Genetic lineage tracing defines myofibroblast origin and function in the injured heart

TLDR

Cardiac fibroblasts become myofibroblasts during injury, driving healing after myocardial infarction and chronic fibrosis, yet the origins and in‑vivo functions of myofibroblasts remain poorly defined. The authors created a tamoxifen‑inducible Postn‑Cre mouse that labels virtually all cardiac myofibroblasts for lineage tracing. Lineage tracing shows that periostin‑expressing myofibroblasts arise from Tcf21+ resident fibroblasts, not endothelial, immune, or smooth muscle cells; deleting these cells reduces collagen and scar after MI, and they revert to a less‑activated state upon injury resolution, establishing periostin‑positive myofibroblasts as essential for adaptive healing and fibrosis.

Abstract

Abstract Cardiac fibroblasts convert to myofibroblasts with injury to mediate healing after acute myocardial infarction (MI) and to mediate long-standing fibrosis with chronic disease. Myofibroblasts remain a poorly defined cell type in terms of their origins and functional effects in vivo . Here we generate Postn (periostin) gene-targeted mice containing a tamoxifen-inducible Cre for cellular lineage-tracing analysis. This Postn allele identifies essentially all myofibroblasts within the heart and multiple other tissues. Lineage tracing with four additional Cre-expressing mouse lines shows that periostin-expressing myofibroblasts in the heart derive from tissue-resident fibroblasts of the Tcf21 lineage, but not endothelial, immune/myeloid or smooth muscle cells. Deletion of periostin + myofibroblasts reduces collagen production and scar formation after MI. Periostin-traced myofibroblasts also revert back to a less-activated state upon injury resolution. Our results define the myofibroblast as a periostin-expressing cell type necessary for adaptive healing and fibrosis in the heart, which arises from Tcf21 + tissue-resident fibroblasts.