OBJECTIVETo screen and identify differentially expressed proteins of mesenchymal stem cells (MSC) during endothelial differentiation.

METHODSMSCs were induced to endothelial differentiation with vascular endothelial growth factor (VEGF) and epithelial growth factor (EGF) mixture. The whole cell proteins were extracted and isolated by two-dimensional gel electrophoresis. After gel was analyzed by Imagemaster 5.0 software, differentially expressed proteins were partially selected and identified by MALDI-TOF-MS.

RESULTSThe differentiated MSC highly expressed endothelial cells related markers, CD31, CD34 and FVIIIAg were 56.8%, 38.8% and 14.5% respectively by flow cytometer. Compared with the primary cultured MSC, the differentiated cells differentially expressed 91 proteins. Among the 19 identified proteins, 11 up-regulated and 8 down-regulated, which include cytoskeletal proteins, such as myosin, filamin, vimentin and vinculin; cell metabolism enzymes, such as ORP-150, ERO1-α, Delta(3,5)-Delta(2,4)-dienoyl-CoA isomerase, protein disulfide-isomerase A3, FAS and enolase 3; nuclear factors, such as TAR DNA binding protein, guanine nucleotide binding protein and hypoxia up-regulated protein 1; VEGF receptors, such as KDR and so on.

CONCLUSIONSCytoskeletal proteins, metabolism enzymes and KDR were all involved in endothelial differentiation of MSC. These proteins may be the regulatory targets for endothelial differentiation of MSC.