All the mice were sacrificed on day 7 with pentobarbital, and the hearts were collected, washed with a heparin-containing saline solution (Sigma-Aldrich), fixed in 10% formalin (Sigma-Aldrich), and embedded in paraffin (Sigma-Aldrich). The paraffin-embedded fixed tissues were then cut into 5-µm-thick sections, placed on polylysine-coated glass slides (HL-H05-2; Nantong Hailun Bio-Medical Apparatus Manufacturing Co., Ltd., Haimen, China) and stained with hematoxylin (Sigma-Aldrich) and Masson's trichrome reagent (Beijin Solarbio Science & Technology Co., Ltd.). The fibrotic areas were quantitated as the ratio of the area that had stained blue to the total section area using the NIS-Elements analysis program (Nikon Corporation, Tokyo, Japan). Immunohistochemistry was performed using a standard procedure as previously described (2 (link)). The sections were incubated overnight at 4°C with antibodies against transforming growth factor β1 (TGF-β1; rabbit polyclonal; sc-146; 1:200; Santa Cruz Biotechnology, Inc., CA, USA), α-smooth muscle actin (α-SMA; rabbit polyclonal; ab66133; 1:300; Abcam, Cambridge, MA, USA), and Mac-2 (galectin-3; rabbit polyclonal; sc-20157; 1:200; Santa Cruz Biotechnology, Inc.). The images were captured using a microscope equipped with a camera (ECLIPSE 80i/90i, Nikon Corporation).