International Journal of Cell Cloning, Vol 7, 330-342, Copyright © 1989 by AlphaMed Press
Diffusion chamber colony-forming unit (CFU-d): a primitive stem cell
E Niskanen, C Chatelain and M Symann
Department of Internal Medicine, University of Virginia, Charlottesville.
Assay of hematopoietic precursor cells in diffusion chambers (DCs)
implanted intraperitoneally in experimental animals provides a powerful
tool for studying stem cell kinetics in vivo. In this system, the effect of
cell migration (which complicates whole animal studies) is eliminated
because the membranes utilized in the construction of the chambers are
impermeable for cells, while permitting free passage of molecules present
in the humoral phase of the host. As judged by light microscopy, conditions
in the DC cultures primarily favor macrophage and granulocyte growth.
However, the use of in vitro and in vivo subculture to further analyze
chamber contents has demonstrated that the system supports proliferation of
early hematopoietic progenitors. Additionally, cells capable of rescuing
lethally irradiated mice proliferate in DC cultures. Development of the
plasma clot DC technique has revealed that most of the growth occurs in
colonies which are derived from single cells (CFU-d). Characterization of
these cells indicates that they are at least as primitive as other
colony-forming cells and, also based on subculture studies, can
differentiate along several hematopoietic lineages. In addition to normal
CFU-d, both embryonal and leukemic cells can give rise to granulocytes,
macrophages, megakaryocytes and erythroid cells in the DC cultures.
Evaluation of the effects of humoral factors on hematopoietic cell
proliferation and differentiation in the system has led to the
identification of both stimulators and inhibitors that may be different
from the well-characterized cytokines. Thus, the system seems to be useful
for detecting molecules controlling the most primitive stages of
hematopoiesis. We believe that the DC culture technique holds enormous
potential in the study of stem cell proliferation and differentiation in
vivo.
