Hematologic Diseases

Hematopoiesis is the formation of cellular components of the blood from a small population of pluripotential stem cells, which are formed in embryonic life and persist thereafter through self-regeneration. When stimulated by hematopoietic growth factors such as cytokines, these precursor cells give rise to progenitor cells committed to development along specific pathways. These progenitor cells, through a series of divisions and maturational changes, give rise to myeloid or lymphoid mature cells in the circulating blood. The earliest recognizable erythroid progenitors are the burst-forming units–erythroid (BFU-E) and the less primitive colony-forming units–erythroid (CFU-E). Erythropoietin, produced by the kidney, circulates to the bone marrow, where it stimulates the erythroid progenitor cells to differentiate and mature into erythrocytes.1