EPO inhibited myocardial fibrosis and cardiomyocyte hypertrophy in diabetic rats and was dependent on the reduction of TGF-β expression. (A) Picrosirius Red staining showing the collagen content in LV sections from control, diabetic, and diabetic EPO–treated rats. The arrowhead indicates elevated collagen content that was stained red in the extracellular matrix in the LV myocardium of diabetic rats and is significantly higher than control and EPO–treated group (200×magnification). (B) Collagen content was quantified from Picrosirius Red staining using Adobe Photoshop. (C) Immunohistochemical staining of TGF-β: quantitative data of TGF-β staining (400× magnification). (D) Immunohistochemical staining of collagen type I: quantitative data of collagen type I staining (400× magnification). (E) Immunohistochemical staining of collagen type III: quantitative data of collagen type III staining (400× magnification). (F) Caridomyocyte size was measured by hematoxylin-eosin staining in cross-sectional areas. (400× magnification). Bar graph shows quantitative analysis of cardiomyocyte cross-sectional area. Data are expressed as the mean ± SEM (n = 5).*P < 0.05 vs control, #P <0.01 vs control, ▴P <0.05 vs diabetes, ▵P <0.01 vs diabetes.