Identification of variables determining the engraftment potential of human acute myeloid leukemia in the immunodeficient NOD/SCID human chimera model (original) (raw)
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Transplanted Hematopoietic Cells Seed in Clusters in Recipient Bone Marrow In Vivo
Stem Cells, 2002
The process of hematopoietic stem and progenitor cell (HSPC) seeding in recipient bone marrow (BM) early after transplantation is not fully characterized. In vivo tracking of HSPCs, labeled with PKH dyes, through an optical window surgically implanted on the mouse femur revealed that transplanted cells cluster in the recipient BM. Within the first day after intravenous injection, 86 +/- 6% of the cells seeded in clusters (p < 0.001 versus scattered cells) in the endosteal surfaces of the epiphyses. The primary clusters were formed by concomitant seeding of 6-10 cells over an area of approximately 70 microm, and secondarily injected cells did not join the already existing clusters but formed new clusters. Major antigen-disparate HSPCs participated in formation of the primary clusters, and T lymphocytes were also incorporated. After 4 to 5 days, some cellular clusters were observed in the more central regions of the BM, where the brightness of PKH fluorescence decreased, indicating cellular division. These later clusters were classified as secondary, assuming that the mechanisms of migration in the BM might be different from those of primary seeding. Some clusters remained in the periphery of the BM and retained bright fluorescence, indicating cellular quiescence. The number of brightly fluorescent cells in the clusters decreased exponentially to two to three cells after 24 days (p < 0.001). The data suggest that the hematopoietic niche is a functional unit of the BM stromal microenvironment that hosts seeding of a number of transplanted cells, which form a cluster. This may be the site where auxiliary non-HSPC cells, such as T lymphocytes, act in support of HSPC engraftment.
An in vivo competitive repopulation assay for various sources of human hematopoietic stem cells
Blood, 2000
The marrow repopulating potential (MRP) of different sources of human hematopoietic stem cells (HSCs) was directly compared using an in vivo assay in which severe combined immunodeficient disease (SCID) mice were implanted with human fetal bones. HSCs from 2 human lymphocyte antigen (HLA)-mismatched donors were injected individually or simultaneously into the fetal bones of a 3rd distinct HLA type and donor and recipient myeloid and lymphoid cells were identified after 8 to 10 weeks. The study compared the MRP of umbilical cord blood (CB) and adult bone marrow (ABM) CD34(+) cells as well as grafts of each type expanded ex vivo. Equal numbers of CB and ABM CD34(+) cells injected individually demonstrated similar abilities to establish multilineage hematopoiesis. However, when CB and ABM cells were transplanted simultaneously, the engraftment of CB cells was markedly superior to ABM. CB and ABM CD34(+) cells were expanded ex vivo using either a porcine microvascular endothelial cell (...
Engraftment of hematopoietic stem cells in nonmyeloablated and myeloablated hosts
Stem Cells, 1997
Hematopoietic stem cell engraftment has traditionally been assessed in irradiated murine hosts. More recently, we and others have shown that engraftment is virtually quantitative in host animals who have received no preconditioning myeloablation. It appears that at the stem cell level, engraftment may even be favored in the normal host. The final phenotypic readout in the engrafted animal is then determined by competition between the engrafted stem cells and the number of residual host stem cells. Further studies have indicated that with cytokine exposure in vitro, in vivo or 5-fluorouracil exposure and consequent stimulation of primitive hematopoietic stem cells to enter cell cycle, an engraftment defect relating to long-term engraftment occurs. This occurs in the face of an expansion of cycling surrogate stem cells as mirrored by the high proliferative potential colony-forming cell. These data indicate that the phenotype of the hematopoietic stem cell, as assessed in vitro, may not give insight into the phenotype of these cells in vivo. Stem Cells 1997;15(supp11):167-170 DISCUSSION Dr. Spangrude: You showed in the NOD-SCID transplants with human cord blood that you could detect human cells in peripheral blood as well as marrow and spleen. I understood from others that you did not normally see circulating human cells in these chimerics.
Bone Marrow Transplantation, 2011
The CD34 รพ compartment of grafts for clinical allogeneic hematopoietic cell transplantation (HCT) is very heterogeneous. It contains hematopoietic stem cells and several different progenitor cell populations. This study assesses (1) the content of these populations in clinical grafts from G-CSF-mobilized PBMCs, BM and cord blood, (2) the functional correlation of the graft composition with time to engraftment of neutrophils, platelets and reticulocytes and (3) donor age-related changes. Quantitative flow cytometry showed that the distribution of the progenitor subsets differed significantly between the graft sources and that donor age-related changes occur. In patients after myeloablative allogeneic HCT, accelerated platelet and reticulocyte engraftment correlated with the content of common myeloid and/or megakaryocyte erythroid progenitors in the graft. These findings show that a better understanding of the progenitor compartment in human hematopoietic grafts could lead to improved strategies for the development of cellular therapies, for example in situations where platelet engraftment is delayed.