A comparative study of the effects of different low-level lasers on the proliferation, viability, and migration of human melanocytes in vitro

Abstract

The aim of this study was to investigate the effects of different low-level laser therapies (LLLTs) of various wavelengths and energies on normal cultured human melanocytes. Various studies have shown the effects of LLLs on various types of cultured cells. Presently, little is known about the biological effects of LLLTs on melanocytes. Melanocytes were exposed to LLLT at 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, or 5.0 J/cm(2) using a blue (457 nm), red (635 nm), or ultraviolet (UV) (355 nm) laser. Melanocyte viability, proliferation, and migration were monitored at 72 h after irradiation. The blue (P < 0.001) and red (P < 0.001 and P < 0.01) lasers significantly enhanced viability at 0.5 to 2.0 J/cm(2), whereas the UV laser (P < 0.001) could significantly enhance viability only at 0.5 and 1.0 J/cm(2) compared with controls. The blue and red lasers also significantly enhanced the proliferation of the melanocytes at 0.5 to 2.0 J/cm(2) (P < 0.001), and the UV laser significantly enhanced proliferation at 0.5 to 1.5 J/cm(2) (P < 0.001 and P < 0.01) compared with controls. The blue laser significantly enhanced melanocyte migration at 0.5 to 4.0 J/cm(2) (P < 0.001 to P < 0.05), but the red (P < 0.001 and P < 0.01) and UV (P < 0.001 to P < 0.05) lasers could significantly enhance such migration at 0.5 to 1.0 J/cm(2) and 0.5 to 2.0 J/cm(2), respectively, compared with controls. LLLT at low energy densities is able to significantly increase melanocyte viability, proliferation, and migration in vitro, and at higher energy densities, it gives non-stimulatory results. Additionally, the blue laser was the best among the three lasers. These findings might have potential application in vitiligo treatment in future.

Effects of low-level laser irradiation on proliferation and functional protein expression in human RPE cells

“…We found that 16 J/cm 2 of laser irradiation did not affect RPE proliferation Nuclei were counterstained with DAPI and are shown in blue on the first day and even had a negative effect on the second day. This is similar with findings by Frigo et al [21] and AlGhamdi et al [22] in different cell types. A higher dose of LLLI would cause over-release of intracellular Ca 2+ and exhaust the ATP reserves.…”

“…Therefore, we concluded that LLLI promoted cell cycle progression by modulating cell cycle-specific proteins. However, the effects of LLLI on cell proliferation or cell cycle progression are mainly determined by cell type [21,23,24], cell metabolic rate [21], cell cycle period [21], and parameters of the laser instrument [22,25].…”

Proposed Mechanisms of Photobiomodulation or Low-Level Light Therapy

“…Melanocytes migration was enhanced by UV, blue and red light in lower doses, but a non-stimulatory effect was observed for higher light doses. Blue light seemed to be more effective compared to UV and red lasers [109]. Human epidermal stem cell migration and proliferation were increased alongside an increased phosphorylation of autocrine extracellular signal-regulated kinase (ERK), which contributed to accelerated wound re-epithelialization [110].…”

Effects of various doses of glutathione on the proliferation, viability, migration, and ultrastructure of cultured human melanocytes

“…The epidermal sheets were then separated from the dermal face, and epidermal cells were released by vigorous pipetting. Suspended cells were harvested by centrifugation (200 g, 5 minutes, at room temperature) and were seeded in two 25 cm 2 tissue culture flasks with a melanocyte growth promoting medium (GIBCO, Grand Island, New York) and incubated at 37°C in a humidified atmosphere containing 5% CO 2 as described by Lerner et al 12 with slight modifications 13 . The melanocyte growth‐promoting medium was changed after 24 hours of seeding to remove the free‐floating cells.…”

“…Three separate counts were performed for each well. Number of cells were counted and compared to the control and graphs were plotted for cell proliferation 13 …”