A better understanding of the complex interplay between cell population dynamics and mass transport is necessary for overcoming the barriers that have slowed down the development of bioartificial tissues.In a recent publication [1], we presented the development of a multi-scale computational model that describes the dynamic behavior of homogeneous cell populations growing under mass transfer limitations in three-dimensional scaffolds. The model has three components: a transient partial differential equation for the simultaneous diffusion and consumption of a limiting nutrient or growth factor; a cellular automaton describing cell migration, proliferation and collisions in a cubic lattice; and equations that quantify how the varying nutrient or growth factor concentration modulates cell division and migration. The hybrid (discrete-continuous) model was parallelized and solved on a distributed-memory multicomputer to study how transport limitations affect tissue regeneration rates under conditions encountered in typical bioreactors. Simulation results revealed that the severity of transport limitations can be estimated by the magnitude of two dimensionless groups: the Thiele modulus and the Biot number. The initial spatial distribution of seed cells, their migration speed and the hydrodynamics of the bioreactor also influenced the overall rate and the pattern of tissue growth.
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