Under hypoxic conditions, AECs secrete higher human-origin proangiogenic cytokine levels, including angiogenin (ANG), EGF, interleukin (IL)-6, and monocyte chemoattractant protein (MCP)-1, contributing to myocardial tissue regeneration in a myocardial infarction rat model [72]. Here, ANG is linked to myocardial infarction.