Fig. 4. Steady state megakaryocyte output from bona fide LT-HSCs.

a, LT-HSCs, MPPs and Lin⁺ cells were purified from bone marrow at 4 and 30 wk and their Tn-tag content was analysed. Only the LT-HSC tags overlapping with detectable Lin⁺ progeny are shown. b, Pie-chart distribution of types of progeny detected from LT-HSCs at 4 weeks and 30 weeks after labeling. Data are pooled from 4 independent M2/HSB/Tn mice per time point. c, Percentage of labelled LT-HSC clones producing progeny at 1-8 weeks. Values are mean +/− s.e.m of 3-4 independent mice. d, Dynamics of Mk vs. non-Mk lineage replacement by LT-HSCs (measured as % of overlapping/total Lin⁺ reads). Values are mean +/− s.e.m. of 3-4 independent mice. Ratio paired t-test p=0.014. e, Dynamics of Mk vs. Er/My lineage replacement by MPPs (measured as % of overlapping/total Lin⁺ reads). Values are mean +/− s.e.m. of 3-4 independent mice. Ratio paired t-test p=0.599. f, Experimental design for parallel analysis of native vs. transplant output of LT-HSC clones. g, Alignment of all post-transplantation LT-HSC-derived lineages with unperturbed donor lineage tags. h, Pie-chart distribution of successfully engrafted LT-HSC clones by donor behaviour. Only Mk-restricted and My-restricted output was observed. Inactive means non-detectable output in the donor. i, Post-transplantation outcomes comparing donor-inactive vs. Mk-producing LT-HSC clones. j, Lineage fate landscape of unperturbed hematopoiesis. Self-renewing LT-HSCs preferentially replace Mk under steady state, and principally contribute to other blood lineages during transplantation or after injury. In contrast, MPPs take care of the majority of steady-state Ly, Er and My blood production. Different MPP sorting gates enrich for heterogeneous collections of lineage-primed and unprimed cell states within a continuum of lineage commitment pathways.