CCK-8 assay
Cell viability was determined using the cell counting kit (CCK) 8-test. Neural stem cells (1×104 cells per well) were incubated in a culture medium. CCK-8 solution (10 μL) was added to the cell culture medium and incubated at 37°C for 4h. The absorbance was measured at 450 nm using a 96-well multi-scanner automatic reader.