Leukaemia progressively invades bone marrow (BM), outcompeting healthy haematopoiesis by mechanisms that are not fully understood. Combining cell number measurements with a short-timescale dual pulse ...labelling method, we simultaneously determine the proliferation dynamics of primitive haematopoietic compartments and acute myeloid leukaemia (AML). We observe an unchanging proportion of AML cells entering S phase per hour throughout disease progression, with substantial BM egress at high levels of infiltration. For healthy haematopoiesis, we find haematopoietic stem cells (HSCs) make a significant contribution to cell production, but we phenotypically identify a quiescent subpopulation with enhanced engraftment ability. During AML progression, we observe that multipotent progenitors maintain a constant proportion entering S phase per hour, despite a dramatic decrease in the overall population size. Primitive populations are lost from BM with kinetics that are consistent with ousting irrespective of cell cycle state, with the exception of the quiescent HSC subpopulation, which is more resistant to elimination.
Lymph nodes (LN) are crucial for immune function, and comprise an important interface between the blood and lymphatic systems. Blood vessels (BV) in LN are highly specialized, featuring high ...endothelial venules across which most of the resident lymphocytes crossed. Previous measurements of overall lymph and BV flow rates demonstrated that fluid also crosses BV walls, and that this is important for immune function. However, the spatial distribution of the BV in LN has not been quantified to the degree necessary to analyse the distribution of transmural fluid movement. In this study, we seek to quantify the spatial localization of LNBV, and to predict fluid movement across BV walls. MicroCT imaging of murine popliteal LN showed that capillaries were responsible for approximately 75% of the BV wall surface area, and that this was mostly distributed around the periphery of the node. We then modelled blood flow through the BV to obtain spatially resolved hydrostatic pressures, which were then combined with Starling's law to predict transmural flow. Much of the total 10 nL/min transmural flow (under normal conditions) was concentrated in the periphery, corresponding closely with surface area distribution. These results provide important insights into the inner workings of LN, and provide a basis for further exploration of the role of LN flow patterns in normal and pathological functions.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
When beta-catenin signalling is disturbed from mid-gestation onwards lineage commitment is profoundly altered in postnatal mouse epidermis. We have investigated whether adult epidermis has the ...capacity for beta-catenin-induced lineage conversion without prior embryonic priming. We fused N-terminally truncated, stabilised beta-catenin to the ligand-binding domain of a mutant oestrogen receptor (DeltaNbeta-cateninER). DeltaNbeta-cateninER was expressed in the epidermis of transgenic mice under the control of the keratin 14 promoter and beta-catenin activity was induced in adult epidermis by topical application of 4-hydroxytamoxifen (4OHT). Within 7 days of daily 4OHT treatment resting hair follicles were recruited into the hair growth cycle and epithelial outgrowths formed from existing hair follicles and from interfollicular epidermis. The outgrowths expressed Sonic hedgehog, Patched and markers of hair follicle differentiation, indicative of de novo follicle formation. The interfollicular epidermal differentiation program was largely unaffected but after an initial wave of sebaceous gland duplication sebocyte differentiation was inhibited. A single application of 4OHT was as effective as repeated doses in inducing new follicles and growth of existing follicles. Treatment of epidermis with 4OHT for 21 days resulted in conversion of hair follicles to benign tumours resembling trichofolliculomas. The tumours were dependent on continuous activation of beta-catenin and by 28 days after removal of the drug they had largely regressed. We conclude that interfollicular epidermis and sebaceous glands retain the ability to be reprogrammed in adult life and that continuous beta-catenin signalling is required to maintain hair follicle tumours.
Blood vessels inside the bone marrow (BM) play a vital role in the maintenance of hematopoietic stem cell (HSCs). Investigating the interaction of HSCs relative to vasculature has become the main ...headline for many recent studies. Advances in microscopy and image analysis using mouse models have allowed detection, identification and automated quantification of HSCs alongside their vascular niche. This resulted in new hypotheses concerning the activation state of HSCs adjacent to different blood vessel types (for example sinusoids vs. arterioles). Identifying the different types of BM vasculature has become critically important, however it still requires the use of complex immunostainings ex vivo or transgenic reporter mouse lines in vivo. To eliminate these requirements and increase the throughput of studies focusing on the HSC niche, we present a machine learning classification approach based on the Decision Tree Classifier to classify different regions of bone marrow vasculature into four distinct classes based on their discriminative features.
Physiological stem cell function is regulated by secreted factors produced by niche cells. In this study, we describe an unbiased approach based on the differential single-cell gene expression ...analysis of mesenchymal osteolineage cells close to, and further removed from, hematopoietic stem/progenitor cells (HSPCs) to identify candidate niche factors. Mesenchymal cells displayed distinct molecular profiles based on their relative location. We functionally examined, among the genes that were preferentially expressed in proximal cells, three secreted or cell-surface molecules not previously connected to HSPC biology—the secreted RNase angiogenin, the cytokine IL18, and the adhesion molecule Embigin—and discovered that all of these factors are HSPC quiescence regulators. Therefore, our proximity-based differential single-cell approach reveals molecular heterogeneity within niche cells and can be used to identify novel extrinsic stem/progenitor cell regulators. Similar approaches could also be applied to other stem cell/niche pairs to advance the understanding of microenvironmental regulation of stem cell function.
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•Single-cell RNA-seq of HSPC-proximal stromal cells identifies niche cells•HSPC-proximal cells have a distinct RNA-seq profile compared to HSPC-distal cells•Proximal cell signature identifies niche regulators of stem/progenitor function•Three representative niche factors regulate HSPC quiescence in vivo
Silberstein et al. describe an approach combining micro-anatomical proximity between stem/progenitor cells and stromal cells and differential single-cell gene expression to identify niche cells and factors regulating HSPC function. With adaptation, this approach could be applied to discover regulatory niche factors for other stem cell populations.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Uno de los genes implicados en el crecimiento de la fibra y los folículos pilosos es el factor de crecimiento fibroblástico 5 (FGF5). La mutación de este gen se ha asociado a fenotipos de pelo largo ...en varias especies animales, incluidas las llamas y las alpacas. Se tomaron muestras de sangre de 16 alpacas (9 Huacaya y 7 Suri), 6 llamas (4 Q'aras y 2 Chak'us), una vicuña y un guanaco. Los polimorfismos relacionados con el crecimiento de las fibras se analizaron a partir de una secuencia del genoma completo. Se encontró que la mutación c.499≥T está presente en alpacas Huacaya y Suri codificando una proteína corta de 166 aminoácidos. Una delección de un nucleótido, c.351 del C y una inserción de 12 nucleótidos (c.348_349insGCCATATAACAT) estaban presentes en las llamas Chak'u. Esta inserción codifica para una proteína corta de 119 aminoácidos que afecta al gen FGF5 y que provocaría el crecimiento de fibras largas. En el caso de la mutación en la posición c.499C>T, que provoca un codón de parada prematuro en el aminoácido 166, estando implicado en la longitud del vellón de las alpacas. Si no hay cambio en el gen FGF5, el crecimiento de la fibra no se estimula y es lo que ocurre en las llamas Q’ara, en la vicuña y guanaco, que presentan una longitud completa del gen con 270 aminoácidos. El estudio indica que, si el gen FGF5 es funcional, los camélidos sudamericanos tendrán un crecimiento de fibra corto, pero si hay mutaciones que afectan la expresión del gen FGF5, los animales tendrán vellones largos, y eso ocurriría en el caso de alpacas Huacaya y Suri, así como en llamas Ckak'u.
In epithelial cells, hepatocyte growth factor (HGF) activates a genetic program involving cell-cell dissociation ("scattering"), growth and invasiveness. The full program is not elicited by other ...growth factors like epidermal growth factor, and is aberrantly activated during cancer progression to the invasive-metastatic phenotype. To identify genes involved in the onset of invasive growth, we explored by cDNA microarrays the in vitro transcriptional response to HGF of mouse embryo liver cells. We identified osteopontin (OPN), a secreted matrix protein, as a major HGF transcriptional target. The wave of OPN induction is maximal at 6 h, in concomitance with the initiation of scattering, and is specific, because no other matrix protein among those explored by the microarray is affected. Interestingly, HGF, but not epidermal growth factor, promotes cell adhesion to OPN via the CD44 receptor. Scattering is significantly impaired by antibodies against OPN and CD44; conversely, constitutive OPN overexpression dramatically increases the motile and invasive responses to HGF, leading to disruption of the ordered morphogenetic program triggered by this ligand.
Using K14ΔNβ-cateninER transgenic mice, we show that short-term, low-level β-catenin activation stimulates de novo hair follicle formation from sebaceous glands and interfollicular epidermis, while ...only sustained, high-level activation induces new follicles from preexisting follicles. The Hedgehog pathway is upregulated by β-catenin activation, and inhibition of Hedgehog signaling converts the low β-catenin phenotype to wild-type epidermis and the high phenotype to low. β-catenin-induced follicles contain clonogenic keratinocytes that express bulge markers; the follicles induce dermal papillae and provide a niche for melanocytes, and they undergo 4OHT-dependent cycles of growth and regression. New follicles induced in interfollicular epidermis are derived from that cellular compartment and not through bulge stem cell migration or division. These results demonstrate the remarkable capacity of adult epidermis to be reprogrammed by titrating β-catenin and Hedgehog signal strength and establish that cells from interfollicular epidermis can acquire certain characteristics of bulge stem cells.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The European Hematology Association (EHA) Roadmap for European Hematology Research highlights major achievements in diagnosis and treatment of blood disorders and identifies the greatest unmet ...clinical and scientific needs in those areas to enable better funded, more focused European hematology research. Initiated by the EHA, around 300 experts contributed to the consensus document, which will help European policy makers, research funders, research organizations, researchers, and patient groups make better informed decisions on hematology research. It also aims to raise public awareness of the burden of blood disorders on European society, which purely in economic terms is estimated at €23 billion per year, a level of cost that is not matched in current European hematology research funding. In recent decades, hematology research has improved our fundamental understanding of the biology of blood disorders, and has improved diagnostics and treatments, sometimes in revolutionary ways. This progress highlights the potential of focused basic research programs such as this EHA Roadmap.The EHA Roadmap identifies nine 'sections' in hematology: normal hematopoiesis, malignant lymphoid and myeloid diseases, anemias and related diseases, platelet disorders, blood coagulation and hemostatic disorders, transfusion medicine, infections in hematology, and hematopoietic stem cell transplantation. These sections span 60 smaller groups of diseases or disorders.The EHA Roadmap identifies priorities and needs across the field of hematology, including those to develop targeted therapies based on genomic profiling and chemical biology, to eradicate minimal residual malignant disease, and to develop cellular immunotherapies, combination treatments, gene therapies, hematopoietic stem cell treatments, and treatments that are better tolerated by elderly patients.
Objetivo: Determinar la prevalencia de anticuerpos para leptospiras en personas asintomáticas en las localidades dedicadas al comercio y la agricultura de la provincia de Coronel Portillo, del ...departamento de Ucayali. Asimismo determinar la prevalencia de leptospirosis en animales domésticos. Material y Métodos: En este estudio transversal analítico, se tomó muestras de suero de 364 pobladores de 4 localidades, en quienes se evaluó la presencia de anticuerpos totales contra leptospiras en suero por el método de ELISA y la prueba de microaglutinación (MAT). Se realizó el análisis estadístico para ver el grado de asociación entre las características generales de la población y la información recopilada en la encuesta con la positividad para anticuerpos para leptospiras. De la misma manera, se tomó muestras de suero de 374 animales domésticos (canes) a los que se realizó MAT. Resultados: Se enrolaron 364 personas de las cuales 227 (62,4%) fueron mujeres y 137 (37,6%) varones, 114 (31,3%) pobladores tuvieron anticuerpos contra leptospiras y los serovares más frecuentes fueron Bratislava y Georgia según MAT, los probables factores asociados a la positividad a anticuerpos para leptospiras en los pobladores fueron: guardar alimentos en el hogar (OR=2,221), ser agricultor (OR=3,418), ser obrero y agricultor (OR=2,088), eliminar basura en el campo (OR=2,348). En canes, 181 (52,2%) tuvieron serología positiva a leptospiras. Conclusiones: Existe una alta prevalencia de serología positiva para leptospiras en población general asintomática y condiciones favorables para la presencia de leptospiras en las localidades estudiadas. En estas zonas se recomienda realizar actividades educativas preventivas frecuentes, tomando en cuenta los resultados de este estudio.
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