A Preliminary Investigation of Cardiac Stem/Progenitor Cells in the Lizard Heart

Resident stem/progenitor cell populations have been identified within many vertebrate tissues, including the hearts of teleost fish, urodeles, and mammals. Although often rare, these populations are considered crucial for normal physiological repair, and may also play a role in tissue regeneration. Here we provide preliminary evidence of the presence of resident cardiac stem/progenitor cells within the lizard Eublepharis macularius (the leopard gecko). Using Proliferating Cell Nuclear Antigen (PCNA) immunostaining, we determined that gecko cardiomyocytes continue to proliferate into adulthood. Next, we performed a 5-bromo-2'-deoxyuridine (BrdU) pulse-chase experiment to identify slow cycling cells within the normal (uninjured) heart. We found BrdU label-retaining cells within cardiac tissues chased for 4, 6 and 20 weeks within the epicardium and myocardium of the ventricular wall and trabeculae, indicating that quiescent or slow-cycling cells are present. Finally, we observed that select BrdU label-retain...