In the absence of conclusive assays capable of determining the functionality of ex vivo expanded human hematopoietic progenitor cells, we combined cell tracking with the membrane dye PKH2, immunostaining for CD34, and limiting dilution analysis to estimate the frequency of long-term hematopoietic culture-initiating cells (LTHC-ICs) among de novo-generated CD34+ cells. Umbilical cord blood (CB) ...

The susceptibility of highly purified human CD34+ cells to monocytotropic (Ba-L) and lymphotropic (A018-post) strains of human immunodeficiency virus-1 (HIV-1) was examined. Liquid cultures initiated with fresh immunomagnetically purified CD34+ cells using the K6.1 CD34 monoclonal antibody (MoAb) (K6.1/CD34+) were positive for HIV expression 2 weeks after exposure to HIV-1 Ba-L. These cells wer...

Hematopoietic progenitor cells migrate in vitro and in vivo towards a gradient of the chemotactic factor stromal cell-derived factor-1 (SDF-1) produced by stromal cells. This is the first chemoattractant reported for human CD34 1 progenitor cells. Concentrations of SDF-1 that elicit chemotaxis also induce a transient elevation of cytoplasmic calcium in CD34 1 cells. SDF-1-induced chemotaxis is ...

To clarify the phenotypes of various classes of human hematopoietic progenitor cells, we used a multicolor staining protocol in conjunction with CD34 and a newly developed mouse antihuman c-kit proto-oncogene product (KIT) monoclonal antibody (MoAb). We characterized three cell fractions in CD34+ cells that express KITlow and KIThigh cells in addition to KIT- cells. A clonogenic assay showed th...

Primed peripheral blood hematopoietic stem cells (PBSC) generate and sustain lymphohematopoiesis in myeloablated animals, and recent reports indicate that allogeneic transplantation using PBSC grafts may be feasible in humans. A major concern with the use of PBSC transplants is that permanent engraftment may be limited because of lack of sufficient numbers of primitive progenitor cells in the g...

Peripheral blood mononuclear cells (PBMC) from patients with multiple myeloma (MM) are here shown to include 23% +/- 2% of CD34+ cells, the majority of which coexpress CD19, as identified by a panel of 17 anti-CD34 antibodies. The expression of CD34 mRNA by sorted CD34+ PBMC from MM was confirmed by in situ reverse transcriptase-polymerase chain reaction (RT-PCR) with CD34-specific primers. The...

CD34 is frequently used as a marker of adipose-derived stem/stromal/progenitor cells (ASCs). However, CD34 expression in human ASCs (hASCs) decreases over time in culture, and the implications of this remain unclear. In this study, we sorted shortly-cultured hASCs into CD34+ and CD34- fractions and compared their biological functions. Results indicated that CD34+ hASCs were more proliferative a...

INTRODUCTION Despite the crucial role of endothelial progenitor cells (EPCs) in vascular regeneration, the specific interactions between EPCs and hematopoietic cells remain unclear. METHODS In EPC colony forming assays, we first demonstrated that the formation of EPC colonies was drastically increased in the coculture of CD34+ and CD34- cells, and determined the optimal concentrations of CD34...

Aplastic anemia (AA) is a bone marrow failure syndrome that is caused largely by profound quantitative and qualitative defects of hematopoietic stem and progenitor cells. However, the mechanisms underlying these defects remain unclear. Under conditions of stress, autophagy acts as a protective mechanism for cells. We therefore postulated that autophagy in CD34+ hematopoietic progenitor cells (H...

Recently we reported that the human thymus contains a minute population of CD34+CD38dim cells that do not express the T-cell lineage markers CD2 and CD5. The phenotype of this population resembled that of CD34+CD38dim cells present in fetal liver, umbilical cord blood, and bone marrow known to be highly enriched for pluripotent hematopoietic stem cells. In this report we tested the hypothesis t...