Employing Nanostructured Scaffolds to Investigate the Mechanical Properties of Adult Mammalian Retinae Under Tension

Abstract

Numerous eye diseases are linked to biomechanical dysfunction of the retina. However, the underlying forces are almost impossible to quantify experimentally. Here, we show how biomechanical properties of adult neuronal tissues such as porcine retinae can be investigated under tension in a home-built tissue stretcher composed of nanostructured TiO2 scaffolds coupled to a self-designed force sensor. The employed TiO2 nanotube scaffolds allow for organotypic long-term preservation of adult tissues ex vivo and support strong tissue adhesion without the application of glues, a prerequisite for tissue investigations under tension. In combination with finite element calculations we found that the deformation behavior is highly dependent on the displacement rate which results in Young’s moduli of (760–1270) Pa. Image analysis revealed that the elastic regime is characterized by a reversible shear deformation of retinal layers. For larger deformations, tissue destruction and sliding of retinal layers occurred with an equilibration between slip and stick at the interface of ruptured layers, resulting in a constant force during stretching. Since our study demonstrates how porcine eyes collected from slaughterhouses can be employed for ex vivo experiments, our study also offers new perspectives to investigate tissue biomechanics without excessive animal experiments.

Mechanical properties of the premature lung: From tissue deformation under load to mechanosensitivity of alveolar cells

“…Such effects are attributed to the given time scales of internal relaxation processes (viz. ergodic contributions due to thermal relaxation or non-ergodic effects occurring during local bond rupture) Frontiers in Bioengineering and Biotechnology frontiersin.org which are affected by the time scales of the external deformation (Juncheed et al, 2020). Moreover, we observed strain stiffening of fetal lung tissue during compression, as well as tension.…”

“…We would like to point out that a change of fluid motion within the poroelastic network of the lung might also contribute to the observed deformation speed dependency. Since we already observed a strong deformation rate dependency for other densely packed tissues such as the retina under uniaxial deformation (Juncheed et al, 2020), we expect that the contribution of porosity to the rate-dependency is small and viscoelasticity is the key. Nevertheless, poroelasticity calculations (Berger et al, 2016(Berger et al, , 2017Concha and Hurtado, 2020) might be an interesting tool to distinguish between the contributions of the porous network structure of the lung including fluid flux and the material properties such as ECM network-cell interaction to the entire lung mechanical response.…”

“…Here, even in the elastic deformation regime for small strains, local rupture events such as bond breaking and irreversible molecular reorganizations and friction between tissue component can result in non-affine, viz. plastic deformation at the microscale (Juncheed et al, 2020;Zapp et al, 2020). We would like to point out that a change of fluid motion within the poroelastic network of the lung might also contribute to the observed deformation speed dependency.…”

“…In contrast, during compression, even for small strains in the elastic regime, viscoelastic properties characterized by a high deformation-rate dependency become prominent, indicating possible non-affine, viz. irreversible events such as rupture on molecular level (Juncheed et al, 2020;Zapp et al, 2020).…”

On the Role of the Water Hammer Pressure in the Modeling of Hydrodynamics of the Human Eye: A Qualitative Analysis and its Consequences for Physical Training and Healthy Lifestyle

“…And it should be emphasized that retina, being the representative of the "soft matter bio-tissue" demonstrates the pronounced viscoelastic properties as demonstrated in ref. 40. Both of these effects enable to decrease the harmful effects of the water hammer pressure, as discussed in ref.…”