Long-term organ cultures of newt hearts

Adult newts regenerate their hearts after injury by initiating proliferation of cardiac muscle and non-muscle cells. Mechanistic studies in vivo to analyze heart regeneration are challenging due to the long reproduction cycle of newts and the complexity of the genome. Culture of primary newt cells might offer alternative experimental approaches, but monolayers of newt cardiomyocytes and slice cultures of newt hearts show extensive morphological changes during cultivation. Hence, we developed a protocol to culture intact newt hearts in vitro, avoiding major morphological changes of explanted organs during a 5-week cultivation. The model provides improved accessibility and allows manipulation of cultured organs by small molecules and viral vectors. We found that dedifferentiation and S-phase entry of cardiomyocytes, which are hallmarks of cardiac regeneration in vivo, can be recapitulated in cultured hearts in vitro. We reason that long-term organ cultures of newts are a versatile tool for mechanistic studies on organ regeneration.