Cell uptake of neurotoxic AβOs. (A) SH-SY5Y cells were exposed to Fluor™488 alone, 5 μM HiLyte Fluor™488-labeled AβMs or AβOs (green) at 37°C for 10, 30, and 180 min. AβMs: 10 kDa-filtrate; AβOs:30 kDa-retentate. Nuclear staining (7-AAD) is shown in red. Vesicular uptake was observed with AβOs, but not with AβMs and Fluor™488 alone. (B) The level of LDH released from SH-SY5Y cells treated for the indicated times (0, 3, 6, and 24 h) with 5 μM AβOs. In the case of 5 μM synthetic Aβ42-1 and AβMs, LDH assay was done for 24 h. Each value indicates the percentage level of LDH released following treatment with incubation mixtures relative to the level of LDH released following treatment with Triton X-100. Each column indicates average ± S.D. The p value was determined by one-way ANOVA, followed by Dannett's test for posthoc analysis: statistical significance compared with AβMs alone (*p < 0.05, **p < 0.001).