702 Age-dependent transformation of skin biomechanical properties and micromorphology during infancy and childhood

Abstract

We investigated for the first time the correlation between the maturation of biomechanical properties of the skin and the evolution of skin topography and micromorphology from infancy to early adulthood. 70 subjects in 7 age groups: 1-15 days, 5 weeks, 5-7 months, 2 years, 4-5 years, 7-8 years, and 20-35 years were included. Skin properties were examined by cutometry and reflectance confocal microscopy (RCM) in vivo, and by immunohistochemistry (IHC) in a limited number of foreskin biopsy samples. Cutometry showed that skin elasticity increased from infancy to 2 years. The viscoelastic component decreased from infancy to adulthood. Total recovery was slightly higher at older ages and total deformation did not vary between age groups. None of the parameters were correlated with stratum corneum (SC) hydration. RCM showed that thickness of the SC and supra papillary epidermis increased with age. The homogeneity and furrow architecture of SC changed dramatically between infants and older children. Dermal papillae increased in number with age, whereas rete ridge thickness remained stable. Circular cuffing of the follicle by collagen fibers was observed only in newborns, age at which collagen fibers were fibrillar and showed a parallel orientation. IHC showed that both fibrillin and elastin fibers increased in length and intensity with age, especially at the dermal-epidermal junction. These data demonstrate the biochemical and structural evolution of the dermis during postnatal development. These changes in these skin biomechanical properties are related to structural maturation rather than hydration. Our data support a contribution of mechanical forces to dermal maturation postnatally.