Interestingly, Cheng et al showed that circulating myocardial microRNAs are released after acute myocardial infarction into the circulation in exosomes and mediate functional crosstalk between the ischemic heart and the bone marrow.136 Furthermore, exosomes mediate the transfer of muscle-specific miRNAs to bone marrow mononuclear cells, where muscle-specific miRNAs downregulate CXCR4 (C-X-C motif chemokine receptor 4) expression and mediate progenitor cell mobilization.136. Here, CXCR4 is linked to acute myocardial infarction.