Treg‐secreted exosomes (Treg‐EXs) were found to markedly decrease the myocardial infarct size and suppress apoptosis of myocardial cells in mice with MI, which was along with a reduction in the M1 marker iNOS and an increase in Arg‐1 M2 marker as well as a reduction in the pro‐inflammatory mediators, such as IL‐1β and TNF‐α, and an increase in the anti‐inflammatory mediators, such as IL‐10 and TGF‐β.109. The gene discussed is ARG1; the disease is myocardial infarction.