Using Direct Analysis of Bioreactor Harvest for Clone Selection and Process Optimization
Therapeutic monoclonal antibodies (MAbs) mostly are manufactured using bioengineered mammalian cells cultured in a bioreactor for two to three weeks. High temperatures and an altered redox environment may compromise the quality of MAbs produced (e.g., fragmentation, truncation), as can the presence of proteases, reductases, and other chemicals released from dead cells. Thus, it would be valuable to establish analytical methods that can help cell culture groups monitor immunoglobulin G (IgG) product integrity in real time during a bioreactor run, especially during cell-line development and process scale-up.
In the early years of bioprocessing, product IgG titers usually were low, and animal serum often was included in culture media. That made direct analysis of IgG quality impractical. In the past 10–20 years, however, use of the animal-free culture media and higher titers of manufactured IgG products from Chinese hamster ovary (CHO) cells have made direct IgG analysis in harvest possible without significant matrix interference from host cell proteins or culture medium (1, 2).
Direct analysis of harvest is a valuable tool for clone selection and bioreactor optimization without requiring IgG purification. This approach will save time from sample preparation. And it will provide a full spectrum of IgG fragmentation or aggregation information without a change in product profile (e.g., loss of fragmented IgG) caused by purification steps. Here, we present how we applied capillary sodium-dodecyl sulfate (cSDS) electrophoresis, surface-plasmon resonance (SPR), and size-exclusion high-performance liquid chromatography (SE-HPLC) to monitor the quality of IgG produced during clone selection and bioreactor optimization.
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