Landscape of Mast cell populations across organs in mice and humans

Mast cells (MCs) are tissue-resident immune cells which exhibit
homeostatic and neuron-associated functions. Here we combined whole-tissue
imaging and single-cell RNA sequencing datasets to generate a pan-organ
analysis of MCs in mice and humans at steady state. In mice, we identify
two mutually exclusive MC populations, MrgprB2+ connective tissue-type MCs
and MrgprB2neg mucosal-type MCs, with specific transcriptomic core
signatures. While MrgprB2+ MCs develop in-utero independently of the bone
marrow, MrgprB2neg MCs develop after birth and are renewed by
bone marrow progenitors. In humans, we unbiasedly identify 7 MC subsets
(MC1 to 7) distributed across 12 organs with different transcriptomic core
signatures. MC1 are preferentially enriched in the bladder, MC2 in the
lungs, and MC4, MC6 and MC7 in the skin. Conversely, MC3 and MC5 are
shared by most organs, but not skin. This comprehensive analysis offers
valuable insights into the natural diversity of MC subtypes in both mice
and humans.