Background Red light is part of the visible light spectrum. The effects of light-emitting diode (LED)-generated red light on human skin are not well-characterized. Objective To study the effect of red LED-generated low-level light therapy (LLLT) on fibroblast proliferation and viability in vitro. Methods and Materials Irradiation of normal human skin fibroblasts using red LED panels was performed in vitro, and modulation of proliferation and viability was quantified using trypan blue dye exclusion assay. Results Statistically significant decreases in cell proliferation were noted at the following fluences (time): 160 J/cm2 (30 minutes, 34 seconds), 320 J/cm2 (61 minutes, 07 seconds) and 640 J/cm2 (122 minutes, 14 seconds) (Figure 1). Irradiation at the 160- (98.5 ± 1.2%) and 320-J/cm2 (98.0 ± 3.1%) doses did not significantly alter viability. Conclusion At certain fluences, red LLLT can effectively inhibit fibroblast proliferation in vitro without altering viability and holds promise for the treatment of scars and other proliferative skin diseases.
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