4.6. MTT and LDH Assays

The MTT assay method was previously described [20]. Briefly, MTT solution (50 μg, Sigma-Aldrich, St. Louis, MO, USA) was added to each well. Following incubation at 37 °C for 1 h, the cells were solubilized with 50% acidified N,N-dimethylformamide (DMF, pH 4.7). The optical density (540 nm) was measured using a microplate reader (Thermo Scientific, Waltham, MA, USA). The LDH assay was carried out according to the manufacturer’s instructions using the Cytotoxicity Detection kit (Roche Diagnostics, Penzberg, Germany).