So. Peters et al., MURINE MARROW-CELLS EXPANDED IN CULTURE WITH IL-3, IL-6, IL-11, AND SCF ACQUIRE AN ENGRAFTMENT DEFECT IN NORMAL HOSTS, Experimental hematology, 23(5), 1995, pp. 461-469
Stimulatory cytokines may induce murine hematopoietic progenitor cells
(HPCs) to survive, self-renew, proliferate, or differentiate. We stud
ied the role of active cell cycling induced by the cytokines interleuk
in-3 (IL-3), IL-6, IL-11, and Steel factor (SF) on murine progenitor c
ell frequency and cell cycle status in an in vitro system and on engra
ftment potential in nonmyeloablated mice. Marrow exposure to IL-3, IL-
6, IL-11, and SF in in vitro liquid culture maintained or expanded sev
en factor-responsive high and low proliferative potential colony-formi
ng cells (HPP-CFC and LPP-CFC). The HPP-CFC and LPP-CFC were dormant a
t the initiation of culture, as determined by H-3-thymidine suicide. T
here was an increase in the number and proliferation of HPP-CFC and LP
P-CFC at 48 hours; by 48 hours, 62% of HPP-CFC and 56% of LPP-CFC were
killed by H-3-TdR exposure. In engraftment studies of cytokine-stimul
ated marrow cells into normal hosts, female BALB/c mice received the e
quivalent of 40x10(6) starting male marrow cells exposed to cytokines
in vitro for 48 hours for 3 consecutive days and were sacrificed 8 wee
ks after transplantation. Control groups received either 40x10(6) male
uncultured marrow cells, 40x10(6) starting marrow cells cultured in m
edium without growth factors for 48 hours, or phosphate-buffered salin
e (PBS) for 3 days. Engraftment of male cytokine-treated cells was ana
lyzed by Southern blot analysis using the Y-chromosome-specific pY2-cD
NA probe. There was minimal engraftment (approaching background levels
) in marrow, spleen, and thymus of nonmyeloablated female recipients.
Transplant recipients that had received uncultured marrow directly aft
er sacrifice showed engraftment levels of 21% (11 mice; range=8 to 44%
) into marrow, of 9% (range=0 to 22%) into spleen, and 13% (range=2 to
43%) into thymus. We conclude that active cell cycling of marrow cell
s induced by cytokine stimulation is associated with an engraftment de
fect in the normal host.