Cultured cells were stained with CellTracker™ Green (Molecular Probes Inc., Eugene, OR, USA) and NucBlue® Live ReadyProbes® Reagent (Thermo Fisher Scientific, Waltham, MS, USA) according to the manufacturer’s instructions. Briefly, 2 drops of NucBlue® Live ReadyProbes® Reagent per milliliter of media were added and the cells were incubated for another 30 min at 37 °C. Finally, the medium was changed with Live Cell Imaging Solution (Thermo Fisher Scientific, Waltham, MS, USA). The cells were observed by using an Olympus CKX41 inverted fluorescent microscope (Olympus, Hamburg, Germany) at 400× magnification.
Cells were also stained with crystal violet. The cells were washed with PBS and fixed with 2.5% glutaraldehyde in PBS (pH = 6.7–7.1) for 30 min at room temperature. After fixation, cells were washed with PBS again and stained with 0.5% solution of crystal violet for 20 min at room temperature. Then, staining solution was removed and cells were rinsed with deionized water three times. Cells were observed and photographed after drying under microscope Leica S9i (Leica Microsystems, Wetzlar, Germany).
Cells were also stained with crystal violet. The cells were washed with PBS and fixed with 2.5% glutaraldehyde in PBS (pH = 6.7–7.1) for 30 min at room temperature. After fixation, cells were washed with PBS again and stained with 0.5% solution of crystal violet for 20 min at room temperature. Then, staining solution was removed and cells were rinsed with deionized water three times. Cells were observed and photographed after drying under microscope Leica S9i (Leica Microsystems, Wetzlar, Germany).