Cardiac fibrosis: Pathobiology and therapeutic targets.

Cardiac fibrosis is characteristic of the end stage in nearly all forms of heart disease. Accumulation of extracellular matrix in the myocardium leads to increased risk of arrhythmia and impaired cardiac function, and ultimately progression to heart failure. Despite the critical need to slow or reverse development of cardiac fibrosis to maintain cardiac function, there are no approved therapies that directly target the extracellular matrix. Research into the underlying causes and therapeutic targets has been hampered, in part, by the lack of a clear marker for cardiac fibroblasts - the cells responsible for regulating extracellular matrix turnover. Lineage tracing studies as well as single-cell RNA sequencing studies have provided new insights into cardiac fibroblast origins and heterogeneity. Moreover, a greater understanding of pathways governing fibroblast activation during ischemic and non-ischemic cardiac remodeling and their communication with other inflammatory and cardiac cells may lead to novel therapeutic targets to slow or reverse fibrotic remodeling. The special issue of Cellular Signaling entitled "Cardiac Fibrosis: Pathobiology and Therapeutic Targets" is comprised of review articles in which these topics, as well as important open questions for future investigation, are discussed.