Steel factor promotes lodgement of hematopoietic progenitor cells in mouse liver

Date of Award




Degree Name

Doctor of Philosophy (Ph.D.)


Physiology and Biophysics

First Committee Member

Brian A. Masters, Committee Chair


Biological factors regulating homing of hematopoietic stem cells (HSC) during embryogenesis have not been identified. Mice that lack Steel Factor (SF) die at midgestation with severe anemia, suggesting that SF could regulate homing of HSC. The hematopoietic potential of liver, spleen, bone marrow, and peripheral blood was analyzed to assay homing of stem cells in mice engineered to ectopically express SF in the liver throughout development. Ectopic SF prolonged hematopoiesis in the liver, where blood islands and megakaryocytes were elevated as much as 250 fold, and myeloid progenitors 2--5 fold, when compared to control mice. Ectopic SF does not alter erythroid differentiation, but acts upon an early myeloid progenitor or pluripotent stem cell. The increased hematopoietic potential in liver results from abnormal retention, rather than enhanced proliferation or survival of stem cells. The results demonstrate that SF governs homing of HSC or early progenitors in the embryo.


Biology, Cell; Biology, Microbiology; Biology, Animal Physiology

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