Fig. 4

Morphometric assessment of the therapeutic effect of aFRLM on MI. a, The representative figures with the whole cross-field of infarction as stained by Masson’s trichrome method were composed of 130 (Trt) and 160 (Ctrl) consecutive microscopic photos (20×). The vehicle-treated MI heart (Ctrl) showed a blue-stained large and thinned infarct area (yellow dashed line surrounding). The fibrous scar of the infarct was stained blue. In contrast, the aFRLM-treated MI heart showed a smaller and less-thinned infarct area (yellow dashed line surrounding). More interestingly, many red-stained myocyte-like cell clusters (green circles) replaced the blue-stained fibrous scar and reduced the infarct volume in the aFRLM-treated MI heart. b: Inf-V, the infarct volumes in both aFRLM- (Trt) and vehicle- (Ctrl) treated hearts. Reg-V, the regenerating myocyte volumes in the hearts of both groups. Note, some newly formed cardiac myocyte clusters (a: green circles) replaced approximately one fourth (6.9 ± 2.3 %) of the original necrosed cardiac tissues, reducing the average infarct volume to 22.3 ± 7.0 % of the left ventricle volume in the aFRLM-treated group. In contrast, the average infarct volume occupied approximately 29.8 ± 7.3 % with less than 2.1 ± 1.1 % regenerating myocyte-like cells as observed in vehicle-treated hearts (P < 0.01)