Extended Data Fig. 6: PD-1 is required for neonatal heart regeneration.
a, Illustration showing time points of antibody injection, MI or sham and sample collection. b, c, Fractional shortening (b) and ejection fraction (c) of IgG-treated or anti-PD-1 antibody (anti-PD-1)-treated mice at 1, 2 and 3 weeks post-MI or sham. The same cohort of mice was measured every week. IgG/ anti-PD-1 sham: n = 5 mice. IgG MI: n = 8, 7, and 7 mice at 1, 2, 3 weeks, respectively. anti-PD-1 MI: n = 8 mice (b c). p = 0.0022 (1 week), p = 0.0175 (2 weeks), p = 0.0175 (3 weeks) (b). p = 0.0014 (1 week), p = 0.0227 (2 weeks), p = 0.0227 (3 weeks) (c). d, Immunofluorescence of TUNEL (magenta), cardiac troponin T (cTnT, green) and DAPI (blue) on heart sections from IgG-treated or anti-PD-1-treated mice at d7 post-MI with infarct and remote zones depicted. Sections were collected at 200μm below the ligation. Scale bar, 100μm. e, Quantification of TUNEL+ cells in (d). p = 0.002577 (Infarct: IgG vs. anti-PD-1). f, Immunofluorescence of pH3 (red), cardiac troponin T (cTnT, green) and DAPI (blue) in hearts from IgG-treated or anti-PD-1-treated mice at d7 post-MI. Sections were collected at 200μm below the ligation, and pictures were taken at the border zone of the injury. Scale bar, 100μm. g, Quantification of pH3+ cardiomyocytes from (f). p = 0.0395 (IgG vs. anti-PD-1). n = 6 mice per group (3 images counted per mouse) (e, g). Results are shown as mean ± s.e.m; *p < 0.05, **p < 0.01 by two-tailed Student’s t-test (e, g) or two-tailed Student’s t-test with correction for multiple comparisons using the Holm-Šidák method (b, c).
