Comparison of Thiel preserved, fresh human, and animal liver tissue in terms of mechanical properties

Sarah-Jane Estermann; Sophie Förster-Streffleur; Lena Hirtler; Johannes Streicher; Dieter H Pahr; Andreas Reisinger

doi:10.1016/j.aanat.2021.151717

Comparison of Thiel preserved, fresh human, and animal liver tissue in terms of mechanical properties

Ann Anat. 2021 Jul:236:151717. doi: 10.1016/j.aanat.2021.151717. Epub 2021 Mar 6.

Authors

Sarah-Jane Estermann¹, Sophie Förster-Streffleur², Lena Hirtler³, Johannes Streicher², Dieter H Pahr⁴, Andreas Reisinger⁵

Affiliations

¹ Department Anatomy and Biomechanics, Karl Landsteiner University of Health Sciences, Dr.-Karl-Dorrek-Straße 30, 3500 Krems an der Donau, Austria; Austrian Center for Medical Innovation and Technology, Viktor Kaplan-Straße 2/1, 2700 Wiener Neustadt, Austria; Institute for Lightweight Design and Structural Biomechanics, University of Technology Vienna, Getreidemarkt 9, 1060 Wien, Austria.
² Department Anatomy and Biomechanics, Karl Landsteiner University of Health Sciences, Dr.-Karl-Dorrek-Straße 30, 3500 Krems an der Donau, Austria.
³ Division of Anatomy, Center for Anatomy and Cell Biology, Medical University of Vienna, Währinger Straße 13, 1090 Wien, Austria.
⁴ Department Anatomy and Biomechanics, Karl Landsteiner University of Health Sciences, Dr.-Karl-Dorrek-Straße 30, 3500 Krems an der Donau, Austria; Institute for Lightweight Design and Structural Biomechanics, University of Technology Vienna, Getreidemarkt 9, 1060 Wien, Austria.
⁵ Department Anatomy and Biomechanics, Karl Landsteiner University of Health Sciences, Dr.-Karl-Dorrek-Straße 30, 3500 Krems an der Donau, Austria; Institute for Lightweight Design and Structural Biomechanics, University of Technology Vienna, Getreidemarkt 9, 1060 Wien, Austria. Electronic address: andreas.reisinger@kl.ac.at.

PMID: 33689839
DOI: 10.1016/j.aanat.2021.151717

Abstract

Background: In medical training and research fresh human tissue is often replaced by preserved human or fresh animal tissue, due to availability and ethical reasons. Newer preservation approaches, such as the Thiel method, promise more realistic mechanical properties than conventional formaldehyde fixation. Concerning animal substitute material, porcine and bovine tissue is often chosen, as it is easily obtainable and certain similarity to human tissue is assumed. However, it has not been thoroughly investigated how Thiel preservation changes non-linear and viscoelastic behaviour of soft organ tissues. Furthermore, differences in these properties between animal tissue and human tissue have not been previously corroborated.

Methods: We conducted ramp and relaxation tensile tests on fresh human and Thiel preserved hepatic tissue, extracting strain-specific elastic moduli, and viscoelastic properties. The results for fresh human liver were then compared to corresponding results for Thiel preserved liver, as well as previously published results for porcine and bovine liver.

Results: Our results showed that Thiel preservation seems to be associated with increased stiffness as well as decreased viscoelastic damping behaviour. Porcine liver was stiffer than human liver with similar viscoelastic properties. Bovine liver exhibited similar stiffness as human liver, however lower viscoelastic damping.

Conclusions: The differences between human and animal liver tissue, concerning their mechanical properties, can be explained by their characteristic histology. Changes in mechanical properties due to Thiel preservation might stem from altered protein cross-linking and dehydration. The results illustrate that appropriate materials for medical training systems must be selected based on which mechanical properties are relevant for the respective application.

Keywords: Human liver tissue; Mechanical properties; Porcine and bovine liver; Thiel preservation; Viscoelasticity.

MeSH terms

Animals
Cattle
Elastic Modulus
Formaldehyde*
Humans
Liver
Preservation, Biological*
Stress, Mechanical
Swine

Substances

Formaldehyde