Fig. 2.

Attenuated apoptosis of MSCs exposed to hypoxia and serum deprivation by exogenous rhHsp90α preconditioning

(a) Annexin V/PI binding by flow cytometry was performed to detect the early apoptosis of MSCs under hypoxia and serum deprivation (SD) conditions or normoxia and serum-contained conditions (SC) as control. Annexin V⁺ and PI⁺ cells were counted as the apoptotic cells (right top), and the percentage of apoptosis cells was calculated. The apoptosis percentage of MSCs preconditioned with rhHsp90α (0.01–10 μmol/L) decreased compared to those without rhHsp90α preconditioning, as exposed to hypoxia and serum deprivation (^* P<0.05 for 0.1–1 μmol/L, ^** P<0.01 for 10 μmol/L); (b) Hoechst 33258 staining was introduced to detect nuclear apoptotic bodies as the late characteristics of apoptosis. Representative immunofluorescence staining of MSCs depicted the nuclear apoptotic bodies (arrows) in the left panel. Cells with nuclear apoptotic bodies were counted as apoptosis cells, and the percentage of apoptosis cells was calculated (right panel). Compared to those without rhHsp90α preconditioning, the apoptosis percentage in MSCs preconditioned with rhHsp90α decreased as exposed to hypoxia and SD (0.01–10 μmol/L) (^** P<0.01). Cells under normoxia and SC as control group