Genetic correlation between multiple myeloma and chronic lymphocytic leukaemia provides evidence for shared aetiology.

The clustering of different types of B-cell malignancies in families raises the possibility of shared aetiology. To examine this, we performed cross-trait linkage disequilibrium (LD)-score regression of multiple myeloma (MM) and chronic lymphocytic leukaemia (CLL) genome-wide association study (GWAS) data sets, totalling 11,734 cases and 29,468 controls. A significant genetic correlation between these two B-cell malignancies was shown (R = 0.

Subpopulations of T Regulatory Cells in Blood Stem Cell Harvests Influence Development of Acute Graft Versus Host Disease in Allogeneic Transplant Recipients.

Background: CD4 FoxP3 regulatory T cells (Tregs) are the potent suppressors of activation and proliferation of conventional T cells. Tregs subdivided by their expression of FoxP3 and CD45RA identify clinically important functional subsets.

Methods: We analyzed Treg subpopulations in hematopoietic stem cell harvests (SCH) from 22 allogeneic (matched unrelated and sibling) donors with flow cytometry by their expression of CD45RA, CD127, CD25, and FoxP3 marker combinations.

Integrin Based Isolation Enables Purification of Murine Lineage Committed Cardiomyocytes.

In contrast to mature cardiomyocytes which have limited regenerative capacity, pluripotent stem cells represent a promising source for the generation of new cardiomyocytes. The tendency of pluripotent stem cells to form teratomas and the heterogeneity from various differentiation stages and cardiomyocyte cell sub-types, however, are major obstacles to overcome before this type of therapy could be applied in a clinical setting. Thus, the identification of extracellular markers for specific cardiomyocyte progenitors and mature subpopulations is of particular importance.

A genome-wide association study identifies multiple susceptibility loci for chronic lymphocytic leukemia.

Genome-wide association studies (GWAS) of chronic lymphocytic leukemia (CLL) have shown that common genetic variation contributes to the heritable risk of CLL. To identify additional CLL susceptibility loci, we conducted a GWAS and performed a meta-analysis with a published GWAS totaling 1,739 individuals with CLL (cases) and 5,199 controls with validation in an additional 1,144 cases and 3,151 controls. A combined analysis identified new susceptibility loci mapping to 3q26.

Retinoic acid is involved in the metamorphosis of the anal fin into an intromittent organ, the gonopodium, in the green swordtail (Xiphophorus hellerii).

In poeciliid fish the male anal fin has been transformed into a gonopodium, an intromittent organ required for internal fertilization. Elevated testosterone levels induce metamorphosis of a subset of anal fin rays to grow and form the specialized terminal structures of the gonopodium. The molecular mechanisms underlying these processes are largely unknown.

Isolation of cardiomyocyte nuclei from post-mortem tissue.

Identification of cardiomyocyte nuclei has been challenging in tissue sections as most strategies rely only on cytoplasmic marker proteins(1). Rare events in cardiac myocytes such as proliferation and apoptosis require an accurate identification of cardiac myocyte nuclei to analyze cellular renewal in homeostasis and in pathological conditions(2). Here, we provide a method to isolate cardiomyocyte nuclei from post mortem tissue by density sedimentation and immunolabeling with antibodies against pericentriolar material 1 (PCM-1) and subsequent flow cytometry sorting.

Pharmacological interference with the glucocorticoid system influences symptoms and lifespan in a mouse model of Rett syndrome.

Rett syndrome (RTT) is caused by loss-of-function mutations in the X-linked gene MECP2 coding for methyl CpG-binding protein 2 (MeCP2). This protein can act as transcriptional repressor, and we showed in a previous study that glucocorticoid-inducible genes are up-regulated in an RTT mouse model and that these genes are direct MeCP2 targets. Here, we report that pharmacological intervention with the glucocorticoid system has an impact on the symptoms and lifespan in an RTT mouse model.

Myogenic reprogramming of bone marrow derived cells in a W⁴¹Dmd(mdx) deficient mouse model.

Lack of expression of dystrophin leads to degeneration of muscle fibers and infiltration of connective and adipose tissue. Cell transplantation therapy has been proposed as a treatment for intractable muscle degenerative disorders. Several reports have demonstrated the ability of bone-marrow derived cells (BMDC) to contribute to non-haematopoietic tissues including epithelium, heart, liver, skeletal muscle and brain following transplantation by means of fusion and reprogramming.

Tumor necrosis factor restricts hematopoietic stem cell activity in mice: involvement of two distinct receptors.

Whereas maintenance of hematopoietic stem cells (HSCs) is a requisite for life, uncontrolled expansion of HSCs might enhance the propensity for leukemic transformation. Accordingly, HSC numbers are tightly regulated. The identification of physical cellular HSC niches has underscored the importance of extrinsic regulators of HSC homeostasis.

Rho-guanine nucleotide exchange factors during development: Force is nothing without control.

The development of multicellular organisms is associated with extensive rearrangements of tissues and cell sheets. The driving force for these rearrangements is generated mostly by the actin cytoskeleton. In order to permit the reproducible development of a specific body plan, dynamic reorganization of the actin cytoskeleton must be precisely coordinated in space and time.

Multiple metastases from cutaneous malignant melanoma patients may display heterogeneous genomic and epigenomic patterns.

Disseminated melanoma is an aggressive disease with fatal outcome. Better understanding of the underlying biology is needed to find effective treatment. We applied microarray-based comparative genomic hybridization, gene expression and CpG island methylation analysis of primary tumors and multiple metastases from five melanoma patients with the aim of analyzing the molecular patterns of melanoma progression.

Cardiomyocyte cell cycle control and growth estimation in vivo--an analysis based on cardiomyocyte nuclei.

Aims: Adult mammalian cardiomyocytes are traditionally viewed as being permanently withdrawn from the cell cycle. Whereas some groups have reported none, others have reported extensive mitosis in adult myocardium under steady-state conditions. Recently, a highly specific assay of 14C dating in humans has suggested a continuous generation of cardiomyocytes in the adult, albeit at a very low rate.

Hedgehog, but not Odd skipped, induces segmental grooves in the Drosophila epidermis.

The formation of segmental grooves during mid embryogenesis in the Drosophila epidermis depends on the specification of a single row of groove cells posteriorly adjacent to cells that express the Hedgehog signal. However, the mechanism of groove formation and the role of the parasegmental organizer, which consists of adjacent rows of hedgehog- and wingless-expressing cells, are not well understood. We report that although groove cells originate from a population of Odd skipped-expressing cells, this pair-rule transcription factor is not required for their specification.

Molecular mechanisms of resistance to Rituximab and pharmacologic strategies for its circumvention.

The introduction of Rituximab has greatly improved therapeutic options for patients with B-cell non-Hodgkin lymphoma (B-NHL). However, a substantial fraction of patients with aggressive B-NHL fails first-line therapy, and most patients with relapsing indolent B-NHL eventually acquire Rituximab resistance. Molecular understanding of the underlying mechanisms facilitates the development of pharmacologic strategies to overcome resistance.

Characterization of bone marrow-derived mesenchymal stromal cells (MSC) based on gene expression profiling of functionally defined MSC subsets.

Background Aims: Human mesenchymal stromal cells (MSC) are promising candidates for cell therapy because of their intriguing properties (high proliferation and differentiation capacity, microenvironmental function and immune modulation). However, MSC are heterogeneous and a better understanding of the heterogeneity of the cells that form the MSC cultures is critical.

Methods: Human MSC were generated in standard cultures and stained with carboxyfluorescein succinimidyl ester (CFSE) for cell division tracking.

FLT3 receptor and ligand are dispensable for maintenance and posttransplantation expansion of mouse hematopoietic stem cells.

Originally cloned from hematopoietic stem cell (HSC) populations and its ligand being extensively used to promote ex vivo HSC expansion, the FMS-like tyrosine kinase 3 (FLT3; also called FLK2) receptor and its ligand (FL) were expected to emerge as an important physiologic regulator of HSC maintenance and expansion. However, the role of FLT3 receptor and ligand in HSC regulation remains unclear and disputed. Herein, using Fl-deficient mice, we establish for the first time that HSC expansion in fetal liver and after transplantation is FL independent.

Distinct and overlapping patterns of cytokine regulation of thymic and bone marrow-derived NK cell development.

Although bone marrow (BM) represents the main site for postnatal NK cell development, recently a distinct thymic-dependent NK cell pathway was identified. These studies were designed to investigate the role of cytokines in regulation of thymic NK cells and to compare with established regulatory pathways of BM-dependent NK cell compartment. The common cytokine receptor gamma-chain (Il2rg) essential for IL-15-induced signaling, and FMS-like tyrosine kinase 3 (FLT3) receptor ligand (Flt3l) were previously identified as important regulatory pathways of the BM NK cell compartment based on lack of function studies in mice, however their complementary action remains unknown.

Successful low-risk hematopoietic cell therapy in a mouse model of type 1 Gaucher disease.

Hematopoietic stem cell-based gene therapy offers the possibility of permanent correction for genetic disorders of the hematopoietic system. However, optimization of present protocols is required before gene therapy can be safely applied as general treatment of genetic diseases. In this study we have used a mouse model of type 1 Gaucher disease (GD) to demonstrate the feasibility of a low-risk conditioning regimen instead of standard radiation, which is associated with severe adverse effects.

FLT3 ligand and not TSLP is the key regulator of IL-7-independent B-1 and B-2 B lymphopoiesis.

Phenotypically and functionally distinct progenitors and developmental pathways have been proposed to exist for fetally derived B-1 and conventional B-2 cells. Although IL-7 appears to be the primary cytokine regulator of fetal and adult B lymphopoiesis in mice, considerable fetal B lymphopoiesis and postnatal B cells are sustained in the absence of IL-7; in humans, B-cell generation is suggested to be largely IL-7-independent, as severe combined immune-deficient patients with IL-7 deficiency appear to have normal B-cell numbers. However, the role of other cytokines in IL-7-independent B lymphopoiesis remains to be established.

Screening for copy-number alterations and loss of heterozygosity in chronic lymphocytic leukemia--a comparative study of four differently designed, high resolution microarray platforms.

Screening for gene copy-number alterations (CNAs) has improved by applying genome-wide microarrays, where SNP arrays also allow analysis of loss of heterozygozity (LOH). We here analyzed 10 chronic lymphocytic leukemia (CLL) samples using four different high-resolution platforms: BAC arrays (32K), oligonucleotide arrays (185K, Agilent), and two SNP arrays (250K, Affymetrix and 317K, Illumina). Cross-platform comparison revealed 29 concordantly detected CNAs, including known recurrent alterations, which confirmed that all platforms are powerful tools when screening for large aberrations.

Critical role of thrombopoietin in maintaining adult quiescent hematopoietic stem cells.

The role of cytokines in regulation of hematopoietic stem cells (HSCs) remains poorly understood. Herein we demonstrate that thrombopoietin (THPO) and its receptor, MPL, are critically involved in postnatal steady-state HSC maintenance, reflected in a 150-fold reduction of HSCs in adult Thpo(-/-) mice. Further, whereas THPO and MPL proved not required for fetal HSC expansion, HSC expansion posttransplantation was highly MPL and THPO dependent.

Elucidation of the phenotypic, functional, and molecular topography of a myeloerythroid progenitor cell hierarchy.

The major myeloid blood cell lineages are generated from hematopoietic stem cells by differentiation through a series of increasingly committed progenitor cells. Precise characterization of intermediate progenitors is important for understanding fundamental differentiation processes and a variety of disease states, including leukemia. Here, we evaluated the functional in vitro and in vivo potentials of a range of prospectively isolated myeloid precursors with differential expression of CD150, Endoglin, and CD41.

DRhoGEF2 and diaphanous regulate contractile force during segmental groove morphogenesis in the Drosophila embryo.

Morphogenesis of the Drosophila embryo is associated with dynamic rearrangement of the actin cytoskeleton mediated by small GTPases of the Rho family. These GTPases act as molecular switches that are activated by guanine nucleotide exchange factors. One of these factors, DRhoGEF2, plays an important role in the constriction of actin filaments during pole cell formation, blastoderm cellularization, and invagination of the germ layers.

Kit regulates maintenance of quiescent hematopoietic stem cells.

Hematopoietic stem cell (HSC) numbers are tightly regulated and maintained in postnatal hematopoiesis. Extensive studies have supported a role of the cytokine tyrosine kinase receptor Kit in sustaining cycling HSCs when competing with wild-type HSCs posttransplantation, but not in maintenance of quiescent HSCs in steady state adult bone marrow. In this study, we investigated HSC regulation in White Spotting 41 (Kit(W41/W41)) mice, with a partial loss of function of Kit.