Figure 3.

Telomerase activity of HeLa cells, BMSCs, PGK-BMSCs, and hTERT-BMSCs (TRAP assay) after disposed with or without heat. There was little telomerase activity in all heat-treated negative control cells; however, in unheated cells, despite extensive doublings, the immortalized cells (hTERT-BMSCs) displayed significantly higher telomerase activity than their primary counterparts and PGK-BMSCs, except the positive control cells (HeLa) and the telomerase activity of the immortalized population remained stable (assessed at P30). Significance level is P < 0.05, indicated by ∗.