A mechanistic view on the aging human skin through ex vivo layer-by-layer analysis of mechanics and microstructure of facial and mammary dermis

Barbara Lynch,Heiva Le Blay,Philippe Bastien,Sébastien Brizion,Thomas Bornschlögl,Yegor Domanov,Hervé Pageon

doi:10.1038/s41598-022-04767-1

Abstract

Age-related changes in skin mechanics have a major impact on the aesthetic perception of skin. The link between skin microstructure and mechanics is crucial for therapeutic and cosmetic applications as it bridges the micro- and the macro-scale. While our perception is governed by visual and tactile changes at the macroscopic scale, it is the microscopic scale (molecular assemblies, cells) that is targeted by topical treatments including active compounds and energies. We report here a large dataset on freshly excised human skin, and in particular facial skin highly relevant for cosmetics and aesthetic procedures. Detailed layer-by-layer mechanical analysis revealed significant age-dependent decrease in stiffness and elastic recoil of full-thickness skin from two different anatomical areas. In mammary skin, we found that the onset of mechanical degradation was earlier in the superficial papillary layer than in the deeper, reticular dermis. These mechanical data are linked with microstructural alterations observed in the collagen and elastic networks using staining and advanced imaging approaches. Our data suggest that with ageing, the earliest microstructural and mechanical changes occur in the top-most layers of dermis/skin and then propagate deeper, providing an opportunity for preventive topical treatments acting at the level of papillary dermis.

Highlights

Age-related changes in skin mechanics have a major impact on the aesthetic perception of skin
As we had access to a wide range of fresh full-thickness human skin samples, we could systematically study the biomechanical properties of skin as a function of donor age
We report for the first time a large dataset for freshly excised human skin, and in particular facial skin, a target very relevant for cosmetics and aesthetic surgery

Summary

Introduction

Age-related changes in skin mechanics have a major impact on the aesthetic perception of skin. We found that the onset of mechanical degradation was earlier in the superficial papillary layer than in the deeper, reticular dermis. These mechanical data are linked with microstructural alterations observed in the collagen and elastic networks using staining and advanced imaging approaches. Our data suggest that with ageing, the earliest microstructural and mechanical changes occur in the top-most layers of dermis/skin and propagate deeper, providing an opportunity for preventive topical treatments acting at the level of papillary dermis. A precise knowledge of the link between skin microstructure and mechanical properties in relationship with age is crucial for therapeutic and cosmetic applications as it bridges the microscopic scale (molecules and their assemblies) with the tissue properties at macroscopic scale. The most noticeable microstructural modifications of the dermis with a ge[5] have been reported as a decrease of c ollagen[2] and elastin c ontents[7], an increase of collagen cross-linking[6], and a deterioration of proteoglycans[8]

Methods

Results

Conclusion