bluuebunny/crossref_metadata_2025_split huggingface dataset:
Matrix Glycoprotein Osteopontin Is a Stem Cell Niche Constituent That Constrains the Hematopoietic Stem Cell Pool Size.
Authors: Stier Sebastian , Ko Yon , Forkert Randolf , Lutz Christoph , Neuhaus Thomas , Gruenewald Elisabeth , Dombkowski David , Rittling Susan R. , Scadden David T. 
Published: October 2019

Abstract
Stem cells reside in a physical niche where a balance of signals controls their growth, differentiation and death. Niche components have generally been defined in terms of cells and positive effects on stem cell maintenance or expansion. Here we define a role for a matrix glycoprotein that provides a constraining function in the hematopoietic stem cell niche. Osteopontin (OPN) is an abundant glycoprotein in bone that can function as either cytokine or cell adhesion mediator. It is known to be produced by multiple cells types including osteoblasts, cells recently defined to be a regulatory component of the hematopoietic stem cell niche. Using studies combining OPN deficient mice and exogenous OPN, we demonstrate that OPN modifies primitive hematopoietic cell numbers and function. In OPN deficient mice, increased primitive cell numbers were observed in vivo associated with reduced progenitors and reduced primitive cell apoptotic fraction. To determine whether the effect of OPN deficiency was stroma dependent, we performed in vitro stem cell assays on OPN−/− stroma and observed greater LTC-IC supportive capacity compared with wild type stroma. Furthermore, OPN−/− recipients showed a significantly higher proportion of hematopoietic stem cells after transplantation of OPN+/+ bone marrow in comparison to wild-type recipients, indicating that the OPN null microenvironment was sufficient to increase stem cell number. A reduction in apoptotic fraction was seen in primitive cells in the OPN−/− recipient marrows. A role for OPN in apoptosis was confirmed by exogenous OPN in in-vitro studies. Hypothesizing that OPN may serve as a physiologic constraint on stem cell pool size, we compared OPN−/− with wild type animals following parathyroid hormone activation of the stem cell niche. The expansion of stem cells by PTH was superphysiologic in the absence of OPN. Therefore, OPN is a restricting element of the stem cell niche, limiting the number of stem cells produced by niche activation. Extracellular matrix components such as OPN may serve as modulable, regulatory participants in the stem cell niche.
Defining the Bone Marrow Stem Cell Niche According to a Hoechst Dye Diffusion Gradient and Hypoxia.
Authors: Down Julian D. , Parmar Kalindi , Clyne James , Mauch Peter M. , Sackstein Robert 
Published: October 2019

Abstract
The spatial organization of hematopoietic cell subsets of differing proliferative potential within the bone marrow microenvironment has come under increasing interest. In particular, it has been suggested that hematopoietic stem cells (HSCs) normally reside in a regulatory niche situated at the endosteal bone surface and in close proximity to osteoblasts. In the present study we have investigated how different hematopoietic cell subsets are distributed along a Hoechst dye perfusion gradient that may reflect the distance from marrow blood vessels and the level of oxygenation. C57BL/6J mice were intravenously injected with two doses of Hoechst 33342 at 10 and 5 min before marrow cell harvesting, a period that we determined was insufficient for active dye exclusion in vitro. Flow cytometric analysis revealed a wide distribution of Hoechst staining over 3 logs fluorescence intensity. The cells were then sorted from 6 different regions of the Hoechst gradient and evaluated for short- and long-term in vitro repopulating cells in the cobblestone area-forming cell (CAFC) assay. The primitive CAFC subset appearing at day 28 in culture was shown to be progressively enriched with decreasing Hoechst fluorescence while the short-term repopulating day 7 CAFC subset frequencies was the highest at an intermediate level of Hoechst staining. We further investigated whether primitive HSCs exist in a very low oxygen tension by administering the reductive 2-nitroimidazole compound pimonidazole in vivo and performed flow cytometric analysis on sorted primitive HSCs residing in high Hoechst dye effluxing side population (SP). In comparison to whole bone marrow or non-SP cells, the SP fraction showed increased intracellular staining with an anti-pimonidazole antibody that recognizes pimonidazole adducts formed only under hypoxic conditions (less than pO2 of 10 mm Hg). Comparison with thymocytes that are already known to be hypoxic in vivo (Hale et al. Am J Physiol Heart Circ Physiol282: H1467–H1477, 2002) showed both low Hoechst dye perfusion and positive anti-pimonidazole antibody staining. These results represent the first direct evidence that the hematopoietic cell hierarchy is spatially organized in relation to blood vessels and that the stem cell niche exists at the lowest end of an oxygen gradient. These findings have important implications in hematopoiesis and stem cell lodgement, and suggest that the location of hematopoietic stem cells in situ may render them more resistant to oxygen-dependent mutagenic and cytotoxic agents.
Mesenchymal Stem Cells (MSC) Display Coordinated Rolling and Adhesion Behaviour on Endothelial Cells under Shear Flow.
Authors: Ruster Brigitte , Bistrian Roxana , Gottig Stephan , Seifried Erhard , Henschler Reinhard 
Published: October 2019

Abstract
Although MSC have been applied in a number of transplantation protocols, the mechanisms which are responsible for their extravasation and tissue specific homing are less well understood. To elucidate the potential of MSC to undergo coordinated interaction with endothelial cells, we investigated MSC under controlled shear flow using a parallel plate flow chamber. MSC were isolated from bone marrow of 6 different donors, depleted of hematopoietic cells by plastic adherence to yield >99% CD45− populations and further expanded up to 106 fold in DMEM/FCS/bFGF over 35 days. Their osteogenic, chondrogenic and adipogenic differentiation potential was maintained during the expansion period. Flow cytometric analysis showed that MSC expressed integrins alpha 1, alpha 4, alpha 5 and beta 1, the chemokine receptor CCR6 and, in a small subpopulation also CXCR4, but that they did not express beta 2 integrin, L-selectin or PSGL-1. During continuous laminar flow on early passage HUVEC at wall shear stresses between 0.1 and 1 dyn/cm2, MSC extended cytoplasmic podia towards endothelium, resulting in capturing and subsequent rolling. This resulted in firm adherence of MSC which resisted shear stresses of 2 dyn/cm2 for >20min. This was, in a similar way, also observed with peripheral blood mononuclear cells or CD34+ primary hematopoietic progenitor cells, whereas erythrocytes and primary endothelial cells did not interact with the HUVEC monolayer. Shear stresses of 2 dyn/cm² and more resulted in a decrease of MSC rolling. Prestimulation of endothelial cells with TNF-alpha increased both MSC rolling (3.7-fold ± 0.6 fold) and firm adhesion (3.3 ± 0.3 fold; means ± SD, n=5; p<0.05). Preincubation of endothelial cells with function-blocking anti-P selectin antibodies reduced the number of rolling MSC by 37.7% ± 5.9% and of firmly adhering MSC by 54.6% ± 11.3% (means ± SD; n=4; p<0.05). Although preincubation with function-blocking antibodies against PSGL-1 did not detectably affect MSC rolling and adhesion, preincubation with O-sialoglycoprotease and with fucosidase but not with neuaminidase significantly reduced MSC rolling and adhesion, indicating that a selectin-type ligand is responsible for the binding. Preincubation of MSC with function-blocking anti-beta 1 integrin antibody also led to a statistically significant reduction of MSC firm adhesion by 21.3% ± 5.7%. Taken together, our results demonstrate that MSC can undergo coordinated rolling and adhesion on endothelium under shear flow involving (i) stimulation in a pro-inflammatory environment, (ii) engagement of P-selectin and a fucosylated ligand on MSC inducing capturing and rolling, and (iii) activation of beta 1 integrins mediating firm adhesion to endothelial cells
Conditional Expression of C/EBPα in Mice Reveals Developmental Plasticity of Lymphoid and Erythroid/ Megakaryocyte Precursors in Vivo.
Authors: Fukuchi Yumi , Shibata Fumi , Ito Miyuki , Goto-Koshino Yuko , Sotomaru Yusuke , Ito Mamoru , Kitamura Toshio , Nakajima Hideaki 
Published: October 2019

Abstract
CCAAT/ enhancer binding protein α (C/EBP α) is a member of the bZIP family of transcription factors that plays a critical role for early myeloid differentiation. C/EBP α knockout mice showed a complete differentiation block at myeloblast stage in hematopoietic system, and mature neutrophils and eosinophils are absent in the peripheral blood. Lineage specification in developmental tree of hematopoiesis is generally determined by a lineage specific transcription factors such as C/EBP α and GATA-1 that allow commitment to the specific lineage with simultaneous extinction of their capacity to differentiate into the other ones. However, recent evidences shown by the ectopic expression of above transcription factors unveiled the unexpected developmental plasticity of various progenitors such as MEP (erythroid/ megakaryocyte progenitor) and CLP (common lymphoid progenitor). GATA-1 is reported to convert CLP and CMP (common myeloid progenitor) into erythroid/ megakaryocyte lineage, however, the effect of C/EBP α on MEP and CLP is still unlcear. In order to investigate the role of C/EBP α in the various aspect of hematopoietic differentiation, especially its effect on the lineage specification at different stages of differentiation in vivo, we generated transgenic mice expressing inducible form of C/EBP α (C/EBP α-ER) under H-2K promoter (C/EBP α-ER Tg). In these mice, C/EBP α activity can be induced conditionally by 4-hydroxy tamoxifen (4-HT) in all hematopoietic cells. As expected, C/EBP α-ER was expressed in almost all hematopoietic tissues including bone marrow, spleen and thymus in these mice. Gel shift analysis revealed that C/EBP α-ER was activated by 4-HT, and showed specific binding to C/EBP-specific oligonucleotide in these tissues. Next we tested differentiation plasticity of erythroid and lymphoid progenitors by ectopically inducing C/EBP α-ER activity in these cells. We sorted MEP and CLP by FACS from C/EBP α-ER Tg and examined their clonogenic activities in the presence or absence of 4-HT. In the absence of 4-HT, MEP and CLP exclusively formed erythroid/ megakaryocyte and lymphoid colonies, respectively, as previously reported. Surprisingly however, these cells dramatically changed their fate of differentiation and formed significant numbers of granulocyte/ macrophage (GM) colonies in the presence of 4-HT, indicating that ectopic activation of C/EBP α-ER activity skewed their differentiation pathways to myeloid lineage. Cytospin preparation of the colonies and RT-PCR analysis revealed that these were accompanied by the morphological differentiation to granulocytes/ macrophages, and upregulation of myeloid-specific genes at mRNA level. These results indicate that MEP and CLP are not fully committed to either erythroid/ megakaryocyte or lymphoid lineage, and possess differentiation plasticity that can be redirected to myeloid lineage.
High-Risk Myelodysplastic Syndrome (MDS): First Results of International Phase 2 Study with Oral Farnesyltransferase Inhibitor R115777 (ZARNESTRATM).
Authors: Kurzrock Razelle , Fenaux Pierre , Raza Azra , Mufti Ghulam , Aul Carlo , Germing Ulrich , Kerstens Rene , DePorre Peter 
Published: October 2019

Abstract
R115777 is an oral selective inhibitor of farnesyltransferase which disrupts critical signaling pathways resulting in antiangiogenic, antiproliferative and apoptotic effects. Single-agent activity of R115777 in patients (pt) with MDS, with manageable toxicity, was previously reported in single-institution studies. The current multicenter study assesses the response rate (IWG-criteria) and survival of R115777 in pt with high-risk MDS, defined by FAB classification as RAEBt and RAEB or CMML with ≥10% bone marrow (BM) blasts. Starting dose of R115777 was 300 mg bid for the first 21 days of every 28-day cycle. Eighty-two pt were enrolled (median age 67 yrs; range 39–86) with RAEBt (n=23), RAEB (n=40) and CMML (n=19). Thirty-six pt (44%) had IPSS score high, 32 (39%) int-2 and 14 (17%) int-1. Fifty-two pt were therapy-naïve, while 30 (37%) had received prior therapy for MDS. Pt were treated for a median of 3 cycles (range: 6 to 553+ days), with 78% relative dose intensity. Pt discontinued treatment primarily for progressive disease (n=37) or for adverse event (n=20), with 6 pt still on therapy. Responses were seen in 28 pt (33%; 6 CR, 2 CR with incomplete platelet recovery, 2 PR, 18 hematological improvement-HI), both in therapy-naïve and pre-treated pt. Responses were durable, with median duration of 14+ months (mo) for CR-PR (11+ to 20+ mo) and 6.7 mo for HI (3–15 mo). In 68 pt with at least 1 on-study BM assessment, BM response (either normalization or ≥50% decrease in BM blast count) was observed in 35 pt (51%). Median time to leukemic transformation (mTTL) was 14.1 mo, median time to leukemia or death (mTTLorD) was 6.4 mo and median overall survival (mOS) was 11.9 mo. Results (in mo) by risk-group are tabulated.
by FAB class by IPSS score RAEBt RAEB CMML high int-2 int-1 n = 23 40 19 36 32 14 mOS 9.2 12.2 15.0 10.4 15.0 15.1 mTTLorD 3.3 7.4 10.8 3.7 7.4 11.9 mTTL 3.7 median was not reached 7.6 median was not reached
Myelosuppression was the most common side effect, with 24% grade (G) 3–4 neutro-penia and 37% G3–4 thrombocytopenia. Non-hematological toxicity was mostly G1–2, rarely G3–4. Most frequently reported were nausea (35%; 4% G3), fatigue (35%; 2% G3), diarrhea (34%; 1% G3), fever (23%, 10% G3), dyspnea (20%; 2% G3–4), purpura (20%; 4% G3) and rash (19%; 2% G3). Conclusion: In a large cohort of pt with high-risk MDS as defined by FAB and IPSS, clinical activity with durable responses and limited toxicity is confirmed for R115777. Further study is warranted.
Expression of Urokinase-Type Plasminogen Activator in Platelets Decreases Oxygen-Induced Lung Injury in Mice.
Authors: Perkowski Sandra Z. , Kowalska M. Anna , Albelda Steven M. , Bdeir Khalil , Cines Douglas B. , Poncz Mortimer 
Published: October 2019

Abstract
We have previously shown that urokinase (uPA) can be ectopically expressed and stored in platelets in a transgenic mouse model and that such platelets can effectively prevent untoward thrombosis. One major advantage of this uPA delivery system is that there is no systemic fibrinolysis and the uPA is selectively released at sites of vascular injury. We have now tested whether such a delivery model may be of use in the care of patients with lung injury where inhibition of fibrinolytic activity and intra-alveolar fibrin deposition are of pathogenic importance. In this study, we evaluated (O2)-induced lung injury in transgenic mice expressing platelet uPA compared to wildtype (WT) littermate controls. Given that pulmonary sequestration of activated inflammatory cells, including neutrophils (PMN) and platelets, occurs relatively early in response to O2, and given the ability of the transgenic uPA platelets to enhance fibrin lysis, we hypothesized that hyperoxic-induced lung injury would be lessened in the transgenic animals. Lung injury was assessed by changes in bronchoalveolar lavage fluid (BAL) protein concentration. In this model, a significant increase in BAL protein concentration, indicative of injury to the alveolar capillary barrier, occurred in WT mice after 72 hr of >95% O2 exposure compared to controls [6.9 ± 0.9 vs. 0.14 ± 0.01 mg/ml (mean ± SEM)], respectively. BAL protein was significantly decreased in platelet uPA+ mice [1.5 ± 0.4 vs. 6.9 ± 0.9 mg/ml, n=6–8, p<0.05]. Immunohistochemical detection of fibrin in control and platelet uPA+ mice lungs using anti-murine fibrin(ogen) antibody showed that very little fibrin(ogen) was detected in control (0 hr) mice or WT mice exposed to >95% O2 for 24 hr. By 72 hr of O2 in WT mice, however, fibrin(ogen) immunoreactivity was seen within the alveolar space and diffusely throughout the interstitium. Fibrin clots within small blood vessels were also seen. In contrast, fibrin(ogen) immunoreactivity was greatly reduced in uPA+ mice. Moreover survival time of uPA+ mice was significantly longer than WT animals (127 ± 28 hr vs. 97 ± 14 hrs, respectively, n=12, p<0.003). Total white blood cell counts and % PMN in the BAL were significantly higher after 72 hr exposure to O2, suggesting that increased pulmonary inflammation is not necessarily associated with increased lung injury, a finding consistent with other studies showing that neutrophils do not play a significant role in the genesis of this lung injury. These data support the hypothesis that a decrease in lung fibrinolytic activity is a primary factor in the development of O2-induced lung injury and that platelet delivery of uPA may be an especially effective and safe way to prevent the development of such lung injury.
Mantle Cell Lymphoma Genotypes Identified with CGH to BAC Microarrays Define Clinical Subgroups of Disease and Strongly Predict Patient Outcome.
Authors: Martinez-Climent Jose A. , Rubio-Moscardo Fanny , Climent Joan , Terol Maria J. , Sarsotti Elena T. , Benet Isabel , Siebert Reiner , Piris Miguel A. , Martin-Subero Inaki , Dyer Martin J.S. , Pinkel Daniel , Garcia-Conde Javier 
Published: October 2019

Abstract
Mantle cell lymphoma (MCL) is a rare, aggressive subtype of B-cell non-Hodgkin lymphoma (B-NHL), characterized by t(11;14)(q13;q32). To identify recurrent genomic events involved in the pathogenesis of this malignancy, we used genome-wide comparative genomic hybridization (CGH) to 1.4 Mb. resolution BAC microarrays in 68 patients and 9 derived MCL cell lines; the genome profiles were compared to those from other B-NHL subtypes. Array-CGH defined a MCL genomic signature different from other B-cell lymphomas, including deletions of chromosomes 1p21.2-p12.3, 11q22.3 at ATM gene locus, 13q14.2 and 13q34, with coincident 10p12-BMI locus amplification and 10p14 deletion, along with a previously unidentified loss within 9q21-q22. Specific genomic alterations were associated with different subgroups of disease. Notably, 11 patients with non-nodal, leukemic MCL, defined on the basis of the absence at diagnosis of lymph node disease, showed a different genomic profile to nodal cases, including deletion of 8p21.2 at TRAIL receptor gene cluster (55 vs. 19%;p=0,01) and gain of 8q24.1 at MYC locus (46 vs. 14%;p=0,015). Additionally, leukemic MCL exhibited frequent IgVH mutation (64 vs. 21%;p=0,009) with preferential VH-39 use (36 vs. 4%;p=0,005), and followed a more indolent course, being 7 of 11 patients (64%) survivors for more than 3 years whereas only 15 of 55 patients (27%) in the nodal group experienced this long survival (median survial time, 42 vs. 18 months; p=0,02). The median overall survival (OS) for the patients in the series was 39 months (range, 0–115). Blastoid variant of MCL, increased number of genomic gains, and deletions of P16/INK4a and P53 genes correlated with poorer outcomes, whilst 1p21 loss was associated with prolonged survival (median OS, 70 vs. 31 months; p=0,02). In multivariate analysis, deletion of chromosome 9q21-q22, which has not been previously reported as a common change in MCL, was the strongest predictor for inferior survival (HR:6; CI:2,3–15,7). Last, the genotypes of 14 patients with MCL who were alive for more than 5 years since diagnosis showed deletion of 1p21 in seven cases (50%), but none exhibited deletions of 9q21-q22, 9p21.3-P16/INK4a or 17p13.1-P53. Our study illustrates the utility of array-CGH in MCL sub-classification and highlights the array genomic profile as the strongest indicator for predicting clinical outcome. The screening of this reduced BAC clone set either by FISH or custom-made array CGH devices could be reliably applied to the clinical diagnostics of MCL.
Enoxaparin Is Effective and Safe as Bridging Anticoagulation in Patients with a Mechanical Prosthetic Heart Valve who Require Temporary Interruption of Warfarin because of Surgery or an Invasive Procedure.
Authors: Turpie Alexander G. , Douketis James D. 
Published: October 2019

Abstract
Background: Enoxaparin is a low-molecular-weight heparin (LMWH) that is widely used in patients with an acute coronary syndrome and venous thromboembolism. However, there is concern about its use in patients with mechanical prosthetic heart valve because of recent reports of fatal TE occurring in pregnant women with a mechanical heart valve who received long-term enoxaparin, instead of warfarin, during pregnancy.
Patients and Methods: We performed a prospective cohort study to assess the efficacy and safety of enoxaparin as bridging anticoagulation in a consecutive patients with a mechanical prosthetic heart valve who required temporary interruption of warfarin therapy because of an elective surgical or other invasive procedure. Patients had warfarin interruption and bridging anticoagulation based on a standardized peri-operative protocol and underwent clinical follow-up for 3 months after surgery. We determined the incidence and associated 95% confidence interval (CI) during the follow-up period for the following outcomes: major bleeding; arterial thromboembolism (stroke, rtansient ischemic attack, systemic embolism, valve thrombosis); all-cause death.
Results: There were 174 patients included in this cohort (100 males; mean age: 67±10 years; mean weight: 76±16 kg; 115 with a mechanical aortic valve; 59 with a mechanical mitral valve or combined mechanical aortic and mitral valves) who received bridging anticoagulation with subcutaneous enoxaparin, 1 mg/kg twice-daily. No patient was lost to follow-up. Warfarin therapy was interrupted 5.7±2.2 days before the procedure. The mean number of doses of enoxaparin (1 mg/kg) administered before the procedure was 5.7±1.4 doses. After the procedure, warfarin was resumed on the evening or the next day after the procedure, and the mean number of doses of enoxaparin administered was 6.0±2.2 doses. After 3 months of clinical follow-up, 4 patients developed non-fatal major bleeding (2.3%; 95% CI: 0.06–5.7), 4 patients died (2.3%; 95% CI: 0.06–5.7), and 1 patient had a non-fatal stroke (0.56%; 95% CI: 0.01–3.1). There were no episodes of valve thrombosis or systemic embolism.
Conclusions: Enoxaparin appears to be effective and safe as bridging anticoagulation in patients with a mechanical prosthetic heart valve who require temporary interruption of warfarin therapy.