Induction of primitive pigment cell differentiation by visible light (helium-neon laser): a photoacceptor-specific response not replicable by UVB irradiation.
Solar lights encompass ultraviolet (UV), visible, and infrared spectrum. Most previous studies focused on the harmful UV effects, and the biologic effects of lights at other spectrums remained unclear. Recently, lights at visible region have been used for regenerative purposes. Using the process of vitiligo repigmentation as a research model, we focused on elucidating the pro-differentiation effects induced by visible light. We first showed that helium-neon (He-Ne) laser (632.8 nm) irradiation stimulated differentiation of primitive pigment cells, an effect not replicable by UVB treatment even at high and damaging doses. In addition, significant increases of mitochondrial DNA copy number and the regulatory genes for mitochondrial biogenesis were induced by He-Ne laser irradiation. Mechanistically, we demonstrated that He-Ne laser initiated mitochondrial retrograde signaling via a Ca(2+)-dependent cascade. The impact on cytochrome c oxidase within the mitochondria is responsible for the efficacy of He-Ne laser in promoting melanoblast differentiation. Taken together, we propose that visible lights from the sun provide important environmental cues for the relatively quiescent stem or primitive cells to differentiate. In addition, our results also indicate that visible light may be used for regenerative medical purposes involving stem cells.
Department of Dermatology, Kaohsiung Medical University Hospital, Faculty of Medicine, College of Medicine, and Center of Excellence for Environmental Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan, Republic of China.
Cheng-Che E
CC
Lan
Shi-Bei
SB
Wu
Ching-Shuang
CS
Wu
Yi-Chun
YC
Shen
Tzu-Ying
TY
Chiang
Yau-Huei
YH
Wei
Hsin-Su
HS
Yu
D000818:Animals; D020013:Calcium Signaling; D002454:Cell Differentiation / Q000528:radiation effects*; D002460:Cell Line; D003576:Electron Transport Complex IV / Q000378:metabolism; D006801:Humans; D054020:Lasers, Gas / Q000627:therapeutic use*; D008027:Light; D028022:Low-Level Light Therapy; D008543:Melanins / Q000378:metabolism; D008544:Melanocytes / Q000166:cytology* / Q000378:metabolism / Q000528:radiation effects; D051379:Mice; D008928:Mitochondria / Q000378:metabolism / Q000528:radiation effects; D009356:Neon; D010858:Pigmentation; D014466:Ultraviolet Rays; D014820:Vitiligo / Q000378:metabolism / Q000532:radiotherapy*
D008543:Melanins; D009356:Neon; D003576:Electron Transport Complex IV