Stage-dependent cardiac regeneration in Xenopus is regulated by thyroid hormone availability

Significance Heart failure is the leading cause of death worldwide. Cardiac regeneration studies currently focus on zebrafish, urodeles, and mammals, bypassing the amphibian Xenopus laevis , despite being considered as a leading model for regeneration research. We thus took advantage of X. laevis as a model to explore thyroid hormone (TH) influence on the cardiac regenerative process. We suggest a possible link between altered TH availability and the loss of cardiac regenerative capacity. Examining heart regeneration in Xenopus provides insight into how TH levels may contribute to the enigmatic loss of cardiac regeneration during vertebrate development, suggesting potential therapeutic leads of major biomedical and fundamental relevance for the development of future regenerative strategies, and ultimately to provide therapies for the human heart.