G-CSF in stem cell mobilization: new insights, new questions

In this article, Bernitz and colleagues (1) utilize a lineage tracing mouse model to show that G-CSF selectively mobilizes quiescent non-dividing hematopoietic stem cells (HSC) from bone marrow (BM) to peripheral blood (PB) and that G-CSF administration does not induce HSC cycling/proliferation. Mobilized non-dividing HSC can return to BM, again without dividing. Moreover, the non-dividing HSC represent the true long-term repopulating cells, and those HSC left in BM after mobilization, while expressing phenotypic markers of HSC, do not in fact have repopulating capacity. (Summarized in Figure 1)