Characterization of a growth-elevated cell line of human bone marrow-derived mesenchymal stem cells by SV40 T-antigen

Abstract

Human bone marrow-derived mesenchymal stem cells (hMSCs) are capable of self-renewal and differentiation into various tissue lineages, attracting attention as tools for use in cell therapy. However, hMSCs have very poor proliferative capacity and a short life span in culture. To overcome this problem, we expressed the T antigen of SV40 in hMSCs because it is known to have the ability to elevate the growth rate of various primary animal cells. We obtained several hMSCs lines (hMSCs-T) known for stable expression of T antigen. Cells expressing T antigen proliferated on the monolayer of hMSCs, forming high density foci. hMSCs-T showed changed morphology and improved growth rate and life span, and demonstrated preservation of the potential for differentiation into osteoblasts. In addition, hMSCs-T did not proliferate in soft agar culture, indicating that the cells did not transform into tumor cells. In order to evaluate metabolic change of amino acids in hMSCs-T compared to primary hMSCs, we investigated altered amino acids (AA) with gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) mode (GC-SIM-MS). A total of 14 AAs were positively measured. Results from the Student’s t-test on the hMSCs group mean of the hMSCs-T group showed significantly elevated levels of glycine, proline, pipecolic acid, aspartic acid, lysine and tryptophan, whereas valine, leucine and isoleucine as branched-chain amino acids (BCAAs), and phenylalanine showed a significant decrease. Altered AAs metabolic pattern in the hMSCs-T may explain the disturbance of AA metabolism related to the expression of SV40 T antigen in hMSCs.