Development of an in vitro cultivated, spontaneously and long-term contracting 3D heart model as a robust test system

The study deals with an in vitro heart model established from rainbow trout larvae. This model is based on spontaneously contracting cell aggregates (SCC) exhibiting fully developed cardiomyocytes connected via gap junctions and building up a functional syncytium with a pacemaker centre. The cellular structure and the electrophysiological properties of the cardiomyocytes resembled that of human heart cells. It was possible to generate more than one SCC from one fish larva. The SCCs contracted spontaneously over several weeks with a stable contracting frequency similar to human heart. Our analysis supports the use of this model as a high-throughput test system in cardiac research with the potential to complement and reduce animal testing.