Research Paper Volume 1, Issue 8 pp 723—732

Figure 1. Self-renewal and differentiation in hematopoiesis. Hematopoietic differentiation is a multi-step process. A small group of long term repopulating hematopoietic stem cells (LT-HSC) replicates very slowly. The down-stream compartments are more and more committed to a specific linage and replicate at faster rates. Some of the progeny have to self-renew to keep the pool of hematopoietic stem and progenitor cells. Our model is based on the hypothesis this percentage of self-renewal versus differentiation is regulated by a feedback mechanism that is related to the number of mature cells in the blood (A). There is evidence, that the dual function of self-renewal and differentiation is regulated by asymmetric cell divisions where one daughter cell retains the stem cell function whereas the other differentiating cell becomes a faster proliferating precursor cell. Alternatively, cells can undergo symmetric cell divisions to produce either two identical, self-renewing cells or two differentiated daughter cells (B).