Figure 3.

Assay optimization and metabolic activity of cryopreserved cells. (A) Post-thaw percentage cell recovery of A549 (white bar, n = 4), HepG2 (grey bar, n = 3), and Caco-2 (dark grey bar, n = 2) cell monolayers, plated at different seeding densities, following cryopreservation with 10% v/v DMSO and 40 mg mL^–1 polyampholyte. Data are presented as average % cell recovery ± SEM of n independent repeats. A resazurin reduction metabolic assay was completed on frozen (B) A549 and (C) HepG2 plated cells (blue line), 24 h post-thaw, and on nonfrozen, conventionally cultured cells (black). The results are presented as average resazurin reduction ± SEM of 2 independent repeats.