Multiscale Mechanics of Skin and Skin-Equivalent Materials

The mechanical properties of the human skin are essential for its primary function as a protective barrier against external insults. These properties derive from the microstructure of the extracellular matrix (ECM), which is complex due to the tissue organization into multiple layers (epidermis, dermis, and hypodermis) of multiple constituents (e.g., interstitial fluid, collagen fibers, elastin, and proteoglycans). The ECM is synthesized and remodeled by dermal cells, which, in turn, sense mechanical cues and use these inputs to make decisions regarding, for example, ECM remodeling, differentiation, proliferation, or apoptosis. This interdependence between dermal cell behavior, tissue microstructure, and tissue mechanics defines a challenging and highly interdisciplinary research field. A few examples of related research questions concern the design of skin-equivalent materials for burn wound treatment and understanding of the role of mechanics in biological processes such as aging and wound healing. In this project, we take a holistic view on skin mechanics. We characterize and model the mechanical behavior of skin and skin-equivalent materials at the micro- and macroscale, with particular attention to the relation between the multiscale and multiphasic tissue microstructure and its deformation and failure behavior. The insights from these investigations are then applied to study the influence of various biophysical stimuli on dermal cell behavior in skin and tissue-engineered skin substitute materials.

afm-experiment
Figure 1. (a) Atomic force microscopy experiment on the cross-section of a human skin sample. (b) Rendering of a discrete fiber network model of the human dermis under equibiaxial tension. (c) Tissue-engineered skin substitute based on a plastically compressed collagen hydrogel.

Collaborations

Tissue Biology Research Unit, University Children’s Hospital Zurich
This work is part of the collaborative research initiative external pageSKINTEGRITY.CH.

Funding

Swiss National Science Foundation (grant no. 179012)

Publications

Wahlsten, A., Rütsche, D., Nanni, M., Giampietro, C., Biedermann, T., Reichmann, E., Mazza, E., Mechanical stimulation induces rapid fibroblast proliferation and accelerates the early maturation of human skin substitutes, Biomaterials 273, 120779 (2021). external pagehttps://doi.org/10.1016/j.biomaterials.2021.120779

Wahlsten, A., Pensalfini, M, Stracuzzi, A., Restivo, G., Hopf, R., Mazza, E., On the compressibility and poroelasticity of human and murine skin, Biomech Model Mechanobiol 18, 1079-1093 (2019). external pagehttps://doi.org/10.1007/s10237-019-01129-1

Guzzi, E.A, Bischof, R., Dranseikiene, D., Deshmukh, D.V., Wahlsten, A., Bovone, G., Bernhard, S., Tibbitt, M., Hierarchical biomaterials via photopatterning-enhanced direct ink writing, Biofabrication, 13 , 044105 (2021). external pagehttps://doi.org/10.1088/1758-5090/ac212f

Sachs, D., Wahlsten, A., Kozerke, S., Restivo, G., Mazza, E. A biphasic multilayer model of human skin, Biomech Model Mechanobiol 20, 969-982 (2021). external pagehttps://doi.org/10.1007/s10237-021-01424-w

Bircher, K., Merluzzi, R., Wahlsten, A., Spiess, D., Simões-Wüst, A.P., Ochsenbein-Kölble, N., Zimmermann, R., Deprest, J., Mazza, E., Influence of osmolarity and hydration on the tear resistance of the human amniotic membrane, J Biomech 98, 109419 (2020). external pagehttps://doi.org/10.1016/j.jbiomech.2019.109419

Sferrazza, C., Wahlsten, A., Trueeb, C., d’Andrea, R., Ground Truth Force Distribution for Learning-Based Tactile Sensing: A Finite Element Approach, IEEE Access 7, 173438-173449 (2019). external pagehttps://doi.org/10.1109/ACCESS.2019.2956882

Stracuzzi, A., Rubin, M.B., Wahlsten, A., A thermomechanical model for porous tissue with diffusion of fluid and micromechanical modeling of porosity, Mech Res Commun 97, 112-122 (2019). external pagehttps://doi.org/10.1016/j.mechrescom.2019.04.007
 

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