735 A novel anti-aging peptide blend facilitates epidermal thickening and cell proliferation in aged skin

Cutaneous photoaging is the biological attrition of skin structure & function due to chronic exposure to solar radiation. It is characterized clinically by wrinkle formation and histologically by epidermal atrophy. Photoaged skin is treated with cosmeceutical formulations often containing peptides that function as matrikines. However, the impact of peptides on epidermal dynamics remains unknown. Synthetic tetra-peptides (pal-GPKG, pal-LSVD) were developed in silico. A blend of the two novel synthetic peptides was assessed for its effect on epidermal cell proliferation in a validated in vivo patch test protocol. Photoexposed extensor forearms of healthy but photoaged white volunteers (5F, 3M; age range 72-84 years) were occluded with either the peptide blend (10ppm), its vehicle or occluded without treatment (baseline) for 12-days. The clinical ‘gold standard’ topical anti-ageing treatment, all-trans retinoic acid (ATRA; 0.025% w/w) was applied under occlusion for 4-days. Resultant punch biopsies were processed for histologic analyses. Compared to baseline (40.8 ± 7.6 μm), epidermal thickness was significantly increased following treatment with both the peptide blend (49.9 ± 7.4 μm, p<0.05) and ATRA (68.4 ± 13.4 μm, p<0.005); treatment with vehicle (47.3 ± 9.8 μm) showed no significant increase in epidermal thickness. The expression of Ki67, a robust keratinocyte proliferative marker, was assessed by immunofluorescence. Similarly, both the peptide blend (3.75% ± 1.82, p<0.05) and ATRA (4.47% ± 1.19, p<0.005) significantly increased the percentage of Ki67+cells within the epidermis. We conclude that this novel peptide blend facilitates epidermal cell proliferation, contributing to increased epidermal thickness & is therefore a promising anti-ageing cosmetic skincare ingredient.