Figure 7. Origins of postnatal cardiomyogenesis in the adult mouse heart by flow cytometry.

• A. FACS-sorted GFP⁺ and GFP⁻ cardiomyocytes were subsequently stained for αSA. Only αSA⁺ cells were examined.
• B, C. Flow cytometric analysis of GFP⁺/αSA⁺ and GFP⁻/αSA⁺ cardiomyocytes for BrdU incorporation reveals that, in the normal mouse heart, cardiomyocyte turnover occurs exclusively through proliferation of adult cardiomyocytes. After MI, cardiomyocyte proliferation is upregulated, while progenitor cells also contribute to the replacement of lost cardiomyocytes. CDCs amplify both stem cell-mediated myocyte replenishment and adult cardiomyocyte proliferation. Numbers in flow cytometry plots indicate averages for groups. Red dots indicate BrdU⁺ while black dots indicate BrdU⁻ cardiomyocytes (colour gating has been applied to the images). (*p < 0.05 compared to GFP⁺ cardiomyocytes; ^#p < 0.05 compared to MI and sham; ∧p < 0.05 to sham; n = 5/group). All error bars represent SDs. One-way ANOVA followed by LSD post hoc test and independent samples t-test were used for statistical analysis (GFP⁺: MI vs sham: p = 0.01, CDCs vs sham p < 0.001, CDCs vs MI p < 0.001; GFP⁻: MI vs sham: p < 0.001, CDCs vs sham p < 0.001, CDCs vs MI p < 0.001; GFP⁺ vs GFP⁻ MI p < 0.001, GFP⁺ vs GFP⁻ CDCs p < 0.001; all other p = ns).