2.3. Cell viability

Cell viability was assessed 4 h or 8 h after suspension culture using 0.4% trypan blue stain (Bio-Rad). Trypan blue solution (0.4%, 10 μL) was transferred to a test tube and 10 μL of the cell suspension was added and mixed; 10 μL of the mixture was then pipetted into the hemocytometer. We counted the trypan blue-negative cells (viable) and stained (dead) cells separately by hemocytometer. However, we utilized the total live cell number as the dead RPE cells were destroyed.