Figure 2. Lung Mks are derived from BM HSCs.

(A) mTmG and Bl6/J mice were given CFSE o.p., and parabiosis surgeries performed 1 week later. Lung Mks were partially replaced by a BM source (n = 8–10 from 2 independent experiments). (B) Mice were given CFSE o.p. and biotin i.p., and 6 hours (n = 2 from 1 experiment), 7 days (n = 3 from 1 experiment), and 28 days (n = 5 from 1 experiment) later, BM and lung Mks were assessed. BM Mks were replaced within 7 days, but lung-resident Mks were detected at each time point. (C) MDS1-TdTomato^Cre-ERT2 mice were treated with tamoxifen (TAM) to label HSCs and HSC-derived cells (n = 4–5; results are representative of 2 independent experiments). Lung Mks were HSC derived. (D) BM, splenic, and lung Mks in FlkSwitch mice were assessed at multiple ages (n = 5 per age time point; results are representative of 2 independent experiments) to determine whether Mk differentiation was Flt3 dependent. Lung Mks were largely Tomato⁺Flt3^–, indicating an HSC-to-Mk differentiation that was distinct from BM and splenic Flt3-dependent differentiation. Data indicate the mean ± SEM. *P < 0.05, ***P < 0.001, and ****P < 0.0001, by (B) 1-way ANOVA with Šidák multiple-comparison correction and (C and D) 2-way ANOVA with Tukey’s multiple-comparison correction and (A) 1-way ANOVA with Šidák multiple comparisons correction.