Researchers in Tennessee have shown that macrophage colony-stimulating factor (CSF-1)-mediated expansion and polarization of resident renal macrophages and dendritic cells is important in the regeneration of renal tubule epithelium following acute kidney injury (AKI). For their study, Zhang et al. used two distinct models of AKI—one caused by ischaemia–reperfusion and one caused by administration of diphtheria toxin to transgenic mice expressing the human diphtheria toxin receptor selectively in the proximal tubule.