Mice with megakaryocyte-specific gene targeting of TGF-β1 are partially protected from developing cardiac hypertrophy and fibrosis 4 weeks after TAC surgery. (A) Heart weight/body weight ratios as calculated by dividing the weight of the perfused heart by total body weight at the time of harvest (4 weeks after the surgery). (B-C) Mice were euthanized and hearts were perfused and fixed in formalin. Heart sections were stained with trichrome and scored for fibrosis by microscopy on a scale from 0 to 4. (B) Perivascular fibrosis scores. (C) Interstitial fibrosis scores. (D) Pretreatment and postsurgery values of plasma TGF-β1 in experimental animals measured by ELISA. (E) The correlations between plasma total TGF-β1 and heart weight/body weight ratio in individual WT mice (r = 0.66; P < .001). (F) The correlation between plasma total TGF-β1 and the combination of interstitial and perivascular fibrosis grade in individual TAC mice of both genotypes.