S100A9 and myocardial infarction: This exploration revealed a notable prevalence of reparative subpopulations (Arg1+ macrophages), rather than inflammatory subpopulations (S100a9+Ly6c+), within the IZ of P1 hearts 3 days after MI injury, in contrast with the scenario observed in P10-MI_3D hearts, where inflammatory subpopulations were more prominent.