The effects of proliferation of human foreskin fibroblasts mediated by light-emitting diode (LED) irradiated human lymphoma cells (U-937)

Macrophages are considered as a source of important mediators to release growth factors that stimulate fibroblast proliferation during wound repair. The goal of the study was to evaluate the potential of stimulation on fibroblast proliferation cultured in the supernatant from low level light irradiated U-937 cells, a macrophage-like lymophoma cell line. The U-937 supernatant was removed twenty-four hours after Light Emitting Diodes (LEDs) exposure and was added to human foreskin fibroblast culture media. The proliferation of fibroblasts was measured by trypan blue stain. The concentration of total collagen and non-collagenous protein of fibroblasts was estimated by Fast green-Sirius red staining assay. The result showed that LEDs irradiation under the setting of 630 nm, 15 mw/cm², and 4J/cm² might encourage U-937 cells to release growth factors to stimulate fibroblast proliferation compared to the control group. The rate of fibroblast proliferation increased 1.1 fold compared to the control group which received supernatant from U-937 culture without light irradiation. The ratio of the concentration of collagen to noncollagenous protein of fibroblasts increased from 38.46±0.25 to 42.50±0.92 μg/mg (p<0.01) at forty-eight hours after fibroblast culture media replaced by light irradiated U-937 culture supernatant. The result suggests that in vitro irradiation of U- 937 cells by LEDs at specific parameter could modify their ability, therefore, affect the proliferation of fibroblasts.