Abstract
According to literature data, self-renewing, multipotent, and clonogenic cardiac c-Kit(+) progenitor cells occur within human myocardium. The aim of this study was to isolate and characterize c-Kit(+) progenitor cells from explanted human hearts. Experimental material was obtained from 19 adult and 7 pediatric patients. Successful isolation and culture was achieved for 95 samples (84.1%) derived from five different regions of the heart: right and left ventricles, atrium, intraventricular septum, and apex. The average percentage of c-Kit(+) cells, as assessed by FACS, ranged between 0.7 and 0.9%. In contrast to published data we do not observed statistically significant differences in the number of c-Kit(+) cells between disease-specific groups, parts of the heart or sexes. Nevertheless, c-Kit(+) cells were present in significant numbers (11-24%) in samples derived from three explanted pediatric hearts. c-Kit(+) cells were also positive for CD105 and a majority of them was positive for CD31 and CD34 (83.7 ± 8.6 and 75.7 ± 11.4%, respectively). Immunohistochemical analysis of the heart tissue revealed that most cells possessing the c-Kit antigen were also positive for tryptase, a specific mast cell marker. However, flow cytometry analysis has shown cultured c-Kit(+) cells to be negative for hematopoietic marker CD45 and mast cell marker CD33. Isolated c-Kit(+) cells display mesenchymal stem cell features and are thought to differentiate into endothelial cells.