Telomerase reverse transcriptase mediated immortalization of human bone marrow stromal cells

Primary human bone marrow stromal cells (hMSCs) were transfected with human telomerase reverse transcriptase (hTERT) gene with lipofection method. The hTERT transfected hMSCs of passage 100 underwent chondrogenesis induction with dexamethasone, transforming the growth factor β and vitamin C, osteogenesis induction with dexamethasone, β glycerophosphoric acid and vitamin C, and cardiomyocyte induction with 5-azacytidine. After 7, 14, 21 and 28 days of induction, immunocytochemistry was performed to detect the expressions of type I and II collagen and osteocalcin, and alizarin red staining was performed to detect the bone nodule formation in osteogenesis induction. Immunocytochemistry was carried out to detect the striated muscle actin expression in cardiomyocytes. The hMSCs undergoing successful transfection were positive for the hTERT. The hTERT transfected cells were grown in vitro successfully and passaged for 136 generations. Results showed that these cells could be induced to differentiate into chondrocytes, bone and myocardial cells. Introduction of exogenous hTERT into hMSCs could achieve immortalized hMSCs with the potential of multi-directional differentiation. Thus, these cells could be applied as seed cells in tissue engineering.