Response of human CD34+ cells to CXC, CC, and CX3C chemokines: implications for cell migration and activation.

Ultrastructural studies of marrow and examination of the in vivo processes of stem cell homing and mobilization show that multipotential hematopoietic progenitors are able to traverse endothelial cells. The regulation of this process by various classes of chemokines was studied in this report, using an in vitro model of transendothelial migration. Human umbilical vein endothelial cells (HUVECs) or bone marrow-derived endothelial cells (BMECs) were grown to confluence on 3-microm microporous membrane inserts and placed in 24-well culture plates.

MIP-1alpha and TGF-beta production in CD34+ progenitor-stromal cell coculture systems: effects of progenitor isolation method and cell-cell contact.

ABSTRACT Macrophage inflammatory protein-1alpha (MIP-1alpha) is a C-C chemokine which has antiproliferative effects on early hematopoietic progenitors and stimulatory effects on later progenitors. It also possesses chemotactic and activating properties for monocytes, macrophages, and T-cells. CD34+ progenitors isolated utilizing an avidin-biotin immunoadsorption column produced significant amounts of MIP-1alpha from 24 h onward when cultured in medium with 10% fetal calf serum (>200 pg/ml).

Effect of stromal cell coculture on progenitor cell expansion and myeloid effector function in vitro.

Stimulation of CD34(+)-enriched marrow or light density marrow with various growth factor combinations can generate granulocyte progenitors and mature neutrophils in vitro. In this work, we have examined the influence of irradiated marrow stromal layers on growth factor-induced myeloid and early multipotential progenitor expansion from enriched marrow CD34+ progenitors. We have also explored whether the addition of early-acting growth factors known to enhance myelopoiesis in long-term culture, such as fibroblast growth factor (b-FGF), insulin growth factor (IGF-1), c-kit ligand or stem cell factor (SCF), and flk-2flt-3 ligand (FL), can lengthen survival of CD34+ progenitors in these cultures.

Stem cell factor and stromal cell co-culture prevent apoptosis in a subculture of the megakaryoblastic cell line, UT-7.

The megakaryoblastic cell line, UT-7, is dependent for its growth upon interleukin-3 (IL-3), erythropoietin, or granulocyte-macrophage colony stimulating factor (GM-CSF). A subculture of this line can be maintained in recombinant human c-kit ligand [stem cell factor (SCF)] at 100 ng/ml without requirement for other growth factors. Removal of this subculture from SCF results in rapid loss of viability and decreased proliferation.

Effect of stem cell factor on myelopoiesis potential in human Dexter-type culture systems.

Hematopoiesis is influenced by the presence of the hematopoietic microenvironment, and Dexter-type liquid culture systems represent an in vitro representation of some aspects of the microenvironment that are optimal for the propagation of myeloid progenitors. Marrow stromal layers, which constitute part of these culture systems, produce growth factors, including stem cell factor (SCF), a ligand for the c-kit proto-oncogene that has been found to increase detection of myeloid, erythroid, and megakaryocytic progenitors in short-term marrow colony assays. In this work, the role of SCF in Dexter-type culture systems was examined to better define its contribution to steady-state myelopoiesis.