Infarct Fibroblasts Do Not Derive From Bone Marrow Lineages
Rationale: Myocardial infarction (MI) is a major cause of adult mortality worldwide. The origin(s) of cardiac fibroblasts that constitute the post-infarct scar remain controversial, in particular the potential contribution of bone marrow lineages to activated fibroblasts within the scar.
Objective:To establish the origin(s) of infarct fibroblasts using lineage tracing and bone marrow transplants, and a robust marker for cardiac fibroblasts, the Collagen1a1-GFP reporter.
Methods and Results: Using genetic lineage tracing or bone marrow transplant, we found no evidence for Collagen-producing fibroblasts derived from hematopoietic or bone marrow lineages in hearts subjected to permanent left anterior descending (LAD) coronary artery ligation. In fact, fibroblasts within the infarcted area were largely of epicardial origin. Intriguingly, collagen-producing fibrocytes from hematopoietic lineages were observed attached to the epicardial surface of infarcted and sham-operated hearts in which a suture was placed around the LAD.
Conclusions: In this controversial field, our study demonstrated that the vast majority of infarct fibroblasts were of epicardial origin and not derived from bone marrow lineages, endothelial-to-mesenchymal transition (EndoMT) or blood. We also noted the presence of collagen-producing fibrocytes on the epicardial surface that resulted at least in part from the surgical procedure.
- Received June 10, 2017.
- Revision received December 18, 2017.
- Accepted December 20, 2017.