Mathematical modelling of immobilized animal cell growth

A two-dimensional mathematical model for animal cell growth was employed to study the suspension, as well as stationary, culture of micro-encapsulated and gel immobilized animal cells. For stationary microcapsules with low-viscosity intracapsular liquid, it was found that capsule radius, capsule loading and medium-change time have the most significant effects on the intracapsular cell density. The model was also adapted to simulate other scenarios of cell growth such as in gel beads and suspended microcapsules. The simulated time course of oxygen concentration and specific growth rate revealed a complicated interaction between material transport and cell growth kinetics. With the mass transfer coefficient for oxygen transfer (KLa') into the medium equal to 4.0 hr-1, for instance, it was found that the specific growth rate of the microencapsulated cells was controlled by the supply of glucose and oxygen. When the value of KLa' was reduced to 0.6 hr-1, however, oxygen supply appeared to be the sole factor affecting the specific growth rate. In the case of suspended gel beads, a simulation revealed a higher cell density towards the gel bead surface. The transport of nutrients and oxygen to the central region of the gel bead was apparently blocked by the surrounding cells.