Yuk Inn H, Russell Stephen, Tang Yun, Hsu Wei-Ting, Mauger Jacob B, Aulakh Rigzen P S, Luo Jun, Gawlitzek Martin, Joly John C
Early Stage Cell Culture, Bioprocess Development, Genentech, 1 DNA Way, South San Francisco, CA, 94080.
Biotechnol Prog. 2015 Jan-Feb;31(1):226-38. doi: 10.1002/btpr.2004. Epub 2014 Oct 24.
Recent reports highlight the impact of copper on lactate metabolism: CHO cell cultures with higher initial copper levels shift to net lactate consumption and yield lower final lactate and higher titers. These studies investigated the effects of copper on metabolite and transcript profiles, but did not measure in detail the dependences of cell culture performance and product quality on copper concentrations. To more thoroughly map these dependences, we explored the effects of various copper treatments on four recombinant CHO cell lines. In the first cell line, when extracellular copper remained above the limit of detection (LOD), cultures shifted to net lactate consumption and yielded comparable performances irrespective of the differences in copper levels; when extracellular copper dropped below LOD (∼13 nM), cultures failed to shift to net lactate consumption, and yielded significantly lower product titers. Across the four cell lines, the ability to grow and consume lactate seemed to depend on the presence of a minimum level of copper, beyond which there were no further gains in culture performance. Although this minimum cellular copper requirement could not be directly quantified, we estimated its probable range for the first cell line by applying several assumptions. Even when different copper concentrations did not affect cell culture performance, they affected product quality profiles: higher initial copper concentrations increased the basic variants in the recombinant IgG1 products. Therefore, in optimizing chemically defined media, it is important to select a copper concentration that is adequate and achieves desired product quality attributes.
初始铜水平较高的CHO细胞培养物会转变为乳酸净消耗，并产生较低的最终乳酸含量和较高的滴度。这些研究调查了铜对代谢物和转录谱的影响，但没有详细测量细胞培养性能和产品质量对铜浓度的依赖性。为了更全面地描绘这些依赖性，我们探索了各种铜处理对四种重组CHO细胞系的影响。在第一个细胞系中，当细胞外铜保持在检测限（LOD）以上时，无论铜水平存在差异，培养物都会转变为乳酸净消耗，并产生相当的性能；当细胞外铜降至LOD以下（约13 nM）时，培养物无法转变为乳酸净消耗，且产品滴度显著降低。在这四种细胞系中，生长和消耗乳酸的能力似乎取决于最低水平铜的存在，超过这个水平，培养性能就不会再有进一步提升。尽管无法直接量化这种细胞对铜的最低需求量，但我们通过应用几个假设估计了第一个细胞系的可能范围。即使不同的铜浓度不影响细胞培养性能，它们也会影响产品质量概况：较高的初始铜浓度会增加重组IgG1产品中的碱性变体。因此，在优化化学成分确定的培养基时，选择一个足够且能实现所需产品质量属性的铜浓度很重要。
