bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intravascular Injection of Murine Mesenchymal Stem Cells in Non-Injured Neonatal Mice Results in Bone Forming Nodules within Pulmonary Vessels.
Authors: Badillo Andrea T. , Tsai Anthony Y. , Flake Alan W. 
Published: April 2020

Abstract
Murine mesenchymal stem cells (mMSC) are capable of differentiation into multiple cell types in vitro, and as a result have been proposed as ideal candidates for the development of cellular based therapy for tissue repair. The distribution, engraftment, and differentiation properties of these cells in vivo have yet to be conclusively defined. Reports of mMSC engraftment and differentiation are confounded by issues of cell population purity, questions of fusion, a reliance on pathologic injury models to demonstrate significant engraftment levels, and immunofluorescent based cell tracking modalities which are prone to artifact and rely on subjective interpretation. In this study, we utilize a non-injured neonatal mouse model to demonstrate the fate of culture expanded, purified mMSC derived from the bone marrow of adult GFP transgenic mice. Following intravascular injection into Swiss Webster neonatal mice on the first day of life, mMSC were tracked with fluorescent stereomicroscopy and corresponding tissue specimens were collected and processed for histology and immunoperoxidase staining for GFP. mMSC were found to concentrate within the lungs with few, isolated cells visualized outside the lungs. Histological examination confirmed the presence of GFP expressing cells within the pulmonary vasculature but occurring as aggregates of bone. These nodules were found as early as 9 days after injection and persisted to 42 days after injection. These nodules were located within the confines of the vessel wall and were surrounded by an inflammatory infiltrate. There was no evidence of tissue invasion nor did these cells demonstrate malignant features. These bony aggregrates were also demonstrated after injection into C57Bl/6 congenic controls. Our findings indicate that mMSC are filtered by the pulmonary vasculature following intravenous injection thereby limiting their capacity to reach other tissues. The large adherent phenotype of these cells makes them prone to vessel lodgment, and this lodgment results is aberrant osteogenesis. These findings have major implications for intravascular stem cell based therapies for tissue repair.
Bortezomib Plus Rituximab in Patients with Indolent Non-Hodgkin’s Lymphoma (NHL): A Phase 2 Study.
Authors: de Vos Sven , Dakhil Shaker , McLaughlin Peter , Saleh Mansoor , Belt Robert , Flowers Christopher , Knapp Mark , Hart Lowell , Patel-Donnelly Dipti , Glenn Martha , Gregory Stephanie A. , Holladay Charles , Boral Anthony , Zhang Tracy , Goy André 
Published: April 2020

Abstract
Background: Bortezomib (VELCADE®, Vc) a novel, first-in-class proteasome inhibitor, is being investigated in the treatment (tx) of non-Hodgkin’s lymphoma (NHL). Preclinical data with combined rituximab (R) and Vc suggest additive cytotoxic activity. This phase 2 study investigated the response rate to R plus Vc, weekly or twice-weekly, in patients (pts) with relapsed follicular (FL) or marginal zone (MZL) NHL.
Methods: Eligibility criteria included CD20+ FL or MZL with measurable disease, and Karnofsky Performance Status (KPS) ≥50% (ECOG 0–2). Pts on any prior regimen including R had to respond and show TTP of ≥4 months. Pts were randomized (1:1) to Vc 1.3mg/m2 twice-weekly on days 1, 4, 8, and 11 of a 21-day cycle (Arm A) or Vc 1.6mg/m2 weekly on days 1, 8, 15, and 22 of a 35-day cycle (Arm B) for up to 15 weeks (5 and 3 cycles in arms A and B, respectively). Starting from day 1, R 375mg/m2 was administered weekly for 4 weeks. Response was evaluated by International Workshop Criteria.
Results: 81 pts were enrolled between May 2004 and August 2005. At data reporting for this abstract, 46 (23 each arm) had received study drug, and 42 (20 Arm A, 22 Arm B) were evaluable for response. Of these 42 pts, 83% had FL and 17% had MZL; 62% were male; 55% were aged &gt;60 years (range 33–80); 93% had KPS ≥90%; 26% had lactic dehydrogenase level &gt;ULN. 71% of pts received prior R (alone or in combination), and 79% of pts received prior CHOP, RCHOP, CVP or RCVP. Of 46 treated pts, 9 (39%) in Arm A and 16 (70%) in Arm B completed all planned cycles. Median Vc dose received was 15.9mg/m2 (61% of max. expected) in Arm A, and 19.0mg/m2 (99% of max. expected) in Arm B. Overall response rate was 50% (1 CR + 9 PR) in Arm A, and 45% (2 CR + 8 PR) in Arm B. 12 pts had PD (6 each arm) and 1 pt died (Arm A). Time to event analyses, including TTP and duration of response, are pending further follow-up. Tx was well tolerated in both arms; grade ≥3 AEs were seen in 10 pts in Arm A and 5 pts in Arm B. The most common grade ≥3 AEs were gastrointestinal toxicities, neutropenia, thrombocytopenia and peripheral neuropathy, but no grade ≥3 thrombocytopenia or neutropenia were observed in Arm B. SAEs were seen in 7 pts in Arm A versus 2 pts in Arm B.
Conclusions: Weekly and twice weekly Vc plus R are active and well tolerated treatments for relapsed/refractory CD20+ indolent NHL. The more convenient weekly regimen appears to offer a similar response rate with less toxicity. Final efficacy and safety data for both regimens will be presented.
Outcome of Bone Marrow Transplantation for Myelofibrosis.
Authors: Ballen Karen , Sobocinski Kathleen A. , Zhang Mei-Jie , Arora Mukta , Horowitz Mary M. , Giralt Sergio ,   the Chronic Leukemia Working Committee of the Center for International Blood Marrow Transplant Research
Published: April 2020

Abstract
Myelofibrosis is a myeloproliferative disorder characterized by splenomegaly, bone marrow fibrosis and immature white and red blood cells. Allogeneic transplantation is the only curative therapy. In this study, we analyzed the outcomes of 320 patients receiving allogeneic hematopoietic stem cell transplants for myelofibrosis between 1989 and 2002, using the databases of the Center for International Bone Marrow Transplant Research (CIBMTR), a research affiliation of the International Bone Marrow Transplant Registry (IBMTR) and the National Marrow Donor Program (NMDP). This is the largest report of transplantation for myelofibrosis. Patients received a variety of conditioning and graft versus host disease prophylaxis regimens. Most patients received ablative conditioning with either TBI (n=117) or Busulfan (n=150) and cyclophosphamide. Bone marrow was the graft source in 208 patients. 170 transplants were from an HLA-identical sibling donor, 117 from an unrelated donor (MUD), and 33 from an alternative related donor. Median ages at transplant were 45 (&lt;1–73), 47 (1–69) and 40 (&lt;1–65) years, respectively. Median follow up times for survivors were 41 (3–136), 48 (4–124) and 32 (7–118) months, respectively. Both early and long-term survival rates were higher after HLA-identical sibling transplantation. 100-day mortality was 22% after sibling transplants, 42% after MUD transplants, and 27% after alternative family donor transplants. Corresponding 5 year overall survival rates were 39%, 31% and 31%. In multivariate analysis of 215 adult recipients of myeloablative transplants, having an HLA-identical sibling donor, Karnofsky performance score greater than or equal to 90%, younger age, more recent date of transplantation, and absence of blasts in peripheral blood prior to transplantation correlated with better survival. Among 18 patients with all of these favorable factors, the five-year probability of survival was 81%. In conclusion, 1) allogeneic transplantation cures approximately 1/3 of patients with myelofibrosis; 2) young patients with HLA-matched sibling donors have superior survival; 3) results have improved over the last decade. Future research directions will focus on the use of nonmyeloablative conditioning regimens for myelofibrosis.
Hematopoietic Stem Cells Fail to Trans-Differentiate into Smooth Muscle-Lineage Cells In Vivo.
Authors: Yokota Takafumi , Sato Sanai , Kawakami Yutaka , Nagai Yoshinori , Ma Jian-xing , Tsai Jen-Yue , Oritani Kenji , Tomiyama Yoshiaki , Matsumura Itaru , Kincade Paul W. , Kanakura Yuzuru 
Published: April 2020

Abstract
Since bone marrow has been shown to contain cells capable of differentiating into various lineages, it is attracting considerable attention as a potential source for tissue regeneration. The plasticity of hematopoietic stem cells (HSC), however, remains controversial. While recent studies have suggested that HSC give rise to other tissue types, others argue against HSC plasticity. Because any tissue injury results in extensive recruitment of inflammatory cells, evidence for stem cell plasticity with non-specific green fluorescent protein (GFP) transgenic mice is often confounded by the results of adhesion and/or cell fusion by macrophages. Some reports using non-specific GFP transgenic mice demonstrated that HSC could contribute to the generation of smooth muscle type α-actin (αSMA)-expressing cells in injured arteries or renal gromeruli. We developed a new transgenic αSMA-GFP mouse with GFP coupled to an αSMA regulatory sequence. Bone marrow transplantation was then used to evaluate the potential of marked cells to generate donor type tissues in irradiation chimeras. There was a highly restricted pattern of GFP expression in the transgenics, marking vascular smooth muscle cells, pericytes and mesangial cells in the kidney, but no hematopoietic cells while the marrow contained infrequent cells positive for αSMA-GFP (0.02% of mononuclear cells). When the marrow cells were cultured, stromal cells with high GFP expression were abundantly produced in two weeks. Similarly cultured glomeruli generated many mesangial cells with high GFP expression. These characteristics, however, were not transferable to lethally irradiated (950rad) RAG-2 deficient mice, even when 1 x !07 transgenic marrow cells per recipient were infused via tail vein and the hematopoietic system was largely replaced by recipient cells. At 6 months after transplantation, no GFP+ cells were observed in either bone marrow or renal glomeruli of 20 RAG-2 deficient recipients. Furthermore, cultivation of their marrow or glomerular cells did not produce αSMA-GFP expressing cells. Our findings support earlier studies suggesting that the bone marrow microenvironment is difficult to transplant by standard methods and indicate that HSC are unlikely to give rise to αSMA expressing progeny.
Caspase-3 Has Apoptotic and Non-Apoptotic Functions in Regulating the Fate of Hematopoietic Stem Cells.
Authors: Janzen Viktor , Fleming Heather , Reynolds Griffin , Waring Michael , Scadden David T. 
Published: April 2020

Abstract
The processes of cell cycle control, differentiation and apoptosis are closely intertwined in controlling cell fate during development and in adult homeostasis. Much emphasis has been placed on differentiation and proliferation in hematopoiesis, but little is known about control of the stem cell pool by mediators of apoptosis. We are particularly interested in the cysteine-aspartic acid protease, Caspase-3, an ‘executioner’ caspase also implicated in the regulation of the cyclin dependent kinase inhibitor, p21Cip1. p21 is known to regulate hematopoietic stem cell (HSC) cycling and we demonstrated high levels of Caspase-3 mRNA and protein in immunophenotypically defined mouse HSC. Using mice engineered to be deficient in Caspase-3, we observed no difference from wild-type in blood counts. However, knock-out animals had reduced bone marrow cellularity and an increase in the stem cell enriched lin-kit+Sca-1+ CD34 low (LKS-CD34lo) cell fraction. The apoptotic rates of LKS cells under homeostatic conditions were minimally different from controls. However, under conditions of stress (gamma irradiation, heat shock or cytokine withdrawal), Caspase-3 deficient LKS cells demonstrated reduced sensitivity to apoptotic cell death as measured by TUNEL or Annexin-V assay. Primitive hematopoietic cells from these animals in vivo also had reduced BrdU incorporation reflecting decreased proliferation and, upon transplantation, demonstrated marked differentiation abnormalities. Caspase-3−/− marrow cells had significantly reduced ability to differentiate into lymphoid and myeloid lineages 12 weeks after transplantation. Similarly, WT bone marrow cells treated prior to transplantation with a selective Caspase-3 inhibitor, z-DEVD.fmk, displayed a significant disadvantage in peripheral blood reconstitution, compared with a mock control. These data indicate that Caspase-3 is involved in the regulation of apoptosis, differentiation and proliferation of HSC. The molecular bases for these effects remain to be determined, but the multi-faceted nature of the changes seen suggest that Caspase-3 is central to multiple regulatory pathways in the stem cell compartment.
The Membrane Proximal Portion of the Thrombopoietin Receptor (Mpl) Elicits Novel Pivotal Signals for Hematopoietic Stem Cell Self-Renewal.
Authors: Tong Wei , Lodish Harvey F. 
Published: April 2020

Abstract
Thrombopoietin (Tpo) and its receptor, mpl, are important for hematopoietic stem cell (HSC) self-renewal in addition to their roles in megakaryocyte and platelet development. In this study we dissected the signaling pathways that mpl transduces to support megakaryocytopoiesis as well as stem cell production and function using knockin mice bearing a truncated mpl receptor lacking the distal 60 amino acids (delta-60). This 60 amino acid deletion removes three major signaling tyrosines on the mpl cytoplasmic domain, but retains the membrane proximal Box 1 and Box 2 domains that are required for JAK2 activation. We show that delta-60 bone marrow (BM) cells cultured in Tpo generated normal numbers of megakaryocytes but with greatly reduced ploidy. Freshly-isolated delta-60 megakaryocytes showed marked reduction in most, if not all, known Tpo-stimulated signaling pathways, including Stat5, Stat3, Akt, and p42/44MAPK. Using competitive bone marrow transplantation (BMT) to analyze HSC activities and serial BMT to assess HSC self-renewal, we found that delta-60 mice displayed normal short-term (ST-HSC) activities and marginally compromised long-term (LT-HSC) stem cell activities in primary BM transplantation. In addition, delta-60 mice supported HSC self-renewal for at least two serial BMTs. Thus, our results reveal a pivotal role for the membrane proximal region of the mpl receptor in maintaining stem cell activity and self-renewal by eliciting novel intracellular signaling pathways.
In Vitro and In Vivo Induction of Human Hematopoietic Stem Cell Migration by Extracellular UTP.
Authors: Rossi Lara , Manfredini Rossella , Bertolini Francesco , Ferrari Davide , Fogli Miriam , Zini Roberta , Salati Simona , Ferrari Sergio , Di Virgilio Francesco , Baccarani Michele , Lemoli Roberto M. 
Published: April 2020

Abstract
Regulatory mechanisms governing homing and engraftment of hematopoietic stem cells (HSCs) involve a complex interplay between chemokines, cytokines, growth factors and adhesion molecules in the intricate architecture of bone marrow (BM) microenvironment. HSCs express P2Y and P2X receptors for extracellular nucleotides, which activation by ATP and UTP has been recently demonstrated (Lemoli et al. Blood. 2004) to produce potent stimulatory effects on HSCs. Moreover extracellular nucleotides are emerging as key factors of flogosis phenomena and related chemotactic responses of several cell types, such as dendritic cells, monocytes and endothelial cells. In this study we investigated the biologic activity of extracellular ATP and UTP and their capacity to cooperatively promote SDF-1 (stromal cell-derived factor-1)-stimulated cell chemotaxis. Low concentrations of UTP (10uM) significantly improved, in vitro, HSCs migration. Moreover, UTP inhibits CXCR4 down-regulation of migrating CD34+ cells and increased cell adhesion to fibronectin filaments. Furthermore, in vivo competitive repopulation assays showed that preincubation with UTP significantly improved the homing efficiency of human CD34+ HSCs in nonobese diabetic/severe combined immunodeficient mice.
Inhibition assays with Pertussis Toxin from B. Pertussis blocked SDF-1- and UTP-dependent chemotactic responses, suggesting that Gαi proteins may provide a converging signal for CXCR4- and P2Y-activated transduction pathways. In addition, gene expression profiling of UTP-treated CD34+ cells and subsequent in vitro inhibition assays with Toxin B from C. Difficile suggest that RhoGTPase Rac2 and his downstream effectors ROCK1 and ROCK2 are involved in the UTP-promoted, SDF-1-dependent HSCs migration.
Taken together, our data suggest that UTP may physiologically modulate HSC migration and homing to the BM, in concert with the chemotactic peptide SDF-1, via the activation of converging signaling transduction pathways between CXCR4 and P2Y receptors, involving Gαi proteins and RhoGTPases.
Histone H3 Lysine 9 Methylation and HP1γ Are Associated with Transcription Elongation through Mammalian Chromatin.
Authors: Vakoc Christopher R. , Mandat Sean A. , Olenschock Ben A. , Blobel Gerd A. 
Published: April 2020

Abstract
Epigenetic regulation of gene expression plays a fundamental role during tissue specification and cellular memory. Cells that are committed to a given lineage, for example during hematopoiesis, “remember” their phenotype throughout successive rounds of cell division, reflecting alterations in chromatin structure at genes that are permanently activated or silenced. Cellular memory is anchored in specific sets of histone modifications, which together form the basis for the histone code. This is illustrated in the methylation of histone molecules: while methylation of histone H3 on lysines 4, 36, and 79 is linked with gene activation, methylation of H3 on lysines 9 and 27 and histone H4 on lysine 20 is associated with transcriptionally silent heterochromatin and repressed genes within euchromatin. Not surprisingly, dysregulation of histone methylation contributes to human diseases such as leukemias. Here we examined the methylation of histone molecules during gene activation and repression triggered by the hematopoietic transcription factor GATA-1. Surprisingly, we found that during activation by GATA-1 in erythroid cells, the levels of H3K9 di- and tri-methylation increase dramatically at all examined GATA-1-stimulated genes, including alpha- and beta-globin, AHSP, Band 3 and Glycophorin A. In contrast, at all GATA-1-repressed genes examined (GATA-2, c-kit, and c-myc) these marks are rapidly lost. Peaks of H3K9 methylation were observed in the transcribed portion of genes with lower signals at the promoter regions. Heterochromatin Protein 1γ (HP1γ), a protein containing a chromo-domain that recognizes H3K9 methylation, is also present in the transcribed region of all active genes examined. We extended these analyses to include numerous genes in diverse cell types (primary erythroid cells, primary T-lymphoid cells, epithelial cells and fibroblast) and consistently found a tight correlation between H3K9 methylation and gene activity, highlighting the general nature of our findings. Both the presence of HP1γ and H3K9 methylation at active genes are dependent upon transcription elongation by RNA polymerase II. Finally, HP1γ is in a physical complex with the elongating form of RNA polymerase II. Together, our results show that H3K9 methylation and HP1γ not only function in repressive chromatin, but play a novel and unexpected role during transcription activation. These results further elucidate new combinations of histone modifications that distinguish between repressed and actively transcribing chromatin.
Maturation Stage-Specific Regulation of Megakaryocytic Genes by Pointed-Domain Ets Proteins.
Authors: Pang Liyan , Wang Xun , Wang Yuhuan , Blobel Gerd , Poncz Mortimer 
Published: April 2020

Abstract
The pointed-domain Ets transcription factor Fli-1 has a critical role during megakaryocyte-specific gene expression. Previously, we demonstrated that Fli-1 occupies the early megakaryocyte-specific gene αIIb in vivo. Moreover, our work suggested a mechanism for Fli-1 function by showing that Fli-1 facilitates GATA-1/FOG-1 dependent expression of the αIIb gene. However, studies by others with a targeted disruption of the Fli-1 gene in mice showed that while Fli-1 is essential for normal megakaryocyte maturation, αIIb mRNA levels were not significantly reduced in the resulting megakaryocytes, suggesting that a related Ets factor(s) might compensate for the loss of Fli-1. Here we show that the widely expressed pointed domain Ets protein GABPα specifically binds in vitro to Ets elements from two early megakaryocyte-specific genes, αIIb and c-mpl. Chromatin immunoprecipitation (ChIP) experiments using primary murine fetal liver-derived megakaryocytes reveal that GABPα associates with αIIb and c-mpl in vivo. Moreover, GABPα is capable of mediating GATA-1/FOG-1 synergy in the context of αIIb promoter constructs. These results suggest that GABPα contributes to megakaryocyte-restricted gene expression and is capable of at least partially compensating for the loss of Fli-1. However, loss of Fli-1 leads to a pronounced decrease in the expression of the late megakaryocyte-specific gene GPIX, indicating that compensation by GABPα is incomplete. Consistent with this observation, ChIP experiments fail to detect significant levels of GABPα at the regulatory region of GPIX while Fli-1 is readily detected there. Together, these results point to a model in which Fli-1 and GABPα serve overlapping, but distinct roles, during the development of megakaryocytes. GABPα may be important during early megakaryopoiesis, but Fli-1 exerting an essential role during late stages of maturation.