Fig. 1

Characterization of senescent PD-MSCs during long-term cultivation. a Expression of stemness related genes was analyzed by qRT-PCR in early and late passage PD-MSCs. b In vitro proliferation of early and late passage PD-MSCs for 4 days were analyzed by Ez-Cytox cell viability assay kit. c Quantitation of cells in the respective phases of cell cycle by FACS analysis. d Expressions of p21 protein were assayed by Western blotting in early and late passage PD-MSCs. e Senescence of PD-MSCs was detected by senescence-associated-β-galactosidase staining (magnification, × 20). f The enlarged cell size was significantly counted and observed in late passage PD-MSCs by Image J program (magnification, × 200). The data were representative of three independent experiments and expressed as means ± S.D. An asterisk indicates P < 0.05 versus early passage