ABSTRACT
Conventional models of hematopoietic regulation propose that a primitive undifferentiated stem cell produces progeny with progressively more lineage restriction and lineage specific function and less renewal, proliferative and differentiation potential. The stem cell itself has tremendous proliferative and differentiative potential, which is diminished with differentiation to different progenitor classes, and is markedly decreased or abolished with differentiation to end-stage functioning cells. 1 This is a classic hierarchical model, and is illustrated in Figure 1.
