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.
SourceAvailable from: onlinelibrary.wiley.com[Show abstract] [Hide abstract]
ABSTRACT: Glycogen synthase kinase-3β (GSK-3β) has been identified as an important regulator of stem cell function acting through activation of the wingless (Wnt) pathway. Here, we report that treatment with an inhibitor of GSK-3β, 6-bromoindirubin 3'-oxime (BIO) delayed cell cycle progression by increasing cell cycle time. BIO treatment resulted in the accumulation of late dividing cells enriched with primitive progenitor cells retaining the ability for sustained proliferation. In vivo analysis using a Non-obese diabetic/severe combined immunodeficient (NOD/SCID) transplantation model has demonstrated that pretreatment with BIO promotes engraftment of ex vivo-expanded hematopoietic stem cells. BIO enhanced the engraftment of myeloid, lymphoid and primitive stem cell compartments. Limiting dilution analysis of SCID repopulating cells (SRC) revealed that BIO treatment increased human chimerism without increasing SRC frequency. Clonogenic analysis of human cells derived from the bone marrow of transplant recipient mice demonstrated that a higher level of human chimerism and cellularity was related to increased regeneration per SRC unit. Gene expression analysis showed that treatment with BIO did not modulate the expression of canonical Wnt target genes upregulated during cytokine-induced cell proliferation. BIO increased the expression of several genes regulating Notch and Tie2 signaling downregulated during ex vivo expansion, suggesting a role in improving stem cell engraftment. In addition, treatment with BIO upregulated CDK inhibitor p57 and downregulated cyclin D1, providing a possible mechanism for the delay seen in cell cycle progression. We conclude that transient, pharmacologic inhibition of GSK-3β provides a novel approach to improve engraftment of expanded HSC after stem cell transplantation.Stem Cells 01/2011; 29(1):108-18. DOI:10.1002/stem.551 · 7.70 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: Over the past decade, advances have been made in the care of patients undergoing transplantation. We conducted a study to determine whether these advances have improved the outcomes of transplantation. We analyzed overall mortality, mortality not preceded by relapse, recurrent malignant conditions, and the frequency and severity of major complications of transplantation, including graft-versus-host disease (GVHD) and hepatic, renal, pulmonary, and infectious complications, among 1418 patients who received their first allogeneic transplants at our center in Seattle in the period from 1993 through 1997 and among 1148 patients who received their first allogeneic transplants in the period from 2003 through 2007. Components of the Pretransplant Assessment of Mortality (PAM) score were used in regression models to adjust for the severity of illness at the time of transplantation. In the 2003-2007 period, as compared with the 1993-1997 period, we observed significant decreases in mortality not preceded by relapse, both at day 200 (by 60%) and overall (by 52%), the rate of relapse or progression of a malignant condition (by 21%), and overall mortality (by 41%), after adjustment for components of the PAM score. The results were similar when the analyses were limited to patients who received myeloablative conditioning therapy. We also found significant decreases in the risk of severe GVHD; disease caused by viral, bacterial, and fungal infections; and damage to the liver, kidneys, and lungs. We found a substantial reduction in the hazard of death related to allogeneic hematopoietic-cell transplantation, as well as increased long-term survival, over the past decade. Improved outcomes appear to be related to reductions in organ damage, infection, and severe acute GVHD. (Funded by the National Institutes of Health.).New England Journal of Medicine 11/2010; 363(22):2091-101. DOI:10.1056/NEJMoa1004383 · 54.42 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: Umbilical cord blood (UCB) is an attractive stem cell graft option for patients who need allogeneic hematopoietic stem cell support, but lack a suitable HLA-matched donor. However, the limited number of hematopoietic progenitor cells in a single cord blood unit can lead to an increased risk of graft failure, delayed hematological recovery and prolonged immunosuppression, particularly in adult patients. Several strategies to overcome these potential limitations are being evaluated. In this review, we discuss promising ex vivo manipulations to enhance cord blood engraftment capacity such as culture of UCB cells with stimulatory cytokines and growth factors, mesenchymal cells, Notch ligand, copper chelators, prostaglandins, complement components, nicotinamide and CD26/DPPIV inhibitors. All these approaches are now in early clinical trials. However, despite the fact that several cord blood enhancement strategies have resulted in increased numbers of progenitor cells and faster neutrophil recovery, the ability of these techniques to significantly shorten engraftment time and permit the use of cord units with low numbers of total nucleated cells, or accomplish reliable engraftment with a single cord, have yet to be convincingly demonstrated. The ultimate clinical value of ex vivo cord blood expansion or manipulation has not been defined yet, and the current data do not permit predicting which technology will prove to be the optimal strategy. Nevertheless, expectations remain high that eventually ex vivo enhancement will be able to improve clinical outcomes and significantly extend the applicability of UCB transplantation.Bone Marrow Transplantation advance online publication, 3 September 2012; doi:10.1038/bmt.2012.163.Bone marrow transplantation 09/2012; 48(7). DOI:10.1038/bmt.2012.163 · 3.47 Impact Factor