Fig. 6: Pericyte coverage loss leads to augmented capillary dilations in the aged brain.
a Comparison of baseline capillary diameters across age. Unpaired t test (two-sided), t(60) = 0.7245; p = 0.4716. N = 30 capillaries from 6 adult mice, n = 32 capillaries from 6 aged mice. Data shown as mean ± SD. Ns = non-significant. b Capillary dilation occurs in region with loss of pericyte coverage, but not in adjacent capillaries that maintain pericyte coverage. Arrowhead points to pericyte targeted for ablation. I.v. dye = intravenous dye. c Example capillary region from adult mouse following triple pericyte ablation. Arrowheads show two targeted cells. Bottom row shows i.v. dye alone, with capillary segments measured over time identified by blue lines. d Plot of capillary diameters over time from adult mice. Repeated measures one-way ANOVA with Tukey’s multiple comparisons test (two-sided), F(1.824, 45.60) = 35.95, ****p < 0.0001. Baseline vs uncovered, ****p < 0.0001; baseline vs. re-covered, p = 0.7393; uncovered vs. re-covered, ****p < 0.0001. N = 26 capillaries from 6 mice. Data are shown as mean ± SD. e Example capillary region from aged mouse following triple pericyte ablation. Arrowheads point to targeted pericytes. Bottom row shows i.v. dye alone, with capillary segments measured over time identified by purple lines. f Plot of capillary diameters over time from aged mice. Repeated measures one-way ANOVA with Tukey’s multiple comparisons test (two-sided), F(1.914, 53.59) = 111.3, ****p < 0.000. Baseline vs uncovered, ****p < 0.0001; baseline vs. re-covered, **p = 0.0018; uncovered vs. re-covered, ****p < 0.0001. N = 29 capillaries from 6 mice. Data shown as mean ± SD. g Change in diameter from baseline at 3 days post ablation, when capillaries lack pericyte coverage. Unpaired t test (two-sided), t(54) = 3.501, ***p = 0.0009. N = 26 capillaries in 6 adult mice, n = 30 capillaries in 6 aged mice. Data are shown as mean ± SD. h Difference between baseline and re-covered capillary diameter detected in adult and aged groups. Adult: One sample t test (two-sided), t(25) = 0.7451; p = 0.4631, for n = 26 from 6 mice. Aged: One sample t test (two-sided), t(33) = 4.172; ***p = 0.0002, for n = 34 capillaries from 6 mice. Difference in re-covered diameter between adult and aged mice. Unpaired t test with Welch’s correction (two-sided), t(41.40) = 2.751; **p = 0.0088. Data shown as mean ± SD. i Dilations persist for capillaries that do no regain pericyte coverage at 21 days in aged mice. Repeated measures one-way ANOVA with Tukey’s multiple comparisons test (two-sided), F(1.967, 19.67) = 31.35; overall effect ****p < 0.0001. Pre-ablation vs 3 days, ****p < 0.0001; pre-ablation vs 21 days, ***p = 0.0002; 3 days vs 21 days, p = 0.5976. N = 11 capillaries from 6 mice. Data are shown as mean ± SD.
