Representative picture of the experimental setup and emission spectra of light-emitting diodes (LEDs). (a) LEDs were irradiated to the 24-well plate from the top and a single-well-shaped mask was fixed on the top surface of the well plate to prevent LED light from being irradiated to adjacent wells. The power of LED light transmitted through the mask was measured with a photodiode sensor to derive the amount of light energy irradiated to the sample. (b) Normalized spectra of LED light sources.|@|~(^,^)~|@|Cell viability measurement by red light-emitting diode (LED) and infrared LED irradiation with fluences of (a) 5 J/cm² and (b) 10 J/cm². All groups showed no cytotoxicity compared to the control group. Every assay was performed 3 times and the results are expressed as mean ± standard deviation (SD). An unpaired two tailed t-test was used for comparisons between two means.|@|~(^,^)~|@|Images of cell migration assay of human corneal epithelial (HCE) cells. HCE cells were inoculated into 6 wells at 2.5 × 10⁵ cells per well. The next day, cell monolayers were scratched using a sterile 200 μL pipette tip followed by the indicated LED irradiation. (a) Scratched cells were exposed to 623, 660, 740, 850, and 940 nm LED light with an intensity of 33.3 mW/cm² and total energy of 10 J/cm². (b) Scratched cells were exposed to 623 nm LED light with an intensity of 0, 3, 5, and 10 J/cm². Cell migration was observed using an inverted microscope (Olympus CKX53; Olympus) and a digital camera at 0, 24, and 48 hours after scratching. (c) Cell wound area at 24 and 48 hours after wounding [(healing area/wounding area) × 100%].|@|~(^,^)~|@|Effect of 623 nm light-emitting diode (LED) irradiation on the expression of migration-related genes in human corneal epithelial (HCE) cells. The expression of the target gene was analyzed by real-time polymerase chain reaction (PCR) in HCE cells. Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) was used as the endogenous control gene for the normalization of mRNA expression. Relative expression of (a) IL-1a, (b) TGF-b, (c) IGF-2, (d) FGF-1, (e) Col2A1, and (f) MMP-2. The data presented are the mean ± standard deviation (SD) of three independent experiments. P < 0.05 compared with the control (non-irradiation group).

2023;34:45~52 https://doi.org/10.3807/KJOP.2023.34.2.045