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A large membrane proteinase 3 (mPR3)-positive neutrophil subset (mPR3high) is a risk for Wegener's granulomatosis (WG). The relationship between mPR3 expression and clinical manifestations was investigated in 81 WG patients and mPR3 expression was studied in CD34+ stem cell-derived human neutrophils. The mPR3high neutrophil percentage correlated with renal function, anemia, and albumin at the time of presentation. The mPR3high neutrophil percentage and renal failure severity correlated directly after 5 yr. For elucidating mechanisms that govern mPR3 expression, studies were conducted to determine whether the genetic information that governs mPR3 expression resides within the neutrophils, even without stimuli possibly related to disease. CD34+ hematopoietic stem cells were differentiated to neutrophils, and their mPR3 expression was determined. A two-step amplification/differentiation protocol was used to differentiate human CD34+ hematopoietic stem cells into neutrophils with G-CSF. The cells progressively expressed the neutrophil surface markers CD66b, CD35, and CD11b. The ferricytochrome C assay demonstrated a strong respiratory burst at day 14 in response to PMA but none at day 0. Intracellular PR3 was detectable from day 4 by Western blotting. An increasing percentage of a mPR3-positive neutrophil subset became detectable by flow cytometry, whereas a second subset remained negative, consistent with a bimodal expression. Finally, human PR3-anti-neutrophil cytoplasmic autoantibodies induced a stronger respiratory burst, compared with human control IgG in stem cell-derived neutrophils. Taken together, these studies underscore the clinical importance of the WG mPR3 phenotype. The surface mPR3 on resting cells is probably genetically determined rather than being dictated by external factors.

Evidence is presented that bone marrow (BM) in addition to CD45(positive) hematopoietic stem cells contains a rare population of heterogenous CD45(negative) nonhematopoietic tissue committed stem cells (TCSC). These nonhematopoietic TCSC (i) are enriched in population of CXCR4(+) CD34(+) AC133(+) lin(-) CD45(-) and CXCR4(+) Sca-1(+) lin(-) CD45(-) in humans and mice, respectively, (ii) display several markers of pluripotent stem cells (PSC) and (iii) as we envision are deposited in BM early in development. Thus, since BM contains versatile nonhematopoietic stem cells, previous studies on plasticity trans-dedifferentiation of BM-derived hematopoietic stem cells (HSC) that did not include proper controls to exclude this possibility could lead to wrong interpretations. Therefore, in this spotlight review we present this alternative explanation of 'plasticity' of BM-derived stem cells based on the assumption that BM stem cells are heterogenous. We also discuss a potential relationship of TCSC/PSC identified by us with other BM-derived CD45(negative) nonhematopoietic stem cells that were recently identified by other investigators (eg MSC, MAPC, USSC and MIAMI cells). Finally, we discuss perspectives and pitfalls in potential application of these cells in regenerative medicine.

We studied the immunoregulatory features of murine mesenchymal stem cells (MSCs) in vitro and in vivo. MSCs inhibited T-cell receptor (TCR)-dependent and -independent proliferation but did not induce apoptosis on T cells. Such inhibition was paired with a decreased interferon (IFN)-gamma and tumor necrosis factor (TNF)-alpha production and was partially reversed by interleukin-2 (IL-2). Thus, we used MSCs to treat myelin oligodendrocyte glycoprotein (MOG)35-55-induced experimental autoimmune encephalomyelitis (EAE) in C57BL/6J mice. We injected intravenously 1 x 10(6) MSCs before disease onset (preventive protocol) and at different time points after disease occurrence (therapeutic protocol). MSC administration before disease onset strikingly ameliorated EAE. The therapeutic scheme was effective when MSCs were administered at disease onset and at the peak of disease but not after disease stabilization. Central nervous system (CNS) pathology showed decreased inflammatory infiltrates and demyelination in mice that received transplants of MSCs. T-cell response to MOG and mitogens from MSC-treated mice was inhibited and restored by IL-2 administration. Upon MSC transfection with the enhanced green fluorescent protein (eGFP), eGFP(+) cells were detected in the lymphoid organs of treated mice. These data suggest that the immunoregulatory properties of MSCs effectively interfere with the autoimmune attack in the course of EAE inducing an in vivo state of T-cell unresponsiveness occurring within secondary lymphoid organs.

Hereditary hemochromatosis (HH), an iron overload disease associated with mutations in the HFE gene, is characterized by increased intestinal iron absorption and consequent deposition of excess iron, primarily in the liver. Patients with HH and Hfe-deficient (Hfe-/-) mice manifest inappropriate expression of the iron absorption regulator hepcidin, a peptide hormone produced by the liver in response to iron loading. In this study, we investigated the contribution of Hfe expression in macrophages to the regulation of liver hepcidin levels and iron loading. We used bone marrow transplantation to generate wild-type (wt) and Hfe-/- mice chimeric for macrophage Hfe gene expression. Reconstitution of Hfe-deficient mice with wt bone marrow resulted in augmented capacity of the spleen to store iron and in significantly decreased liver iron loading, accompanied by a significant increase of hepatic hepcidin mRNA levels. Conversely, wt mice reconstituted with Hfe-deficient bone marrow had a diminished capacity to store iron in the spleen but no significant alterations of liver iron stores or hepcidin mRNA levels. Our results suggest that macrophage Hfe participates in the regulation of splenic and liver iron concentrations and liver hepcidin expression.

Aldehyde dehydrogenase (ALDH) is a cytosolic enzyme that is responsible for the oxidation of intracellular aldehydes. Elevated levels of ALDH have been demonstrated in murine and human progenitor cells compared with other hematopoietic cells, and this is thought to be important in chemoresistance. A method for the assessment of ALDH activity in viable cells recently has been developed and made commercially available in a kit format. In this study, we confirmed the use of the ALDH substrate kit to identify cord blood stem/progenitor cells. Via multicolor flow cytometry of cord blood ALDH+ cells, we have expanded on their phenotypic analysis. We then assessed the incidence, morphology, phenotype, and nonobese diabetic/ severe combined immunodeficiency engraftment ability of ALDH+ cells from acute myeloid leukemia (AML) samples. AML samples had no ALDH+ cells at all, an extremely rare nonmalignant stem/progenitor cell population, or a less rare, leukemic stem cell population. Hence, in addition to identifying nonmalignant stem cells within some AML samples, a high ALDH activity also identifies some patients' CD34+/ CD38- leukemic stem cells. The incidence of normal or leukemic stem cells with an extremely high ALDH activity may have important implications for resistance to chemotherapy. Identification and isolation of leukemic cells on the basis of ALDH activity provides a tool for their isolation and further analysis.

Oligonucleotides with a CpG" motif trigger a proinflammatory response through activation of Toll-like receptor 9 (TLR9) and are being studied to exploit these properties for use as adjuvants and cancer therapies. However�

Murine embryonic stem cells can differentiate in vitro to form cystic embryoid bodies (CEB) that contain different structures and cell types. The blood islands are one such structure that consist of immature hematopoietic cells surrounded by endothelial cells, the first identifiable vascular cells. CEBs differentiated in vitro developed blood islands initially, and subsequently these blood islands matured to form vascular channels containing hematopoietic cells. Phase contrast microscopy demonstrated the presence of channels in mature CEBs grown in suspension culture, and high resolution light and electron microscopy showed that the cells lining these channels were endothelial cells. The channels appeared less organized than the vasculature of the mature yolk sac. The hematopoietic cells were occasionally seen 'flowing' through the CEB channels, although their numbers were reduced relative to the yolk sac. Analysis of primary CEB cultures showed the presence of cells with two characteristics of endothelial cells: approximately 30% of the cells labelled with fluorescent acetylated low density lipoprotein and a small number of cells were positive for von Willebrand's factor by immunostaining. Thus we conclude that a primitive vasculature forms in CEBs differentiated in vitro, and that not only primary differentiation of endothelial cells but also some aspects of vascular maturation are intrinsic to this cell culture system. CEBs are therefore a useful model for the study of developmental blood vessel formation.

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.

Imatinib, a Bcr-Abl tyrosine kinase inhibitor, is a highly effective therapy for patients with chronic myelogenous leukemia (CML). Despite durable responses in most chronic phase patients, relapses have been observed and are much more prevalent in patients with advanced disease. The most common mechanism of acquired imatinib resistance has been traced to Bcr-Abl kinase domain mutations with decreased imatinib sensitivity. Thus, alternate Bcr-Abl kinase inhibitors that have activity against imatinib-resistant mutants would be useful for patients who relapse on imatinib therapy. Two such Bcr-Abl inhibitors are currently being evaluated in clinical trials: the improved potency, selective Abl inhibitor AMN107 and the highly potent dual Src/Abl inhibitor BMS-354825. In the current article, we compared imatinib, AMN107, and BMS-354825 in cellular and biochemical assays against a panel of 16 kinase domain mutants representing textgreater90% of clinical isolates. We report that AMN107 and BMS-354825 are 20-fold and 325-fold more potent than imatinib against cells expressing wild-type Bcr-Abl and that similar improvements are maintained for all imatinib-resistant mutants tested, with the exception of T315I. Thus, both inhibitors hold promise for treating imatinib-refractory CML.

Kaposi's sarcoma (KS) is a common neoplasm in HIV-1-infected individuals causing significant morbidity and mortality. Despite recent advances, the pathogenesis of this potentially life-threatening neoplasm remains unclear, and there is currently no cure for KS. Notch proteins are known to play a fundamental role in cell fate decisions including proliferation, differentiation, and apoptosis. It is, therefore, not surprising that Notch proteins have been implicated in tumorigenesis and appear to function as either oncogenes or tumor suppressor proteins depending on cellular context. In this report, we demonstrate elevated levels of activated Notch-1, -2, and -4 in KS tumor cells in vivo and in vitro compared to endothelial cells, the precursor of the KS cell. Notch activation was confirmed through luciferase reporter assays and localization of Hes (Hairy/Enhancer of Split)-1 and Hey (Hairy/Enhancer of Split related with YRPW)1 (primary targets of the Notch pathway) in KS cell nuclei. Studies using gamma-secretase inhibitors (GSI and LY-411,575), which block Notch activation, resulted in apoptosis in primary and immortalized KS cells. Similar studies injecting GSI into established KS cell tumors on mice demonstrated growth inhibition or tumor regression that was characterized by apoptosis in treated, but not control tumors. The results indicate that KS cells overexpress activated Notch and interruption of Notch signaling inhibits KS cell growth. Thus, targeting Notch signaling may be of therapeutic value in KS patients.

BACKGROUND AND AIM An oral trypsin inhibitor, camostat (CM), has a beneficial effect on chronic pancreatitis, but its mechanism is not yet fully understood. Recently, pancreatic stellate cells (PSC) have been reported to play an essential role in pancreatic fibrosis. An experimental model of pancreatic fibrosis induced by a superoxide dismutase (SOD) inhibitor (diethyldithiocarbamate [DDC]) was developed in rats. Thus, the effect of an oral trypsin inhibitor on pancreatic fibrosis and PSC was investigated. METHODS Pancreatic fibrosis was induced in rats using DDC (DDC rats). DDC + CM rats were administered DDC, and subsequently were fed a diet containing CM. Immunohistochemistry of the pancreas was performed with monoclonal anti-alpha-smooth muscle actin (alpha-SMA) antibody and anti-desmin antibody. RESULTS The DDC rats showed a significant increase in alpha-SMA-positive cells or desmin-positive cells compared with control rats. These significant increases in the fibrotic area improved after treatment with CM. The level of prolyl hydroxylase in the pancreas, which significantly increased as a result of DDC, decreased after treatment with CM. CONCLUSION Camostat has a beneficial effect on pancreatic fibrosis induced by the administration of a SOD inhibitor, which inhibits the proliferation and activation of PSC.

The self-renewing epithelium of the small intestine is ordered into stem/progenitor crypt compartments and differentiated villus compartments. Recent evidence indicates that the Wnt cascade is the dominant force in controlling cell fate along the crypt-villus axis. Here we show a rapid, massive conversion of proliferative crypt cells into post-mitotic goblet cells after conditional removal of the common Notch pathway transcription factor CSL/RBP-J. We obtained a similar phenotype by blocking the Notch cascade with a gamma-secretase inhibitor. The inhibitor also induced goblet cell differentiation in adenomas in mice carrying a mutation of the Apc tumour suppressor gene. Thus, maintenance of undifferentiated, proliferative cells in crypts and adenomas requires the concerted activation of the Notch and Wnt cascades. Our data indicate that gamma-secretase inhibitors, developed for Alzheimer's disease, might be of therapeutic benefit in colorectal neoplastic disease.