Role of cytokines in sustaining long-term human megakaryocytopoiesis in
vitro
RA Briddell, JE Brandt, TB Leemhuis and R Hoffman
Department of Medicine, Indiana University School of Medicine,
Indianapolis.
An in vitro liquid suspension culture system was used to determine the role
of cytokines in sustaining long-term human megakaryocytopoiesis. Bone
marrow cells expressing CD34 but not HLA-DR (CD34+DR-) were used as the
inoculum of cells to initiate long-term bone marrow cultures (LTBMC).
CD34+DR- cells (5 x 10(3)/mL) initially contained 0.0 +/- 0.0 assayable
colony-forming unit-megakaryocytes (CFU-MK), 6.2 +/- 0.4 assayable
burst-forming unit-megakaryocytes (BFU-MK), and 0.0 +/- 0.0 megakaryocytes
(MK). LTBMCs were recharged every 48 hours with granulocyte-macrophage
colony-stimulating factor (GM-CSF), interleukin- 1 alpha (IL-1 alpha),
IL-3, and/or IL-6, alone or in combination. LTBMCs were demidepopulated
weekly or biweekly, the number of cells and MK enumerated, and then assayed
for CFU-MK and BFU-MK. LTBMCs receiving no cytokine(s) contained no
assayable CFU-MK or BFU-MK and no observable MK. LTBMCs receiving GM-CSF,
IL-1 alpha, and/or IL-3 contained assayable CFU-MK and MK but no BFU-MK for
10 weeks of culture. The effects of GM-CSF and IL-3, IL-1 alpha and IL-3,
but not GM-CSF and IL-1 alpha were additive with regards to their ability
to augment the numbers of assayable CFU-MK during LTBMC. LTBMCs
supplemented with IL-6 contained modest numbers of assayable CFU-MK for
only 4 weeks; this effect was not additive to that of GM-CSF, IL-1 alpha,
or IL-3. The addition of GM-CSF, IL-1 alpha, and IL-3 alone or in
combination each led to the appearance of significant numbers of MKs during
LTBMC. By contrast, IL-6 supplemented cultures contained relatively few MK.
These studies suggest that CD34+DR- cells are capable of initiating
long-term megakaryocytopoiesis in vitro and that a hierarchy of cytokines
exists capable of sustaining this process.
Volume 79,
Issue 2,
pp. 332-337,
01/15/1992
Copyright © 1992 by The American Society of Hematology
