Gata2 in Embryonic Hematopoiesis

Hematopoiesis is a word originating from the two greek words αἷμα (haima) which means blood and the verb ποιεῖν (poien) which means to make/create. Hematopoiesis describes the process by which the organism creates and replenishes all the blood cell types that are required for the physiologic functions of the organism. The importance of the blood tissue can be highlighted by the many and discrete functions that it performs. These are accomplished through several different cell types forming the blood tissue (erythrocytes, platelets, macrophages, neutrophils, eosinophils, basophils, B-cells, T-cells, NK-cells). For example, the red blood cells or erythrocytes found in the circulating blood are mainly involved in the transport of O2 and CO2. Lymphocytes which are white blood cells are part of the immune system and actively participate in the defense of the organism against pathogens. In the adult organism hematopoietic cells are found not only in the blood but also in hematopoietic tissues such as the bone marrow, spleen, lymph nodes and thymus. Importantly, all mature hematopoietic cell types found in the blood tissues originate from rare hematopoietic stem cells (HSCs). These founder cells are quiescent, long-lived and are at the base of a well-studied cell differentiation hierarchy. HSCs robustly produce all the billions of mature blood cells that are required daily and throughout the entire life of the organism. HSCs are clinically relevant cells that have been used for over 50 years in transplantation and cell replacement therapies for leukemia and monogenic blood-related diseases.