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Vitiligo is a skin condition in which pigment-producing cells are removed by the immune system, leading to patches of white skin on different parts of the body. Treatments, including UVB light therapy and skin micro-grafting, may lead to repigmentation of the skin; however, treatments are not uniformly successful, and it is currently unclear why some vitiligo areas repigment more rapidly than others. An optical imaging technique that allows non-invasive visualization of melanocytic activity in skin may advance the knowledge about this skin condition and help understand treatment impact. In this pilot study, we employ in-vivo multiphoton microscopy (MPM) to evaluate architectural and structural features of the melanocytes that repigment vitiligo skin. MPM is a nonlinear laser scanning microscopy technique that features sub-cellular resolution and label-free molecular contrast. MPM contrast in skin is derived from two-photon excited fluorescence of NADH/FAD+, keratin, melanin, and elastin, and second-harmonic generation of collagen. We employed a clinical MPM tomograph (MPTflex, JenLab, Germany) to image vitiligo and adjacent normal areas in 10 patients undergoing treatment. The treatment consisted of either UVB light therapy or skin micro-grafting treatment followed by UVB light therapy. We visualized pigment producing melanocytes near hair follicles, migrating melanocytes within the human epidermis, newly pigmented keratinocytes in the basal layer, and epidermal melanin granules. The overarching goal is to use this technology to better define the phenotypic characteristics of migrating melanocytes in the hope of improving transplantation therapies for vitiligo.
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