*2.5. Cell Metabolic Activity*

At the established time points (24 and 72 h), the incubation medium was harvested for further analyses, and complete alpha-MEM containing 0.5 mg/mL MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide) (Sigma-Aldrich, St. Louis, MO, USA) was added to each well. Afterwards, cells were incubated for 5 h at 37 ◦C and cell metabolic activity was measured as already reported [29].
