MRC1 and myocardial infarction: Thirdly, cardiac CD206+F4/80+ M2-like macrophages isolated from the post-MI heart expressed higher levels of major pro-fibrotic factors, including Tgfb and Spp12, 26 (Fig. 2a), compared to primary cardiac fibroblasts, indicating an ability of cardiac M2 macrophages to activate cardiac fibroblasts post-MI.