Extended Data Fig. 3: Capillary flow and associated macrophage loss in mice and humans.
From: Niche-specific dermal macrophage loss promotes skin capillary ageing
a, Representative images of capillary blood flow in WT mice before and after placement of a coverslip on top of hind paw skin of 6 month old mice. b, Quantification of capillary blood flow (n = 3 mice in total; two 500 µm2 regions per mouse; capillary blood flow (Before Coverslip vs With Coverslip) was compared in the same imaging areas by paired Student’s t test; mean with paired lines). c, Quantification of capillaries with blood flow as measured by stalled RBCs as described in Extended Data Fig. 2 in 1, 2-, 4-, 10-, and 18-month-old mice (n = 878 CAM+ capillary segments, n = 215 CAM- capillary segments; n = 4 mice in each age group; capillary blood flow (CAM+ vs CAM-) was compared by two-way RM ANOVA and Tukey multiple comparison tests; mean ± SD). d, Quantification of capillaries with blood flow in in bone marrow chimeras with Csf1r-GFP;CAG-dsRed bone marrow transferred into lethally irradiated Csf1r-GFP mice (n = 207 host-derived CAM+ capillary segments, n = 79 donor-derived CAM+ capillary segments; n = 3 mice in total; CAM+ capillary blood flow (Host-derived vs Donor-derived) was compared by paired Student’s t test; mean with paired lines). e,f Quantification of capillary niche age-associated changes, (e) Capillary density and (f) CAM / Capillary segment ratio (n = 4 mice in each age group; two 500 µm2 regions per mouse; comparison across age groups was by one-way ANOVA and Tukey multiple comparison tests; mean ± SD). g, Representative immunohistochemistry of CD68+ macrophage and Erg+ capillary density (magenta arrows) in the upper dermis (within 100 µm from epidermal boundary) of both young (< 40 y) and old (> 75 y) human samples. Epidermal boundary marked by yellow dashed line. h-j, Quantification of capillary niche age-associated changes: (h) CD68+ macrophage density, (i) Erg+ capillary density, (j) Upper dermal macrophage / Capillary endothelium ratio (n = 5 patient samples in young group; n = 6 patient samples in old group; three imaging regions per sample; Comparison by unpaired Student’s t test; mean ± SD). Scale bar, 50 µm.
