Fig. 6: Lipomatous metaplasia in the late chronic phase of MI is unique to hemorrhagic Infarcts.

Serial paraffin sections from a 6-month-old hemorrhagic MI stained with elastin-modified Masson’s trichrome (EMT), H&E, and Prussian Blue (PB) stains are presented in panel a. Larger fat depots typically penetrated scar tissue at its internal core (Zone A) were observed. Notably, these larger foam cell clusters typically colocalized with iron deposits along the fat depot periphery while the core of the growing adipose tissue contained traces of iron deposits (Zone B, arrows). Serial frozen sections from a dog with 6-month-old hemorrhagic MI stained with H&E, EMT, Oil-Red-O (ORO), and PB stains are presented in Panel b. Note the extensive colocalization of iron deposits and foam cells in the fat depot penetrating the internal core of the hemorrhagic scar. Additional examples of LM in the peripheral zone of the sub-endocardium and midmyocardium and at the border zone of the MI territories and its relation to iron and foam cells in 6-month-old scars are shown in Supplementary Figs. 5–7). For 6-month-old non-hemorrhagic MI scenario, refer to Supplementary Fig. 8. Scale bar of images in panel a is 500 and 250 µm (zoom-in images), while those in panel b are 100 µm. The number of samples per timepoint/animal group used is depicted in Supplementary Fig. 1.