FGF10 Cardiac Differentiation Figure 1. Gene expression profiles of FGF members during cardiomyocyte differentiation from embryonic stem cells. A, Schematic presentation of the cardiomyocyte differentiation process showing the intermediate stages denoted by the expression of specific marker genes. B, RT-PCR results showing temporal expression patterns of these marker genes on days 2 (D2), 4 (D4), 6 (D6) and 8 (D8) of hanging drop cultivation (n = 3). Purified embryonic stem cell-derived cardiac precursors (CP) and neonatal (1 – 2 days after birth) cardiomyocytes (CM) served as controls. C, RT-PCR data showing temporal expression patterns of FGF members (n = 3). Note that FGF-3, FGF-8, FGF-10, FGF-11, FGF-13, and FGF-15 are mainly expressed during the mesodermal and cardiovascular progenitor stages. D, Cardiomyocyte differentiation following treatment with FGF-3, FGF-7, FGF-8, FGF-10, FGF-11, FGF-13, and FGF-15 (n = 3). FGF-2 served as a control. ***p,0.001, NS = not significant. doi:10.1371/journal.pone.0014414.g001 The enhancement of cardiomyocyte differentiation by FGF-10 is also apparent in iPS cells Research on iPS cells is gaining momentum because of their accessibility, similar pluripotency, and fewer ethical concerns than ES cells [16,17]. While iPS cells have been shown to differentiate into cardiomyocytes for cardiac repair, the cardiomyocyte differ- entiation ratio is as low as that of ES cells [18]. It is thus instructive to examine the effects of FGF-10 on cardiomyocyte differentiation in iPS cells. Similar to its effect on ES cells, FGF-10 doubled cardiomyocyte differentiation from iPS cells (Figure 4A, and 4B), while FGF-10 inhibition by its neutralizing antibody and FGFR inhibition by the PLoS ONE | www.plosone.org 3 December 2010 | Volume 5 | Issue 12 | e14414