Abstract:

BACKGROUND: Derived from the mesoderm, bone marrow mesenchymal stem cells (BMSCs) have the ability of differentiation into a variety of tissues. BMSCs can differentiate into endothelial cells under certain conditions to improve regeneration of blood vessel and repair of injured myocardium.
OBJECTIVE: On the bases of establishment of BMSCs cultural system, myocardial infarction (MI) model and differentiating system into endothelial, this study was going to investigate the characters of BMSCs differentiating into endothelial cells and to initially observe the influence of infarcted myocardial micro-circumstances on BMSCs differentiation into endotheliod cells in vitro.
METHODS: The bone marrow was extracted from the thighbone and tibiae of SD rats. BMSCs was isolated from rat marrow, cultured and expanded in vitro. Through evaluating the change of morphology, ability of multiplication and differentiating abilities into osteoblast and adipocytes, BMSCs were identified. After a rat MI model was made and myocardial tissue extract of different time after MI: 8 hours, 3 days, 1 week, 4 weeks was prepared, these different tissue extract was combined with the endothelial inducing system including vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF) and insulin growth factor-1 (IGF-1) to induce BMSCs. After 2 weeks, the influence of different inducing circumstances on BMSCs expansion and differentiation into endothelium was observed. Special antigen of Von Willarbrand factor (vWF) was tested at the same. Main outcome measures include: (1)The shapes of the cells, growth curves and the abilities of differentiating into osteoblast and adipocytes were observed; (2)Induced cells:①growth curves; ②the expression rate of the antigen vWF through immunohistochemical; ③RT-PCR method used to test vWF-mRNA expression through semi-quantitative analysis.
RESULTS AND CONCLUSION: It was confirmed that the cultured cells was BMSCs and could differentiate into osteoblasts, adipocytes and endotheliod cells. Partial BMSCs induced by growth factors showed positive of vWF and infarcted myocardium tissue extract have cooperative effect with these factors that could improve the process of BMSCs differentiating into endothelial cells (P < 0.05). RT-PCR showed BMSCs induced by infarcted myocardial tissue extract of 1 week could improve this differentiation into endothelium had the highest vWF positive rate. BMSCs are another kind of marrow stem cells apart from hematopoietic stem cells and have ability of multi-potential differentiation into many kind of lineage including endothelium. The induce system contained infarcted myocardium tissue extract could improve BMSCs differentiating into endothelial cells in vitro. This ability may cause BMSCs to play an important role in the repair of injured myocardium and may be the major mechanism of improving the cardiac function during cell therapy. The optimal time of cell therapy is probably at 1 week after MI.