Human Cardiac Stem Cells

Abstract

Listen

Translate article

The view of the heart as a static organ implies that myocyte death and formation play a negligible role in cardiac homeostasis. Although stem cells have been unexpectedly identified in several organs, including the brain, kidney, lung, and skeletal muscle, the search for a cardiac stem cell (CSC) has been perceived as a futile effort, given the acknowledged lack of regenerative potential of the myocardium. Nevertheless, in the past several years, the demonstration of myocyte renewal in the normal and diseased heart has revealed a new, dynamic, and lively picture of this organ. Components of the cell cycle machinery and markers of cell replication have been detected in cardiomyocytes. The demonstration that karyokinesis and cytokinesis involve cells expressing contractile proteins has provided evidence that cardiomyocyte division occurs in the adult heart.1 More recently, pulse-chase assays with thymidine analogs,2 lineage tracing protocols,3 and 14C birth dating of cells4 have shown the existence of myocyte turnover, a process that has been found to differ in magnitude according to the methods used for its documentation and quantification. Article see p 2559 Over the years, the heart has provided us with the evidence that solves the critical problem of the origin of cardiomyocytes. At this moment in time, paraphrasing Eugenio Montale, we could say that the human heart is “on the verge of betraying [its] final secret offering the opportunity to uncover…the still point of the world, the link that won't hold, the thread to untangle that will finally lead to the heart of a truth.”5 Newly generated myocytes may derive from division of preexisting parenchymal cells or from activation and differentiation of resident CSCs. Discriminating between these two possibilities is not an easy task. Fate-mapping strategies, which are commonly used to track the origin of cells and …