HeaLED: Assessment of skin healing under light-emitting diode (LED) exposure-A randomized controlled study versus placebo

The Therapeutic and Preventive Effects of Light-Emitting Diode (LED) for Post-Inflammatory Erythema and Hyperpigmentation: A Pilot Study

Background/Purpose Photobiomodulation (PBM) using light-emitting diodes (LEDs) benefits tissue regeneration and wound healing. However, evidence regarding the efficacy of LED for post-inflammatory erythema (PIE) and post-inflammatory hyperpigmentation (PIH) is limited. The aim of this study was to explore the effect of medical LED (830 nm and 590 nm) in the prevention and treatment of PIE and PIH. Methods The in vivo PIE/PIH model was simplified to erythema and pigmentation reaction after acute UVB exposure. 308 nm LED light (225 or 270 mJ/cm2) was induced in vivo in the PIE/PIH model on the thigh of ten healthy subjects. Every subject received therapeutic and preventive irradiation (n = 10 in each group). 830 nm (60 J/cm2) and 590 nm LEDs (20 J/cm2) were irradiated, respectively. For therapeutic irradiation, the PIE/PIH model was induced on D1, and LEDs were irradiated on D0, 1, 3, 6 and 8. For preventive irradiation, LEDs were irradiated on D0, 1, 3, 6, and 8 and the PIE/PIH model was induced on D9. Erythema index (EI), melanin index (MI), transdermal water loss (TEWL), and C-Cube photography were measured during 10-day follow-up visits. Results For therapeutic irradiation, ΔEI and ΔMI in the 830 nm treatment group were significantly lower than in the control group (ΔEI: 9.30 vs. 11.52, p = 0.027; ΔMI: 7.79 vs. 9.25, p = 0.026). No significant difference was found between the 590 nm treatment group and the control group in ΔEI or ∆MI (p > 0.05). For preventive irradiation, ΔEI in the 830 nm prevention group and the 590 nm prevention group were both significantly lower than the control group (830 nm: 9.85 vs. 19.90, p = 0.001; 590 nm: 12.50 vs. 19.90, p = 0.008). No significant difference was found between the two prevention LED groups (p > 0.05). Conclusions Both 830 nm and 590 nm LEDs showed preventive effects for PIE, and 830 nm LEDs could effectively improve PIE and PIH.

The effect of combined red, blue, and near-infrared light-emitting diode (LED) photobiomodulation therapy on speed of wound healing after superficial ablative fractional resurfacing

Objective of the study is to assess the effects of wound healing with a commercially available light emitting diode (LED) photo biomodulation (PBM) device that emits three wavelengths (465, 640 and 880nm) after ablative fractional laser (AFL) treatment to healthy skin on the bilateral inner biceps. We conducted a prospective intraindividual randomized controlled study with 25 volunteers. AFL treatment was performed on healthy skin of the bilateral inner biceps. Subjects applied the LED light device for 30 min to the assigned bicep 3 times a week over 4 weeks, beginning on day 0. Subjects were followed up on days 2, 4, 6, 9, 13, 20 and 27 for treatment with the PBM device, clinical digital photography of the test and control sites, and in-person subject assessment, with follow ups on days 34 and 55 for clinical photography and assessment. Three blinded evaluators were asked to determine which bicep healed faster between day 0 to day 13. Pain, discomfort, and itch were also assessed. The three blinded evaluators chose the treatment arm as the faster healed arm in greater than 50% of the images, although the results were not statistically significant. There was no statistically significant difference between test and control arms in terms of pain, discomfort and itch. In conclusion, PBM therapy has the potential to improve wound healing. In this study, a three wavelength PBM device resulted in some subjects achieving faster healing after AFL but the results were not statistically significant.

Recognition of Melanocytes in Immuno-Neuroendocrinology and Circadian Rhythms: Beyond the Conventional Melanin Synthesis

Melanocytes produce melanin to protect the skin from UV-B radiation. Notwithstanding, the spectrum of their functions extends far beyond their well-known role as melanin production factories. Melanocytes have been considered as sensory and computational cells. The neurotransmitters, neuropeptides, and other hormones produced by melanocytes make them part of the skin's well-orchestrated and complex neuroendocrine network, counteracting environmental stressors. Melanocytes can also actively mediate the epidermal immune response. Melanocytes are equipped with ectopic sensory systems similar to the eye and nose and can sense light and odor. The ubiquitous inner circadian rhythm controls the body's basic physiological processes. Light not only affects skin photoaging, but also regulates inner circadian rhythms and communicates with the local neuroendocrine system. Do melanocytes "see" light and play a unique role in photoentrainment of the local circadian clock system? Why, then, are melanocytes responsible for so many mysterious functions? Do these complex functional devices work to maintain homeostasis locally and throughout the body? In addition, melanocytes have also been shown to be localized in internal sites such as the inner ear, brain, and heart, locations not stimulated by sunlight. Thus, what can the observation of extracutaneous melanocytes tell us about the "secret identity" of melanocytes? While the answers to some of these intriguing questions remain to be discovered, here we summarize and weave a thread around available data to explore the established and potential roles of melanocytes in the biological communication of skin and systemic homeostasis, and elaborate on important open issues and propose ways forward.