Evaluation of human mesenchymal stem cell expansion without differentiation by 2-dimensional electrophoresis

Mesenchymal stem cells(MSCs) are adult stem cells, which have been shown to contribute to the regeneration of mesenchymal tissues such as bone, cartilage, and adipose. Recent studies have suggested that these cells also have the potential to differentiate into other lineage cells, thereby possibly providing ample sources for cell therapy, in the treatment of a variety of diseases. These cells, however, constitute such a small population within aspirated bone marrow that in vitro expansion steps without differentiation are absolutely required prior to any such treatment. Here, we used 2-DE(2-dimensional gel electrophoresis) analytical method to evaluate the differentiation of expanded human mesenchymal stem cells(hMSCs). Our RT-PCR results indicated that hMSCs from passages 4 and 7 spontaneously differentiated into osteoblasts, and this was confirmed by detecting mRNA expression of alkaline phosphatase in the cells. However, when the protein spots of the hMSCs at each passage were compared with those of passage 2, which was used as a control, we detected no meaningful spots that would suggest differentiation including differentiating into osteoblasts. This indicates that hMSCs can be proliferated for 7 passages with no significant suspicion of differentiation.