A cell bank represents homogeneously frozen cells in the form of aliquots, which are used as starting material for the production of recombinant therapeutic agents (proteins) in the biopharmaceutical industry. It is therefore important that the cell bank production process is optimised, robust and reproducible and that the cells are in an exponential growth phase at all times. Freezing is a critical step in the production of cell banks, as the cells undergo temperature, oxidative and osmotic shock during this process, which can cause physiological and mechanical changes. This can have a negative effect on their growth and consequently on their ability to produce recombinant therapeutic agents. In order to improve cell growth and viability, four different antioxidants were used in a model of a deliberately attenuated cell bank with reduced cell viability and concentration. The effect of the type and concentration of the added antioxidant and the time point of the added antioxidant were tested. The optimal assay to test the effect of antioxidants on a weak bank is to add antioxidants at the time of inoculation into the posterior passage and to use a 15 min exposure to DMSO before freezing. We tested all this in the CHO-X cell line and then tested the preparation of the bad bank and the effect of the ascorbic acid concentration in the CHO-Y cell line. We found that the use of 5 mM ascorbic acid (A2) can have an effect on increasing the viability of the bad bank by 20-30% and the concentration (above 1.0 × 106 live cells/mL).
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