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An investigation into the culturing of lactate re-utilising CHO cells

Paoli, T.Z.; (2011) An investigation into the culturing of lactate re-utilising CHO cells. Doctoral thesis, UCL (University College London).

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Abstract

Mammalian cell technology, whilst a mature platform for monoclonal antibody production, remains poorly understood from a metabolic perspective. The metabolic activity of two cell lines through three scales of a commercial scale-up train, each a 10-fold increase on the previous volume. In large scale mammalian cell culture the key toxic by-products assessed and monitored are lactate and ammonia. Often no distinction between the two isoforms of lactate is made. Profiles of both D- and L- lactate at multiple scales and under a range of controlled physiochemical conditions are presented. D-lactate unlike L-lactate is not commonly re-utilised, and although during normal culture time frames it represents one tenth of total lactate, during L-lactate consumption it represents nearly 35 %. The behaviour of D-lactate is different from that of L-lactate with the level of one isoform changing whilst the concentration of the other remains constant. The main route for the creation of D-lactate in culture is the methylglyoxal pathway. Methylglyoxal (MG) requires a lengthy purification process for analysis; however the close association between D-lactate and methylglyoxal concentrations alleviates the requirement for direct measurement of extracellular MG concentration. High concentrations of free MG observed in the medium (up to 63 μM), the levels of MG observed are higher than those reported to have a toxic effect (Roy 2005). The physiochemical impact on culture performance is investigated, with cultures conducted under varying environmental conditions. The impact of dissolved oxygen tension and temperature on metabolism is investigated, with the result that changing DOT has a quantifiable impact on culture metabolism. The approaches developed were undertaken so with the understanding of trends within industrial practice towards low volume, high throughput culture systems. The assay techniques utilised are capable of being applied to an automated micro-scale analysis method in order to maintain a high level of data density.

Type:Thesis (Doctoral)
Title:An investigation into the culturing of lactate re-utilising CHO cells
Language:English
Additional information:Permission for digitisation not received
UCL classification:UCL > School of BEAMS > Faculty of Engineering Science > Biochemical Engineering

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