<i>hapln1</i> Defines an Epicardial Cell Subpopulation Required for Cardiomyocyte Expansion During Heart Morphogenesis and Regeneration

Abstract

Our findings identify a subset of epicardial cells that emerge in postembryonic zebrafish and sponsor regions of active cardiomyogenesis during cardiac growth and regeneration. We provide evidence that, as the heart achieves its mature structure, these cells facilitate hyaluronic acid deposition to support formation of the compact muscle layer of the ventricle. They are also required, along with the function of <i>hapln1b</i> paralog, in the production and organization of hyaluronic acid-containing matrix in cardiac injury sites, enabling normal cardiomyocyte proliferation and muscle regeneration.