Hepatocyte growth factor (HGF) is a pleiotropic cytokine promoting 
proliferation, migration and survival in several cell types. HGF and its cognate 
receptor c-Met are expressed in cardiac cells during early cardiogenesis, but 
data concerning its role in cardiac differentiation of embryonic stem cells 
(ESCs) and the underlying molecular mechanisms involved are limited. In the 
present study we show that HGF significantly increases the number of beating 
embryoid bodies of differentiating ESCs without affecting beating frequency. 
Furthermore, HGF up-regulates the expression of the cardiac-specific 
transcription factors Nkx 2.5 and GATA-4 and of markers of differentiated 
cardiomyocytes, i.e. alpha-MHC, beta-MHC, ANF, MLC2v and Troponin T. The 
HGF-induced increase in Nkx 2.5 expression was inhibited by co-treatment with 
the PI3 kinase inhibitors Wortmannin and LY294002, but not by its inactive 
homolog LY303511, suggesting an involvement of the PI3 kinase/Akt pathway in 
this effect. We conclude that HGF is an important growth factor involved in 
cardiac differentiation and/or proliferation of ESCs and may therefore be 
critical for the in vitro generation of pre- or fully differentiated 
cardiomyocytes as required for clinical use of embryonic stem cells in cardiac 
diseases.