The concept that cardiac-derived cKit+ cells can regenerate the injured adult heart by transdifferentiating into functioning cardiomyocytes was proposed 13 years ago, although it remains controversial because of negative data from multiple independent laboratories. Irreproducibility of cardiac cKit+ cell studies was attributed to the differences in cell isolation, selection and expansion before in vivo application. This Viewpoint will discuss recent results that again change the formula for how cardiac cKit+ cells must be isolated and processed in order to be cardiomyogenic, as well as discuss the uncertain in vivo relevance of cKit+ cells as putative cardiomyocyte-producing stem cells.
Keywords: cell line; isoproterenol; myocardial infarction; myocytes, cardiac; stem cells.