J Thorac Cardiovasc Surg 2008;136:798
© 2008 The American Association for Thoracic Surgery
Reply to the Editor:
Julia Pouly, MD,
Patrick Bruneval, MD,
Philippe Menasche, MD, PhD
Hopital Europeen Georges Pompidou, Department of Cardiovascular Surgery, Paris, France
We thank Koninckx and colleagues for their comments. As stated in our article, data were obtained from both endomyocardial biopsies and atrial appendages, and these 2 sampling sites yielded concordant data. However, the major difference is that we performed in situ detection and characterization of cells, whereas Koninckx and colleagues cultured cells for 2 weeks before immunostainings. Such a time interval can change the cell phenotype and delete some cell populations that do not survive under these conditions. The latter phenomenon could explain why Koninckx and colleagues did not find any mast cell in their myocardial tissue cultures, whereas it is well established that the myocardium does contain such cells. Because a minor component of the c-kit-positive cells could have represented a subset of cells different from mast cells, we also tested them for other markers of stemness (CD105, islet-1, and MDR1). However, in our hands, these markers remained negative. The data of Koninckx and colleagues suggest that after a period of culture, c-kit-positive cardiac "stem" cells can be identified, but it would be clinically relevant that they provide a quantitative estimate of these cells to assess whether this number allows one to reasonably envision their use for therapeutic purposes.
