Abstract
A microfluidic system provides an excellent platform for cellular studies. Most importantly, a three-dimensional (3D) cell culture model reconstructs more accurately the in vivo microenvironment of tissue. Accordingly, microfluidic 3D cell culture devices could be ideal candidates for in vitro cell culture platforms. In this paper, two types of 3D cellular aggregates, i.e., toroid and spheroid, are numerically studied. The studies are carried out for microfluidic systems containing U-shaped barrier as well as microwell structure. For the first time, we obtain oxygen and glucose concentration distributions inside a toroid aggregate as well as the shear stress on its surface and compare its performance with a spheroid aggregate of the same volume. In particular, we obtain the oxygen concentration distributions in three areas, namely, oxygen-permeable layer, multicellular aggregates and culture medium. Further, glucose concentration distributions in two regions of multicellular aggregates and culture medium are investigated. The results show that the levels of oxygen and glucose in the system containing U-shaped barriers are far more than those in the system containing microwells. Therefore, to achieve high levels of oxygen and nutrients, a system with U-shaped barriers is more suited than the conventional traps, but the choice between toroid and spheroid depends on their volume and orientation. The results indicate that higher oxygen and glucose concentrations can be achieved in spheroid with a small volume as well as in horizontal toroid with a large volume. The vertical toroid has the highest levels of oxygen and glucose concentration while the surface shear stress on its surface is also maximum. These findings can be used as guidelines for designing an optimum 3D microfluidic bioreactor based on the desired levels of oxygen, glucose and shear stress distributions.
Highlights
Three-dimensional (3D) multicellular aggregates with the capability to mimic cell-cell and cell-matrix interactions can bridge the gap between two-dimensional (2D) monolayer cultures and animal models
A spheroid with equal volume to the toroid is used for the comparison
The simulations are done to find the effect of trap shapes on the oxygen and glucose concentration distributions
Summary
Three-dimensional (3D) multicellular aggregates with the capability to mimic cell-cell and cell-matrix interactions can bridge the gap between two-dimensional (2D) monolayer cultures and animal models. The use of a microfluidic system [3,4,5,6,7] to culture 3D multicellular aggregates presents a precise and suitable model for cellular studies [8]. Oxygen and glucose concentration distributions inside toroid and spheroid are investigated numerically. We compared the performance of two commonly used microfluidic platforms to trap and culture 3D multicellular aggregates, namely, a microfluidic device with a U-shaped barrier [24,25,26] and the one with microwell structures [27,28,29] by solving continuity, momentum and convection-diffusion equations. The concentration distributions of oxygen and glucose under various conditions are examined and compared In these simulations, the wall permeability, the concentration jump between the regions and the non-linear reaction inside the aggregates are considered
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