A serum substitute for fed-batch culturing of hybridoma cells

Quantitative analysis of glycation and its impact on antigen binding

Glycation has been observed in antibody therapeutics manufactured by the fed-batch fermentation process. It not only increases the heterogeneity of antibodies, but also potentially affects product safety and efficacy. In this study, non-glycated and glycated fractions enriched from a monoclonal antibody (mAb1) as well as glucose-stressed mAb1 were characterized using a variety of biochemical, biophysical and biological assays to determine the effects of glycation on the structure and function of mAb1. Glycation was detected at multiple lysine residues and reduced the antigen binding activity of mAb1. Heavy chain Lys100, which is located in the complementary-determining region of mAb1, had the highest levels of glycation in both stressed and unstressed samples, and glycation of this residue was likely responsible for the loss of antigen binding based on hydrogen/deuterium exchange mass spectrometry analysis. Peptide mapping and intact liquid chromatography-mass spectrometry (LC-MS) can both be used to monitor the glycation levels. Peptide mapping provides site specific glycation results, while intact LC-MS is a quicker and simpler method to quantitate the total glycation levels and is more useful for routine testing. Capillary isoelectric focusing (cIEF) can also be used to monitor glycation because glycation induces an acidic shift in the cIEF profile. As expected, total glycation measured by intact LC-MS correlated very well with the percentage of total acidic peaks or main peak measured by cIEF. In summary, we demonstrated that glycation can affect the function of a representative IgG1 mAb. The analytical characterization, as described here, should be generally applicable for other therapeutic mAbs.

The Role of Different Supplements in Expression Level of Monoclonal Antibody against Human CD20

BACKGROUND

Recombinant monoclonal antibodies have been marketed in last three decades as the major therapeutic proteins against different cancers. However choosing a proper medium and supplements to reach the high expression is a challenging step. Despite of commercial serum free and chemically defined media, there are still numerous researches seeking the optimum media to gain higher expression titer. Selecting the best basal media followed by proper supplementation to increase the cell density and expression titer needs proper and accurate investigation.

METHODS

In this study, we have determined the expression titer of monoclonal antibody against human CD20 using soy extract, Essential Amino Acid, Non-Essential Amino Acid, Panexin NTS, Peptone, Yeast extract, Insulin-transferrin selenite, Human Serum Albumin, Bovine Serum Albumin, Lipid, and two commercially available supplements, Power and Xtreme feed. In each experiment, the expression level was compared with a well defined media, ProCHO5, RPMI 1640 and DMEM-F12.

RESULTS

It has been shown that supplementing the ProCHO5 basal medium with 10% power feed or combination of 5% PanexinNTS,1.5 g/L yeast and 1.5g/L peptone results in the best production levels with 450 and 425 mg/L of anti CD20 mAb expression level, respectively.

CONCLUSION

Panexin NTS, yeast and peptone cane be proper supplement for fed-batch cell culture instead of commercial Power feed supplement which is a cost effective way to increase expression level. And thereby ProCHO5 may be replaced with common media such as RPMI 1640 and DMEM-F12.

Enhanced antibody production following intermediate addition based on flux analysis in mammalian cell continuous culture

Generally, mammalian cells utilize glucose and glutamine as primary energy sources. To investigate the effect of energy sources on metabolic fluxes and antibody production, glucose- or glutamine-limited serum-free continuous culture of hybridoma 3A21 cells, which produce anti-ribonuclease A antibody, was carried out. The cell volume and dry cell weight were evaluated under various steady-state conditions. The specific consumption and production rates were evaluated on the basis of dry cell weight. On the basis of these results, the fluxes of the metabolic pathway were calculated. It was found that increasing the specific growth rate causes the specific ATP and antibody production rates to decrease. The fluxes between malate and pyruvate also decreased with the increase in specific growth rate. To increase the ATP production rate under steady-state conditions by the enhancement of fluxes between malate and pyruvate, the reduced metabolic fluxes were increased by an intermediate (pyruvate, malate, and citrate) addition. As a result, higher specific ATP and antibody production rates were achieved following the intermediate addition at a constant dilution rate.