Assessment of nanoindentation protocols for murine skin matrix biomechanics

Changes in biomechanical properties in tissue extracellular matrix is increasingly recognised as a major regulator of cell behaviour in health and disease. Microscopically heterogeneous and soft biological materials like skin present several technical challenges when quantifying their local biomechanics. While nanoindentation is used for high resolution mapping of mechanical properties across highly heterogenous, soft biological materials, standardisation is lacking. For skin, developing standard nanoindentation protocols on full-thickness sections requires considering parameters like sample thickness, spatial resolution, plasticity, probe velocity, and contact-force models on the resultant nano mechanics. Here, we report, using full-thickness healthy mouse skin, the results of a study on the effect of these parameters on nanoindentation scans, finding that a consistent anatomical variation is the most significant determinant of change from the subcutaneous layer to the epidermis, with the other factors either not significant or consistent across measurements.