Transcriptomic characterisation of haematopoietic stem and progenitor cells from human adult bone marrow, spleen and peripheral blood

Haematopoietic stem and progenitor cells (HSPCs), the precursors of all blood cells, reside predominantly in the bone marrow (BM). Recent evidence suggests that other anatomical sites may contribute significantly to blood production, but the cellular, molecular and functional composition of extramedullary HSPC pools remains unexplored. Here, we comprehensively characterized the single-cell composition of the adult human HSPC pool within paired BM, spleen and peripheral blood (PB) from two healthy organ donors. 10x scRNA-seq of 30000 HSPCs from all three sites defined transcriptionally distinct cell clusters that correspond to precursors of all haematopoietic lineages but also stem cells (HSCs). Although most clusters were common to all organs, their proportions significantly differed between tissues. Altogether our data provides evidence that different organs sustain distinct topologies of the hematopoietic hierarchy, originating from HSC subsets with distinct lineage preferences. This dataset is part of the Human Cell Atlas.