Newly established cell lines derived from Chinese hamster for production of biologics

The Chinese hamster (Cricetulus griseus) is a species of hamster that was used as a laboratory animal more than 50 years ago. The Chinese hamster ovary (CHO) cell line was established in 1957 by Puck et al. and maintained in ex vivo conditions (1). CHO cells are now a workhorse for recombinant biopharmaceutical production. Puck et al. continuously cultivated lung, kidney, spleen and ovary-derived cells for more than 10 months using serum medium. In this study, we established a cell line from female Chinese hamster tissues: lung, kidney and ovary. Primary cells were obtained from these tissues and maintained for several months or more (Figure 1). We were ultimately able to construct three immortal cell lines, CHL-YN (fibroblast) from lung, CHK-Q (epitheliocyte) from kidney and CHO-MK (epitheliocyte) from ovary, respectively. Infinite proliferation of these cell lines is obtained by spontaneous transformation. Please click Additional Files below to see the full abstract

Newly-established Chinese hamster-derived cell line for protein production

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Intracellular secretion analysis of therapeutic antibodies in engineered high- producible CHO cells

The Chinese Hamster Ovary (CHO) cell is the most commonly used cell line for the production of therapeutic recombinant proteins. The improvements in target gene amplification and culture method have contributed in achieving a very high productivity. Some studies have focused on post-translational secretion processes, and overexpression of proteins which work in the secretion pathway successfully increased the productivity [1]. However, those studies were performed based on the knowledge obtained from the normal, adherent cultured cells, and the detailed secretion processes of recombinant proteins in engineered, suspension cultured cells is still unclear. To clarify problems and to find new targets for a more efficient establishment of high producers, the basic analyses about the secretion in engineered, high-producible CHO cells were performed. Please click Additional Files below to see the full abstract

Cre-loxP-controlled cell-cycle checkpoint engineering in Chinese Hamster ovary cells

The gene amplification system is widely used in Chinese hamster ovary (CHO) cells for the productive cell line construction of therapeutic proteins. To enhance the efficiency of conventional gene amplification systems, we previously presented a novel method using cell-cycle checkpoint engineering1). Here, we constructed high-producing and stable cells by the conditional expression of mutant cell division cycle 25 homolog B (CDC25B) using the Cre-loxP system2). A bispecific antibody-producing CHO DG44-derived cell line was transfected with floxed mutant CDC25B. After inducing gene amplification in the presence of 250 nM methotrexate, mutant CDC25B sequence was removed by Cre recombinase protein expression. Overexpression of the floxed mutant CDC25B significantly enhanced the efficiency of transgene amplification and productivity. Moreover, the specific production rate of the isolated clone CHO Cre-1 and Cre-2 were approximately 11-fold and 15-fold higher than that of mock-transfected clone CHO Mock-S. Chromosomal aneuploidy was increased by mutant CDC25B overexpression, but Cre-1 and Cre-2 did not show any changes in chromosome number during long-term cultivation, as is the case with CHO Mock-S. Our results suggest that high-producing and stable cells can be constructed by conditionally controlling a cell-cycle checkpoint integrated in conventional gene amplification systems

Construction of a novel kinetic model for the production process of a CVA6 VLP vaccine in CHO cells

Bioprocess development benefits from kinetic models in many aspects, including scale-up, optimization, and process understanding. However, current models are unable to simulate the production process of a coxsackievirus A6 (CVA6) virus-like particle (VLP) vaccine using Chinese hamster ovary cell culture. In this study, a novel kinetic model was constructed, correlating (1) cell growth, death, and lysis kinetics, (2) metabolism of major metabolites, and (3) CVA6 VLP production. To construct the model, two batches of a laboratory-scale 2 L bioreactor cell culture were prepared and various pH shift strategies were applied to examine the effect of pH shift. The proposed model described the experimental data under various conditions with high accuracy and quantified the effect of pH shift. Next, cell culture performance with various pH shift timings was predicted by the calibrated model. A trade-off relationship was found between product yield and quality. Consequently, multiple objective optimization was performed by integrating desirability methodology with model simulation. Finally, the optimal operating conditions that balanced product yield and quality were predicted. In general, the proposed model improved the process understanding and enabled in silico process development of a CVA6 VLP vaccine.The version of record of this article, first published in Cytotechnology, is available online at Publisher’s website: https://doi.org/10.1007/s10616-023-00598-

Synthesis of Human Antibodies Against HBsAg in Newly Established Chinese Hamster Lung (CHL-YN) Cell Line

Hepatitis B immunoglobulin (HBIG) is an effective treatment for hepatitis B, including postexposure prophylaxis of HBV infection, prevention of HBV reinfection in liver transplant patients, and reducing sexual transmission. This study investigated the synthesis of human IgG antibodies that specifically target HBsAg subtype adr in CHL-YN cells, a newly established cell line that grows faster than CHO-K1. To achieve the synthesis of human IgG antibodies, a plasmid vector encoding DNA sequences for human IgG antibodies against HBsAg was constructed and then transiently transfected into CHL-YN cells. The expression and antigen-binding capacity of the recombinant human IgG antibodies were analyzed using western blot and ELISA. The results showed successful expression and secretion of human IgG antibodies that recognize HBsAg subtype adr in CHL-YN cells. The ELISA test confirmed the specificity of the human IgG antibodies towards HBsAg subtype adr. Thus, this study concluded that human IgG antibodies that target HBsAg subtype adr were transiently expressed in CHL-YN cells

Synthesis of Human Antibodies Against HBsAg in Newly Established Chinese Hamster Lung (CHL-YN) Cell Line

Hepatitis B immunoglobulin (HBIG) is an effective treatment for hepatitis B, including postexposure prophylaxis of HBV infection, prevention of HBV reinfection in liver transplant patients, and reducing sexual transmission. This study investigated the synthesis of human IgG antibodies that specifically target HBsAg subtype adr in CHL-YN cells, a newly established cell line that grows faster than CHO-K1. To achieve the synthesis of human IgG antibodies, a plasmid vector encoding DNA sequences for human IgG antibodies against HBsAg was constructed and then transiently transfected into CHL-YN cells. The expression and antigen-binding capacity of the recombinant human IgG antibodies were analyzed using western blot and ELISA. The results showed successful expression and secretion of human IgG antibodies that recognize HBsAg subtype adr in CHL-YN cells. The ELISA test confirmed the specificity of the human IgG antibodies towards HBsAg subtype adr. Thus, this study concluded that human IgG antibodies that target HBsAg subtype adr were transiently expressed in CHL-YN cells

Build-up functionalization of anti-EGFR × anti-CD3 bispecific diabodies by integrating high-affinity mutants and functional molecular formats

Designing non-natural antibody formats is a practical method for developing highly functional next-generation antibody drugs, particularly for improving the therapeutic efficacy of cancer treatments. One approach is constructing bispecific antibodies (bsAbs). We previously reported a functional humanized bispecific diabody (bsDb) that targeted epidermal growth factor receptor and CD3 (hEx3-Db). We enhanced its cytotoxicity by constructing an Fc fusion protein and rearranging order of the V domain. In this study, we created an additional functional bsAb, by integrating the molecular formats of bsAb and high-affinity mutants previously isolated by phage display in the form of Fv. Introducing the high-affinity mutations into bsDbs successfully increased their affinities and enhanced their cytotoxicity in vitro and in vivo. However, there were some limitations to affinity maturation of bsDb by integrating high-affinity Fv mutants, particularly in Fc-fused bsDb with intrinsic high affinity, because of their bivalency. The tetramers fractionated from the bsDb mutant exhibited the highest in vitro growth inhibition among the small bsAbs and was comparable to the in vivo anti-tumor effects of Fc-fused bsDbs. This molecule shows cost-efficient bacterial production and high therapeutic potential