Palmitoyl­RGD promotes the expression of dermal­epidermal junction components in HaCaT cells.

With age, the dermal­epidermal junction (DEJ) becomes thinner and production of its protein components decreases; this may be associated with increased fragility and wrinkling of skin. Topical treatment with palmitoyl­Arg­Gly­Asp (PAL­RGD) improves facial wrinkles, skin elasticity and dermal density in humans. In the present study, the effect of PAL­RGD on expression of DEJ components, such as laminin and collagen, was assessed. Human HaCaT keratinocytes were treated with PAL­RGD. The protein expression levels of laminin­332, collagen IV and collagen XVII were examined by western blotting. Reverse transcription-quantitative PCR was used to analyze laminin subunit (LAM)A3, LAMB3, LAMC2, collagen type IV α 1 chain (COL4A1) and COL17A1 mRNA expression levels. Western blot analysis showed that the expression levels of proteins comprising the DEJ, including laminin α3, ß3 and γ2 and collagen IV and XVII demonstrated a significant dose­dependent increase following PAL­RGD treatment. Furthermore, PAL­RGD treatment significantly enhanced LAMA3, LAMB3, LAMC2, COL4A1 and COL17A1 mRNA expression levels. PAL­RGD may enhance the DEJ by inducing the expression of laminin­332, collagen IV and collagen XVII.

Quantitative two-photon microscopy imaging analysis of human skin to evaluate enhanced transdermal delivery by hybrid-type multi-lamellar nanostructure: retraction.

[This retracts the article on p. 3974 in vol. 9, PMID: 30338168.].

Quantitative two-photon microscopy imaging analysis of human skin to evaluate enhanced transdermal delivery by hybrid-type multi-lamellar nanostructure.

Transdermal skin delivery is a method to transport various topical formulations to a deeper skin layer non-invasively. Permeability analysis of many delivering agents has been mostly conducted by a simple tape stripping method. However, it cannot reveal a detailed depth-dependent distribution profile of transdermally delivered agents in the skin. In this work, we achieved a cellular-level depth-defined visualization of fluorophore-labelled human epidermal growth factor (EGF) transdermally delivered to human skin by using encapsulation with common liposomes and newly fabricated multi-lamellar nanostructures using a custom-design two-photon microscopy system. It was able to generate 3D reconstructed images displaying the distribution of human EGF inside the human skin sample with high-resolution. Based on a depthwise fluorescence intensity profile showing the permeation of human EGF, a quantitative analysis was performed to assess the transdermal delivery efficacy achieved by each formulation, showing a significant improvement of the efficacy with the utilization of multi-lamellar nanostructure.

Topical application of palmitoyl-RGD reduces human facial wrinkle formation in Korean women.

Maintaining a youthful appearance is a common desire among the aging population. Loss of elasticity and dermal density constitutes major causes of wrinkle formation during skin aging. In particular, periorbital wrinkles comprise the critical assessment point of skin aging. To address these issues, cosmetic industries have been making increasing efforts to develop efficient agents against wrinkle formation. Arg-Gly-Asp (RGD) is a tripeptide sequence used for surface coating because of its integrin-binding property. However, its pharmacological properties on skin have not yet been studied. Here, we synthesize the novel palmitoyl-Arg-Gly-Asp (Palm-RGD) and investigate its effects on periorbital wrinkle formation by clinical and in vitro studies. We observed that Palm-RGD cream application for 12 weeks decreased global photodamage and skin roughness (R1, R2, R3, and Ra) scores without causing skin irritation. In addition, topical application of Palm-RGD cream time-dependently increased skin elasticity and dermal density. An in vitro study using human dermal fibroblasts (HDFs) demonstrated increased type I procollagen production by Palm-RGD treatment. Furthermore, Palm-RGD suppressed MMP-1 expression in HDFs. Our results demonstrate that Palm-RGD has protective effects against wrinkle formation, likely through the activation of collagen expression and the protection against collagen degradation. Therefore, Palm-RGD could be used as a potential agent for the prevention of wrinkle formation consequent to aging.

Effects of palmitoyl-KVK-L-ascorbic acid on skin wrinkles and pigmentation.

Wrinkle formation and abnormal pigmentation are major clinical alterations associated with skin aging. As the aim of our study was to investigate the effects of palmitoyl-KVK-L-ascorbic acid on skin aging, the anti-wrinkle and depigmentation effects of palmitoyl-KVK-L-ascorbic acid were evaluated by measuring collagen expression in dermal fibroblast cells and inhibition of melanogenesis in B16F1 cells, respectively. The anti-aging effect of palmitoyl-KVK-L-ascorbic acid cream was also evaluated against a placebo cream in a clinical trial. Our results confirmed that the expression of type Ι collagen in dermal fibroblast cells treated with palmitoyl-KVK-L-ascorbic acid (0.1-4 µg/mL) increased in a dose-dependent manner. In B16F1 cells, treatment with 20 µg/mL palmitoyl-KVK-L-ascorbic acid reduced the melanin content by approximately 20% compared to alpha-melanocyte stimulating hormone treatment. In the clinical trial, application of palmitoyl-KVK-L-ascorbic acid cream led to an improvement in skin roughness and lightness in 12 and 8 weeks, respectively. Our data show that palmitoyl-KVK-L-ascorbic acid is an effective anti-aging agent that reduces wrinkles and abnormal skin pigmentation.

Cyclohexanediol bis-ethylhexanoate inhibits melanogenesis of murine B16 melanoma and UV-induced pigmentation in human skin.

The role of cyclohexane diester analogues in the formation of melanin has been recently reported. In the present study, we investigated the inhibitory effect of cyclohexanediol bis-ethylhexanoate (CHEH) on melanogenesis in B16 melanoma cells and on UV-B-induced pigmentation in human skin. CHEH significantly reduced the melanin content in a dose-dependent manner, without cytotoxic effects at the effective concentrations. Moreover, CHEH dose-dependently inhibited tyrosinase activity in B16 melanoma cells, as confirmed by Western blot analysis of the tyrosinase protein levels. However, tyrosinase transcript levels remained unchanged under the same experimental conditions. These results indicate that CHEH inhibited melanogenesis in B16 melanoma cells by regulating tyrosinase activity at the post-transcriptional level. On the other hand, in a cell-free system, CHEH did not inhibit tyrosinase activity. This indicated that CHEH suppressed the pigmentation of melanocytes by indirectly regulating tyrosinase activity. Finally, in a clinical trial, a cream containing 1.0% CHEH showed good whitening effect on UV-induced pigmented human skin without adverse effects. In conclusion, we suggest that CHEH may be an effective inhibitor of melanogenesis and useful effects in the treatment of hyperpigmented disorders.