EPCR expression marks CD150(neg) deeply dormant long-term hematopoietic stem cells.

EPCR+ CD150− long-term hematopoietic stem cells (LT-HSC2) sustain serial multi-lineage reconstitution and are more deeply dormant than EPCR+ CD150+ LT-HSC1s.

• Why it matters: CD150 is used to isolate multipotent LT-HSCs, but it may not capture the full spectrum of long-term repopulating HSC heterogeneity and dormancy states.
• What they did: The authors identified an EPCR+ CD150− HSC subset (LT-HSC2) and used long-term label-retaining assays plus inflammatory stress readouts and marker combinations with HSC/MPP markers to map early lineage divergence.
• The result: LT-HSC2s show reduced cell cycle activation under inflammatory stress and preserve stemness for prolonged periods in vivo, resolving earliest lineage divergence into megakaryocytic/erythroid-biased CD150+ and lymphoid-biased CD150− trajectories.