(1) Evaluate the safety of mesenchymal stem cell extracellular vesicle therapy in patients with acute myocardial infarction (2) Evaluate the effectiveness of mesenchymal stem cell extracellular vesicle therapy in patients with acute myocardial infarction and explore its possible mechanisms of action. Myocardial infarction (AMI) is one of the major fatal diseases of cardiovascular disease in China, and its incidence rate is on the rise. Myocardial infarction (AMI) is one of the major fatal diseases of cardiovascular disease in China, and its incidence rate is on the rise. With the implementation of the "China AMI Standardized Treatment Project", the mortality rate of AMI in China has decreased from around 8% to around 3.8%. Nevertheless, the incidence of heart failure after AMI remains high. The loss of functional myocardial cells and the limited proliferation and differentiation ability of remaining myocardial tissue are important pathological foundations for irreversible damage to cardiac structure and function caused by AMI. Therefore, how to achieve myocardial regeneration and repair after infarction is an urgent issue that needs to be addressed at this stage. As an important tool for information exchange between cells, stem cell derived exosomes participate in the repair of damaged myocardium after AMI, promote angiogenesis, inhibit myocardial fibrosis, and can significantly reduce the size of myocardial infarction and improve cardiac function. However, stem cell derived exosomes are still in the preclinical research stage, and there are no clinical studies on the treatment of myocardial infarction with exosomes. This study selected patients who received PCI treatment within one month after myocardial infarction in our hospital and received continuous treatment with stem cell derived extracellular vesicles for four weeks. They were followed up for observation, and underwent cardiac ultrasound, blood biochemistry, and other examinations before treatment, 1 month, 3 months, 6 months, and 1 year of treatment to observe their safety, observe their impact on cardiac function, and explore their possible mechanisms of action, in order to find effective methods for damaged myocardial regeneration and repair.