Multiple-wavelength radiation promotes hair growth by enhancing the early stages of hair follicle development in human dermal papilla cells and C57BL/6 mice

Abstract

Background: We aimed to clarify the safety and efficacy of simultaneous skin exposure to blue, red, and infrared light. The purpose of this study was to confirm the mechanism by which multiple wavelengths increase hair development both in vivo and in vitro.Methods: Cultured human dermal papilla cells (hDPCs) were exposed to a 470/655/850 nm light-emitting diode (LED) array with a fixed energy density of 3.0 mW/cm2. We analyzed alkaline phosphatase (ALP) staining and activity. The relative expressions of ALP, VEGF, Shh, and OPN3 were examined using reverse transcriptase-polymerase chain reaction arrays 48 hours post-exposure and the protein levels related to extracellular signal-regulated kinase (ERK)/protein kinase B (AKT)/glycogen synthase kinase 3 (GSK3)β signaling were assessed by western blotting. Next, we used H&E staining, hair growth scoring, skin thickness measurement, and the immunohistochemical analysis of the dorsal skin of C57BL/6 mice to investigate the effects of the mono- or combined-photobiomodulation (PBM) groups.Results: According to our findings, simultaneous irradiation with multi-wavelength LEDs at 470/655/850 nm increased the proliferation of hDPCs. Also, compared to the control group, the red wavelength and combined PBM groups had significantly improved skin thickness measurements. Overall, we concluded that the combined PBM therapy successfully induced the early onset of anagen and stimulated hair growth.Conclusion: These results suggest that PBM therapy regulates hair growth by activating the ERK/AKT/GSK3β signaling pathway. Thus, multiple-wavelength radiation from devices combining radiation emitted by low-power lasers and LEDs could be a new approach for promoting PBM-induced beneficial effects.