Figure 1  A meta-analyses of microRNA microarrays during in the developing and aging cardiogenesis. Panel A illustrates the heatmap of the differentially expressed microRNAs during mouse ventricular development, as described by Chinchilla et al. [14]. Panel B illustrates the heatmap of the comparative analyses of the differentially expressed microRNAs in the developing and aging mouse heart. Observe that while those differentially expressed during cardiogenesis display increasing expression trends, the young and adult heart display no significant trends. In contrast, comparative analyses of the differentially expressed microRNAs in the developing heart and induced pluripotent stem cell-derived cardiomyocytes, over a maturation period ranging incipient cardiomyocytes (day zero) to 120 days after differentiation, nicely show subset of microRNAs with similar trends (i.e., let7 cluster) or opposite trends (see, for example, miR-103 and miR-106b), as illustrated in this heatmap on panel C. Panels A'. B', C' and C'' are graphical illustrations of microRNA representative expression trends as depicted in heatmaps on panels A, B and C, respectively. Panel A' displays only a small representation of the full list of microRNAS represented in heatmap of panel A. More detailed information can be found in Chinchilla et al. [14]. Panel C' represents a subset of panel C microRNAs displaying increased expression levels in both ventricular maturation and iPS-cardiomyogenesis, while panel C'' represents a microRNA subset display increasing expression levels during ventricular maturation, but decreasing expression levels in iPS-cardiomyogenesis.