Background: Human amniotic epithelial cells (hAECs) are seed cells used to treat acute myocardial infarction (AMI), but their mechanism remains unclear.

Methods: We cultured hAECs and extracted exosomes from culture supernatants. Next, we established a stable AMI model in rats and treated them with hAECs, exosomes, or PBS. We assess cardiac function after treatment by echocardiography. Additionally, heart tissues were collected and analyzed by Masson’s trichrome staining. We conducted the tube formation and apoptosis assays to explore the potential mechanisms.

Results: Cardiac function was improved, and tissue fibrosis was decreased following implantation of hAECs and their exosomes. Echocardiography showed that the EF and FS were lower in the control group than in the hAEC and exosome groups, and that the LVEDD and LVESD were higher in the control group (P<0.05). Masson’s trichrome staining showed that the fibrotic area was larger in the control group. Tube formation was more efficient in the hAEC and exosome groups (P<0.0001). Additionally, the apoptosis rates of myocardial cells in the hAEC and exosome groups were significantly decreased (P<0.0001).

Conclusions: hAECs and their exosomes improved the cardiac function of rats after AMI by promoting angiogenesis and reducing the apoptosis of cardiac myocytes.