Evaluating Aβ42 Cytotoxicity and API Neuroprotection

SH-SY5Y neuroblastoma cells purchased from ATCC (VA, USA) were grown, sub-cultured and treated with different concentrations (1, 5, 10, 20, 50, 100 μM) of pre-aggregated Aβ42 with or without the highest concentration of API that was not cytotoxic [Gandbhir and Sundaram et al., 2019 (link)]. Cell cultures were incubated for 72 hrs. and cell viability was assessed using CellTiterGlo (CTG) reagent from Promega. The cell growth inhibition from the cells that are exposed only to pre-aggregated Aβ42 was used to estimate the concentration of Aβ42 that results in 50% inhibition (IC₅₀). The IC₅₀ for Aβ42 was derived by dividing the mean cell growth by the mean blanked control cell growth for each concentration, then multiplied by 100. The percent toxicity data was fitted for the 4-Parameter (4P) curve, with interpolation set to 50. The concentration of the Aβ42 that results in 50% inhibition was calculated from this curve. A second experiment was done where SH-SY5Y cells were incubated with Aβ42 at IC₅₀ and with different concentrations (1, 5, 10, 20, 50, 100, 200 μM) of API. Cell viability was measured, and IC₅₀ for ATC is estimated as described [Gandbhir and Sundaram et al., 2019 (link)].