Hematopoietic stem cells (HSCs) comprise a rare population of cells that can regenerate and maintain lifelong blood cell production. This functionality is achieved through their ability to undergo many divisions without activating a poised, but latent, capacity for differentiation into multiple blood cell types. Throughout life, HSCs undergo sequential changes in several key properties. These affect mechanisms that regulate the self-renewal, turnover and differentiation of HSCs as well as the properties of the committed progenitors and terminally differentiated cells derived from them. Recent findings point to the Lin28b-let-7 pathway as a master regulator of many of these changes with important implications for the clinical use of HSCs for marrow rescue and gene therapy, as well as furthering our understanding of the different pathogenesis of childhood and adult-onset leukemia.
Animals ; Cell Differentiation ; *Cell Lineage ; Embryonic Stem Cells/cytology/*metabolism ; HMGA2 Protein/genetics/metabolism ; Hematopoietic Stem Cells/cytology/*metabolism ; Humans ; Leukemia/etiology/metabolism/surgery ; MicroRNAs/genetics/metabolism ; RNA-Binding Proteins/genetics/metabolism

The aim of this study was to investigate the reconstitution of CD4(+)CD25(+) T cells after haplo-identical bone marrow transplantation (hiBMT) and its correlation with graft versus host disease (GVHD) and relapse. Peripheral blood samples from 27 patients after hiBMT were harvested and the percentage and absolute counts of CD4(+)CD25(+) T cells were detected by flow cytometry. The correlations of GVHD occurrence and disease relapse with the reconstitution of CD4(+)CD25(+) T cells were analyzed. The results showed that the percentage of CD4(+)CD25(+) T cells of peripheral blood samples increased significantly after G-CSF priming. At day 30 after hiBMT, CD4(+)CD25(+) T cells were recovered to the 20% of normal level, followed by a slowly process in 3 months, and up to one half of the normal level at 180 days. There was no evidence to prove relationship between CD4(+)CD25(+) T cells and acute GVHD, while CD4(+)CD25(+) T cells were increased significantly in the chronic GVHD group. The absolute count of CD4(+)CD25(+) T cells showed no relations with relapse of leukemia during the first year after hiBMT. In conclusions, chronic but not acute GVHD was in relation to the reconstitution of CD4(+)CD25(+) T cells based on the anti-CD25 antibody therapy model for the prevention of GVHD after hiBMT. Further investigation is needed to clarify whether the relapse of leukemia after hiBMT is related to the reconstitution of CD4(+)CD25(+) T cells.
Bone Marrow Transplantation ; CD4 Lymphocyte Count ; CD4-Positive T-Lymphocytes ; immunology ; Graft vs Host Disease ; etiology ; Humans ; Interleukin-2 Receptor alpha Subunit ; metabolism ; Leukemia ; immunology ; surgery