Altered gene expression in CHO cells following polyamine starvation

Differential polyamine metabolism in CHO cell lines: Insights into cell growth and antibody quality

Chinese hamster ovary (CHO) cell lines are widely utilized host cell lines in cell culture bioprocessing. Although they originated from a common ancestor, accumulated genetic mutations have led to significant heterogeneity in their behavior under specific conditions. This study investigates the cell line-specific impact of polyamine (PUT; putrescine) withdrawal on the growth, metabolism, and antibody production among three CHO clones derived from different parental cell lines: CHO-K1, CHO-S, and CHO-DG44. CHO-K1 cells strongly depended on external polyamines, showing a 77 % reduction in viable cell density and an 88 % decrease in growth rate under PUT depletion, although their culture longevity was extended. In contrast, CHO-S and CHO-DG44 cells demonstrated greater resilience, with CHO-DG44 experiencing only a 25 % reduction in cell density. PUT deprivation also impacted antibody production across all cell lines, with CHO-K1 displaying the lowest yield, antibody purity and altered charge heterogeneity. Notably, PUT depletion led to increased galactosylation of antibodies, suggesting that modulating PUT levels in the media could be used as a strategy to tailor the quality of therapeutic antibodies. These findings, together, provide valuable insights in the design of cell line-specific media, thereby optimizing both bioprocess efficiency and product quality in biopharmaceutical production.

Systematic identification of genomic hotspots for high-yield protein production in CHO cells

The efficient and stable production of therapeutic proteins in Chinese hamster ovary (CHO) cells hinges on robust cell line development (CLD). Traditional methods relying on random transgene integration often result in clonal variability, requiring extensive and resource-intensive screening. To address this limitation, we established a systematic, multiomics-driven framework that integrates 202 RNA-sequencing datasets and whole-genome sequencing data to identify genomic "hotspot" loci for precise and high-yield transgene integration. From an initial pool of 20 candidate loci, 5 top-performing hotspots were validated using site-specific integration in CHO-DG44 cells via the CRISPR/Cas9 system with Recombinase-mediated cassette exchange (RMCE). These genomic hotspots achieved 2.2- to 15.0-fold higher relative specific productivity compared to previously known controls (Fer1L4 and Locus1 sites), across multiple therapeutic proteins, including a lysosomal storage disorder-related enzyme and an Immunoglobulin G (IgG)-related monoclonal antibody (mAb) expression. This study offers a transformative approach to CLD, achieving significant improvements in productivity, genomic stability, and efficiency, as well as paving the way for enhanced biopharmaceutical manufacturing.

Advances in serum-free media for CHO cells: From traditional serum substitutes to microbial-derived substances

The Chinese hamster ovary (CHO) cell is an epithelial-like cell that produces proteins with post-translational modifications similar to human glycosylation. It is widely used in the production of recombinant therapeutic proteins and monoclonal antibodies. Culturing CHO cells typically requires the addition of a certain proportion of fetal bovine serum (FBS) to maintain cell proliferation and passaging. However, serum is characterized by its complex composition, batch-to-batch variability, high cost, and potential risk of exogenous contaminants such as mycoplasma and viruses, which impact the purity and safety of the synthesized proteins. Therefore, search for serum alternatives and development of serum-free media for CHO-based protein biomanufacturing are of great significance. This review systematically summarizes the application advantages of CHO cells and strategies for high-density expression. It highlights the developmental trends of serum substitutes from human platelet lysates to animal-free extracts and microbial-derived substances and elucidates the mechanisms by which these substitutes enhance CHO cell culture performance and recombinant protein production, aiming to provide theoretical guidance for exploring novel serum alternatives and developing serum-free media for CHO cells.

A study on phytogenotoxicity induced by biogenic amines: cadaverine and putrescine

Among the compounds present in necro-leachate, a liquid released during the process of decomposition of the human body, are the biogenic amines cadaverine and putrescine. Although some studies on necro-leachate have indicated a potential ecotoxicological and public health risk associated with it, the research on this type of contamination is still rather limited. This study presents information about the phytotoxic and cytogenotoxic potential of cadaverine and putrescine, evaluated separately and within a mixture. Phytotoxicity was evaluated through a germination test, the initial growth of seedlings with Lactuca sativa, and cytogenotoxicity through chromosomal aberration and micronucleus tests with Allium cepa. The L. sativa results showed a phytotoxic effect for the evaluated amines, by reducing root (> 90%) and hypocotyl (> 80%) elongation. The co-exposure of cadaverine and putrescine potentiated cytogenotoxic activity by aneugenic action in the meristematic cells of A. cepa. From this result, it is possible to infer the eco-toxicogenic potential of cadaverine and putrescine. This study not only highlights the importance of the phytotoxic and cytogenotoxic effects of these amines but also emphasizes the urgent need for further investigation into contamination originating from cemetery environments. By evaluating the risks associated with necro-leachate, this research is aimed at informing global efforts to protect ecological and public health.

Enhanced cell growth, production, and mAb quality produced in Chinese hamster ovary-K1 cells by supplementing polyamine in the media

Polyamines such as putrescine (PUT), spermidine (SPD), and spermine (SPM) are amine group-containing biomolecules that regulate multiple intracellular functions such as proliferation, differentiation, and stress response in mammalian cells. Although these biomolecules can be generated intracellularly, lack of polyamine-synthesizing activity has occasionally been reported in a few mammalian cell lines such as Chinese hamster ovary (CHO)-K1; thus, polyamine supplementation in serum-free media is required to support cell growth and production. In the present study, the effects of biogenic polyamines PUT, SPD, and SPM in media on cell growth, production, metabolism, and antibody quality were explored in cultures of antibody-producing CHO-K1 cells. Polyamine withdrawal from media significantly suppressed cell growth and production. On the other hand, enhanced culture performance was achieved in polyamine-containing media conditions in a dose-dependent manner regardless of polyamine type. In addition, in polyamine-deprived medium, distinguishing metabolic features, such as enriched glycolysis and suppressed amino acid consumption, were observed and accompanied by higher heterogeneity of antibody quality compared with the optimal concentration of polyamines. Furthermore, an excessive concentration of polyamines negatively affected culture performance as well as antibody quality. Hence, the results suggest that polyamine-related metabolism needs to be further investigated and polyamines in cell growth media should be optimized as a controllable parameter in CHO cell culture bioprocessing. KEY POINTS: • Polyamine supplementation enhanced cell growth and production in a dose-dependent manner • Polyamine type and concentration in the media affected mAb quality • Optimizing polyamines in the media is suggested in CHO cell bioprocessing.