RESUMEN
Recently we have demonstrated batch suspension culture of mammalian cells in microwell plates. Here we describe a method for fed-batch culture of an industrially relevant GS-CHO (Glutamine Synthetase-Chinese Hamster Ovary) cell line in shaken 24-standard round well (24-SRW) plates. Use of a commercially available 'sandwich lid' and appropriate dilution of the bolus feeds counteracted liquid evaporation from the wells resulting in similar cell growth and antibody formation kinetics in both 24-SRW plates (800 mul) and shaken flasks (50 ml). Peak viable cell densities obtained were 8 +/- 0.5 x 10(6) and 9 +/- 1.3 x 10(6) ml(-1), respectively, while comparable final titres of a whole IgG of approximately 1.5 g l(-1) were recorded. Use of microwells provides at least a 50-fold reduction in medium requirements compared to shake-flask and other culture devices currently used in early stage cell culture process development. The ability to run multiple wells in parallel and to automate culture operation also offers considerable enhancements in experimental throughput.