudomallei and B. cenocepacia. Soil particles (<10% w/v) did not significantly reduce the antibacterial activity of TiO2-Pt in water. These findings suggest that the TiO2-Pt photocatalyst may have potential applications in the development of bactericides for soil-borne pathogens

Differential cross section measurements for the production of a W boson in association with jets in proton–proton collisions at √s = 7 TeV

Measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, including the transverse momenta (pT) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HT), and the difference in azimuthal angle between the directions of each jet and the muon. The data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 fb[superscript −1]. The measured cross sections are compared to predictions from Monte Carlo generators, MadGraph + pythia and sherpa, and to next-to-leading-order calculations from BlackHat + sherpa. The differential cross sections are found to be in agreement with the predictions, apart from the pT distributions of the leading jets at high pT values, the distributions of the HT at high-HT and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio

Juxtaposing BTE and ATE – on the role of the European insurance industry in funding civil litigation

One of the ways in which legal services are financed, and indeed shaped, is through private insurance arrangement. Two contrasting types of legal expenses insurance contracts (LEI) seem to dominate in Europe: before the event (BTE) and after the event (ATE) legal expenses insurance. Notwithstanding institutional differences between different legal systems, BTE and ATE insurance arrangements may be instrumental if government policy is geared towards strengthening a market-oriented system of financing access to justice for individuals and business. At the same time, emphasizing the role of a private industry as a keeper of the gates to justice raises issues of accountability and transparency, not readily reconcilable with demands of competition. Moreover, multiple actors (clients, lawyers, courts, insurers) are involved, causing behavioural dynamics which are not easily predicted or influenced. Against this background, this paper looks into BTE and ATE arrangements by analysing the particularities of BTE and ATE arrangements currently available in some European jurisdictions and by painting a picture of their respective markets and legal contexts. This allows for some reflection on the performance of BTE and ATE providers as both financiers and keepers. Two issues emerge from the analysis that are worthy of some further reflection. Firstly, there is the problematic long-term sustainability of some ATE products. Secondly, the challenges faced by policymakers that would like to nudge consumers into voluntarily taking out BTE LEI

Penilaian Kinerja Keuangan Koperasi di Kabupaten Pelalawan

This paper describe development and financial performance of cooperative in District Pelalawan among 2007 - 2008. Studies on primary and secondary cooperative in 12 sub-districts. Method in this stady use performance measuring of productivity, efficiency, growth, liquidity, and solvability of cooperative. Productivity of cooperative in Pelalawan was highly but efficiency still low. Profit and income were highly, even liquidity of cooperative very high, and solvability was good

Search for stop and higgsino production using diphoton Higgs boson decays

Results are presented of a search for a "natural" supersymmetry scenario with gauge mediated symmetry breaking. It is assumed that only the supersymmetric partners of the top-quark (stop) and the Higgs boson (higgsino) are accessible. Events are examined in which there are two photons forming a Higgs boson candidate, and at least two b-quark jets. In 19.7 inverse femtobarns of proton-proton collision data at sqrt(s) = 8 TeV, recorded in the CMS experiment, no evidence of a signal is found and lower limits at the 95% confidence level are set, excluding the stop mass below 360 to 410 GeV, depending on the higgsino mass

Severe early onset preeclampsia: short and long term clinical, psychosocial and biochemical aspects

Preeclampsia is a pregnancy specific disorder commonly defined as de novo hypertension and proteinuria after 20 weeks gestational age. It occurs in approximately 3-5% of pregnancies and it is still a major cause of both foetal and maternal morbidity and mortality worldwide1. As extensive research has not yet elucidated the aetiology of preeclampsia, there are no rational preventive or therapeutic interventions available. The only rational treatment is delivery, which benefits the mother but is not in the interest of the foetus, if remote from term. Early onset preeclampsia (<32 weeks’ gestational age) occurs in less than 1% of pregnancies. It is, however often associated with maternal morbidity as the risk of progression to severe maternal disease is inversely related with gestational age at onset2. Resulting prematurity is therefore the main cause of neonatal mortality and morbidity in patients with severe preeclampsia3. Although the discussion is ongoing, perinatal survival is suggested to be increased in patients with preterm preeclampsia by expectant, non-interventional management. This temporising treatment option to lengthen pregnancy includes the use of antihypertensive medication to control hypertension, magnesium sulphate to prevent eclampsia and corticosteroids to enhance foetal lung maturity4. With optimal maternal haemodynamic status and reassuring foetal condition this results on average in an extension of 2 weeks. Prolongation of these pregnancies is a great challenge for clinicians to balance between potential maternal risks on one the eve hand and possible foetal benefits on the other. Clinical controversies regarding prolongation of preterm preeclamptic pregnancies still exist – also taking into account that preeclampsia is the leading cause of maternal mortality in the Netherlands5 - a debate which is even more pronounced in very preterm pregnancies with questionable foetal viability6-9. Do maternal risks of prolongation of these very early pregnancies outweigh the chances of neonatal survival? Counselling of women with very early onset preeclampsia not only comprises of knowledge of the outcome of those particular pregnancies, but also knowledge of outcomes of future pregnancies of these women is of major clinical importance. This thesis opens with a review of the literature on identifiable risk factors of preeclampsia