Myofibroblast diversity with injury and aging Fibroblasts deposit extracellular matrix (ECM) molecules to regulate tissue strength and function. However, if too much ECM is deposited, fibrosis and scarring results. Shook et al. examined cells during mouse skin wound healing, fibrosis, and aging (see the Perspective by Willenborg and Eming). They identified distinct subpopulations of myofibroblasts, including cells identified as adipocyte precursors (APs). In cellular ablation mouse models, CD301b-expressing macrophages selectively activated proliferation of APs, but not other myofibroblasts. Myofibroblast composition and gene expression changed during aging. Thus, macrophage-fibroblast interactions are important during tissue repair and aging, which may have therapeutic implications for chronic wounds and fibrotic disease. Science , this issue p. eaar2971 ; see also p. 891