Determination of Aldehyde Dehydrogenase Activity

After a 24-h transfection period, the cells were resuspended in ALDEFLUOER buffer to adjust the cell density to 1 × 10⁶ cells/mL. The activity of aldehyde dehydrogenase (ALDH) in each group was then detected according to the instructions of the ALDEFLUOER kit (STEMCELL Technologies, Inc., Vancouver, British Columbia, Canada). The detailed procedures are described below. Cells were incubated with 15 μmol/L ALDH-specific inhibitor diethylaminoazobenzene (DEAB) and 0.15 μmol/L ALDH substrate at 37°C for 25 min, followed by the detection of ALDH activity using a flow cytometer (Becton, Dickinson and Company, NJ, USA). The experiment was repeated three times to obtain the mean value.