MS06 - CDEV-2
Interfaith Prayer and Reflection Room (#3020C) in The Ohio Union

Recent Studies on the Biomechanics and Fluid Dynamics of Living Systems: Cellular Biomechanics and Microfluidics

Thursday, July 20 at 10:30am

SMB2023 SMB2023 Follow Thursday during the "MS06" time block.
Room assignment: Interfaith Prayer and Reflection Room (#3020C) in The Ohio Union.
Note: this minisymposia has multiple sessions. The other session is MS07-CDEV-2 (click here).

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Wanda Strychalski, Alexander Hoover


From the blebbing of cells to the undulations of fish, biomechanical and biofluidic systems are ubiquitous in nature. Many of these systems involve interplay of multiple physics, such as the structures’ elasticity, the fluid dynamics of differing length scales, and neural activity. Other times, these processes can include chemical signaling, rheological properties of biomaterials, as well as osmotic and the biochemical processes that drive their motion. In this minisymposium, we focus on modeling the biological processes that undergird these biofluidic and biomechanical systems, with methods that range from computational simulation to asymptotic analysis. Talks in this session focus on the modeling and simulation of microscale phenomena, such as cell migration, bone cell signaling, fiber dynamics, and embryogenesis. This minisymposium aims to bring together these communities to discuss recent advances in modeling, analysis, and computational simulation for investigating the interplay of biological processes with fluid mechanics. This is the companion minisymposium of 'Recent Studies on the Biomechanics and Fluid Dynamics of Living Systems: Locomotion and Fluid Transport'.

Wanda Strychalski

Case Western Reserve University (Mathematics, Applied Mathematics, and Statistics)
"Quantifying the role of fluid mechanics during confined cell migration"
Cell migration is critical for many vital processes, such as embryogenesis and tissue repair, as well as harmful processes, such as cancer cell metastasis. In experiments, cells have been shown to exhibit different migration strategies based on the properties of their external environment. Here, we leverage modeling and computational tools to reveal the step-by-step cycle of locomotion for cells in confined environments that use blebs as leading-edge protrusions. We present two models of a blebbing cell migrating in a confined microchannel to quantify the role of hydrodynamics on confined cell migration. One model consist of a cell modeled by an elastic membrane, poro-(visco)elastic cortex, membrane-cortex adhesion, and the fluid cytoplasm. The fluid-free model consists of a force balance that includes the cell membrane, cortex, membrane-cortex adhesion, and viscous drag with outside environment. The channel walls are modeled as rigid structures. The fluid model is formulated using the method of regularized Stokeslets. Results show that cells can effectively migrate only if the cortical turnover is included by modeling the cortex as a poro-viscoelastic structure. We also show that blebbing generates a favorable intracellular pressure gradient that aids migration in the fluid model.
Additional authors: Calina Copos, Departments of Biology and Mathematics, Northeastern University

Jared Barber

Indiana University-Purdue University Indianapolis (Mathematical Sciences)
"A 2D model to assess stresses on flexible osteocytes and the influence of elastic properties"
Osteocyte are cells residing deep in bone that are widely believed to play a key role in regulating bone growth by sensing and responding to forces as we use our bodies daily. Despite several experimental and theoretical studies providing strong support for this paradigm, there are still several uncertainties surrounding the process by which the cells turn those forces into usable biochemical signals. For instance, studies suggest that to initiate any appreciable response from osteocytes, the average stresses we typically experience on a macroscale level must multiplied at least tenfold as they make their way towards the microscale level. In addition, there are several parts of the osteocyte that have been theorized to play a role in the mechanotransduction process. To help understand how forces may be magnified in and near the osteocyte region and which parts of the cell are more likely to be the location of subcellular mechanosensors, we have produced a two-dimensional model of a flexible osteocyte. The cell is represented by a network of interconnected viscoelastic elements (damped springs) immersed in interstitial flow that is, in turn, encased in rigid bone matrix material. We utilize a lattice-Boltzmann method combined with the immersed boundary method to produce simulations that allow us to explore the force distributions experienced by such cells. We share our results including pictures of where forces seem to centralize in such systems as well as how the elastic properties of different parts of the cell affect force localization in both steady state and oscillatory regimes.
Additional authors: Isaac Manring, Indiana University-Purdue University Indianapolis; Luoding Zhu, Indiana University-Purdue University Indianapolis

Thomas Fai

Brandeis University (Mathematics)
"Lubricated Immersed Boundary Method with Application to Fiber Bundles"
Fluid-mediated near contact of elastic structures is a recurring theme in biofluids. The thin fluid layers that arise in applications such as the flow of red blood through blood vessels are difficult to resolve by standard computational fluid dynamics methods based on uniform fluid grids. A key assumption of the lubricated immersed boundary method, which incorporates a subgrid model to resolve thin fluid layers between immersed boundaries, is that the average velocity of nearby boundaries can be accurately computed from under-resolved simulations to bridge between different spatial scales. Here, we present a one-dimensional numerical analysis to assess this assumption and quantify the performance of the average velocity as a multiscale quantity. We explain how this analysis leads to more accurate formulations of the method and present examples from two-dimensional simulations, including applications to filament bundles.

Luoding Zhu

Indiana University - Purdue Univiersity Indianapolis (Mathematics)
"Computational modeling of stress/strain amplification of an osteocyte process interacting with a viscous flow in a 3D canaliculus"
Computational modeling of stress/strain amplification of an osteocyte process interacting with a viscous flow in a 3D canaliculus Jared Barber (1), Maxim Mukhin (2), Vanessa Maybruck (3), Luoding Zhu (4) 1. Indiana University – Purdue University Indianapolis, USA; 2. Vanderbilt University, USA; 3. University of Colorado Boulder, USA; 4. Indiana University – Purdue University Indianapolis, USA. Osteocytes are bone cells stationed in fluid-filled cavities (lacunae) within hard bone matrix. Each osteocyte is equipped with numerous finger-like structures (processes) radiating outwards through cylindrical openings (canaliculi). Osteocytes are responsible for mechanosensation in the body; however, the tissue level stress and strain needs to be amplified at least 10 times in order for osteocytes to respond on the cellular level. The mechanism for such magnification is not yet fully understood. Previous studies suggest that the processes are primary sites for mechanosensation thanks to the existence of tethering elements attaching the process membrane to the canalicular wall. However, other studies suggest that potential contributing factors may also include the canalicular wall geometry and pericellular matrix. In our work, computational modelling, based on the lattice Boltzmann immersed boundary framework, is designed and used to assess possible effects of canalicular wall roughness in stress/strain amplification and the underlying mechanism. Our results indicate that canalicular wall roughness contributes substantially to stress and strain amplification and the underlying reason is the increased resistance to flow induced by wall roughness. Acknowledgements This work was supported by grants DMS-1951531 and DMS-1852146 from NSF USA and SoS Near-Miss Grant from IUPUI.
Additional authors: Jared Barber, Indiana University – Purdue University Indianapolis, USA; Maxim Mukhin, Vanderbilt University, USA; Vanessa Maybruck, University of Colorado Boulder, USA; Luoding Zhu, Indiana University – Purdue University Indianapolis, USA.

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Annual Meeting for the Society for Mathematical Biology, 2023.