Fig. 4: Small hematopoietic clones with JAK2V617F lead to development of pulmonary hypertension, associated with selective migration of neutrophils into the lungs and maturation from the lung hematopoietic precursors for the myeloid lineage.

a Schematic depiction of the competitive transplantation. The different ratios of WT-GFP or JAK2^V617F-GFP and WT without GFP competitor were transplanted into the lethally irradiated recipient WT mice. b The recipients with donor chimerism of 1–19% at 8 weeks after bone marrow transplantation (BMT), determined by the percentages of GFP⁺ cells within CD45⁺ cells by flow cytometry, were enrolled for statistical comparison (n = 5, 6, 6, 7). The other categories of the donor chimerism are presented in Supplementary Fig. 16. RVSP and RV/LV + S are shown (n = 5, 6, 6, 7, ^*P = 0.0008 [left], <0.0001 [right], ^†P = 0.0113 for RVSP, n = 5, 6, 6, 7 ^*P = 0.0029 [left], <0.0001 [right], ^†P = 0.0049 for RV/LV + S). ^*P < 0.05 versus the corresponding normoxia-group and ^†P < 0.05 versus the corresponding WT-GFP-BMT mice by the one-way ANOVA with Tukey post-hoc analysis. c, d JAK2V617F neutrophils showed an intrinsic increased migration capability into the lungs. The percentages of GFP⁺ cells within CD45⁺ cells in the peripheral blood and the lungs were analyzed at 8 weeks in the BMT mice with 1–19% chimerism by flow cytometry (c, n = 5, 5, 6, 6). The comparison was performed by the paired Student’s t test (two-sided). NS, not significant. The differences of GFP⁺ cells within CD45⁺ cells between the lungs and the peripheral blood are shown (d, n = 5, 5, 6, 6). ^†P = 0.0173 versus the corresponding WT-GFP-BMT mice by the one-way ANOVA with Tukey post-hoc analysis. e Chemotaxis migration assay. The sorted Ly6G⁺ neutrophils from the blood in WT or JAK2^V617F mice were placed on the top of Transwell in triplicate and were allowed to migrate for 1 or 3 h. Data are expressed as a relative ratio to WT-3 h from six independent experiments and presented as mean ± SEM. *P < 0.01 versus corresponding 1 h (*P = 0.0009 for WT, < 0.0001 for JAK2^V617F) and ^†P = 0.0342 versus WT-3 h by the two-way ANOVA with Tukey post-hoc analysis. f Colony-forming assay of the hematopoietic progenitors in the lungs. CD117 (c-kit)⁺ cells sorted from the lungs of WT-BMT and JAK2^V617F-BMT mice were grown in the methylcellulose-based medium for 7 days. Representative images of the 35 mm plates are shown in the left panels. Scale bars, 10 mm. Right, quantification of numbers of the colonies derived from colony-forming unit (CFU)-granulocyte, -erythroid, -macrophage, -megakaryocyte (CFU-GEMM), CFU-granulocyte, -monocyte (CFU-GM), CFU-granulocyte (CFU-G). The comparison was performed by the two-sided unpaired Student’s t test (n = 5 in each group). All data are presented as mean ± SEM. Source data are provided as a Source Data file.