Pre-existing fibroblasts of epicardial origin are the primary source of pathological fibrosis in cardiac ischemia and aging. - Quijada, Pearl; Misra, Adwiteeya; Velasquez, Lissette S.; Burke, Ryan M.; Lighthouse, Janet K.; Mickelsen, Deanne M.; Dirkx, Ronald A.; Small, Eric M. (Journal of Molecular & Cellular Cardiology, 2019)