Cardiomyocyte proliferation in the lizard heart: exploring criteria for spontaneous self-repair

Abstract

Cardiac self-repair varies across vertebrates. Whereas mammals demonstrate a poor cardiac reparative capacity, species such as zebrafish and urodeles can completely regenerate lost or damaged portions of the heart. A number of features are associated with this regenerative potential, including a cardiomyocyte population capable of postnatal proliferation, a trabeculated myocardium, and the presence of a reservoir of normally quiescent, possibly stem-like cells. Here we explore these criteria in an emerging model of multi-tissue regeneration, the leopard gecko (Eublepharis macularius). Using multiple methods, we determined that cardiac cells proliferate in the homeostatic heart, including ~10% of the cardiomyocyte population. Our findings confirm that the myocardium is trabeculated, and constitutively expresses a number of growth factors. Moreover, we identify a reservoir of slow-cycling cells, some of which co-localize with the stem/progenitor cell marker c-kit. These findings demonstrate that the gecko is an appropriate model to study spontaneous cardiac regeneration.