Fig. 5: Type S vessels postnatally establish a satellite niche for HSPCs.
From: Spatial heterogeneity of bone marrow endothelial cells unveils a distinct subtype in the epiphysis
a–g, Immunohistochemistry of femur sections at 3 months after birth (a–c), P7 (d), P11 (e), P13 (f) and P18 (g). Panels b and c show the high magnification views of the area indicated in a. The c-Kit+ cells start to appear in the entry point of type S vessels around P11 (arrows) and gradually spread in the epiphysis thereafter (arrowheads). h–m, Immunohistochemistry of femur sections from Cxcl12+/DsRed mice at P7 (h), P11 (i), P13 (j) and P18 (k), and 3 months after birth (l,m). Panel m shows the high magnification view co-stained with cKit and Emcn. The arrows indicate DsRed expression detected in arteries. MSCs appear at P11 and spread throughout the epiphysis thereafter (open arrowheads). Most c-Kit+ cells are located in contact with MSCs (closed arrowhead) or ECs (open arrow). n,o, Quantification of c-Kit+ cells (n) and Cxcl12-DsRed+ cells (o) in BM sections at various stages (n = 3, biologically independent experiments). p, Protocol for 4OHT injection in neonates. q,r, Immunohistochemistry of femur sections. Panel r shows the high magnification view of the area indicated in q. Lineage tracing using Cdh5-BAC-CreERT2 mice shows that c-Kit+ cells (arrowheads) do not originate from haemogenic endothelium in type S vessels. s, A heatmap showing HSPC niche factors based on the scRNA-seq data shown in Fig. 1. t,u, Immunohistochemistry of femur sections from a mouse at 3 months (t) and quantification (u) (n = 8, biologically independent experiments). The distance between HSCs (open arrowheads) and ECs is smaller in epiphyses than in metaphyses. Asterisks are CD31+ megakaryocytes. Scale bars, 1 mm (a and q); 200 µm (b–g and h–l,r); 50 µm (m); and 10 µm (t). Data presented are the mean ± s.d. *P < 0.05. The comparisons between the averages of two groups were evaluated using the two-tailed Student’s t-test.
