International Journal of Cell Cloning, Vol 7, 373-384, Copyright © 1989 by AlphaMed Press
Multilineage hemopoiesis induced by cloned stromal cells
M Tamir, N Harris, N Trainin, J Toledo and D Zipori
Department of Cell Biology, Weizmann Institute of Science, Rehovot, Israel.
Long-term hemopoiesis in culture depends upon the presence of an adherent
layer composed of a variety of stromal cells. A subtype of
endothelial-adipocytes from the bone marrow stroma (clone 14F1.1) was
previously shown to induce long-term myelopoiesis and renewal of
pluripotent stem cells. One of a series of stromal cell lines and clones
from mouse thymus stroma (STAC-1.2) has now been found to support long-term
hemopoiesis. These marrow- and thymus-derived stromal cell clones also have
lymphopoietic activities: precursor T cells, or pre-B cells accumulated in
co-cultures of thymus cells and the stromal clones, as indicated by cell
surface markers, T cell receptor and immunoglobulin gene rearrangements.
The predominance of a cell type in these cultures depended upon the serum
used to supplement the medium. Recombinant interleukin 2 (IL-2) and the
14F1.1 clone synergistically promoted the proliferation of thymocytes,
while a thymus hormone, THF- gamma 2, shifted the population to a
relatively mature phenotype. It is proposed that one major function of
stromal cells, whether from the bone marrow or thymus, is to restrain the
maturation flow and preferentially support the accumulation of cells at
early differentiation stages.
