Blue light inhibits melanin synthesis in B16 melanoma 4A5 cells and skin pigmentation induced by ultraviolet B in guinea-pigs

Wearable Surface-Lighting Micro-Light-Emitting Diode Patch for Melanogenesis Inhibition

Wearable light-emitting diode (LED)-based phototherapeutic devices have recently attracted attention as skin care tools for wrinkles, acne, and hyperpigmentation. However, the therapeutic effectiveness and safety of LED stimulators are still controversial due to their inefficient light transfer, high heat generation, and non-uniform spot irradiation. Here, a wearable surface-lighting micro-LED (SµLED) photostimulator is reported for skin care and cosmetic applications. The SµLEDs, consisting of a light diffusion layer (LDL), 900 thin film µLEDs, and polydimethylsiloxane (PDMS), achieve uniform surface-lighting in 2 × 2 cm² -sized area with 100% emission yields. The SµLEDs maximize photostimulation effectiveness on the skin surface by uniform irradiation, high flexibility, and thermal stability. The SµLED's effect on melanogenesis inhibition is evaluated via in vitro and in vivo experiments to human skin equivalents (HSEs) and mouse dorsal skin, respectively. The anti-melanogenic effect of SµLEDs is confirmed by significantly reduced levels of melanin contents, melan-A, tyrosinase, and microphthalmia-associated transcription factor (MITF), compared to a conventional LED (CLED) stimulator.

The review of the light parameters and mechanisms of Photobiomodulation on melanoma cells

Photobiomodulation (PBM) uses low-intensity visible or near-infrared light to produce beneficial effects on cells or tissues, such as brain therapy, wound healing. Still there is no consistent recommendation on the parameters (dose, light mode, wavelength, irradiance) and protocols (repetition, treatment duration) for its clinical application. Herein, we summarize the current PBM parameters for the treatment of melanoma, and we also discuss the potential photoreceptors and downstream signaling mechanisms in the PBM treatment of melanoma cells. It is hypothesized that PBM may inhibit the melanoma cells by activating mitochondria, OPNs, and other receptors. Regardless of the underlying mechanisms, PBM has been shown to be beneficial in treating melanoma. Through further in-depth studies of the underlying potential mechanisms, it can strengthen the applications of PBM for the therapy of melanoma.

Role of Visible Light on Skin Melanocytes: A Systematic Review

In the last few years, the focus of phototherapy has shifted toward the visible (400-700 nm) part of the electromagnetic spectrum of light. Lately, it has been demonstrated that visible light (VL) can have both beneficial and detrimental effects, especially on the skin. Previously and until now, the most harmful effects on the skin are associated with ultraviolet radiation (UVR). After exposure to natural light, the most evident and immediate change is observed on skin pigmentation. Various wavelengths within the visible spectrum have been reported to alter skin pigmentation. However, the underlying mechanisms are incompletely understood so far. The article aims to shed light on the progress made in the photobiology field (photobiomodulation, PBM) to study the role of visible light on skin melanocytes.

Irradiance plays a significant role in photobiomodulation of B16F10 melanoma cells by increasing reactive oxygen species and inhibiting mitochondrial function

Melanoma is a type of aggressive cancer. Recent studies have indicated that blue light has an inhibition effect on melanoma cells, but the effect of photobiomodulation (PBM) parameters on the treatment of melanoma remains unknown. Thus, this study was aimed to investigate B16F10 melanoma cells responses to PBM with varying irradiance and doses, and further explored the molecular mechanism of PBM. Our results suggested that the responses of B16F10 melanoma cells to PBM with varying irradiance and dose were different and the inhibition of blue light on cells under high irradiance was better than low irradiance at a constant total dose (0.04, 0.07, 0.15, 0.22, 0.30, 0.37, 0.45, 0.56 or 1.12 J/cm²), presumably due to that high irradiance can produce more ROS, thus disrupting mitochondrial function.

Blue light-induced immunosuppression in Bactrocera dorsalis adults, as a carryover effect of larval exposure

Detrimental effects of ultraviolet (UV) light on living organisms are well understood, little is known about the effects of blue light irradiation. Although a recent study revealed that blue light caused more harmful effects on insects than UV light and blue light irradiation killed insect pests of various orders including Diptera, the effects of blue light on physiology of insects are still largely unknown. Here we studied the effects of blue light irradiation on cuticular melanin in larval and the immune response in adult stage of Bactrocera dorsalis. We also evaluated the effects of blue light exposure in larval stage on various age and mass at metamorphosis and the mediatory role of cuticular melanin in carryover effects of larval stressors across metamorphosis. We found that larvae exposed to blue light decreased melanin contents in their exoskeleton with smaller mass and delayed metamorphosis than insects reared without blue light exposure. Across metamorphosis, lower melanotic encapsulation response and higher susceptibility to Beauveria bassiana was detected in adults that had been exposed to blue light at their larval stage, thereby constituting the first evidence that blue light impaired adult immune function in B. dorsalis as a carryover effect of larval exposure.

Effect of monochromatic visible light on intracellular superoxide anion production and mitochondrial membrane potential of B16F1 and B16F10 murine melanoma cells

We have investigated the effect of visible light on animal cells using light-emitting diodes to emit monochromatic visible light (red, yellow, green and blue light). To explore the relevant mechanism of apoptosis, we assessed the intracellular superoxide anion production and mitochondrial membrane potential (ΔΨm) of B16F1 and B16F10 murine melanoma cells after monochromatic light irradiation. Blue light caused ΔΨm depolarization subsequent to elevation of intracellular superoxide production. However, red and yellow light had no affect on both cell lines. Green light induced ΔΨm collapse only in B16F1 melanoma cells. ΔΨm is a key indicator of mitochondrial function, therefore its disruption causes mitochondria-dependent apoptosis. Thus, blue light causes mitochondrial dysfunction and subsequent cell death.