Identification of plateled-derived growth factor-BB as cardiogenesis-inducing factor in mouse embryonic stem cells...

Embryonic stem (ES) cells may represent an alternative source of functionally mature cardiomyocytes for the treatment of heart diseases. ES cells spontaneously differentiate into spheroidal aggregates, also referred to as embryoid bodies (EBs). The identification of growth factors playing a decisive role in cardiogenesis is a crucial issue for the generation of mature cardiomyocytes.

In order to identify growth factors promoting cardiac development, we established a new differentiation protocol using a defined serum-replacement medium (SRM) containing 5 microg/ml insulin and 5 microg/ml transferrin in combination with Dulbecco's Modified Eagle Medium (DMEM). Furthermore, we added platelet-derived growth factor-BB (PDGF-BB) or sphingosine-1-phosphate (SPP) to promote cardiac differentiation.

Using SRM/DMEM, we obtained a 6-fold increase of cardiac specific myosin heavy chain alpha and beta (cMHCalpha/beta) in relation to 0,2% foetal calf serum (FCS)/DMEM (= 100%). Stimulation of EBs with PDGF-BB in the presence of SRM/DMEM resulted in a further 2,6-fold enhancement in comparison with the SRM/DMEM-induced increase of cMHCalpha/beta (= 100%). A parallel increase in the number of beating EBs was observed. Similar results were obtained after stimulation of EBs with 5 microg/ml SPP.

We established a serum-free protocol and identify PDGF-BB and SPP as potent factors promoting cardiogenesis in ES cells.