Growing and aging of hematopoietic stem cells

Figure 3 Model of increased proliferation in aging hematopoietic stem cells. Aged hematopoietic stem cells (HSC) have a reduced productive potential and generate a fraction of ineffective (gray) progenitor cells, thus producing a reduced number of blood cells. This reduced production of blood cells triggers a stimulus to generate more blood cells, which increases the proliferation rate of the hematopoietic compartment. Increased proliferation is accompanied by telomere shortening, which, in turn, makes HSC even more aged. In this way, the absolute number of HSC increases, but the fraction of ineffective HSC also increases. HSC: Hematopoietic stem cells; PC: Progenitor cells; BC: Blood cells.