Effect of basic fibroblast growth factor on cardiomyocyte differentiation from mouse embryonic stem cells.

OBJECTIVES: To investigate the effect of basic fibroblast growth factor (bFGF) on the differentiation of embryonic stem cells (ESCs) into early cardiomyocytes.

METHODS: Embryoid bodies (EBs) were produced from mouse ESC line (Royan B1) in hanging drops and cultured for 5 days as suspension. During the first 2 days of suspension, the EBs of the experimental group were treated with 10 ng/ml of bFGF and subsequently plated onto gelatin-coated tissue culture dishes (day 7). The differentiated cells were evaluated pharmacologically, by immunocytochemistry, and so forth. The study was carried out in the Department of Stem Cells, Royan Institute, Tehran, Iran in 2005.

RESULTS: The beating frequency in the bFGF treated EBs was less than that in the control group. In addition, the beating in the EBs of the experimental group, treated with isoprenaline and phenylephrine, was only more than 7+3 days in comparison to the control group. The response of the EBs to carbachol was more in the bFGF group than 7+14 days. In all the stages of development, the beating cells in the EBs of both groups expressed beta-actinin, myosin light chain isoform 2V, cardiac alpha-myosin heavy chain (alpha-MHC), and cardiac beta-myosin heavy chain (beta-MHC). Nonetheless, during 7+3 days, the last 2 genes were more advanced in the bFGF group. The atrial natriuretic factor was also expressed at a late stage in both groups.

CONCLUSIONS: Basic fibroblast growth factor can only promote the early maturation of ESC-derived cardiomyocytes in terms of chronotropic characteristics and expression of cardiac alpha-MHC and beta-MHC.