Extended Data Fig. 10. Deregulated GMP cluster formation in leukemic mice.

a, ELISA measurements of cytokine levels in BM fluids of BA, jB and respective Ctrl mice. b, qRT-PCR measurement of Cxcl4 expression in BM and Meg-enriched BSA gradient of Ctrl and BA mice. c, Quantification of vascular leakage in diseased BA, jB and respective Ctrl BM. Results are quantified as dragon green (DG) microsphere MFI upon masking of laminin⁺ blood vessels. d, Representative FACS plots showing Gr regeneration in 5-FU-treated Ctrl and BA mice at the indicated days post-treatment. e, Revised model of emergency myelopoiesis. At steady state, blood production reflects the differential generation by HSCs of a small number of myeloid-biased MPP2/3 and a large number of lymphoid-biased MPP4, which both give rise to GMPs and contribute to myeloid output. In contrast, in emergency situations, HSCs are induced to overproduce MPP2/3, and MPP4 are reprogrammed towards almost exclusive myeloid output in large part due to cytokine stimulations and the triggering of specific regulatory pathways. An important consequence of the activation of this myeloid regeneration axis is the generation of localized pGMP/cGMP differentiation foci in the BM cavity, which drive the overproduction of granulocytes. This entire process is tightly regulated by BM niche signals and is transient during emergency myelopoiesis, but is constantly activated in myeloid leukemia. Important emerging questions are what controls the switch from self-renewing (SR) pGMP to differentiating (diff.) cGMP clusters, if expanded MPP2/3 and myeloid-reprogrammed MPP4 also generate pGMP/cGMPs or continue to produce regular GMPs (dotted lines), and whether Grs produced through this regeneration axis functionally differ from steady state Grs (heterogeneity). Results are expressed as mean ± SD; *p ≤ 0.05, ***p ≤ 0.001.