Figure 3.

Serum concentration in the culture medium reduces the inhibitory effect of blue light (450 nm) on the metabolic activity of human dermal fibroblasts. (A) Phase-contrast images of human reticular fibroblasts on day 0 (8 days after seeding) at low initial confluency and cultured in DMEM with two serum concentrations 2% and 10% (upper line), and after three daily light treatments on day 4 at a low initial confluency (lower line). Papillary fibroblasts were found to behave similarly (not shown). A second donor responded similarly (not shown). (B) Relative metabolic activity of human reticular fibroblasts after light treatment at 450 nm, 50 mW.cm⁻² with 60 J.cm⁻² (log scale). We observe a 60% reduction in 2% FBS against 40% reduction in 10% FBS case compared to control. The high confluency level showed similar variation as a function of the change in FBS concentration (not shown), except for the cytotoxic effects observed in low serum/low confluency only. Statistical significance was evaluated using ANOVA. A second donor responded similarly (not shown as the scale is absolute). The control group has an average relative metabolic activity of 1. (N = 2, 2 lineages and 3 replicates).