Je. Barker, EARLY TRANSPLANTATION TO A NORMAL MICROENVIRONMENT PREVENTS THE DEVELOPMENT OF STEEL HEMATOPOIETIC STEM-CELL DEFECTS, Experimental hematology, 25(6), 1997, pp. 542-547
Our previous results showed that hematopoietic stem cells from 16-week
-old Sl/Sl(d) mice are not as competitive as congenic +/+ control stem
cells. Possible explanations for these findings are that the Steel st
em cells are either inherently defective or lose competitive ability b
y residence in an environment lacking membrane-bound Steel factor. Ln
the present report, any long-term effects of the Steel microenvironmen
t were eradicated by transferring neonatal Sl(d)/Sl(d) marrow and sple
en cells into an irradiated but otherwise normal adult hematopoietic m
icroenvironment. Host cells were completely replaced by donor cells wi
thin 6 weeks. Eight months after transplantation, the Sl(d)/Sl(d) and
similarly treated +/+ littermate control cells from tile primary recip
ient marrow were competed against genetically marked normal cells in a
n irradiated secondary host. The Steel cells were as competitive as th
e control cells demonstrating that Steel stem cells are not inherently
defective. Results suggest that the stem cells, when retained in the
mutant environs into adulthood, are either reduced in number or phenot
ypically altered by lack of the membrane-bound Steel factor.