Lineage tracing studies suggest that the placenta is not a de novo source of hematopoietic stem cells
Fig 6
Expression of HEC marker genes in the first-trimester human placenta.
(A) Immunofluorescence staining for RUNX (red), CD31 (green) and KRT7 (magenta) on human placenta sections of 5 weeks gestational age (3 sections for N = 1 placenta). Lower panels show enlarged views of the boxed region in the upper left panel. VC, villous cord; CC, cytotrophoblast cell column. (B) Immunofluorescence staining for RUNX (red), CD31 (green) and KRT7 (magenta) on human placenta sections of 6 weeks gestational age (3 sections per placenta, N = 2 placentas). Lower panels show enlarged view of the boxed regions in the upper panels. Arrows indicate RUNX + hematopoietic cells encircled by CD31 + ECs. VC, villous cord. (C) Immunofluorescence staining for RUNX (red), CD31 (green) and KRT7 (magenta) on human placenta sections of 7 weeks gestational age (3 sections per placenta for N = 2 placentas). Lower panels show enlarged view of the boxed region in the upper panel. Arrows indicate RUNX + cells in the perivascular, stromal region of the villi. VC, villous cord. (D) Immunofluorescence staining for ALDH1A1 (red) and CD31 (green) on human placenta sections of 6 weeks gestational age (N = 2 placentas). Lower panels show enlarged view of the boxed region in the upper panel. (E) Immunofluorescence staining for ALDH1A1 (red), and CD31 (green) on human placenta sections of 12 weeks gestational age (3 sections per placenta for N = 2 placentas). Lower panels show enlarged view of the boxed regions in the upper panels. Arrow indicates abluminal ALDH1A1 + Hofbauer cells within the villi. (F) Immunofluorescence staining for KCNK17 (red), and CD31 (green) on human placenta sections of 6 weeks gestational age (3 sections per placenta for N = 2 placentas). Lower panels show enlarged view of the boxed regions in the upper panels. Scale bars, 100 μm for upper panels in A, B, C, D and upper three images in E. Twenty μm for lower panels in A, B, C, D and lower three images in E.