Abstract 1463: Neuregulin-1 Promotes Embryonic Stem Cell Differentiation into the Cardiac Lineage in vitro
Our previous studies demonstrated that transplantation of embryonic stem cell (ESCs) derived cardiomyocytes improved the cardiac function in myocardial infarction injured mice. However, significant challenges remain to be solved, such as how to produce sufficient amount and mature differentiated cardiomyocytes for the therapy. Neuregulin-1 (NRG-1) is essential for the development of the heart. Here, we tested whether NRG-1 could promote the differentiation of ESCs into cardiomyocytes. Differentiation of murine ESCs was induced by the hanging-drop method. NRG-1 was added at different points of ESC differentiation. The expression of cardiac specific genes, as well as NRG-1 and its erbB receptors were measured by quantitative RT-PCR and Western blot analysis. Our results showed that during the course of hanging-drop induced ESC differentiation, the mRNA level of cardiac-specific structure proteins cardiac troponin T (cTNT), cardiac troponin I (cTNI), myosin light chain 2a (MLC2a) and alpha-sarcomeric actin was elevated. The mRNA level of cardiac transcription factors NKX2.5 and GATA4 was also increased. In addition, beating EBs first appeared on day7 and about 90% of beating EBs was observed on day12. Further, the mRNA level of NRG-1α and NRG-1β, and both mRNA and protein levels of erbB receptors were elevated during the differentiation of ESCs. When NRG-1 was added during a certain developmental window, the mRNA level of cTNT, MLC2a and MEF2c, as well as the protein level of cTNT, CXN40, a marker for cardiac conduction system, and transcriptional factors NKX2.5, GATA4 were increased in NRG-1 treated ESCs compared to untreated cells. These results demonstrated that NRG-erbB signaling was activated during the course of hang-drop induced ESC differentiation; NRG-1 treatment further promoted ESC differentiation into the cardiac lineage in vitro. Our results suggest that NRG-1 might be used to produce more and/or more mature ESC derived cardiomyocytes for the treatment of cardiovascular diseases in the clinical setting.