INFLUENCING HOLLOW-FIBER BIOREACTOR HYDRODYNAMICS THROUGH OSMOTIC PRESSURES - A MODEL STUDY

Experiments have shown that secondary fluid hows within the extra-capi llary space (ECS) of hollow fiber bioreactors (HFBRs) can lead to the downstream polarization of cells and growth factors and subsequent red uctions in reactor productivity. Recent model studies and experimental investigations of this system have demonstrated further that the pola rization of ECS solutes can be reduced through increased loading of bo vine serum albumin within the ECS, which leads to a concomitant reduct ion in solute convection via osmotic pressure effects. The following s tudy extends previous models of HFBR hydrodynamics to include the effe ct of multiple solute species on the transient distribution of ECS sol utes. The model is then used to study the relative effectiveness of de xtran 500, dextran 70, hydroxyethylstarch 120, and bovine serum albumi n, as well as periodic switching of the fiber lumen flow direction, in eliminating solute polarization. The high molecular weight additives are found to be more effective than flow switching in reducing polariz ation, particularly when the membranes display permeabilities characte ristic of some polysulfone fibers (i.e. 6 x 10(-13) m).