Diffusion in Brain Parenchyma: A Physical Model of Molecular Transport
Leonid Y. Polynkin1, Pavel A. Libet1, Nikita P. Kryuchkov1, Alla B. Salmina2,1, Pavel P.
Tregub2, Stanislav O. Yurchenko 1;
1 Bauman Moscow State Technical University, 2nd Baumanskaya Street 5, 105005 Moscow, Russia
2 Brain Science Institute, Research Center of Neurology, Volokolamskoe Highway 80, 125367, Moscow, Russia
Abstract
Molecular diffusion within the brain parenchyma is a fundamental process governing drug delivery, metabolic waste clearance, and the progression of neuropathologies such as cerebral edema. Despite its importance, realistic computational modeling of diffusive transport remains challenging due to the complex microstructural organization and dynamic changes in extracellular volume under pathological conditions. In this study, we develop a finite element-based numerical model to simulate the diffusion of low-molecular-weight solutes through a porous medium mimicking brain tissue. The model incorporates various cellular packing geometries—primitive cubic, body-centered cubic, face-centered cubic, hexagonal close-packed, and random arrangements—to systematically evaluate how microstructural organization and volume fraction affect transport properties. We demonstrate that concentration profiles exhibit significant spatial oscillations dependent on packing geometry and volume fraction, reflecting local variations in extracellular pathways. Furthermore, our analysis reveals that hexagonal close-packed and random configurations produce the most substantial reduction in effective diffusivity within the physiological range (φ ≈ 0.2–0.4), with nearly identical behavior, indicating that hexagonal packing can serve as an efficient computational alternative to resource-intensive random packing simulations. These results underscore the critical role of tissue microstructure in regulating diffusion and provide a mechanistic basis for predicting solute transport in both healthy and edematous brain tissue. The model offers a scalable framework for future studies aimed at optimizing therapeutic agent delivery and understanding edema dynamics through realistic in silico reconstructions of brain parenchyma.
Speaker
Leonid Y. Polynkin
Centre for Soft Matter and Physics of Fluids, Bauman Moscow State Technical University, 2nd Baumanskaya Street 5, 105005 Moscow, Russia
Russia
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