International Journal of Cell Cloning, Vol 10, 105-115, Copyright © 1992 by AlphaMed Press
Peripheral blood hematopoietic progenitor/stem cells proliferate to form colonies in liquid culture but require contact with vascular endothelial cells and GM-CSF
RL Monroy, TA Davis, TB Nielsen and AJ Staton
Immune Cell Biology Program, Naval Medical Research Institute, Bethesda, Maryland 20889-5055.
To test the hypothesis whether peripheral blood hematopoietic
progenitor/stem cells (PBSCs) interact with vascular endothelial cells
during events leading to extramedullary hematopoiesis, we cocultured T-
cell depleted, peripheral blood mononuclear cells obtained from cytokine
treated primates in liquid culture containing a monolayer of porcine aortic
endothelial cells (PAECs) for 7 days. Recombinant human
granulocyte-macrophage colony-stimulating factor (GM-CSF) added to
cocultures of PBSC-PAEC stimulated colony formation, while only a few
clusters were observed in cultures without GM-CSF. In contrast, colony
formation was not stimulated when either interleukin 1 (IL-1) or IL-3 were
added to the cultures. Colony and cluster formation in response to GM-CSF
was dose dependent; 20 +/- 5 colonies/5,000 cells were formed at 3 U/ml,
and optimal colony formation of 42 +/- 11/5,000 cells occurred at 100 U/ml.
Colonies formed in the presence of GM-CSF were large, and most contained
greater than 200 cells. Morphological and phenotypical characterization of
cells from isolated colonies suggested that the majority of cells were
predominantly immature myeloid elements. However, there was also a low but
consistent frequency of megakaryocytic lineage cells. Thus, PBSCs interact
with non-bone marrow- -derived vascular endothelial cells and proliferate,
but only in the presence of GM-CSF, suggesting that PBSC interaction with
vascular endothelial cells in vivo could lead to extramedullary
hematopoiesis.
