Biology subjects

Braeuer, L.

Publications and source records attributed to Braeuer, L..

3 recordsLinked to original sources

bioRxiv2026

Tuning the mechanical properties of polymer-based surrogate materials for articular cartilage and vocal fold repair

The macroscopic biomechanical characteristics of soft and ultrasoft tissues, such as articular cartilage and vocal folds, significantly determine their physiological function. Treatments of widespread tissue degradations due to osteoarthritis in the knee or vocal fold impairment remain an unresolved challenge. For the design of implants for tissue repair after injury or disease, it is key to thoroughly understand the unique biomechanical properties of native tissues and potential substitute materials. We use multimodal mechanical testing methods combined with hyperelastic nonlinear continuum mechanics modeling, and finite element simulations to determine the macroscopic behavior of surrogate materials for human articular cartilage in the knee and human vocal folds. Our cyclic loading experiments reveal qualitative similarities for both tissues and their surrogates, including a nonlinear stress-strain behavior, hysteresis, and conditioning. We demonstrate the tunability of biomimetic and biosimilar stiffnesses of synthetic articular cartilage and vocal fold surrogates through tissue-specific process-material combinations. Our results demonstrate the feasibility of synthetic metamaterials in replicating essential passive biomechanical functions with great potential for future treatment options.

bioengineering↗

bioRxiv2026

The Mechanical Fingerprint of Hippocampal Sclerosis Linking Neuronal Cell Loss and Gliosis to Tissue Stiffness

Hippocampal sclerosis (HS) is the most common pathology in drug-resistant temporal lobe epilepsy (TLE). However, clinical diagnosis, prevalent epileptogenicity, and drug drug-resistance in individuals with HS remain an ongoing challenge demanding multidisciplinary research efforts. In this study, we examined the mechanical properties of neurosurgically en bloc resected HS specimens (n=8) ex vivo under compression, tension, and torsional shear. We fitted a two-term Ogden hyperelastic model to the measured mechanical responses to quantify nonlinear mechanical tissue properties. The resulting parameters revealed higher strain stiffening under compression in HS compared to hippocampus obtained post mortem (n=7). The distinction was most noticeable in the large-strain regime, which has important implications for using mechanical tissue properties as valuable diagnostic biomarker. Furthermore, we correlated the tissue microstructure with mechanical parameters. We trained a deep-learning histopathology classifier to detect and classify neurons and glial cells from hematoxylin-stained whole slide images (WSI). We identified a strong association between the small-strain stiffness (shear modulus {micro}) and the overall cell density as well as the glial cell density. The negative relationship between the neuron-to-glia ratio and shear modulus is consistent with the hypothesis that neuronal cell loss and gliosis drives tissue stiffening, respectively. Magnetic resonance imaging (MRI) analysis of the specimens confirmed the previously reported negative association between MRI-derived fractional anisotropy and shear modulus {micro}. Taken together, our study establishes a direct link between tissue mechanics and microstructure, suggesting nonlinear continuum mechanics models as promising new tools for clinical diagnosis and novel research strategies.

bioengineering↗

bioRxiv2026

Fractional Anisotropy as a Surrogate Marker of Brain Mechanics

Understanding the mechanical properties of brain tissue may provide crucial insights into brain development, injury, disease and surgical planning. Conventionally, these properties are measured ex vivo or in vivo during surgical procedures, while non-invasive in vivo alternatives are sparse. This study investigates whether fractional anisotropy (FA) derived from diffusion-weighted magnetic resonance imaging can serve as a surrogate marker for brain tissue stiffness in healthy human brains. MRI data were collected from three body donor brains, 28 healthy adults, and a publicly available independent dataset of 26 adults. FA values were compared with mechanical properties from ex vivo mechanical testing of brain tissue. Statistical analysis revealed a strong negative correlation between FA and the mechanical response for small strains expressed as shear modulus of a one-term hyperelastic Ogden model, indicating that higher FA values are associated with lower tissue stiffness. The nonlinearity parameter alpha exhibited a qualitatively similar, but considerably weaker correlation with FA. These findings were consistent across datasets. The findings suggest that FA can be a robust, non-invasive marker for estimating mechanical properties of brain tissue, with potential applications in clinical diagnosis and computational modeling of brain mechanics and the study of brain development. Further research is needed to clarify the relationship in lesional tissues and to optimize clinical utility.

neuroscience↗