Fig. 2

Changes in senescent markers with serial passaging of TMSCs. a Doubling times were calculated at each passage of TMSCs using Patterson formula. Morphological changes of control and culture-aged TMSC groups were determined by measuring cell length (b) and width (c). Control TMSCs exhibited a polygonal morphology, whereas culture-aged TMSCs formed dispersed shapes. d Senescent cells were identified as blue-stained cells under an optical microscope. Magnification: × 40, × 100, and × 200; scale bar, 200 μm. White dotted boxes indicate magnified images of the same region. e The average absorbance intensity of SA-β-gal staining (405 nm) from 5 randomly selected fields between control and culture-aged TMSCs were compared. f Gene expression of TRF-1 in control and culture-aged TMSCs. g Bar graph indicates relative fold changes in the expression of TRF-1. The p values were considered statistically significant at the p < 0.05 (*), p < 0.01 (**), and p < 0.001 (***), and significant differences among experimental groups were indicated with different alphabetical letters in figures