Unhealthy Competition

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Science  19 Dec 2008:
Vol. 322, Issue 5909, pp. 1753
DOI: 10.1126/science.322.5909.1753k

Hematopoietic progenitor cells (HPCs), the cells that ensure the body is supplied with healthy blood cells throughout life, reside within a specific bone marrow microenvironment, or “niche,” that regulates their survival, growth, and differentiation. Colmone et al. (p. 1861) explored the impact of leukemia on normal HPC niches by applying real-time in vivo imaging methods to mouse leukemia models. Leukemic cells were found to create a malignant niche that out-competes normal niches in attracting HPCs. This competition leads both to a reduction in the number of HPCs and to disruption of HPC function, as evidenced by failure of the cells to mobilize into the circulation in response to cytokine stimulation. These effects were mediated in part by stem cell factor, a chemoattractant secreted by the leukemic cells. Thus, therapeutic inhibition of stem cell factor may be a valuable way to increase hematopoietic reserves in patients with leukemia.

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