Defining Macrophages in the Heart One Cell at a Time

Macrophages in the heart have dual roles in injury and repair after myocardial infarction, and understanding the two sides of this coin using traditional ‘bulk cell’ technologies has been challenging. By combining genetic fate-mapping and single-cell transcriptomics, a new study ( Nat. Immunol. 2019;20:29–39) reveals how distinct macrophage populations expand and diverge across the healthy heart and after infarction