The treatment of myocardial infarction by stem cells is mainly due to the paracrine role of stem cells secreting various bioactive factors in the myocardium [143], such as VEGF, PDGF (platelet-derived growth factor), SDF-1 (stromal cell-derived factor-1) [144,145], etc. The introduction of bioactive factors is one of the approaches to treat myocardial infarction. The gene discussed is CXCL12; the disease is myocardial infarction.