Abstract:Objective:To investigate whether rat bone marrow-derived mesenchymal stem cells(BMSCs) could spontaneously differentiate into endothelial cells in normal culture condition. Methods:Primary rat BMSCs were separated and cultured to passage 7. The passage 3 and passage 7 BMSCs were prepared for this experiment. The expression of endothelial cell markers CD31,tyrosine kinase with immunoglobulin-like and EGF-like domains 2 (Tie-2) and von Willebrand factor (vWF) in passage 3 and passage 7 BMSCs were determined by Real-time PCR,and the ability of angiogenesis were determined by an in vitro angiogenesis kit (Matrigel). Futhermore,the expression of vWF protein in BMSCs were detected using immunofluorescence staining. Results:After normal cultured to passage 7,BMSCs partly formed an oval shape. Real-time PCR and immunofluorescence showed that the expression of endothelial cell markers were significantly higher in passage 7 BMSCs than in passage 3 BMSCs. In vitro angiogenesis experiments showed that passage 7 BMSCs could form a mesh structure in matrigel. Conclusion:BMSCs in normal culture condition changed their phenotypes,and could partially differentiate into endothelial cells spontaneously.