GSK-3β inhibition promotes early engraftment of ex vivo- expanded haematopoietic stem cells
ABSTRACT 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.
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- "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). "
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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.Nature Reviews Endocrinology 10/2014; 10(12). DOI:10.1038/nrendo.2014.169 · 12.96 Impact Factor
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