Fig. 2 |. An aged systemic milieu induces senescence transfer in multiple young tissues.

a, Experimental setup for heterochronic blood exchange. b, Luminescence images of young p16-3MR mice receiving young blood from C57BL/6J mice (YY) and young p16-3MR mice receiving old blood from C57BL/6J mice (YO) 14 days after blood exchange (left) and quantification of the luminescence (right) (in arbitrary units, a.u.) (n = 7, 4, 3, 4 or 4 mice). c, Ratio of circulating SASP proteins (>1.5-fold) of old mouse blood (n = 7) normalized to young mouse blood (n = 3) measured by antibody array. d, Gene expression of the senescence and SASP markers in lung, hippocampus, heart, skeletal muscles (gastrocnemius (GA) and tibialis anterior (TA)), kidney and liver (n = 6 for YY; n = 7 for YO). Whisker plots represent the 10th and 90th percentiles and the line corresponds to the median. e, Representative images of SA-β-gal staining in skeletal muscle (n = 4 for YY and n = 5 for YO; 3–6 images per mouse) and quantification of SA-β-gal⁺ cells per area of YY and YO mice. Scale bar, 50 μm. f, Representative images of SA-β-gal staining (n = 8 mice for each group/7–10 images per mouse) and HMGB1 immunohistochemistry (n = 5 for YY; n = 7 for YO; 6–10 images per mouse) and quantification of SA-β-gal⁺ cells per area (n = 8 per group) of kidney sections of YY and YO mice. Scale bars, 100 μm. g, Representative SA-β-gal staining in liver (n = 9 for YY; n = 8 for YO; 7–10 images per mouse) and quantification of SA-β-gal⁺ cells per area in YY and YO mice and γ-H2AX foci in a hepatocyte (n = 6 per group; 5–8 images per mouse). this experiment was performed three independent times. Scale bar, 100 μm. Data are means ± s.e.m. of biologically independent samples. Statistical significance was calculated using a two-tailed t-test with a Welch’s correction (b,e–g) with *P < 0.05; **P < 0.01 and multiple Mann–Whitney tests with a two-stage linear step-up procedure by Benjamini, Krieger and Yekutieli, with Q = 5%, *q < 0.05 (c,d).