Figure 6: Histological analysis of the infarcted hearts after stem cell transplantation compared with controls. Rat hearts stained with picrosirius red after myocardial infarction (A) hESC-CMs (B) hESC-CMs + MSCs (C) hESC-CMs + MSCs over-expressing HO-1 and (D) saline. The scar (picrosirius red area which is positive for collagen) in the control group (D) is thin and appears stretched while the scars in the three cell-treated groups (A,B,C) were thicker and less stretched.