BACKGROUNDIn a suitable microenvironment, bone marrow mesenchymal stem cells (BMSCs) can transdifferentiate into myocardial cells whose special gene can be expressed as structural proteins. Growth factor (GF) plays an important role in the cell migration, survival and differentiation. However, the effect of GF on the cellular differentiation is not well understood. In this study, the hepatocyte growth factor (HGF) and insulin like growth factor-1 (IGF-1) were used in the mixed culture of BMSCs and myocardial cells and the effects of these growth factors on the GATA-4 expression of BMSCs were investigated.

METHODSBMSCs were isolated from the marrow of rabbit femurs and tibias and foetal rabbit ventricular myocytes were isolated with trypsin sequential digestion. These two kinds of cells were cocultured in a ratio of 1:1 for 6 weeks; cocultured cells with added HGF and IGF-1 were the experimental group. The differentiated BMSCs were collected using the laser capture, microdissection system and their RNA isolated. Immunocytochemical staining, transmission electron microscopy and reverse transcription-polymerase chain reaction were used to evaluate the transformation of the stem cells into cardiomyocytes like cells.

RESULTSWhen cultured separately, BMSCs did not express alpha-actin and the stem cells had many nucleoli. However, when cocultured with cardiomyocytes, BMSCs expressed alpha-actin and the cardiac transcription factor GATA-4 and showed cardiomyocyte like ultrastructure. In comparison with the control group, the experimental group exhibited the enhanced expression level of GATA-4. The GATA-4 expression of BMSCs increased gradually following the addition of HGF and IGF-1, reached the maximal level after two weeks and decreased slightly thereafter.

CONCLUSIONSBMSCs can transdifferentiate into cardiomyocytes like cells and express the cardiac transcription factor GATA-4 after being cocultured with myocardial cells. HGF and IGF-1 can stimulate transdifferentiation of BMSCs into cardiac phenotype and enhance the expression of GATA-4. These results indicate that growth factors have a great potential in clinical cellular therapy.