Mitochondria-Targeted Vitamin E Protects Skin from UVB-Irradiation

Mitochondria-targeted vitamin E (MVE) is designed to accumulate within mitochondria and is applied to decrease mitochondrial oxidative damage. However, the protective effects of MVE in skin cells have not been identified. We investigated the protective effect of MVE against UVB in dermal fibroblasts and immortalized human keratinocyte cell line (HaCaT). In addition, we studied the wound-healing effect of MVE in animal models. We found that MVE increased the proliferation and survival of fibroblasts at low concentration (i.e., nM ranges). In addition, MVE increased collagen production and downregulated matrix metalloproteinase1. MVE also increased the proliferation and survival of HaCaT cells. UVB increased reactive oxygen species (ROS) production in fibroblasts and HaCaT cells, while MVE decreased ROS production at low concentration. In an animal experiment, MVE accelerated wound healing from laser-induced skin damage. These results collectively suggest that low dose MVE protects skin from UVB irradiation. Therefore, MVE can be developed as a cosmetic raw material.

Knowledge, Attitude And Practices Of Adults In Relation To Sun Exposure And Photodamage

Background: Protection from sun exposure is key in the prevention of photodamage and skin cancer, and is particularly important in countries that experience high ultraviolet exposure. We compare the knowledge, attitude and behaviour towards sun exposure in Singapore between adults with and without photodamage. We also describe the clinical features of patients with photodamage in Singapore. Methods: 532 subjects were recruited from the dermatology specialist outpatient of a tertiary hospital in Singapore. Each subject was assessed clinically by a dermatologist for evidence of photodamage, and answered a questionnaire assessing his knowledge, attitude and behaviour towards sun exposure and protection. Results: Subjects with photodamage were older, and had lower education and employment rates compared to subjects without photodamage. There was no significant difference in knowledge on the harmful effects of sun exposure and on sun protection or in sun avoidance behaviour (other than use of protective sunglasses) between the two groups, though more patients with photodamage felt that they take adequate sun protection measures. Of note, only a low percentage of subjects in both groups (24.5% of subjects with photodamage and 23.1% of subjects without photodamage) practise regular use of sunscreen. Conclusion: There was no significant difference between the knowledge, attitudes and behaviours of subjects with and without photodamage, though demographic differences between the two groups exist. Regular sunscreen usage is low in Singapore, a country with high exposure to ultraviolet light, and measures to educate and modify the behaviour of the public need to be developed.

Solar ultraviolet radiation induces biological alterations in human skin in vitro: Relevance of a well-balanced UVA/UVB protection.

Cutaneous damages such as sunburn, pigmentation, and photoaging are known to be induced by acute as well as repetitive sun exposure. Not only for basic research, but also for the design of the most efficient photoprotection, it is crucial to understand and identify the early biological events occurring after ultraviolet (UV) exposure. Reconstructed human skin models provide excellent and reliable in vitro tools to study the UV-induced alterations of the different skin cell types, keratinocytes, fibroblasts, and melanocytes in a dose- and time-dependent manner. Using different in vitro human skin models, the effects of UV light (UVB and UVA) were investigated. UVB-induced damages are essentially epidermal, with the typical sunburn cells and DNA lesions, whereas UVA radiation-induced damages are mostly located within the dermal compartment. Pigmentation can also be obtained after solar simulated radiation exposure of pigmented reconstructed skin model. Those models are also highly adequate to assess the potential of sunscreens to protect the skin from UV-associated damage, sunburn reaction, photoaging, and pigmentation. The results showed that an effective photoprotection is provided by broad-spectrum sunscreens with a potent absorption in both UVB and UVA ranges.

The ultraviolet B protection effects of topically applied melanosomes onto human skin

Melanosome is a cellular organelle that is composed of a melanosomal matrix and a brown biochrome, melanin which is formed by tyrosine-tyrosinase reactions. The melanosome is formed within the melanocyte and transferred to the surrounding keratinocytes through dendritic processes. Human skin color is related to the number, size, type and distribution of melanosomes, and the major role of melanosomes is to prevent skin from injurious nonionizing ultraviolet radiation. Controlled NaOH hydrolysis and centrifugation of human hair make it possible to isolate large amounts of melanosomes which are synthesized within the follicular melanocytes and transferred to hair matrix cells. In this study, the sun protection factors of topically applied melanosomes isolated from human hair were evaluated using ultraviolet B phototesting. Topically applied melanosomes increased the minimal erythemal doses. And the sun protection factors of each 50% and 25% melanosomal preparation were 12.3 +/- 5.5 and 3.1 +/- 1.3 respectively, and these ultraviolet B protection effects showed statistically significant differences from 10%, 5% and 1% melanosomal preparations and vehicle. Form these results, the dose-related photoprotective role of melanosomes was confirmed.