This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Pijnappels, D. A. Articles by Atsma, D. E. Search for Related Content PubMed PubMed Citation Articles by Pijnappels, D. A. Articles by Atsma, D. E.

(Circulation Research. 2009;104:e8.)
© 2009 American Heart Association, Inc.

Letter to the Editor

Response to the Letter by Rose et al

Daniël A. Pijnappels, Martin J. Schalij, Douwe E. Atsma

Department of Cardiology, Leiden University Medical Center, Leiden, The Netherlands, E-mail M.J.Schalij@lumc.nl

An extract of the first 250 words of the full text is provided, because this article has no abstract.

We would like to reply to the letter by Drs Rose, Keating, and Backx,¹ in which they gave their response to our recent publication in Circulation Research.² In this study, we introduced alignment of transplanted stem cells as a novel determinant of functional integration of these cells with native cardiac tissue. In this study, we used neonatal rat mesenchymal stem cells (MSCs), which differentiated into functional cardiac cells after coculture with neonatal rat cardiomyocytes (CMCs). In their letter, Rose et al raise the important question of whether MSCs can differentiate into functional CMCs.¹ However, we demonstrated that neonatal rat MSCs do differentiate into functional CMCs. Although we were one of the first to address the issue of cell alignment and stem cell transplantation, cardiomyogenic differentiation of MSCs derived from a premature or young organism has been shown previously by other groups.^3,4 On the other hand, a number of groups, including ourselves, have shown the inability of adult MSCs to fully differentiate into CMCs.^5,6 Rose et al suggest that the de novo CMCs observed in our study were not derived from MSCs but from contaminating hematopoietic stem cells. The neonatal rat MSCs used in our study contained a small fraction of CD45-positive cells, suggesting a hematopoietic origin; however, only 1.5% of the MSCs were positive for CD34, which is considered to be a key surface marker of hematopoietic stem cells. Moreover, in a study by Nishiyama et al, more than 40% of neonatal human MSCs, which were CD45-negative, differentiated into . . . [Full Text of this Article]