Application Note | ElastoSens™ Bio
Measuring mechanical properties of liver tissue using ElastoSens™ Bio
Introduction
The liver’s ability to perform its diverse physiological functions depends not only on its cellular and biochemical activity but also on its mechanical behavior. Properties such as elasticity, stiffness, and viscoelasticity reflect the underlying tissue architecture and composition, which are altered when disease is present. Measuring these characteristics provides valuable information for both clinical practice and research. By studying them, scientists and clinicians can better understand how a healthy liver functions, detect early signs of disease, and design therapies that restore or preserve performance.
Key mechanical properties of the liver
Elasticity
Elasticity refers to the liver’s ability to return to its original shape after deformation. It reflects the structural integrity of hepatocytes, sinusoidal networks, and connective tissue, making it an essential property for evaluating how the organ accommodates blood flow and pressure changes.
Stiffness
Stiffness is a measure of resistance to deformation and is one of the most clinically important parameters of liver mechanics. Increases in stiffness often indicate pathological changes such as excess extracellular matrix deposition, which can signal the onset or progression of fibrosis.
Viscoelasticity
The liver is a viscoelastic organ, meaning it exhibits both elastic and viscous behavior when subjected to stress. This dual nature captures how the tissue both stores and dissipates mechanical energy, reflecting its complex microstructure. Assessing viscoelasticity helps in understanding disease processes that alter tissue organization.
Relationship between diseases and mechanical properties of liver tissue
Fibrosis
Fibrosis leads to significant increases in liver stiffness due to the accumulation of collagen and other extracellular matrix proteins. This change in mechanical behavior is a hallmark feature that can be detected non-invasively with elastography techniques.
Cirrhosis
Cirrhosis represents an advanced stage of liver remodeling, where stiffness is markedly elevated and viscoelastic behavior is disrupted. The profound alterations in tissue structure compromise both function and mechanical integrity, making mechanical properties central to its evaluation.
Hepatitis
Chronic hepatitis can progressively alter liver mechanics by initiating inflammation and early fibrotic changes. Monitoring variations in stiffness and elasticity provides valuable insight into the disease trajectory and supports early detection of complications.
How liver tissue mechanics are assessed
In Vivo techniques (Clinics)
In the clinic, the mechanical properties of the liver are primarily evaluated using elastography-based imaging techniques. Magnetic resonance elastography (MRE) combines MRI with low-frequency vibrations to visualize shear wave propagation, producing maps that represent tissue stiffness and viscoelasticity. Ultrasound elastography methods, including shear wave elastography and transient elastography, rely on acoustic waves or external vibrations to generate and track shear waves in the liver, with stiffness inferred from their velocity. These technologies provide a non-invasive and reproducible means to assess liver health and monitor disease progression.
Ex Vivo techniques (Research)
In research, liver mechanics are characterized through a variety of laboratory-based mechanical testing techniques. Dynamic mechanical analysis (DMA) is widely used, applying oscillatory forces to quantify viscoelastic properties such as elasticity and viscosity. Other established approaches include uniaxial and biaxial tensile testing, which stretch tissue to assess stiffness and anisotropy, as well as compression tests that evaluate deformation under load. Indentation methods are also applied, using controlled probes to measure local mechanical response.
Case study: Liver tissue mechanical characterization with ElastoSens™ Bio
ElastoSens™ Bio: a contactless tool for Ex Vivo tissue testing
In the field of liver biomechanics, the ElastoSens™ Bio provides an innovative approach to ex vivo testing. This instrument measures viscoelastic properties continuously and non-destructively, preserving tissue integrity throughout experiments. Its technology enables precise characterization of soft samples and allows repeated testing over extended periods under varying environmental conditions, helping to expand on the information obtained from traditional mechanical assays.
To illustrate the capabilities of the ElastoSens™ Bio, we conducted an ex vivo study on liver tissue samples. The following section details the materials and methods used in this experiment, followed by the results, providing a practical example of the instrument’s application.
Material and methods
Livers from pork and sheep were collected from a local farm. Tissue fragments with an approximate cylindrical shape (23 mm internal diameter, variable height) were excised using a biopsy-style punch. Each sample was placed into the macro holder of the ElastoSens™ Bio instrument, and measurements were carried out at room temperature over a 1-minute period.
The instrument delivered continuous viscoelastic parameters, specifically the shear storage modulus (G′) and damping ratio (Tan𝛿). Results for each condition represent the mean of five independent specimens, obtained from the same anatomical site across five different livers (n=5).
Figure 1. Liver tissue sample.
Results and discussion
Using the ElastoSens™ Bio non-destructive testing system, Figure 2 shows that pig liver tissue exhibited a higher shear storage modulus (G′ = 1450 ± 350 Pa) compared to sheep (1090 ± 82 Pa), indicating greater stiffness and elastic energy storage. In contrast, sheep liver tissue displayed a slightly higher damping ratio (Tanδ = 0.43 ± 0.08 vs. 0.35 ± 0.01), suggesting greater viscous energy dissipation. Overall, pig liver tissue demonstrated higher stiffness, while sheep liver tissue showed a marginally more dissipative mechanical response.
These values align with elastography studies that reported porcine liver shear moduli of 1390–2730 Pa depending on frequency (Chintada et al., 2020; Kruse et al., 2000). For sheep, indentation experiments coupled with inverse finite element analysis on lamb liver yielded an initial elastic modulus of 13,500 Pa, corresponding to an initial shear modulus of approximately 4500 Pa (Resapu & Bradshaw, 2021). Differences in measurements across studies are due to variations in experimental methodology—including the measurement technology, strain level, stimulation direction, and sample handling and preparation, among other factors. Overall, the ElastoSens™ Bio provides a direct, non-destructive shear measurement under controlled hydration and standardized loading. This setup reduces variability linked to specimen mounting, and enables repeatable assessment of physiologically relevant viscoelastic properties.
Figure 2: Viscoelastic properties of liver tissue for sheep and pig: shear storage modulus (G′) (left) and damping ratio (Tan𝛿) (right) obtained with the ElastoSens™ Bio non-destructive testing system (mean ± SD, n=5).
Conclusions and perspectives
The mechanical behavior of liver tissue, encompassing elasticity, stiffness, viscoelasticity, and anisotropy, plays a critical role in both healthy function and pathological remodeling. Findings from this study confirm that non-destructive viscoelastic assessment with the ElastoSens™ Bio provides robust measurements of liver mechanics, capturing essential parameters such as shear storage modulus (G′) and damping ratio (Tan𝛿). This approach delivers reproducible and precise data, supporting cross-condition and cross-species comparisons.
Beyond these outcomes, the ElastoSens™ Bio offers specific advantages for liver and biomaterials research:
- Simple preparation and setup minimize handling and preserve liver tissue hydration and integrity during testing.
- High sensitivity and repeatability ensure consistent measurements across different lobes and regions of the liver, capturing intra-organ variability.
- Cross-species benchmarking enables translational research by directly comparing liver mechanics in animal models and humans.
- Platform versatility supports testing of diverse soft tissues and biomaterials under identical conditions, useful for applications such as liver scaffolds or regenerative therapies.
- Engineered tissue applications benefit from non-destructive, repeated measurements that capture the dynamic development of bioengineered liver constructs.
- Controlled incubation and repeated testing make it possible to monitor changes in viscoelastic properties over time, whether due to disease progression, pharmacological treatment, or environmental factors.
Collectively, these features establish the ElastoSens™ Bio as a versatile instrument for hepatology research, biomaterials development, and translational applications.
References
Ahookhosh, K., Vanoirbeek, J., & Vande Velde, G. (2023). Lung function measurements in preclinical research: What has been done and where is it headed?. Frontiers in Physiology, 14, 1130096.
Neelakantan, S., Xin, Y., Gaver, D. P., Cereda, M., Rizi, R., Smith, B. J., & Avazmohammadi, R. (2022). Computational lung modelling in respiratory medicine. Journal of The Royal Society Interface, 19(191), 20220062.
Chintada, B. R., Rau, R., & Goksel, O. (2020). Nonlinear characterization of tissue viscoelasticity with acoustoelastic attenuation of shear-waves. Ultrasound in Medicine & Biology, 46(6), 1415–1427.
Kruse, S. A., Smith, J. A., Lawrence, A. J., Dresner, M. A., Manduca, A., Greenleaf, J. F., & Ehman, R. L. (2000). Tissue characterization using magnetic resonance elastography: preliminary results. Physics in Medicine and Biology, 45(6), 1579–1590.
Resapu, R. R., & Bradshaw, R. D. (2021). Application of micro-computer tomography and inverse finite element analysis for characterizing the visco-hyperelastic response of bulk liver tissue using indentation. SN Applied Sciences, 3, 574.
Discover how our technology non-destructively measures the viscoelastic properties of soft biomaterials and tissues using micro-volumes of samples
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