Application Note | ElastoSens™ Bio
Measuring mechanical properties of kidney tissue using ElastoSens™ Bio
Introduction
The kidney’s ability to filter blood and regulate fluid balance depends not only on its biochemical activity but also on its mechanical behavior. Properties such as elasticity, stiffness, and viscoelasticity reflect the composition and structure of the renal parenchyma as well as its perfusion. When these properties are altered, they can signal changes in tissue integrity, fibrosis, or vascular function. By studying them, scientists and clinicians can better understand how a healthy kidney functions, detect early signs of disease, and design therapies that restore or preserve performance.
Key mechanical properties of the kidney
Elasticity
Elasticity describes how the kidney tissue deforms when stress is applied and then returns to its original shape. In both clinical and experimental settings, ultrasound-based elastography and direct mechanical testing have been used to quantify renal elasticity. These measurements are closely linked to the structural organization of the cortex and medulla, as well as the presence of perfusion.
Stiffness
Stiffness, often derived from elasticity measurements, reflects the resistance of kidney tissue to deformation. It can vary between different compartments of the kidney and is influenced by blood flow and microstructural composition. As stiffness increases or decreases, it can provide important insight into underlying functional or pathological states.
Viscoelasticity
The kidney exhibits viscoelastic behavior, meaning it combines both elastic and time-dependent viscous responses under loading. Laboratory tests on porcine kidneys demonstrate how tissue stress and strain evolve over time, highlighting the role of viscoelasticity in kidney biomechanics. This property is essential for understanding how renal tissue adapts to changing pressures and fluid dynamics.
Anisotropy
Renal tissue is not mechanically uniform in all directions. Its anisotropy stems from the radial alignment of nephrons and blood vessels, which makes stiffness and elasticity vary depending on the measurement angle. Recognizing this directional dependence is important for both accurate elastography assessments and biomechanical modeling.
Relationship between diseases and mechanical properties of kidney tissue
Chronic Kidney Disease (CKD)
CKD often involves interstitial fibrosis and tubular atrophy, which alter the mechanical environment of the kidney. These structural changes typically modify stiffness and elasticity, making elastography a potential tool for assessing disease progression and severity.
Diabetic Kidney Disease
In diabetes, changes in glomeruli and tubules can impact renal mechanical properties. Altered stiffness values have been observed in patients with diabetic nephropathy, reflecting the combined effects of fibrosis, hypertrophy, and perfusion changes.
Kidney Transplant Rejection
In transplanted kidneys, mechanical measurements can provide early insights into graft health. Variations in stiffness detected by elastography have been associated with scarring, inflammation, and vascular complications, offering a non-invasive complement to biopsy.
How kidney tissue mechanics are assessed
In Vivo techniques (Clinics)
In clinical settings, the mechanical properties of the kidney are most often assessed using ultrasound-based elastography. This non-invasive imaging method applies focused ultrasound pulses to generate shear waves in the tissue, then measures their speed to estimate stiffness. It provides real-time information about renal health and is increasingly used for both native and transplanted kidneys.
Ex Vivo techniques (Research)
In research, kidney mechanics are typically studied with direct mechanical testing systems such as uniaxial tension, compression, and relaxation setups. These instruments allow precise measurement of viscoelastic behavior under controlled loading conditions, helping scientists build biomechanical models and better understand tissue response. Ex-vivo elastography can also be applied to study how perfusion or structure affect elasticity.
Case study: Kidney tissue mechanical characterization with ElastoSens™ Bio
ElastoSens™ Bio: a contactless tool for Ex Vivo tissue testing
In the field of kidney biomechanics, the ElastoSens™ Bio offers a novel solution for ex vivo testing. This instrument enables continuous, non-destructive measurement of viscoelastic properties, ensuring that kidney samples remain intact throughout the experiment. Its technology provides accurate characterization of soft tissue behavior and allows repeated monitoring under controlled conditions, delivering insights that go beyond conventional mechanical assays.
To demonstrate the potential of the ElastoSens™ Bio, we performed an ex vivo study on kidney tissue samples. The following section outlines the materials and methods of this experiment, followed by the results, illustrating the instrument’s practical application.
Material and methods
Kidneys from pork and sheep were sourced from a local farm. Using a biopsy-like punch, tissue pieces with a roughly cylindrical geometry (23 mm internal diameter, variable height) were prepared. Each specimen was mounted in the macro holder of the ElastoSens™ Bio instrument and tested for one minute at room temperature.
During testing, the instrument continuously recorded viscoelastic properties, including the shear storage modulus (G′) and damping ratio (Tan𝛿). For each condition, mean values were calculated from five independent specimens, each taken from the same anatomical region of five separate kidneys (n=5).
Figure 1. Kidney tissue sample.
Results and discussion
Using the ElastoSens™ Bio non-destructive testing system, Figure 2 shows that pig kidney tissue exhibited a higher shear storage modulus (G′ = 2.4 ± 0.37 kPa) compared to sheep (2.1 ± 0.33 kPa), indicating slightly greater stiffness and elastic energy storage. The damping ratio values were similar between species (Tanδ ≈ 0.4), suggesting comparable dissipation. Overall, pig kidney tissue displayed marginally higher stiffness, while both species showed similar viscoelastic balance.
Our kidney results fall within the 2–5.1 kPa range reported in rheometry and elastography studies of porcine kidney (Nicolle et al., 2010; Nasseri et al., 2002; Amador et al., 2009) . The close correspondence reinforces that ElastoSens™ Bio yields values consistent with literature, while avoiding destructive clamping or pre-compression artifacts. In sheep, Pirsoltan and Karafi (2025) reported shear storage moduli ranging from 1 to 48 kPa, measured using DMA and rheometry. The wide spread of values reflects differences introduced by sample preparation, mounting conditions, and pre-load forces, which are known to influence the response of soft tissues. Overall, the ElastoSens™ Bio uses standardized holders and controlled hydration, allowing repeat testing on the same sample and reducing variability.
Figure 2: Viscoelastic properties of kidney 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, sheep n=4, pig n=5).
Conclusions and perspectives
The mechanical properties of kidney tissue—such as elasticity, stiffness, viscoelasticity, and anisotropy—are fundamental for understanding renal physiology and alterations caused by disease. This study shows that non-destructive viscoelastic testing with the ElastoSens™ Bio enables reliable evaluation of kidney tissue mechanics, providing key indicators including shear storage modulus (G′) and damping ratio (Tan𝛿). The method ensures accuracy and reproducibility, forming a robust basis for comparative investigations across species and experimental conditions.
In addition, the ElastoSens™ Bio offers distinctive benefits for kidney and biomaterials research:
- Simple preparation and setup minimize handling, preserving kidney tissue hydration and microstructural integrity.
- High sensitivity and repeatability allow consistent measurements across different renal regions (cortex, medulla, sinus), capturing intra-organ variability.
- Cross-species benchmarking enables translational research by directly comparing kidney mechanics in animal models and humans.
- Platform versatility supports testing of diverse soft tissues and biomaterials under identical conditions, valuable for developing renal implants, scaffolds, or protective devices.
- Engineered tissue applications benefit from non-destructive, repeated measurements that reflect the dynamic evolution of bioengineered kidney constructs.
- Controlled incubation and repeated testing make it possible to monitor changes in viscoelastic properties over time, whether due to perfusion changes, pharmacological interventions, or disease progression.
Together, these advantages highlight the ElastoSens™ Bio as a powerful tool for advancing renal tissue research, comparative physiology, and tissue engineering studies.
References
Zhang, Z., Tan, X., Li, M., M, W., Zeng, S., & Wu, Y. (2024). Evaluation of the mechanical properties of porcine kidney. Plos one, 19(7), e0307778.
Urban, M. W., Rule, A. D., Atwell, T. D., & Chen, S. (2021). Novel uses of ultrasound to assess kidney mechanical properties. Kidney360, 2(9), 1531-1539.
Liu, X., Li, N., Xu, T., Sun, F., Li, R., Gao, Q., … & Wen, C. (2017). Effect of renal perfusion and structural heterogeneity on shear wave elastography of the kidney: an in vivo and ex vivo study. BMC nephrology, 18(1), 265.
Nicolle, S., Vezin, P., & Palierne, J. F. (2010). A strain-hardening bi-power law for the nonlinear behaviour of biological soft tissues. Journal of Biomechanics, 43(5), 927–932.
Nasseri, S., Bilston, L. E., & Phan-Thien, N. (2002). Viscoelastic properties of pig kidney in shear, experimental results and modelling. Rheologica Acta, 41(1–2), 180–192.
Amador, C., Urban, M. W., Warner, L. V., & Greenleaf, J. F. (2009). In vitro renal cortex elasticity and viscosity measurements with shearwave dispersion ultrasound vibrometry (SDUV) on swine kidney. Proceedings of the IEEE Engineering in Medicine and Biology Society, 4428–4431.
Pirsoltan, F. A., & Karafi, M. R. (2025). Investigation of the mechanical frequency response of ovine renal tissue at low frequencies. Scientific Reports, 15, 16467.
Discover how our technology non-destructively measures the viscoelastic properties of soft biomaterials and tissues using micro-volumes of samples
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