Fig. 3

In vivo contribution of B-CPC to homeostasis in the adult mammalian heart. a Timeline for B-CPC and progeny analysis. b Immunohistochemistry of mature YFP⁺ SαA-positive CM surrounded by laminin, at 6 (n = 2) and 12 months (n = 2) post-TM induction, were scattered throughout the heart. Bars, 20 μm (left), 50 μm (right). c-f Flow cytometry of total adult CM from (c) Bmi1-YFP^NI (n = 3), (d) Bmi1-YFP 5d-postTM (n = 8), (e) Bmi1-YFP at two months (n = 5) and (f) Bmi1-YFP mice one year post-TM induction (n = 6). g Expression of contractility proteins in YFP⁺ and YFP⁻ CM; SαA, tropomyosin (TPM) and connexin 43 (CX43). Bars, 50 μm. h Number of YFP⁺ CM, measured by flow cytometry and immunocytochemistry, increases from 2 to 12 months post-TM induction, 3 ± 0.6 % at 2 months (2m; n = 7), 3.8 ± 0.7 % at 6 months (6m; n = 3) and 6.7 ± 2 % at 12 months (12m; n = 9). Data shown as mean ± SEM. P value was calculated by unpaired Student’s t-test with Welch’s correction. * P < 0.05, ** P < 0.01. i Analysis of ploidy in freshly plated adult CM. To count, plated CM were immunostained with YFP and SαA antibodies and scored for DAPI-stained nuclei. A mean of 1,000 CM were scored for each mouse (n = 6). Data shown as mean ± SEM. B-CPC Bmi1-expressing cardiac progenitor cells, YFP yellow fluorescent protein, SαA sarcomeric α-ctinin, CM cardiomyocytes, TM tamoxifen