Figure 5.

PMF stem cells moving from niches to niches. In response to several environmental factors, an imbalance between endosteal and vascular niches within the bone marrow would favor the proliferation and mobilization of pathological stem cells from the bone marrow to the blood. These stem cells would migrate into the spleen/liver where newly created or reinitialized vascular niches would favor their homing and differentiation resulting in an extramedullary hematopoiesis in these organs.