Light emitting diode-generated blue light modulates fibrosis characteristics: fibroblast proliferation, migration speed, and reactive oxygen species generation

Background and objective: Blue light is part of the visible light spectrum that does not generate harmful DNA adducts associated with skin cancer and photoaging, and may represent a safer therapeutic modality for treatment of keloid scars and other fibrotic skin diseases. Our laboratory previously demonstrated that light-emitting diode (LED) red and infrared light inhibits proliferation of skin fibroblasts. Moreover, different wavelengths of light can produce different biological effects. Furthermore, the effects of LED blue light (LED-BL) on human skin fibroblasts are not well characterized. This study investigated the effects of LED-BL on human skin fibroblast proliferation, viability, migration speed, and reactive oxygen-species (ROS) generation.

Methods and materials: Irradiation of adult human skin fibroblasts using commercially-available LED-BL panels was performed in vitro, and modulation of proliferation and viability was quantified using the trypan blue dye exclusion assay, migratory speed was assessed using time-lapse video microscopy, and intracellular ROS generation was measured using the dihydrorhodamine flow cytometry assay. Statistical differences between groups were determined by ANOVA and Student's t-test.

Results: Human skin fibroblasts treated with LED-BL fluences of 5, 10, 15, 30, and 80 J/cm(2) demonstrated statistically significant dose-dependent decreases in relative proliferation of 8.4%, 29.1%, 33.8%, 51.7%, and 55.1%, respectively, compared to temperature and environment matched bench control plates, respectively. LED-BL fluences of 5, 30, 45, and 80 J/cm(2) decreased fibroblast migration speed to 95 ± 7.0% (P = 0.64), 81.3 ± 5.5% (P = 0.021), 48.5 ± 2.7% (P < 0.0001), and 32.3 ± 1.9% (P < 0.0001), respectively, relative to matched controls. LED fluences of 5, 10, 30, and 80 J/cm(2) resulted in statistically significant increases in reactive oxygen species of 110.4%, 116.6%, 127.5%, and 130%, respectively, relative to bench controls.

Conclusion: At the fluences studied, LED-BL can inhibit adult human skin dermal fibroblast proliferation and migration speed, and is associated with increased reactive oxygen species generation in a dose-dependent manner without altering viability. LED-BL has the potential to contribute to the treatment of keloids and other fibrotic skin diseases and is worthy of further translational and clinical investigation.