MEPs from ID mice are Mk biased. (A) Representative histograms of flow cytometric analysis of calcein-AM fluorescence in MEPs exposed to chelator, 2,2′-bipyridyl (red lines) or PBS control (blue lines) from Tmprss6^−/− and WT littermate controls. (B) LIP as calculated by the change in calcein MFI in WT and Tmprss6^−/− MEPs with and without chelator (n = 4 WT, n = 6 Tmprss6^−/−). (C) Representative images (acquired at 5× with a Leica 6000 microscope and accompanying software) of murine MEP-derived colonies: Mk/E showing staining with CD71 fluorescein isothiocyanate (false-colored red) and CD41-PE (false-colored green), Mk-only colonies showing staining with only CD41, and E-only colonies showing staining with only CD71. (D-E) Colony counts by type per 90 cells plated of Tmprss6^−/− and littermate controls (n = 4 mice/genotype) (D) and AI diet– vs ID diet–fed mice (n = 3 per group) (E). (F-H) Surface expression of CD71 (fluorescence intensity) from index single sorted MEPs; by colony type generated by MEPs from AI diet– (F) and ID diet–fed (G) mice. Individual cells are shown in blue (Mk/E), red (E-only), and green (Mk-only). (H) Comparison of total sorted MEPs from AI diet– and ID diet–fed mice. (I) Proliferation index of carboxyfluorescein succinimidyl ester–stained MEPs after 72 hours in culture analyzed by flow cytometry (n = 5 WT, n = 7 Tmprss6^−/−). Data are presented as mean + SD. *P < .05, **P < .01, ***P < .001, and ****P = .0001 calculated by 2-tailed unpaired Student t test.