Despite the macrophage M2 polarization induced by theses Exo, it seems that S1P/ sphingosine kinase 1 (SK1)/sphingosine-1-phosphate receptor-1 (S1PR1) axis is responsible for AMSCs- exosomes -mediated myocardial recovery because S1PR1 silencing mitigated the suppressive influences of Exo on MI-stimulated cardiac apoptosis and fibrosis in vitro. Here, S1PR1 is linked to myocardial infarction.