CHANGES IN ANIMAL-CELL NATURAL AGGREGATES IN SUSPENDED BATCH CULTURES

Some anchorage-dependent animal cells can form natural aggregates in s tirred tanks. Baby hamster kidney (BHK) natural aggregates are describ ed and characterized. Total cell concentration and viability could be obtained after aggregate mechanical dissociation, with negligible cell lysis and no change in cell membrane permeability. During a normal ba tch run, aggregates were formed immediately after inoculation, a few s pherical aggregates increasing in size during the initial growth phase . At the end of the growth phase, an increase in aggregate concentrati on was observed, without a considerable increase in aggregate diameter . At the end of the batch run, 160 h after inoculation, aggregates dis integrated into smaller, non-spherical units, following, a sharp viabi lity decrease. Cell concentrations of 1.2.10(6) cells/ml were obtained , with 60% of the total cells being in aggregates; the cell concentrat ion in aggregates achieved 5.10(8) cells/ml, with a porosity of 55%. V iability was consistently in the range 85-90%, both for aggregate and suspended cells.