Propofol induces neural progenitor cell cytotoxicity in a time- and dose-dependent manner. ReNcell CX human neural progenitor cells were exposed to different concentrations of propofol (1 to 300 μM) for 2, 6, or 24 h. (A) The 3-(4,5-dimethyithiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) reduction assay was used to determine relatively early cell damage. Treatment with 10 μM propofol increased, whereas 200 μM propofol decreased cell viability after 6- and 24-h exposures. 300 μM propofol induced remarkable cell damage at all three time points relative to vehicle control. #P < 0.05, ##P < 0.01, ####P < 0.0001 compared with treatment for 2 h with the same concentration; &&&P < 0.001 compared with treatment for 6 h; *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001 compared with vehicle controls at corresponding time points (n = 19 at 2 h; n = 12 at 6 h; n = 17 at 24 h). (B) Relatively late cell damage was determined by lactate dehydrogenase (LDH) release assay. Only 200 μM propofol treatment for 24 h exhibited significant cell damage. ****P < 0.0001 compared with vehicle controls (n = 18). All data are expressed as the means ± SD from at least three separate experiments in duplicate or triplicate and analyzed by two-way ANOVA followed by Tukey multiple comparison tests.