Cardiac stem cells: Tales, mysteries and promises in heart generation and regeneration

For long time, the heart was categorized as a post-mitotic organ, unable to undergo substantial renewal during the adult life. The heart scenario was opposite to the situation of other organs such as the liver, the skin and the bone marrow, whose ability to regenerate has been known for longtime. Today, several proofs exist that the heart has a self renewal capacity similar to that in other organs due to the discovery of resident stem cells that have been shown to produce new myocytes throughout the adult life. If the discovery of stem cells in the heart has resolved the issue of myocardial renewal, it has not resolved yet the issue of the best biological treatment to efficiently repair myocardium after ischemic damage. In fact, up to date, no clear indication exists about the identity of progenitor cells that are best suited as biological drugs for myocardial repair. In addition, despite the always growing number of publications describing the ability of cardiac and non-cardiac derived cells to repair the ischemic heart in preclinical models, the limited, although remarkable, clinical benefits obtained in first generation clinical trials in patients, have raised the issue of stem cell-mediated cardiac repair efficiency. In this contribution, the present and the future of heart repair will be outlined in the view of the most recent advancements in the understanding of basic biology, preclinical testing and clinical translation.