Fig. 4: Mural cell remodeling capacity varies with age across microvascular zones.

a In vivo two-photon image of a microvascular network from penetrating arteriole to ascending venule, with branch orders in white. Bottom image highlights mural cell subtypes within zones. This is a representative view from 14 separate ablation experiments in regions containing different microvascular zones. I.v. dye  =  intravenous dye. Venule SMC  =  venular smooth muscle cell. b Example of an ensheathing pericyte from an adult mouse remodeling into the capillary zone. Arrow indicates position of leading process terminus over time. Bottom row shows high-resolution image of the cell at 21 days post-ablation. This is a representative example from 13 processes observed in arteriole-capillary transition zone. c Example of a mesh and thin-strand pericyte from an adult mouse growing within the capillary bed. Arrows show growing terminal ends of processes. This is a representative example from 35 processes observed in capillary zone. d Example of a venule SMC process from an adult mouse growing into the capillary bed, as indicated by arrows. This is a representative example from 7 processes observed in venular zone. e Average process growth by mural cells in different microvascular zones. Two-way ANOVA with Tukey’s multiple comparisons test (two-sided), For age comparison, F(1,102) = 21.45; overall effect, ****p = 0.0001; Arteriole-capillary transition (adult vs. aged) ****p < 0.0001; capillary (adult vs. aged) **p = 0.0016; Venule (adult vs. aged) p > 0.9999. For vessel type comparison, F(2,102) = 0.1838; overall effect, p = 0.8324, For interaction between age and vessel type, F(2,102)  =  6.029, overall effect, **p = 0.0033. Arteriole-capillary transition vs. capillary (adult), p = 0.5833; arteriole-capillary transition vs. venule (adult), p = 0.4125; capillary vs. venule (adult), p = 0.9533. Arteriole-capillary transition vs. capillary (aged), p = 0.4855; arteriole-capillary transition vs. venule (aged), *p < 0.0398; capillary vs. venule (aged), p = 0.4516. Adult: n = 13 arteriole-capillary transition, n = 35 capillary, n = 7 venule from 6 mice; aged: n = 12 arteriole-capillary transition, n = 30 capillary, n = 10 venule from 6 mice. Data are shown as mean ± SEM. f Maximum process extension by mural cells in different microvascular zones. Two-way ANOVA. For age comparison, F(1,97) = 0.1455; overall effect, p = 0.7037. For vessel type comparison, F(2,97) = 2.613; overall effect, p = 0.0784. For interaction between age and vessel type, F(2,97) = 5.532; **p = 0.0053. Arteriole-capillary transition vs. capillary (adult), p > 0.9999; arteriole-capillary transition vs. venule (adult), p < 0.9897; capillary vs. venule (adult), p = 0.3511. Arteriole-capillary transition vs. capillary (aged), p = 0.8750; arteriole-capillary transition vs. venule (aged), **p < 0.0014; capillary vs. venule (aged), **p = 0.0044. Adult: n = 13 arteriole-capillary transition, n = 35 capillary, n = 7 venule from 6 mice; aged: n = 12 arteriole-capillary transition, n = 30 capillary, n = 10 venule from 6 mice. Data are shown as mean ± SEM.