High levels of committed erythroid and granulocytic/monocytic progenitor cells have been demonstrated in fresh blood obtained at fetoscopy. The fetal progenitor cells were more sensitive to appropriate stimuli (erythropoietin and colony-stimulating factor) than adult progenitor cells grown under the same conditions, and this was shown to be due to intrinsic differences in the progenitor cells a...

The aim of the present study was to determine whether stem cell factor (SCF) and erythropoietin (EPO) act differently on defined subsets of progenitor cells, and if potential differences correlate with the receptor density on each subset. To investigate this possibility directly, we optimized conditions for the identification and purification of homogeneous progenitor cell subpopulations from h...

Erythropoietin (EP), insulin-like growth factor I (IGF-I) and stem cell factor (SCF) each reduce apoptosis of human erythroid progenitor cells. To determine if these growth factors have additional roles in stimulating erythropoiesis, the proliferation, maturation, and survival of highly purified human erythroid colony-forming cells (ECFCs) were studied during the application of different combin...

Several lines of evidence indicate that macrophage inflammatory protein-1alpha (MIP-1alpha) modulates the proliferation of hematopoietic progenitor cells, depending on their maturational stages. To clarify the mechanisms for the modulation of hematopoiesis by this chemokine, we examined the expression of a receptor for MIP-1alpha, CCR1, on bone marrow cells of normal individuals using a specifi...

To study the expression of integrins at the erythroid progenitor level we isolated selected populations of cells from human fetal liver after immunoadherence to anti-beta 2 integrin (CD18) coated plates. These CD18 adherent cells (CD18-Ad), in contrast to CD18 nonadherent cells (CD18-NAd), have a blastlike cell morphology and are highly enriched in all progenitor types (14% to 37% progenitors)....

Diamond-Blackfan anemia (DBA), a congenital erythroblastopenia, is a model disease for the study of erythroid differentiation but is poorly understood. RPS19 is the only gene yet to have been associated with DBA, but its relevance to erythroid differentiation is unclear. The molecular basis for the stimulation of erythropoiesis by glucocorticoids in patients with DBA has not been identified. We...

Stem cell factor (SCF) and erythropoietin (Epo) effectively support erythroid cell development in vivo and in vitro. We have studied here an SCF/Epo-dependent erythroid progenitor cell from cord blood that can be efficiently amplified in liquid culture to large cell numbers in the presence of SCF, Epo, insulin-like growth factor-1 (IGF-1), dexamethasone, and estrogen. Additionally, by changing ...

Early erythroid precursor cells and myaloid progenitor cells (CFU-GM) from four patients with 5q syndrome ware cultured in order to study the in vitro growth patterns and to determine the clonal origin of this hamatologic disorder. Cultures of CFU-GM exhibited normal colony growth. while erythroid progenitor cells demonstrated a marked decrease or absence of colony growth. Chromosomal studas in...

In order to study the role of the cytokine interleukin-3 (IL-3) and its signaling pathways in erythropoiesis of beta-thalassemia/HbE erythroid progenitor cells, CD34 positive cells were isolated from peripheral blood of patients and healthy subjects. After culturing the cells in the presence or absence of IL-3, cell viability was measured by trypan blue staining and apoptotic cells were analyze...

Two tumor necrosis factor receptors (TNFRs) with molecular weights of 55 kD (TNFR-p55) and 75 kD (TNFR-p75) have recently been identified and cloned. In previous studies, TNFR-p55 has been shown to exclusively mediate bidirectional effects of TNF-alpha on committed bone marrow granulocyte-macrophage progenitor cells, whereas both TNFR-p55 and TNFR-p75 can mediate inhibition of primitive progeni...