Stable multilineage hematopoietic chimerism in alpha-thalassemic mice
induced by a bone marrow subpopulation that excludes the majority of day-12
spleen colony-forming units
JC van der Loo, C van den Bos, MR Baert, G Wagemaker and RE Ploemacher
Institute of Hematology, Erasmus University, Rotterdam, The Netherlands.
We have investigated the contribution of highly purified day-12 spleen
colony-forming units (CFU-S-12) as well as more primitive cells to
sustained blood cell production using in vivo and in vitro assays that
allow frequency analysis. Normal or day-6 post-5-fluorouracil light-
density bone marrow (BM) was sorted on the basis of differences in
rhodamine-123 (Rh123) retention or wheat germ agglutinin (WGA) affinity and
tested in vivo using a recently developed alpha-thalassemic chimeric mouse
model. In addition, short-term and long-term clonal activity was assessed
in vitro using a limiting dilution-type long-term BM culture, the
cobblestone area forming cell assay. When sublethally irradiated
alpha-thalassemic mice were transplanted with as many as 281 purified
WGAbright CFU-S-12, derived from a fraction containing 95% of all CFU-S-12
from day-6 post-5-fluorouracil light-density BM of wild- type mice,
detectable chimerism was not observed at 6 months posttransplantation. In
contrast, only three CFU-S-12 were included in the Rh123dull and WGAdim
subpopulations that induced 29% to 58% and 21% to 31% stable multilineage
donor-type chimerism of erythrocytes and leukocytes, respectively. The
Rh123dull and WGAdim cells were up to 240- fold enriched for long-term
repopulating ability (LTRA) as compared with unseparated BM. A comparable
level of chimerism was found in the different hematopoietic organs and at
the level of BM CFU-S-12. The frequency of the LTRA unit capable of
inducing a 10% sustained level of donor-type erythrocytes was calculated to
be 1 to 2 per 10(5) BM cells. Several reports have suggested that LTRA and
spleen colony formation could be capacities of the same stem cell subset.
However, the present results show that the majority of CFU-S-12 have only
short-term repopulating ability and are physically separable from more
primitive stem cells with long-term multilineage reconstituting capacities.
Volume 83,
Issue 7,
pp. 1769-1777,
04/01/1994
Copyright © 1994 by The American Society of Hematology
