The mammalian heart contains a population of resident macrophages that expands in response to myocardial infarction through the recruitment of monocytes. Infarct macrophages exhibit high phenotypic diversity and respond to microenvironmental cues by altering their functional properties and secretory profile. In this issue of the
Nikolaos G. Frangogiannis
Abundant macrophages infiltrate the infarcted heart and can be primed to exert reparative, cardioprotective, and regenerative functions.