Résumé
Unlike most adult organs, the blood system regenerates continuously to maintain homeostasis in a life-long process orchestrated by a complex collection of hematopoietic stem and progenitor cells. Self-renewing HSCs reside at the apex of this hierarchy and produce all blood lineages, including the erythroid lineage that forms red blood cells, the megakaryocytic lineage that gives rise to platelets, and the myeloid and lymphoid lineages that generate cells of the innate and adaptive immune systems. Most HSCs exist in a quiescent state, dividing occasionally to self-renew and produce various lineage-biased multipotent progenitors that form a transit amplifying compartment sustaining the daily output of the blood system. We will consider how emerging concepts in cell differentiation and lineage priming are developing our understanding of the hematopoietic hierarchy and its functional attributes.
