AN INVESTIGATION OF CELL-DENSITY EFFECTS ON HYBRIDOMA METABOLISM IN AHOMOGENEOUS PERFUSION REACTOR

In this work, metabolite and antibody production kinetics of hybridoma cultures were investigated as a function of cell density and growth r ate in a homogeneous perfusion reactor. Hydrophilized hollow fiber pol ypropylene membranes with a pore size of 0.2 mum were used for medium perfusion. Oxygen was supplied to the cells through thin walled silico ne tubing. The mouse-mouse hybridoma cells were grown in three identic al bioreactors at perfusion rates of 1.1, 2.0, and 3.2/day for a perio d of eight days during which the viable cell concentrations reached st able values of 2.6 x 10(6), 3.5 x 10(6), and 5.2 x 10(6) cells/ml, res pectively. Total cell densities reached values ranging from 8 x 10(6) to 1 x 10(7) cells/ml. Specific substrate consumption and product form ation rates responded differently to changes in cell density and appar ent specific growth rate, which were not varied independently. Using m ultiple regression analysis, the specific glucose consumption rate was found to vary with viable cell density while the specific glutamine u ptake and lactate production rates varied with both viable cell densit y and apparent specific growth rate. These results suggest that cell d ensity dictates the rate of glucose consumption while the cell growth rate influences how glucose is metabolized, i.e., through glycolysis o r the TCA cycle. The specific antibody production rate was found to be a strong function of cell density, increasing as cell density increas ed, but was essentially independent of the specific growth rate for th e cell line under study.