The nano-scale mechanical properties of the extracellular matrix regulate dermal fibroblast function.

Changes in the mechanical properties of dermis occur during skin aging or tissue remodeling and affect the activity of resident fibroblasts. With the aim to establish elastic culture substrates that reproduce the variable softness of dermis, we determined Young's elastic modulus E of human dermis at the cell perception level using atomic force microscopy. The E of dermis ranged from 0.1 to 10 kPa, varied depending on body area and dermal layer, and tended to increase with age in 26-55-year-old donors. The activation state of human dermal fibroblasts cultured on "skin-soft" E (5 kPa) silicone culture substrates was compared with stiff plastic culture (GPa), collagen gel cultures (0.1-9 kPa), and fresh human dermal tissue. Fibroblasts cultured on skin-soft silicones displayed low mRNA levels of fibrosis-associated genes and increased expression of the matrix metalloproteinases (MMPs) MMP-1 and MMP-3 as compared with collagen gel and plastic cultures. The activation profile exhibited by fibroblasts on "skin-soft" silicone culture substrates was most comparable with that of human dermis than any other tested culture condition. Hence, providing biomimetic mechanical conditions generates fibroblasts that are more suitable to investigate physiologically relevant cell processes than fibroblasts spontaneously activated by stiff conventional culture surfaces.