bluuebunny/crossref_metadata_2025_split huggingface dataset:
Clonal Analysis Reveals a Common Progenitor for Endothelial, Myeloid, and Lymphoid Precursors in Cord Blood.
Authors: Akbarloo Nasrin , Perlingeiro Rita R. 
Published: October 2019

Abstract
Several recent studies demonstrate that hematopoietic tissues, including bone marrow (BM), umbilical cord blood (UCB), and peripheral blood (PB) are a source of endothelial progenitor cells (EPCs), which contribute to newly formed blood vessels during tissue repair in adults. However, it is not clear which cell type in hematopoietic tissues gives rise to EPCs, and therefore might be preferable for vascular regeneration. It has been suggested that EPCs might derive from an adult hemangioblast, the primitive bipotential precursor for hematopoietic and endothelial cells, but to date, this hypothesis has not been proven. To test the possibility that a hemangioblast may exist in UCB, we compared the ability of UCB-derived CD34+CD133+ and CD34+CD133− to form blast colonies using the clonogenic BL-CFC assay, previously described for embryonic hemangioblasts (Perlingeiro et al, 2003). All the blast colonies (BL-CFCs) were present in the CD133+ fraction. Bipotentiality of these BL-CFCs was confirmed by replating in hematopoietic and endothelial conditions. To illuminate the lineage position of the hemangioblast within the hematopoietic system, we added CD38 to the antibody combination and adapted the colony assay to liquid culture in 96-well dishes. Clones derived from single cells deposited by FACS were expanded for a week, and each divided into 4 conditions for T and B lymphoid, myeloid, and endothelial cell growth. Whereas myeloid and lymphoid progeny were evident from the CD133+CD38− fraction, these clones were not able to differentiate into endothelial cells. On the other hand, 86% of clones derived from the triple positive (CD34+CD133+CD38+) population were able to produce all 4 lineages. Endothelial cells were characterized by the expression of VE-cadherin, KDR, vWF (and lack of CD45 and c-fms), and the ability to form vessels in vivo in a matrigel plug transplantation assay. Myeloid differentiation was assayed in methylcellulose media, where several BFU-E, CFU-GM, and CFU-GEMM were enumerated. Lymphoid differentiation was assayed by co-culture on OP9-DL1 and MS-5 stroma, for T and B lymphoid differentiation, respectively. Double positive CD4+CD8+ T lymphocytes were observed after 40 days in culture. The presence of B lymphocytes was demonstrated by expression of CD19 and IgM. Final maturation was detected by DJH and VDJH recombination. That the adult hemangioblast should be CD38+ is highly unexpected, as it positions the hemangioblast below the LTR-HSC. An alternate explanation would place the CD38+ hemangioblast upstream, with CD38 being switched off in the LTR-HSC, and back on the STR-HSC. We are currently investigating these possibilities.
Bone Marrow-Derived Cells Regenerate Kit+ Cardiac Stem Cells (CSCs) in Damaged Heart.
Authors: Cerisoli Francesco , Barile Lucio , Gaetani Roberto , Cassinelli Letizia , Frati Giacomo , Giacomello Alessandro , Messina Elisa , Ottolenghi Sergio , Magli Maria Cristina 
Published: October 2019

Abstract
A growing amount of data indicates that the heart harbours stem cells (CSCs) with regenerative potential, however the origin(s) of adult CSCs is still unknown. The expression of Kit a marker of several stem cell types, including hematopoietic and cardiac stem cells, suggests that Kit positive-CSCs may derive, at least in part, from extracardiac sources. In addition, it has been suggested that bone marrow (BM) cells may be mobilized, home into the heart and trans-differentiate into cardiomyocytes, following myocardial infarction.
To investigate whether BM cells can contribute to repopulate the cardiac Kit+ stem cell pool, we transplanted BM cells from a mouse line expressing transgenic Green Fluorescent Protein (GFP) under the control of Kit regulatory elements, into wild type irradiated recipients. After hematological reconstution (4–5 months) and following cardiac infarction, cardiac cells were grown in vitro into typical “cardiospheres” (Messina et al., Circ. Res. 95,911;2004). The cardiospheres obtained, although not numerous, were all GFP fluorescent; this result was confirmed by PCR analysis of genomic DNA of individual CSs. At confocal microscopy, cells at the periphery of CSs showed coexistence of low GFP with cardiac markers, such as Troponin I and the transcription factor NKx2.5, consistent with the expected kit downregulation during cardiac differentiation.
Our results show that cells of bone marrow origin can give rise, after homing into the heart, to cells with properties of Kit+ CSC. In contrast, CSCs isolated from kit/GFP transgenic mice are not able, upon transplantation, to repopulate the bone marrow of wild-type irradiated recipients.
Thus, at least in pathological conditions, part of the Kit-positive CSCs population may be generated by BM-derived cells, capable of adopting in the heart the same function and features of cardiac stem cells.
Improved Endothelial Function with Combined Chelation Therapy in Thalassaemia Major.
Authors: Tanner Mark A. , Galanello Renzo , Dessi Carlo , Agus Annalisa , Smith Gillian C. , Westwood Mark A. , Assomull Ravi , Nair Sunil V. , Walker J. Malcolm , Pennell Dudley J. 
Published: October 2019

Abstract
Background: In β-thalassemia major (TM) myocardial iron toxicity is the dominant cause of ventricular dysfunction, with heart failure responsible for the majority of deaths. Abnormal endothelial function has also been described in these patients and could further contribute to cardiovascular complications. Endothelial function can be determined by measurement of flow mediated dilatation of the brachial artery (FMD). This can be assessed reproducibly by cardiovascular magnetic resonance (CMR).
Aims: To report the changes in endothelial function, LV ejection fraction and ferritin from a randomized placebo controlled trial comparing combined chelation therapy (deferiprone and deferoxamine) with deferoxamine monotherapy.
Methods: 65 patients (male 27, female 38, age 28.7+/−4.8years) with mild-moderate myocardial iron loading (heart T2* 8–20ms) were randomized to receive either deferoxamine with placebo (placebo group), or deferoxamine with deferiprone (combined group). FMD was assessed at baseline and after 12 months.
Results: There were significant improvements in endothelial function in the combined treatment group compared with the placebo group (+8.8% vs 3.1% p=0.013). This was in accord with improvements in the combined group in left ventricular ejection fraction (+2.4% vs +0.6%, p=0.02), and serum ferritin (−870 vs −194 μg/L; p<0.001). These findings were in accord with improved myocardial T2* in the combined group (+43% vs +23%, p=0.017),
Conclusion: In patients with mild-moderate cardiac iron loading, the combined therapy of deferiprone and deferoxamine is superior to deferoxamine alone in improving endothelial function, cardiac function and ferritin, as well as reducing myocardial iron.
The Role of Platelet Adhesion Receptor GPIb α Far Exceeds That of Its Main Ligand von Willebrand Factor in Arterial Thrombosis.
Authors: Bergmeier Wolfgang , Piffath Crystal L. , Goerge Tobias , Cifuni Stephen M. , Ruggeri Zaverio M. , Ware Jerry , Wagner Denisa D. 
Published: October 2019

Abstract
GPIbα binding to von Willebrand factor (VWF) exposed at a site of vascular injury is thought to be the first step in the formation of a hemostatic plug. However, our previous studies in VWF-deficient mice demonstrated delayed but not absent arterial thrombus formation suggesting that, under these conditions, GPIbα may bind other ligands or that a receptor other than GPIbα can mediate platelet adhesion. Here we studied thrombus formation in transgenic mice expressing GPIbα in which the extracellular domain was replaced by that of the human interleukin-4 receptor (IL4Rα/GPIbα-tg mice). Platelet adhesion to ferric chloride-treated mesenteric arterioles in IL4Rα/GPIbα-tg mice was virtually absent in contrast to avid adhesion in wild-type (WT) mice. As a consequence, arterial thrombus formation was completely inhibited in the mutant mice. Our studies further show that, when infused into WT recipient mice, IL4Rα/GPIbα-tg platelets or WT platelets lacking the 45 kD N-terminal domain of GPIbα failed to incorporate into growing arterial thrombi, even if the platelets were activated prior to infusion. Surprisingly, platelets lacking β3 integrins, which are unable to form thrombi on their own, incorporated efficiently into WT thrombi. Our studies provide in vivo evidence that GPIbα is absolutely required for recruitment of platelets to both exposed subendothelium and thrombi under arterial flow conditions. Thus, GPIbα contributes to arterial thrombosis by important adhesion mechanisms independent of the binding to VWF.
Association of Endothelial Microparticles (EMP) and Endothelial Progenitors with Serum Cholesterol Levels.
Authors: Jimenez Joaquin J. , Ferreira Alexander , Dodson Hannah J. , Lens Katherine M. , Mauro Lucia M. , Jy Wenche , Peter Arley , De Marchena Eduardo , Horstman Lawrence L. , Ahn Yeon-Soong 
Published: October 2019

Abstract
INTRODUCTION: High cholesterol (HC) is known to adversely affect endothelial cells (EC) and has been shown to correlate with decreased levels of circulating endothelial progenitor cells (CEPC). We assayed endothelial microparticles (EMP), a sensitive indicator of EC perturbation, to investigate relations among HC, CEPC, and injury of coronary artery endothelial cells (CAEC), both in vivo and in vitro.
METHODS: Twelve subjects with normal cholesterol (150 ±30 mg/dL, control) and 12 with HC (250 ±25) were studied. EMP were assayed by flow cytometry using fluorescent antibodies and CAEC were cultured as previously described [Jimenez et al, Thromb Res 109:175, 2003]. CEPC were isolated, cultured, and assayed for endothelial colony formation (CFU) as described [Hill et al, NEJM 348:593, 2003].
RESULTS: Comparing the two groups, EMP measured by CD31+/CD42b− were nearly 2.5-fold elevated in HC as compared to controls (1.7 ±0.5 ×106/mL vs.0.35 ±0.02 ×106/mL; p<0.01). Cholesterol levels correlated well with this measure of EMP (R=0.60, p=0.002). However, no significant correlation was found between CD62E+ EMP and cholesterol levels. Assay of CEPC revealed a nearly 2.5-fold decrease in CFU in HC vs. controls (10 ±2 vs. 25 ±4; p<0.01). In studies in vitro, CEPC from controls were cultured in presence of 20% 0.1μm filtered plasma from members of both groups. The HC group plasma inhibited CEPC colony formation by almost 50% (23 ±3.5 CFU for control plasma vs. 13 ±4 colonies for HC plasma). We next assessed the longer-term effect of HC plasma on CAEC cultures. Six-day culture of CAEC in the presence of 20% plasma resulted in a significant increase of CD31+/CD42b− EMP from CAEC treated with HC plasma vs. normal plasma (6.5 ±0.7 ×106/mL vs. 0.23 ±0.03 ×106/mL; p=0.02).
CONCLUSION: These results suggest that EMP are useful markers to monitor cholesterol mediated-EC changes. High EMP levels inversely reflect the vascular endothelial cell regeneration potential due to decreased circulating endothelial progenitor cells.
A Novel Cellular Pathway of SCL T-Leukemogenesis Revealed by a Conditional Transgenic Mouse Model.
Authors: Gothert Joachim R. , Brake Rachael , Begley C. Glenn , Izon David J. 
Published: October 2019

Abstract
The acquired activation of stem cell leukemia (SCL) during T-lymphopoiesis is a common event in T-cell acute lymphoblastic leukemia. Here, we generated a novel tamoxifen-inducible transgenic mouse model (lck-ERT2-SCL) to study the cellular targets of acquired SCL activation during T-cell development. Upon tamoxifen treatment we observed the thymic emergence of abnormal, non-cycling CD8+TCRβlow and immature CD4+CD8+ (double-positive, DP) cells displaying increased viability. Unexpectedly, fetal thymic organ culture analysis of lck-ERT2-SCL thymi revealed the development of DP cells before the emergence of CD8+TCRβlow cells, which implied the derivation of CD8+TCRβlow cells from DPs rather than immature CD8 single-positive (SP) thymocytes. Interestingly, histone deacetylase (HDAC) inhibition with trichostatin A (TSA) had a divergent effect on SCL perturbed thymopoiesis: TSA increased T-cell receptor surface expression within DP and CD8 SP cells however did not alter the CD8 shifted CD4/CD8-ratio. Furthermore, we studied the expression of NOTCH1 in SCL induced TCRβlow thymocytes. Strikingly, we found that SCL induced NOTCH1-upregulation in DP TCRβlow cells. We therefore conclude that SCL promotes the emergence of abnormal CD8+TCRβlow cells by an only partially HDAC dependent mechanism from DP TCRβlow cells. Moreover, SCL induced DP TCRβlow cells are characterized by upregulated NOTCH1, which in turn might promote the effect of acquired NOTCH1 mutations during T-leukemogenesis.
Rapid Clearance of PEG-Asparaginase in ALL Patients by an Antibody Against Poly (Ethylene Glycol).
Authors: Armstrong Jonathan , Hempel Georg , Koling Susanne , Chan Linda S. , Meiselman Herbert J. , Fisher Timothy C. , Garratty George 
Published: October 2019

Abstract
Background: Rapid clearance of poly(ethylene glycol)-asparaginase (PEG-asparaginase) has been reported for up to one third of patients treated for acute lymphoblastic leukemia, potentially rendering their treatment ineffective [Hempel G, Lanvers-Kaminsky C, Mueller, HJ, Würtwein G, Boos J. Blood. 2004;11:751A]. Poly(ethylene glycol) is an inert, biocompatible synthetic polymer and has long been claimed to be non-immunogenic; several PEG-conjugated drugs are FDA approved and many other PEGylated agents are in development. However, we have previously reported a 25% occurrence of an antibody against PEG (anti-PEG) in healthy blood donors, which suggests that PEG is an immunogenic agent. [Garratty G. Trans Med Rev. 2004;18:245–56].
Objective: To determine whether an anti-PEG could account for the rapid clearance of PEG-asparaginase.
Methods: This study re-analyzed stored serum samples from pediatric patients who were enrolled in the Acute Lymphoblastic Leukemia Berlin-Frankfurt-Münster 2000 studies. Samples were selected to include 15 subjects who showed undetectable asparaginase activity after receiving PEG-asparaginase (Oncaspar®) and 13 with normal sustained levels of asparaginase activity after treatment with PEG-asparaginase. Sixteen subjects treated with unmodified asparaginase (Medac®) were also included, 8 with negligible asparaginase activity. Sera were tested for the presence of an anti-PEG using two techniques: 1) Serology, by agglutination of PEG-coated red blood cells; 2) Flow cytometry, by analysis of 10 μm PEG beads (Tentagel®-OH) pre-incubated with sera and stained for bound immunoglobulins with fluorescein-anti-human IgG and R-phycoerythrin-anti-human IgM. Testing for anti-PEG was performed in a blinded manner.
Results: For the PEG-asparaginase treated patients, of the 15 who showed undetectable asparaginase activity, 9 tested positive for anti-PEG by serology and 13 tested positive for anti-PEG by flow cytometry. All PEG-asparaginase treated patients with normal sustained asparaginase activity tested negative for anti-PEG. Four sera yielded somewhat unusual results: One weak IgM anti-PEG positive sample showed measurable asparaginase activity and three anti-PEG negative patients had low asparaginase activity, two of which were positive for anti-asparaginase. No relationship was observed between the presence of anti-PEG and serum asparaginase activity for the patients treated with unmodified asparaginase (Medac®).
Conclusions: The presence of anti-PEG was very closely associated with rapid clearance of PEG-asparaginase. Screening and monitoring for anti-PEG would allow for identification of a subset of patients for whom a modified dosing strategy or use of a non-PEGylated drug would be appropriate.
Increased Infection-Related Mortality for Children with Down Syndrome (DS) in Contemporary Children’s Oncology Group (COG) Acute Lymphoblastic Leukemia (ALL) Clinical Trials.
Authors: Maloney Kelly W. , Larsen Eric , Mattano Leonard A. , Friedmann Alison , Devidas Meenakshi , Sather Harland , Hunger Stephen , Winick Naomi , Carroll William L. 
Published: October 2019

Abstract
In prior COG ALL trials, children with DS have had increased treatment-related morbidity without major increases in mortality, when compared to children without DS. Recently, COG opened phase III, randomized trials for the treatment of children with high risk (AALL0232) and standard risk (AALL0331) precursor-B ALL. COG AALL0232 uses an augmented BFM backbone regimen with randomized comparisons of 28 days of prednisone (PDN) 60 mg/m2 vs. 14 days of dexamethasone (DXM) 10 mg/m2 during induction (IND), and high dose methotrexate with leucovorin rescue (HD MTX) vs. escalating IV MTX without rescue plus Peg asparaginase using the Capizzi schedule (CMTX) during a two-month interim maintenance (IM) phase of therapy. Children with DS participated in the induction steroid randomization, but were non-randomly assigned to CMTX arm due to known increased sensitivity to HD MTX. During the first 22 months of accrual to AALL0232, there were 4 deaths among 20 patients with DS, 3 of these 4 deaths occurred in pts receiving DXM in IND yielding an IND mortalaity rate of 15%, which is significantly higher than the 4.3% rate in CCG 1961 (the prior high risk trial). COG AALL0331 utilizes a standard 3-drug IND consisting of DXM 6 mg/m2 for 28 days, vincristine and PEG asparaginase. Post-IND therapy includes a 2 × 2 randomization between intensified vs. standard consolidation, and escalating CMTX combined with augmented delayed intensification (DI) vs. standard IM and DI phases. On AALL0331, there were 6 deaths among 26 children with DS during the first 10 months of accrual. The deaths occurred in IND (3), intensified consolidation (1) and standard DI (2). The IND mortality rate for DS children on AALL0331 is 11.5% compared to 1.3% in CCG 1991 and 0% in CCG 1952 which used identical IND therapy. During DI, patients on CCG 1991 received DXM on days 1–7 and 15–21, whereas those on AALL0331 receive DXM on days 1–21; this difference could contribute to an increased risk of infection in the DS population during the DI phases of the latter trial. The majority of deaths have been due to overwhelming infection with cardiovascular collapse during times of neutropenia. Both COG AALL0232 and AALL0331 suspended enrollment to DS patients pending subsequent therapy changes and expanded supportive care guidelines. This experience emphasizes that children with DS carry a significant risk of infection-related mortality and mandates increased vigilance for early detection and treatment of symptoms suggestive of infection.
Increasing FLT3-ITD Length Increases Expression of bcl-xl in AML.
Authors: Seedhouse Claire H. , Pallis Monica , Grundy Martin , Russell Nigel 
Published: October 2019

Abstract
Internal tandem duplications (ITDs) within the FLT3 tyrosine kinase receptor occur in approximately 25% of patients with acute myeloid leukaemia (AML) and are associated with poor prognosis. The ITDs can range from just three nucleotides to hundreds of nucleotides in length and the duplicated sequence is always in-frame. Recent data has suggested that the size of the ITD may be of importance prognostically and increasing ITD size has been shown to be associated with decreasing overall survival and relapse-free survival1. Very little is known about the biological effects of FLT3-ITDs of differing length and it is possible that such findings would help shed light upon the clinical findings. We have therefore studied various biological parameters in 102 primary AML blast cell samples including FLT3 mutation status, FLT3-ITD length, FLT3 and bcl-xl mRNA expression levels and STAT5 phosphorylation (activation).
38 AML samples had FLT3-ITDs and 64 samples were FLT3-wild type (WT); samples were also screened for D835 point mutations and any samples found to have such a mutation were not included in further analyses, therefore WT denotes neither an ITD nor a D835 mutation. FLT3 mRNA levels were determined by real time PCR and normalised to the housekeeper beta 2 microglobulin (b2M). Samples with a FLT3-ITD had a higher level of FLT3 mRNA than WT samples (p=0.02) and the transcript level of FLT3 was also correlated with phosphorylation of the downstream signalling target STAT5 (measured by flow cytometry; n=22; p=0.02), such an association was not seen in the WT samples (n=23; p=0.37). FLT3-ITD mutations have been shown to activate the anti-apoptotic gene bcl-xl via STAT5 signalling, therefore levels of bcl-xl were also assessed in these samples. A strong correlation was found between increasing levels of FLT3 and bcl-xl transcripts in the FLT3-ITD samples (n=30, p=0.002), this was not found in the FLT3-WT samples (n=50, p=0.42). Bcl-xl levels were found to be dependent upon the level of phosphorylated STAT5 (n=20, p=0.03) and the length of the ITD (n=17, p=0.03) in FLT3-ITD samples. However, as of yet no correlation has been found between STAT5 activation and FLT3-ITD length.
These findings suggest that increasing levels of FLT3 transcripts are associated with increasing activation of the STAT5 signalling molecule and its downstream target bcl-xl. Moreover, the length of the FLT3-ITD was also found to correlate with the level of bcl-xl, although whether this is via a STAT5-dependent mechanism remains to be established. Enhanced levels of bcl-xl may mediate chemoresistance and explain the adverse effect of FLT3-ITD length on outcome in AML.
Bcl-xl mRNA levels correlate with FLT3-ITD length Bcl-xl mRNA levels correlate with FLT3-ITD length