Figure 1. Cell viability MTT test. Cellular viability of 3D-HCEs treated with PBS, 0.01% BAC, NAA-BAC(-), CRO-BAC(-), KETO-BAC(-), KETO-BAC(+), OPA-BAC(+), EPI-BAC(+), or LEVO-BAC(+) for 24 h followed or not by a 24 h post-incubation period (24 h+24 h-recovery). BAC induced a concentration-dependent decrease of cellular viability. At 24 h, the unpreserved NAA-BAC(-), CRO-BAC(-), and KETO-BAC(-) formulations induced a slight or insignificant decrease of cellular viability, while the KETO-BAC (+), OPA-BAC(+), EPI-BAC(+), and LEVO-BAC(+) BAC-containing formulations induced a marked decrease of cellular viability compared to control. After the 24-h recovery period, the unpreserved formulations showed a weak additional decrease of cellular viability, while the BAC-containing formulations still induced a strong decrease of cellular viability compared to control, showing irreversible damage to 3D-HCE. Results are expressed as percentage of cell viability compared to the PBS control.