Grivas, DimitriosGonzález-Rajal, Álvarode la Pompa, José Luis2022-12-222022-12-222021Cell Dev Biol. 2021 May 7;9:6694392296-634Xhttp://hdl.handle.net/20.500.12105/15380Unlike the hearts of mammals, the adult zebrafish heart regenerates after injury. Heart cryoinjury in zebrafish triggers the formation of a fibrotic scar that gradually degrades, leading to regeneration. Midkine-a (Mdka) is a multifunctional cytokine that is activated after cardiac injury. Here, we investigated the role of mdka in zebrafish heart regeneration. We show that mdka expression was induced at 1-day post-cryoinjury (dpci) throughout the epicardial layer, whereas by 7 dpci expression had become restricted to the epicardial cells covering the injured area. To study the role of mdka in heart regeneration, we generated mdka-knock out (KO) zebrafish strains. Analysis of injured hearts showed that loss of mdka decreased endothelial cell proliferation and resulted in an arrest in heart regeneration characterized by retention of a collagenous scar. Transcriptional analysis revealed increases in collagen transcription and intense TGFβ signaling activity. These results reveal a critical role for mdka in fibrosis regulation during heart regeneration.engVoRhttp://creativecommons.org/licenses/by/4.0/Atribución 4.0 Internacional34026760966943910.3389/fcell.2021.669439Frontiers in cell and developmental biologyopen access