Figure 5.

Response of human dermal fibroblasts to variable number of treatments with blue light (450 nm) occurring on consecutive days. (A) Phase-contrast images of human reticular fibroblasts 24 h after the last treatment, when 1, 2, 3 or 4 daily treatments (30 J.cm⁻²) were performed (lower line), together with the images of the control group (upper line). (B) Relative metabolic activity of human papillary and reticular fibroblasts (merged) after light treatment for 2 radiant exposures of 450 nm light (at a fixed 50 mW.cm⁻² irradiance) and with variable number of treatments occurring on consecutive days. An irradiance of 50 mW.cm⁻² was used. Statistical analysis was evaluated using student t-tests between the control group and treated group (N = 2, 2 lineages and 3 replicates), with following thresholds *p < 0.05, **p < 0.01, ***p < 0.001. The control group has an average relative metabolic activity of 1. The significance of the interaction between the radiant exposure and the number of iterative treatment was much lower than 0.001.