Do Mesenchymal Stromal Cells Transdifferentiate Into Functional Cardiomyocytes?

To the Editor:We would like to comment on the recent and interesting report by Pijnappels et al1 showing that mesenchymal stem (stromal) cells (MSCs) can transdifferentiate along the cardiac lineage in culture. The ability of MSCs to transdifferentiate into cardiomyocytes is highly controversial, with numerous studies suggesting that the phenomenon occurs, whereas many others conclude that it does not. Pijnappels et al have provided data showing that under their cell culture conditions, some MSCs in coculture with neonatal cardiomyocytes undergo cardiac differentiation, as indicated by the expression of sarcomeric α-actinin, cardiac troponin I, and connexin-43. Furthermore, Pijnappels et al recorded action …