S1PR1 and myocardial infarction: AdMSC-Exos also facilitate macrophage polarization to the M2 phenotype through the activation of the sphingosine-1-phosphate/sphingosine kinase 1/sphingosine-1-phosphate receptor 1 (S1P/SK1/S1PR1) signaling pathway, thus ameliorating cardiac injury following myocardial infarction [69].