Questioning the relevance of circulating cardiac progenitor cells in cardiac regeneration

Abstract

See article by Ausoni et al. [10] (pages 394–404) in this issue . Regeneration of injured myocardium would offer relief to millions of patients with left ventricular dysfunction. Cell implantation and induction of stem cell-mediated myocardial self-repair represent potential means to achieve myocardial regeneration [1,2]. The latter requires homing of cardiogenic cells to diseased myocardium or activation of resident cardiogenic stem cells. Both mechanisms have been described in the literature and would be preferable to exogenous cell engraftment with its drawbacks of invasive cell harvesting, cell propagation, and invasive cell deposition in the heart [3–6]. However, recent studies questioned the principal capacity of circulating adult stem cells to give rise to cardiac myocytes and support myocardial regeneration [7–9]. In the current issue of Cardiovascular Research , Ausoni et al. provide further evidence against the role of circulating stem cells in cardiac regeneration [10]. Assessment of stem cell-mediated cardiac regeneration requires unambiguous identification of these cells and their progeny in the heart. Several markers, including c-kit, sca-1, and isl-1, have been described to denote cardiac precursor cells, but are lost once progenitors differentiate into somatic cells, making cell fate mapping difficult [3–5]. Stable, preferably genetic, marking of stem cells and their progeny is thus a requirement if the fate of an individual cell is to be followed from the multipotent progenitor state to the differentiated somatic cell. Quiani et al. were the first to utilize sex-mismatched heart … *Corresponding author. Tel.: +49 40 42803 7205; fax: +49 40 42803 5925. Email address: w.zimmermann{at}uke.uni-hamburg.de