No abstract

We have studied the characteristics of the heart in the adult Giant danio (Danio aequipinnatus), the wound repair response and the ability to regenerate following cautery injury. Electron microscopy studies revealed cardiac myocyte ultrastructure and organization similar to that observed in the zebrafish (Danio rerio). Apical cauterization resulted in injury to 25% of the ventricle. The injury initiated a robust inflammatory response with early recruitment of heterophils and mast cells, and the persistence of myeloperoxidase‐positive cells beyond the first week post‐injury. Bromodeoxyuridine and proliferating cell nuclear antigen‐positive cells, including endothelial cells and cardiac myocytes, were present in areas adjacent to the site of injury during the repair process, but primarily in adjacent subepicardial compact heart region by the second week. We observed marked collagen accumulation on day 14 that persisted through day 45. The collagen accumulation did not result in permanent fibrosis but appears to be resolved by 60 days when the ventricle was completely regenerated. Our data suggest that the Giant danio possesses robust repair mechanisms in the ventricle and may serve as an important model of cardiac inflammation, remodeling and regeneration.

Heart disease remains the number one cause of death in the United States. Mammalian and non‐mammalian models are used to study heart healing and regeneration following injury. In the teleost zebrafish, the removal of ventricular tissue by resection is fully replaced by thirty days with little to no scarring. We hypothesized that the goldfish (Carassius auratus) is able to regenerate its heart in a manner analogous to the zebrafish. We have performed cautery injury of 25% of the ventricle of goldfish that resulted in significant destruction of the ventricular wall and ventricular myocytes. We found an intense inflammatory response in the area of injury, followed the recruitment or proliferation of cells 3 days post injury. We also found a marked increased in collagen deposition at 3 days and 7 days that is resolved by 21 days. This observation is in contrast to the lack of collagen deposition reported in other models. Our data suggests that following cautery injury the goldfish ventricular wall is rebuilt by one week and a quasi complete healing is observed by 21 days. This is the first study showing healing following cautery injury in a fish heart.FundingDePauw University