The realistic prediction of oxygen transport in a tissue-engineered scaffold by introducing time-varying effective diffusion coefficients.

ABSTRACT

An adequate oxygen supply is one of the most important factors needed in order to regenerate or engineer thick tissues or complex organs. To devise a method for maximizing the amount of oxygen available to cells, it is necessary to understand and to realistically predict oxygen transport within an engineered tissue. In this study, we focused on the fact that oxygen transport through a tissue-engineered scaffold may vary with time as cells proliferate. To confirm this viewpoint, effective oxygen diffusion coefficients (D(e)(,)(s)) of scaffolds were deduced from experimental measurements and simulations of oxygen-concentration profiles were performed using these D(e)(,)(s) values in a two-dimensional (2-D) perfusion model. The results of this study indicate that higher porosity, hydraulic permeability and interconnectivity of scaffolds with no cells are responsible for the prominent diffusion capability quantified using D(e)(,)(s). On the other hand, the D(e)(,)(s) of scaffolds with cells has a negative linear relationship with cell density. Cell proliferation with time leads to a significant decrease in oxygen concentration in the 2-D perfusion model. This result demonstrates the gradual restriction of oxygen transport in a porous scaffold during cell culture. Therefore, the realistic prediction of oxygen transport using a time-varying D(e)(,)(s) will provide an appropriate basis for designing optimal transport networks within a thick scaffold.