Simulation of cell growth and diffusion in tissue engineering scaffolds

With the development in recent years, tissue engineering is becoming one of the therapeutic strategies that have the potential for repairing the damaged or malfunctioned human tissues. The proposed scheme of tissue engineering generally contains seeding cells onto a porous scaffold. The cell-scaffold construct is then cultured in vitro for a period of time and transplanted into the patient afterward. Because the biochemical materials are expensive and the experimental procedures are time-consuming, it is valuable to have a simulation model that can assess the cultivation conditions beforehand. We develop a continuum mathematical model for the simulation of cell growth and migration in porous scaffolds based on the basic principle of mass conservation for both cells and nutrients. In addition to cell growth kinetics, we incorporate cell diffusion term to treat the macroscopic effect of cell random walks on cell distributions. The model is validated by comparison with experimental data available in literature. The simulation model is applied to investigate cell growth and distribution under uniform and various concentrated seeding circumstances. Results show that the overall cell growth rate in a scaffold is affected both by the extent of the cell diffusion surface and the amount of the nutrient supply. Uniform seeding finishes the first growth rate out of the seeding cases considered, because uniformly seeded cells can diffuse evenly in all directions, preventing nutrients uptake only from some over crowded, local areas. For the concentrated seeding cases, the larger the cell diffusion surface the faster the cells can grow. Moreover, cells grow faster when seeded close to the scaffold periphery because cells can obtain more nutrient supplies in such cases. The model provides an efficient way of assessing cell-scaffold developments in vitro for tissue engineering applications.