The production of small quantities of monoclonal antibodies and recombinant proteins was carried out using a new low cost production system, the Super Spinner. Into a 1 1 standard Duran | flask a membrane stirrer equipped with a polypropylene hollow fiber membrane was installed to improve the oxygen supply by bubble-free aeration. The aeration was facilitated by using the CO 2 conditioned incubator gas, which was pumped through the membrane stirrer via a small membrane pump. The maximal oxygen transfer rate (OTRmax) of the Super Spinner was detected. For this purpose one spinner flask was equipped with an oxygen electrode. The OTRma ~ was measured by the dynamic method. The ratio of membrane length to culture volume was adapted corresponding to the oxygen uptake rate of the cells according to the desired cell density. A balanced nutrient supply resulted in an optimal formation and yield of products.
Based on experiments in bench scale, a recycling of spent cell culture medium was performed in a 100-1 pilot scale bioreactor. The cell cultivation has been done as a repeated batch procedure after the initial batch in the following four repeated batches spent medium from the previous batch was partially re-used. After microfiltration and ultrafiltration a part of the filtrate was mixed v, ith a concentrate of amino acids and glucose, sterile filtered and subsequently filled back into the bioreactor. Lip to 65%. of the harvested cell-and product-free spent medium was re-used in each repeated batch. This procedure results in a saving of pure and waste ~ater volume and sa~ing of supplemented proteins as transferrin, insulin and lipoproteins and, therefore, also in a reduction of the production costs.A strongl} acidic membrane ion exchanger v, as evaluated for the ability to purifs, the monoclonal antibodies from the pilot scale cultivation. Within minutes, gram quantities of product could be purified in a high flux system, especially developed for this purpose, achieving purities of 80%. The capacit3 of the acidic membrane ion exchanger was found in former investigations to be 1 mg cm -" with recoveries up to 96%. Final purification was carried out by gel column filtration.
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