2.2. Cell viability assay
SPFP-MSCs from passage 1 were seeded into 96‐well plates at a density of 1×104 cells/well in triplicate for 24 hours and then the cells were incubated with control blank medium (fresh DMEM) and blank medium with increasing concentrations of AG (1.56, 3.125, 6.25, 12.5, 25, 50 and 100μM)for 24 hrs. Next, the cells in each well were washed with PBS and replaced by 100 μl of 0.5 mg/ml MTT solution. The cells were then incubated for another 4 hours at 37 °C under 5 % CO2, after which the MTT solution in each well was carefully discarded and replaced by 50 μl of dimethyl sulfoxide (DMSO) to dissolve formazan crystals. The optical density (OD) was then measured with multimode microplate reader (Infinite M200 PRO, Tecan Group Ltd., Männedorf, Switzerland) at a wavelength of 590 nm. The cell viability was calculated relative to the control using the following formula: (sample group OD − zeroing OD)/ (control group OD − zeroing OD).