ACTA1 and myocardial infarction: Eight weeks after MI, greater vessel density (vWF + /α-SMA + vessels) was observed in the border zone myocardium in the cell sheet-treated animals compared to that in the untreated MIs (cell sheet vs. untreated, 4.8 ± 1.4/mm2 vs. 3.2 ± 1.1/mm2, respectively) (Fig. 6D), suggesting enhanced angiogenesis in the cell sheet group.