In-Won Lee, Yesenia Earth, Yoon-A Kang
Red blood cells constitute over 99 % of all blood cells and 2-3 million erythrocytes are generated every second in human body. The process of generating red blood cells, erythropoiesis, is tightly regulated at the multiple levels of the hematopoietic hierarchy to fulfil this intensive demand for oxygen carrying cells. Recent studies uncovered that lineage specification begins at the multipotent stages such as hematopoietic stem cell (HSC) and multipotent progenitor (MPP) populations. In this review, we discuss lineage-biased HSCs and MPPs, the erythroid linage bias in HSCs and MPPs, how erythroid fate decisions are made in common myeloid progenitors (CMPs) and megakaryocyte-erythroid progenitors (MEPs), and what alters erythroid lineage commitment in aging and disease conditions.