Topography and Elastic Properties of Tissues Following Self-Inflating Tissue Expansion

Objective: Connective tissues mainly comprise of collageneous material. The collagen fibrils play a major role in the mechanical properties of connective tissues. During expansion, the collagen fibrils will elongate and realign themselves in a parallel manner to resist deformation before failure. The advent of Atomic Force Microscopy (AFM) has enabled the researchers to measure the mechanical properties at the ultrastructure level such as collagen fibrils. Therefore, the objectives of this study were to investigate the surface topography and elastic properties of collagen fibrils in normal and expanded skin tissue. Method: Two groups of five adult male Dorper sheeps were used in the study. One group acted as a control group and the other was implanted with 20 x 5 mm osmotic tissue expanders subcutaneously at the lower limb region and allowed to reach equilibrium. Upon explantation, the skin were sectioned to 50 um thickness. The surface roughness and elastic modulus analysis were carried out using Alicona and BioAFM (Nanowizard 3, JPK, Germany). The force spectroscopy was performed on collagen fibrils at 10 points. Result: The average surface roughness (0.55 ± 0.27 μm) was significantly (p<0.05) lower in the expanded group (1.42 ± 0.64 μm). It was observed that the collagen fibrils in the expanded tissues were elongated and thinner. The elastic property of the collagen fibrils in the expanded skin was 48.2 ± 25.4 MPa whereas the elasticity of collagen fibrils in normal skin was 40.6 ± 28.8 MPa. Conclusion: The findings suggest that there is a change in the morphology of collagen fibrils in the expanded tissue which resulted in an alteration of the elastic properties.