Common Myeloid Progenitors

This chapter presents a brief history of hematopoietic stem and progenitor cell biology, emphasizing commitment to the myeloerythroid fates. It also describes the cell surface profiles of recently identified stem and progenitor cell subsets in both mice and humans, and explains potential therapeutic applications of committed progenitor cells. Hematopoiesis is initiated by rare hematopoietic stem cells (HSCs) that maintain production of blood cells for life. This astounding production is the result of mitotic amplification of the lineage-committed progenitor cells that are the daughters of HSCs. Although the existence of lineage-restricted hematopoietic progenitors has been postulated for many years, the ability to prospective isolate HSCs paved the way for the phenotypic discovery of lineage-restricted progenitors downstream of HSCs, such as common lymphoid progenitors (CLPs) and common myeloid progenitors (CMPs), which can be similarly isolated by cell surface characteristics. The modern era of HSC biology began with the first rigorous, prospective isolation of murine HSCs by cell surface phenotype. Investigators showed that long-term, multilineage reconstitution activity was present only within a population of Lin /loThy1.1loSca-1⁺ bone marrow cells.