“…We found that IGF-1 mildly increased the size of hPSC-CMs, but more importantly proved an essential factor in revealing a positive functional role for the glucocorticoid dexamethasone in this system. Synergistic effects for IGF-1 and dexamethasone have been reported in skeletal muscle and heart, with pro-differentiation and anti-atrophic effects observed ( Chrysis et al., 2011 , Pansters et al., 2013 , Schakman et al., 2008 ). Glucocorticoids also promote the structural and functional maturation of fetal mouse cardiomyocytes ( Rog-Zielinska et al., 2013 , Rog-Zielinska et al., 2015 ) but have little effect on hPSC-CMs when added alone although do affect calcium handling (G.K., C.L.M., M. Bellin, B. van Meer, L. Tertoolen, and S. Casini, unpublished data).…”