Cellquest pro facs

A calcein acetoxymethylester (calcein AM) assay was performed using the MultiDrugQuantTM Assay kit (CHEMICON). Briefly, cells were plated at a density of 1×10⁵ cells/well in a 24-well plate. After 24 h, the cells were transfected with the indicated plasmid for 48 h. Calcein-AM was added at 25 nM into each well and the cells were incubated for 20 min before being trypsinized with 0.25% trypsin-EDTA for 2 min and pelleted. Supernatant was removed after centrifugation at 800 g. One ml medium was used to resuspend the cell pellet for FLOW cytometry analysis using Cellquest Pro FACS (BD Biosciences, San Jose, CA, USA). Distribution of the green-fluorescent protein calcein in the cells was observed by FLOW cytometry. The percentage relative fluorescence (RFL) in the cells was expressed as: % FL = [(FL treatment - FL nontreatment)/FL nontreatment] × 100%.

Cell cultures were fixed and detection of DNA-strand breaks was performed by the terminal deoxynucleotidyltransferase-mediated UTP end labeling (TUNEL) method using the Apo-BrdU In Situ DNA Fragmentation Assay Kit (BioVision, Mountain View, CA) according to the manufacturer's instructions and as previous reported [71 (link)]. TUNEL staining-positive cells were detected by flow cytometry using Cellquest Pro FACS (BD Biosciences, San Jose, CA).