BACKGROUND: Human skin has the crucial roles of maintaining homeostasis and protecting against external environment. It offers protection against mechanical trauma due to the reversible deformation of its structure; these biomechanical properties are amenable to dynamic testing using non-invasive devices.
OBJECTIVES: To characterise the biomechanical properties of young, white Caucasian and black African/African-Caribbean skin from different anatomical sites; and to relate underlying skin architecture to biomechanical function.
METHODS: Using cutometry and ballistometry, the biomechanical properties of buttock and dorsal forearm skin were determined in black African/African-Caribbean (n=18) and white Caucasian (n=20) individuals aged 18-30 years. Skin biopsies were obtained from a subset of the volunteers (black African/African-Caribbean: n=5; white Caucasian: n=6) and processed for histological and immunohistochemical detection of the major elastic fibre components and fibrillar collagens.
RESULTS: We have determined that healthy skin from young African and Caucasian individuals has similar biomechanical properties (F3) in that skin is resilient (capable of returning to its original position following deformation; R1), exhibits minimal fatigue (R4) and is highly elastic (R2, R5 and R7). At the histological level, skin with these biomechanical properties is imbued with strong interdigitation of the rete ridges at the dermal-epidermal junction (DEJ) and candelabra-like arrays of elastic fibres throughout the papillary dermis. Dramatic disruption to this highly organised arrangement of elastic fibres, effacement of the rete ridges and alterations to the alignment of the fibrillar collagens is apparent in white Caucasian forearm and coincides with a marked decline in biomechanical function.
CONCLUSIONS: Maintenance of skin architecture - both epidermal morphology and elastic fibre arrangement - is essential for optimal skin biomechanical properties. Disruption to underlying skin architecture, as observed in young white Caucasian forearm, compromises biomechanical function.