Apoptosis detection by flow cytometry

The cells from all groups were harvested and digested, and then were washed twice with PBS and collected at 1×10⁵ cells per tube. Apoptosis was detected using a Fluorescein isothiocyanate (FITC) Annexin V Apoptosis Detection kit (BD Biosciences). After 5 µl Annexin V-FITC and 5 µl propidium iodide dyes were added to each well, the cells were incubated at room temperature for 15 min. Then apoptosis was detected by flow cytometry within 1 h. The upper left quadrant represents a mechanically injured cell and the upper right quadrant is a late apoptotic cell. The lower left quadrant is a normal cell and the lower right quadrant is an early apoptotic cell. In this experiment, the proportion of the upper right quadrant + the lower right quadrant was used as the percentage of apoptotic cells. The data was analyzed using FlowJo software version 7.6.1.