Mechanical Forces in the Skin: Roles in Tissue Architecture, Stability, and Function

Abstract

Tissue shape emerges from the collective mechanical properties and behavior of individual cells and the ways by which they integrate into the surrounding tissue. Tissue architecture and its dynamic changes subsequently feed back to guide cell behavior. The skin is a dynamic, self-renewing barrier that is subjected to large-scale extrinsic mechanical forces throughout its lifetime. The ability to withstand this constant mechanical stress without compromising its integrity as a barrier requires compartment-specific structural specialization, and capability to sense and adapt to mechanical cues. This review discusses the unique mechanical properties of the skin and the importance of signals that arise from mechanical communication between cells and their environment. Adams JC, Watt FM. Fibronectin inhibits the terminal differentiation of human keratinocytes. Nature. 1989;340(6231):307-9 Adams JC, Watt FM. Changes in keratinocyte adhesion during terminal differentiation: Reduction in fibronectin binding precedes α5β1 integrin loss from the cell surface. Cell. 1990;63(2):425-35 Aw WY, Devenport D. Planar cell polarity: global inputs establishing cellular asymmetry.

A biomechanical switch regulates the transition towards homeostasis in esophageal epithelium

“…This is exemplified during postnatal development, when individual tissues grow at their own particular pace generating significant levels of mechanical stress at the organ level 25, 27 . In this context, physical forces influence cell adhesion, shape, as well as niche availability, and, in return, feedback on tissue growth, organization and maturation 15, 28 .…”

The bioengineering theory of the key modes of action of a cyanoacrylate liquid skin protectant

“…The mechanical behaviour of skin also depends on the loading mode, magnitudes, and rates of the applied forces (skin is a highly non‐linear and viscoelastic material) as well as the osmolarity of the testing environment 10 . Considering the aforementioned turnover cycles of skin, the mechanical properties of skin depend on the regeneration and repair capacities of the individual, which are, in turn, age‐dependent and may be affected by the function of the inflammatory system, by acute conditions as well as by chronic diseases 11,12 . This inherent biological/physiological variability across individuals partially explains the vast variation in reported mechanical properties for skin and skin layers, such as values of elastic moduli that span over several orders of magnitude, 0.04 to 1000 kPa for physiological deformations 13 .…”

Mechanical Instability of Adherens Junctions Overrides Intrinsic Quiescence of Hair Follicle Stem Cells

“…AJs have emerged as a mechanosensitive hub that have critical functions in regulating tissue development and maintaining homeostasis (Biggs et al, 2019;Fernandez-Sanchez et al, 2015;Miroshnikova et al, 2018;Pinheiro and Bellaïche, 2018;Vasquez and Martin, 2016). Mechanical forces applied on AJs are known to affect various important cellular functions such as stemness, proliferation, differentiation, collective cell migration, and apoptosis (Gilmour et al, 2017;Heisenberg and Bellaïche, 2013;Petridou et al, 2017).…”