Mechanical Stimulation Alters the Collagen Protein Structure in Skin Tissue

Soft tissue remodelling is the response of mechanical signal sensed by the molecular structure. However, the response of soft tissue molecular structure against the external mechanical stimulation is not well known. Some studies illustrated that the tissue remodelling depends on the rate of mechanical stimulation, however its cause is not well known. Understanding the response of molecular structure against the mechanical stimulation is crucial for the development of physiotherapeutic criteria to improve tissue health and wound healing. In this study, we investigated the effect of rate of mechanical stimulation on the alteration of nano and molecular structure of skin. For mechanical stimulation, pig skin was cyclically stretched at three different frequencies 0.1, 2.0 and 5.0 Hz. Whereas, nano and molecular structure of virgin and mechanical tested skin was assessed under atomic force microscope (AFM) and attenuated total reflectance Fourier transform infrared spectroscopy (FTIR–ATR), respectively. The alteration in nano and molecular structure was found sensitive to rate of mechanical stimulation as change in collagen fibril d-periodicity and collagen molecular (tropocollagen, protein structure) was found significantly larger corresponding to 0.1 Hz than 2.0 Hz and 5.0 Hz. A significant negative correlation (r = 0.74, p = 0.041) was found between stretching frequency and alteration in collagen protein structure. These results indicate that slow mechanical stimulation during physiotherapy may improve the tissue remodelling.