Figure 3

Aging increased the apoptosis of MSCs induced by H/SD injury. (A) Representative immunofluorescence images of apoptosis (TUNEL, green fluorescent) and DAPI (blue fluorescence) in young and aged MSCs under hypoxic or normoxic conditions (Scale bars: 50 μm). (B) Apoptosis was also analyzed by flow cytometry after staining with Annexin V and propidium iodide (PI). (C) Quantification of the apoptotic MSCs is presented as the percentage of apoptotic cells. (D) Quantification of the FACS analysis. Viable cells: Annexin V^-/PI^-; early apoptosis: Annexin V⁺/PI^-; late apoptosis: V⁺/PI⁺; necrotic: V^-/PI⁺. (E): Caspase-3 activity of MSCs in all groups. Data expressed as mean ± SEM. n = 5, *P <0.05, #P <0.05 versus young + H/SD. DAPI, 4,6-diamidino-2-phenylindole; FACS, fluorescence-activated cell sorting; H/SD, hypoxia and serum deprivation; MSC, mesenchymal stem cells; SEM, standard error of the mean; TUNEL, terminal- deoxynucleotidyl transferase mediated nick end labeling.