Figure 1. P16^INK4A expression is associated with the aging/senescence of cardiac progenitor cells.

Representative images showed the senescence-associated β-galactosidase staining in hCPCs from patients at the age of 44 years old (A), 71 years old (B), and 93 years old (C). D. Quantitative analysis of total β-galactosidase staining. E. Multiple lines of hCPCs showed variation in population doubling times as measured by CyQuant and viability assay cell counts from different groups of patients (n=3 independent experiments). See the Supplemental Table S2 for the basic demographic information for the cardiac tissue donors. F. Differences in proliferation rates were observed in three different hCPC groups (n=3 lines of hCPCs per group). G. Real time qPCR data showed the p16^INK4A gene expression in hCPCs from different groups of patients (n=3 independent experiments). * indicates p<0.05 versus the group of hCPCs-Y for panel E, F, G. H. Quantitative analysis of Western blot showing the significant increase of p16^INK4A expression in the group of hCPCs-A versus the group of hCPCs-Y at passage 6 (P6) (n=3 lines of hCPCs per group). I. Quantitative analysis of Western blot revealed an increase in p16^INK4A protein after replicative passaging (P15 versus P6) of three lines of hCPCs in the hCPCs-Y group. J. Quantitative analysis of Western blot showed an increase in p16^INK4A protein expression in three lines of hCPCs at passage 6 (P6) in the hCPCs-Y group following induction of stress-induced premature senescence through treatment in 0.5 μM doxorubicin for 18 h. * indicates p<0.05. All data were presented as means ± SD from either 3 independent experiments or 3 lines of hCPCs per group.