Biology subjects

Urcun, S.

Publications and source records attributed to Urcun, S..

3 recordsLinked to original sources

bioRxiv2024

Mechanics of knee meniscus results from precise balance between material microstructure and synovial fluid viscosity

The meniscus plays a crucial role in the biomechanics of the knee, serving as load transmitter, and reducing friction between joints. Understanding the biome-chanics of the meniscus is essential to effective treatments of knee injuries and degenerative conditions. In this study, we used two central meniscus samples extracted from a human knee and acquired high-resolution {micro}-CT images. Using an implicit immersed boundary technique, we reconstructed two 3D computational models of the menisci. By eroding the channels of the original meniscus geometry, we created new microstructures with varying porosities (0.53 to 0.8) whilst preserving the connectivity of the porous structure. We investigate the fluid dynamics of the meniscus using a mesh-free numerical method, considering various inlet pressure conditions and analysing the fluid flow within the microstructures. The results of the original microstructure associated with a physiological dynamic viscosity of synovial fluid are in accordance with biophysical experiments on menisci. Furthermore, the eroded microstructure with a 33% increase in porosity exhibited a remarkable 120% increase in flow velocity. This emphasises the sensitivity of meniscus physiology to porous microstructure properties, showing that detailed computational models can explore physiological and pathological conditions, advancing further knee biomechanics research.

bioengineering↗

bioRxiv2023

Non-operable glioblastoma: proposition of patient-specific forecasting by image-informed poromechanical model

We propose a novel image-informed glioblastoma mathematical model within a reactive multiphase poromechanical framework. Poromechanics offers to model in a coupled manner the interplay between tissue deformation and pressure-driven fluid flows, these phenomena existing simultaneously in cancer disease. The model also relies on two mechano-biological hypotheses responsible for the heterogeneity of the GBM: hypoxia signaling cascade and interaction between extra-cellular matrix and tumor cells. The model belongs to the category of patient-specific image-informed models as it is initialized, calibrated and evaluated by the means of patient imaging data. The model is calibrated with patient data after 6 cycles of concomitant radiotherapy chemotherapy and shows good agreement with treatment response 3 months after chemotherapy maintenance. Sensitivity of the solution to parameters and to boundary conditions is provided. As this work is only a first step of the inclusion of poromechanical framework in image-informed glioblastoma mathematical models, leads of improvement are provided in the conclusion.

biophysics↗

bioRxiv2020

Quantifying the role of mechanics in the free and encapsulated growth of cancer spheroids

Spheroids encapsulated within alginate capsules are emerging as suitable in vitro tools to investigate the impact of mechanical forces on tumor growth since the internal tumor pressure can be retrieved from the deformation of the capsule. Here we focus on the particular case of Cellular Capsule Technology (CCT). We show in this contribution that a modeling approach accounting for the triphasic nature of the spheroid (extracellular matrix, tumor cells and interstitial fluid) offers a new perspective of analysis revealing that the pressure retrieved experimentally cannot be interpreted as a direct picture of the pressure sustained by the tumor cells and, as such, cannot therefore be used to quantify the critical pressure which induces stress-induced phenotype switch in tumor cells. The proposed multiphase reactive poro-mechanical model was cross-validated. Parameter sensitivity analyses on the digital twin revealed that the main parameters determining the encapsulated growth configuration are different from those driving growth in free condition, confirming that radically different phenomena are at play. Results reported in this contribution support the idea that multiphase reactive poro-mechanics is an exceptional theoretical framework to attain an in-depth understanding of CCT experiments, to confirm their hypotheses and to further improve their design.

biophysics↗