Fig. 3: Yolk-sac-derived myeloid cells control VCAM1 expression and colonization by neutrophils and HSC.
a Experimental design depleting yolk-sac-derived myeloid cells as previously reported4,21,37,38,39. b Representative images of whole-mounted E18.5 femurs and maps of the indicated regions. c Number of CD61+ osteoclasts after depletion of yolk-sac-derived myeloid cells. Each dot corresponds to one femur section from one E18.5 fetus. d Number of indicated cells per section; n = 5 sections from 5 E18.5 fetuses. e Cell numbers and percent VCAM1+ cells of CD45-Ter119-CD31+CD105+ vascular endothelial cells (VEC) or CD45-Ter119-CD31-PDGFRβ+ stromal cells (PDGFRβ+). Each dot corresponds to one E18.5 fetus from two independent litters. f, g Zoomed-in image from b and quantifications showing de novo misexpression of VCAM1 and subsequent recruitment of neutrophils (Ly6C+) in the metaphysis of anti-CD115-treated fetuses. For VCAM1 quantifications; IgG n = 5 and αCD115 n = 4 sections from femurs of different E18.5 fetuses in each group. For metaphyseal neutrophil quantifications; n = 5 femur sections from five E18.5 fetuses in each group. h Number of total hematopoietic cells along with Lin-Sca1+CD117+ multipotent progenitor numbers and frequency in the femur of anti-CD115- or IgG-treated E18.5 fetuses quantified by FACS. Each dot corresponds to one mouse. i Percentage of donor (CD45.2+) cells in the peripheral blood of CD45.1+ recipients at the indicated time points after transplantation of all the hematopoietic cells found in one femur of anti-CD115- or IgG-treated E18.5 fetuses along with 1 ×105 CD45.1+ competitor cells purified from adult mice. Each dot corresponds to one mouse, n = 7 IgG and 8 anti-CD115 recipients in two experiments. Statistics shown are for total engraftment at 16 weeks. j Representative pentachrome stain and quantification of bone marrow area (not occupied by cartilage or bone) in E18.5 femur from IgG or αCD115 groups. Each dot corresponds to one femur from one fetus. For all panels, p values are shown, and statistical differences were calculated using a two-tailed Student’s t-test if the distributions were normal or Mann-Whitney if not normal. Source data are provided as a Source Data file.
