Figure 4.

(A) Phase-contrast images of keratinocytes, fibroblasts, and a mix of both types in different media. Left panel shows cultured cells 36 h post-seeding. Right panel shows cells with reduced formazan crystals before placing on the plate reader. All cells were seeded into 96-well plates and at the same total number of cells (1 × 10⁵) with the same volume (100 μL). For co-culture wells, the total amount was the same (5 × 10⁴ for K and F). All scale bars are 50 μm. (B) Metabolic activity measured by absorbance at 570 nm. More signal correlates to more metabolic activity. The horizontal dashed line for each group corresponds to mean absorbance for the control group (i.e., the media used during mono-culture experiments). The “blank” group shows absorbance results for wells filled with the MTT solvent (i.e., dimethyl sulfoxide—DMSO) or wells that were left empty.