Concentration‐ and time‐dependent effects of progesterone on
EPC
viability. Low concentration of progesterone (5 nm) enhanced EPC viability to the greatest extent (*P < 0.05 versus control, vehicle, 10 and 100 nm at 12 h) when incubation was sustained for a short term (no more than 12 h, §
P < 0.05 versus 3, 6 and 24 h at 5 nm concentration). High‐dose progesterone treatment (100 nm) dramatically impaired viability of EPCs compared to control. There was no statistical difference in OD values between vehicle and control groups.*Two‐way ANOVA: Significant effect among 3, 6, 12 and 24 h in 5 nm group (P < 0.01) #Two‐way ANOVA: Significant treatment effect between 5 nm group and 10 nm group (P < 0.05), &Two‐way ANOVA: treatment effect between 5 nm group and control (P < 0.05), ▵Two‐way ANOVA: Impaired treatment effect between 100 nm group and control (P < 0.05).