Expression of interferon-gamma by stromal cells inhibits murine long-term repopulating hematopoietic stem cell activity.
Several lines of evidence suggest that overexpression of interferon gamma (IFN-gamma) in the marrow microenvironment may play a role in the pathogenesis of marrow suppression in aplastic anemia. We previously showed that overexpression of IFN-gamma by marrow stromal cells inhibits human long-term culture initiating cell activity assayed in vitro to a much greater degree than the addition of soluble IFN-gamma. The effect of IFN-gamma on true repopulating stem cells assayed in vivo has not been studied previously. We compared the effect of co-culture of murine marrow cells in the presence of stromal cells transduced with a retroviral vector expressing murine IFN-gamma vs stromal cells transduced with a control neo vector. Using a murine congenic competitive repopulation assay, there was significantly less long-term repopulating stem cell activity remaining after culture on mIFN-gamma-expressing stroma as compared to control stroma. We also investigated the effect of directly transducing murine bone marrow cells with the mIFN-gamma or control vector. Marrow cells transduced with either vector were transplanted into W/Wv recipient mice. The percentage of vector-containing cells in the mIFN-gamma mice was significantly lower than in the control mice, suggesting that mIFN-gamma-transduced primitive cells may not have survived culture, or that mIFN-gamma directly decreases gene transfer into repopulating cells. Despite no significant differences in white or red blood cells in the mice transplanted with the mIFN-gamma-transduced cells, the number of bone marrow colony-forming unit-C 16 weeks after transplantation was significantly lower in the IFN-gamma group. These data indicate that ectopic or overexpression of mIFN-gamma, especially by marrow microenvironmental elements, may have a marked effect on primitive hematopoiesis as assayed in vivo.
Yu
J M
JM
Hematology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
Emmons
R V
RV
Hanazono
Y
Y
Sellers
S
S
Young
N S
NS
Dunbar
C E
CE
D000818:Animals; D001483:Base Sequence; D002455:Cell Division / Q000235:genetics*; D018920:Coculture Techniques; D017931:DNA Primers; D005260:Female; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D006801:Humans; D007371:Interferon-gamma / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D011994:Recombinant Proteins / Q000235:genetics; D012190:Retroviridae / Q000235:genetics; D017154:Stromal Cells / Q000378:metabolism*; D014161:Transduction, Genetic
D017931:DNA Primers; D011994:Recombinant Proteins; D007371:Interferon-gamma