2.1.1. Sample preparation
The cells are seeded the day before analysis in 96-well plates at
5–20 103 cells in 100 ll per well. After induction of cell death,
50 ll of cell supernatant is transferred to a new 96-well plate for
the LDH assay (see below), while the original 96-well plate is used
for the MTT assay at a pre-defined time. After adding 20 ll of MTT
solution (prepared as a 5 mg/ml stock solution in PBS and used at
500 lg/ml) to the cells in each well, the plate is incubated in a CO2
incubator at 37 C for 4–6 h. Then 80 ll of SDS–HCl buffer (10% SDS
and 0.01 N HCl) is added to each well and incubation is continued
for 6–8 h at 37 C to dissolve the formazan crystals. Finally, absorbance
is measured at 595 nm (put reference filter at 655 nm) in a
plate reader. Alternatively, one can use commercially available
assays based on XTT, MTS or WST, and follow the manufacturer’s
instructions.