Hyperelastic Material Properties of Mouse Skin under Compression

Area of Science:

• Biomechanical Engineering
• Dermatology
• Mammalian Physiology

Background:

• Skin is a dynamic organ with complex material properties crucial for mechanical stress tolerance, growth, and repair.
• Hair cycles in mice cause significant skin thickness fluctuations, but their impact on skin mechanics is not well understood.
• Mouse models are vital for studying skin biology, aging, UV damage, and somatosensory signaling.

Purpose of the Study:

• To quantitatively define the mechanical properties of mouse skin under physiological variations.
• To investigate how skin thickness, stiffness, and modulus change with hair cycle, body weight, and anatomical location.
• To establish baseline mechanical data for mouse skin relevant to sensory perception and injury models.

Main Methods:

• Uniaxial compression tests were performed on 105 freshly isolated, full-thickness mouse skin specimens from the hind limb.
• Skin thickness, stiffness, and hyperelastic modulus were measured.
• Analyses considered physiological variables: body weight, hair-cycle stage, maturity, skin site, and individual differences.

Main Results:

• Skin thickness and stiffness were primarily influenced by hair-cycle stage in younger mice and body weight in mature mice.
• Stiffness showed an inverse relationship with thickness, maintaining a consistent hyperelastic modulus across different hair cycles and body weights.
• Skin mechanics varied significantly by anatomical location, with sites containing fascial structures exhibiting a greater modulus.

Conclusions:

• Mouse skin maintains a constant elastic modulus to compression despite dramatic structural changes throughout adult life.
• Hair cycle and body weight significantly impact skin thickness and stiffness but not the fundamental elastic modulus.
• Anatomical location is a key determinant of mouse skin mechanical properties, particularly in areas with integrated fascial structures.