We found that the level of secreted Aβ42 was significantly higher in both A15 and A16 AD-NPCs differentiation culture than that in N-NPCs differentiation culture on day 28, while AD-NPCs differentiation culture had a significantly elevated ratio of Aβ42/Aβ40 than N-NPCs differentiation culture at day 25 and day 28 of neuronal differentiation (Figure 3a). Moreover, protein levels of p-tau were higher in both A15 and A16 differentiating AD-NPCs compared to those of differentiating N-NPCs on day 28 (Figure 3b and 3c). Considering that the premature neuronal differentiation was evident in AD-NPCs at as early as differentiation day 21, it was possible that the premature neuronal differentiation occurred prior to the alterations of Aβ42/Aβ40 ratio and p-tau levels.
