MECP2 and myocardial infarction: Feng et al. determined that miR-22 is highly enriched in exosomes secreted by mouse bone marrow-derived MSCs after ischemic preconditioning, and administration of these exosomes significantly reduced infarct size and cardiac fibrosis by targeting methyl-CpG-binding protein 2 (Mecp2) in a mouse myocardial infarction (MI) model [44].