Figure 3.

(a) Immunostaining of a human CS showing cells expressing cardiac α-sarcomeric actinin (red) in the outer sheet; nuclear staining with DAPI (blue). (b) PCR expression analysis of early and late cardiac genes by CS-forming cells (CfCs), CSs, and human cardiac biopsy tissue. CfCs express lower levels of early genes (Nkx2.5 and GATA4 transcription factors) compared to CSs, but no α-sarcomeric actinin (SA) nor cardiac troponin I (cTnI). CSs express high levels of both early and late cardiac genes.