Low-energy helium-neon lasers (632.8 nm) have been employed in a variety of clinical treatments including vitiligo management. Light-mediated reaction to low-energy laser irradiation is referred to as biostimulation rather than a thermal effect. This study sought to determine the theoretical basis and clinical evidence for the effectiveness of helium-neon lasers in treating vitiligo. Cultured keratinocytes and fibroblasts were irradiated with 0.5-1.5 J per cm2 helium-neon laser radiation. The effects of the helium-neon laser on melanocyte growth and proliferation were investigated. The results of this in vitro study revealed a significant increase in basic fibroblast growth factor release from both keratinocytes and fibroblasts and a significant increase in nerve growth factor release from keratinocytes. Medium from helium-neon laser irradiated keratinocytes stimulated [3H]thymidine uptake and proliferation of cultured melanocytes. Furthermore, melanocyte migration was enhanced either directly by helium-neon laser irradiation or indirectly by the medium derived from helium-neon laser treated keratinocytes. Thirty patients with segmental-type vitiligo on the head and/or neck were enrolled in this study. Helium-neon laser light was administered locally at 3.0 J per cm2 with point stimulation once or twice weekly. The percentage of repigmented area was used for clinical evaluation of effectiveness. After an average of 16 treatment sessions, initial repigmentation was noticed. Marked repigmentation (>50%) was observed in 60% of patients with successive treatments. Basic fibroblast growth factor is a putative melanocyte growth factor, whereas nerve growth factor is a paracrine factor for melanocyte survival in the skin. Both nerve growth factor and basic fibroblast growth factor stimulate melanocyte migration. It is reasonable to propose that helium-neon laser irradiation clearly stimulates melanocyte migration and proliferation and mitogen release for melanocyte growth and may also rescue damaged melanocytes, therefore providing a microenvironment for inducing repigmentation in vitiligo.

Our study provides in vitro evidence demonstrating that direct interaction between FK506 and KCs creates a favourable milieu for MC growth and migration. Furthermore, our findings provide a possible mechanism explaining how tacrolimus ointment induces repigmentation in patients with vitiligo.

Helium-neon laser (He-Ne Laser, 632.8 nm) is a low-energy laser that has therapeutic efficacy on various clinical conditions. Our previous study has demonstrated efficacy of He-Ne laser on vitiligo, a disease characterized by skin depigmentation. To regain skin tone on vitiligo lesions, the process began by the migration of the immature melanoblasts (MBs) to the epidermis, which was followed by their functional development to produce melanin. In this study, we investigated the physiologic effects of He-Ne laser irradiation on two MB cell lines: the immature NCCmelb4 and the more differentiated NCCmelan5. The intricate interactions between MBs with their innate extracelluar matrix, fibronectin, were also addressed. Our results showed that He-Ne laser irradiation enhanced NCCmelb4 mobility via enhanced phosphorylated focal adhesion kinase expression and promoted melanogenesis in NCCmelan5. In addition, He-Ne laser decreased the affinity between NCCmelb4 and fibronectin, whereas the attachment of NCCmelan5 to fibronectin increased. The alpha5beta1 integrin expression on NCCmelb4 cells was enhanced by He-Ne laser. In conclusion, we have demonstrated that He-Ne laser induced different physiologic changes on MBs at different maturation stages and recapitulated the early events during vitiligo repigmentation process brought upon by He-Ne laser in vitro.

Vitiligo is an acquired pigmentary disorder characterized by depigmentation of skin and hair. Melanocyte migration is an important event in re-pigmentation of vitiligo. We have demonstrated that narrow-band ultraviolet B (UVB) irradiation stimulated cultured keratinocytes to release a significant amount of basic fibroblast growth factor (bFGF). Furthermore, narrow-band UVB enhanced migration of melanocytes via increased expression of phosphorylated focal adhesion kinase (p125(FAK)) on melanocytes. The aim of this study was to investigate the effect of recombinant human bFGF (rhbFGF) on melanocyte migration. The relationship between the expression of p125(FAK) and melanocyte migration induced by rhbFGF was also studied. Our results demonstrated that rhbFGF significantly enhanced migration of melanocytes and p125(FAK) expression on melanocytes. Herbimycin A, a potent p125(FAK) inhibitor, effectively abolished rhbFGF-induced melanocyte migration. The combined results indicated that p125(FAK) plays an important role in the signal transduction pathway of melanocyte migration induced by bFGF.

In summary, we have demonstrated that the He-Ne laser imparts a growth stimulatory effect on functional melanocytes via mitochondria-related pathways and proposed that other minor pathways including DNA damage may also be inflicted by laser treatment on irradiated cells. More importantly, we have completed the repigmentation scheme of vitiligo brought about by He-Ne laser light in vitro and provided a solid theoretical basis regarding how the He-Ne laser induces recovery of vitiligo in vivo.

Inorganic arsenic is an environmental toxin and a human carcinogen. Being a co-mutagen, arsenic enhances carcinogenesis of ultraviolet irradiation on the mouse skin. Apoptosis, a well-regulated cell death process, is essential for cell development and tissue homeostasis. Dysregulation of apoptosis will lead to various kinds of pathological conditions, such as cancers. The purpose of this study is to investigate the apoptotic effect induced by the interactions of arsenic and UVB on cultured human keratinocytes. Cultured keratinocytes were treated with sodium arsenite (1 microM) and/or UVB 50 mJ/cm2 irradiation in different combinations, including arsenic alone (As group), UVB alone (UVB group), arsenic followed by UVB (As/UVB group), and UVB followed by As (UVB/As group) treatments. Our results revealed that a low concentration of sodium arsenite did not induce keratinocytes apoptosis. The UVB group showed obvious elevation of caspase-8, -9, and -3 activities in addition to strong induction of apoptosis as determined by terminal deoxynucleotidyl transferase-mediated deoxyuridine nick-end labeling (TUNEL) assay. Similar pro-apoptotic effects were observed in the UVB/As group. In contrast, only subtle changes of cell morphology and survival rate were noticed in the As/UVB group. In addition, the results of Western blot and activity assay of caspase-8, -9, and -3 revealed that neither the receptor nor the mitochondrial apoptotic signaling pathway was activated in the As/UVB group. Therefore, we conclude that the pretreatment of keratinocytes with sodium arsenite decreased the pro-apoptotic effects induced by UVB. This finding corroborated with the animal model studying the effects of arsenic and UVB on carcinogenesis. The molecular mechanisms by which arsenic decreased UVB-induced apoptosis remain to be elucidated.