Umbilical cord blood (UCB) is a source of stem cells used for allogeneic transplantation, in addition to bone marrow and peripheral blood. Limited numbers of stem cells in a single UCB unit is associated with slow haematopoietic recovery and high risk of graft failure, particularly in adult patients. UCB stem cells can be expanded ex vivo; however, rapid differentiation reduces their regenerative potential. We have recently shown that Wnt/β-catenin signalling is down-regulated in ex vivo-expanded stem cells; therefore, we propose that re-activation of Wnt signalling using GSK-3β inhibition may act to improve regenerative potential of these ex vivo-expanded stem cells.
Immunocompromised mice were employed in transplantation studies to determine stem-cell engraftment. Flow cytometry was used to phenotype the engrafted human cells. Retroviral gene transfer was used to examine the role of Myc gene up-regulated by GSK-3β inhibition, in ex vivo-expanded stem cells.
Treatment with GSK-3β inhibitor, 6-bromoindirubin 3'-oxime (BIO) improved early human cell engraftment in the mice and elevated the numbers of myeloid progenitor cells in cytokine-stimulated culture. BIO up-regulated β-catenin and c-myc in ex vivo-expanded stem cells. Ectopic expression of Myc acted to increase clonogenic potential and to delay differentiation of haematopoietic progenitor cells, suggesting the potential mechanism to improve regenerative potential of ex vivo-expanded grafts.
Pharmacological inhibition of GSK-3β provided a novel approach to improve early engraftment of ex vivo-expanded haematopoietic progenitor cells.
"In this regard, it was reported that Wnt1 signaling could stimulate ex vivo expansion of CB by enhancing HSC proliferative properties and by stabilizing the expression of pluripotency and self-renewal genes (Chotinantakul et al., 2013). Other studies have shown that GSK-3beta inhibitors determine an activation of Wnt signaling, an expansion of HSCs and improved early human cell engraftment in nude mice (Dolnikov et al., 2014). In addition to Wnt, the NOTCH signaling pathway is of fundamental importance in the control of HSC self-renewal: in fact, ex vivo culture of CD34 þ CB stem/progenitor cells in the presence of NOTCH ligand resulted in a greater than 100-fold increase in CD34 þ cells repopulating immunodeficient mice (Delaney et al., 2010). "
[Show abstract][Hide abstract] ABSTRACT: MicroRNAs (miRNAs) are important regulators of several cellular processes. During hematopoiesis, specific expression signatures have been reported in different blood cell lineages and stages of hematopoietic stem cell (HSC) differentiation. Here we explored the expression of miRNAs in umbilical cord blood stem (HSC) and progenitor cells (HPC) and compared it to unilineage granulocyte and granulo-monocyte differentiation as well as to primary blasts from patients with acute myeloid leukemia (AML). CD34+CD38- ad CD34+CD38+ cells were profiled using a global array consisting of about 2000 miRNAs. An approach combining bioinformatic prediction of miRNA targets with mRNA expression profiling was used to search for putative biologically enriched functions and networks. At least fifteen miRNAs to be differentially expressed between HSC and HPC cell population, a cluster of 7 miRNAs are located in the q32 region of human chromosome 14 (miR-377-3p, -136-5p, 376a-3p, 495-3p, 654-3p, 376c-3p and 381-3p) whose expression decreased during the early stages of normal myelopoiesis but were markedly increased in a small set of AML. Interestingly, miR-4739 and -4516, two novel microRNA whose function and targets are presently unknown, showed specific and peculiar expression profile during the hematopoietic stem cells differentiation into unilineages and resulted strongly upregulated in almost all AML subsets. miR-181, -126-5p, -29b-3p and -22-3p resulted dis-regulated in specific leukemias phenotypes.This study provides the first evidence of a miRNA signature in human cord blood stem and progenitor cells with a potential role in hematopoietic stemness properties and possibly in leukemogenesis of specific AML subtypes. This article is protected by copyright. All rights reserved
[Show abstract][Hide abstract] ABSTRACT: Obesity markedly increases susceptibility to a range of diseases and simultaneously undermines the viability and fate selection of haematopoietic stem cells (HSCs), and thus the kinetics of leukocyte production that is critical to innate and adaptive immunity. Considering that blood cell production and the differentiation of HSCs and their progeny is orchestrated, in part, by complex interacting signals emanating from the bone marrow microenvironment, it is not surprising that conditions that disturb bone marrow structure inevitably disrupt both the numbers and lineage-fates of these key blood cell progenitors. In addition to the increased adipose burden in visceral and subcutaneous compartments, obesity causes a marked increase in the size and number of adipocytes encroaching into the bone marrow space, almost certainly disturbing HSC interactions with neighbouring cells, which include osteoblasts, osteoclasts, mesenchymal cells and endothelial cells. As the global obesity pandemic grows, the short-term and long-term consequences of increased bone marrow adiposity on HSC lineage selection and immune function remain uncertain. This Review discusses the differentiation and function of haematopoietic cell populations, the principal physicochemical components of the bone marrow niche, and how this environment influences HSCs and haematopoiesis in general. The effect of adipocytes and adiposity on HSC and progenitor cell populations is also discussed, with the goal of understanding how obesity might compromise the core haematopoietic system.
[Show abstract][Hide abstract] ABSTRACT: Small molecule inhibitors of glycogen synthase kinase 3β (GSK3β) have demonstrated strong anti-leukaemia effects in pre-clinical studies. Here we investigated the effect of GSK3β inhibitor 6-Bromoindirubin-3-oxime (BIO) previously shown to inhibit leukaemia cell growth in vitro and animal models on haematopoietic regeneration in recipients of stem cell transplant. BIO administered to immunocompromised mice transplanted with human haematopoietic stem cells inhibited human stem cell engraftment in the bone marrow and peripheral blood. BIO reduced CD34+ progenitor cells in the bone marrow, and primitive lymphoid progenitors re-populated host thymus at later stages post-transplant. The development of all T cell subsets in the thymus was suppressed in BIO-treated mice. Human cell engraftment was gradually restored after discontinuation of BIO-treatment, however, T cell depletion remained until the end of experiment which correlated with the attenuated thymic function in the host. BIO delayed CD34+ cell expansion in stroma-supported or cytokine only cultures. BIO treatment delayed progenitor cell divisions and induced apoptosis in cultures with sub-optimal cytokine support. In addition, BIO inhibited B and T cell development in co-cultures with MS5 and OP9-DL1 BM stroma cells, respectively. These data suggest that administration of GKS3β inhibitors may act to delay haematopoietic regeneration in patients that received stem cell transplant.
Stem Cells and Development 10/2014; 24(6). DOI:10.1089/scd.2014.0230 · 3.73 Impact Factor
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