(444h) Image-Based Mass Transport Simulation Shows How to Optimize Tissue Engineering Scaffold Architecture for Optimal Oxygen and Nutrient Transport

According to the U.S. Department of Health & Human Services, nearly
115,000 people in the U.S needed a lifesaving organ transplant in 2018, while
only ~10% of them have received it. Yet, almost no artificial products are
commercially available today – three decades after inception of tissue
engineering. One of the main obstacles plaguing all current artificial tissue
culture methods is the inability to distribute oxygen and nutrients throughout
organ-sized scaffolds. This leads to product size limitations. For that reason,
the study of mass transfer of in 3D tissue engineering scaffolds has gained a
lot of attention recently. However, due to the inability to visualize the
transport of these molecules within the scaffolds experimentally, image-based
simulation offers a viable alternative.

In this study, we investigate the transport of the oxygen and nutrient
molecules within two common scaffold types: salt leached and non-woven fiber
mesh (shown in the left pane of the figure below). Their structures are
obtained using high resolution computed tomography imaging. Using these
geometries, we simulate the exact micro-environment that the scaffolds
experience within flow perfusion bioreactors. Specifically, the cell culture
media flow field is first solved via Lattice Boltzmann Method (LBM), and then
interpolated by reactive Lagrangian Scalar Tracking (rLST) particles. The latter also experience Brownian
motion, which depends on the molecular weight of the simulated molecules.
Additionally, the rLST particles react upon colliding
with the scaffolds, with a probability that depends on the rates with which the
cultured cells consume them.

Our results showed that the oxygen and nutrient molecules
penetrate deeper into the scaffold with higher cell culture media flows and/or
lower surface area-to-volume ratios of the scaffold structure (see the right
pane of the figure above). Additionally, the nonwoven fiber-mesh scaffolds were
found to result in the lowest surface area-to-volume ratios, which translates
to a more efficient mass transfer in their pores. Furthermore, the generalized
results of this study may be applicable to many other similar scaffolds
cultured under flow perfusion. Finally, the computational methodology used in
this study could be applied to a wide variety of scaffold systems, independent
of structural and material properties. Therefore, it is expected that the
results of this work will be beneficial to future scaffold design and culturing
condition optimization studies.