ETV2 and fibrosis: Importantly, Masson’s trichrome staining of cardiac tissues harvested at 8 weeks also confirmed that the ETV2-injected group showed significantly reduced cardiac fibrosis compared to the control group (16.3 ± 2.4% in ETV2 vs. 39.1 ± 1.1% in control, n = 3; p < 0.05) (Fig. 3c, d).