Low-concentration staurosporine improves recombinant antibody productivity in Chinese hamster ovary cells without inducing cell death

Effects and mechanism of small molecule additives on recombinant protein in CHO cells

Chinese hamster ovary (CHO) cells can produce proteins with complex structures and post-translational modifications which are similar to human-derived cells, and they have been the ideal host cells for the production of recombinant therapy proteins (RTPs). Nearly 70% of approved RTPs are produced by CHO cells. In recent years, a series of measures have been developed to increase the expression of RTPs to achieve the lower production cost during the process of large-scale industrial production of recombinant protein in CHO cells. Among of them, the addition of small molecule additives in the culture medium can improve the expression and production efficiency of recombinant proteins, and has become an effective and simple method. In this paper, the characteristics of CHO cells, the effect and mechanism of small molecule additives are reviewed. KEY POINTS: • Small molecular additives on the expression of RTPs in CHO cells are reviewed • Small molecular additives improve the yield of RTPs • Small molecular additives provide methods for the optimization of serum-free medium.

Capacitance spectroscopy enables real-time monitoring of early cell death in mammalian cell culture

BACKGROUND/AIMS

Previous work developed a quantitative model using capacitance spectroscopy in an at-line setup to predict the dying cell percentage measured from a flow cytometer. This work aimed to transfer the at-line model to monitor lab-scale bioreactors in real-time, waiving the need for frequent sampling and enabling precise controls.

METHODS AND RESULTS

Due to the difference between the at-line and in-line capacitance probes, direct application of the at-line model resulted in poor accuracy and high prediction bias. A new model with a variable range and offering similar spectral shape across all probes was first constructed, improving prediction accuracy. Moreover, the global calibration method included the variance of different probes and scales in the model, reducing prediction bias. External parameter orthogonalization, a preprocessing method, also mitigated the interference from feeding, which further improved model performance. The root-mean-square error of prediction of the final model was 6.56% (8.42% of the prediction range) with an R² of 92.4%.

CONCLUSION

The culture evolution trajectory predicted by the in-line model captured the cell death and alarmed cell death onset earlier than the trypan blue exclusion test. Additionally, the incorporation of at-line spectra following orthogonal design into the calibration set was shown to generate calibration models that are more robust than the calibration models constructed using the in-line spectra only. This is advantageous, as at-line spectral collection is easier, faster, and more material-sparing than in-line spectra collection.

Violacein improves recombinant IgG production by controlling the cell cycle of Chinese hamster ovary cells

Chinese hamster ovary (CHO) cells are used as host cells for industrial monoclonal antibody (mAb) production. Cell cycle control is an effective approach to increase mAb production in the cell culture. Violacein, a purple-colored pigment produced by microorganisms, has diverse bioactive properties and has been proposed for various industrial applications. In this study, we evaluated the potency of violacein for cell cycle control and improvement of recombinant immunoglobulin G (IgG) production in CHO cells. Compared with the control, 0.9 μM violacein in a 14-day fed-batch culture increased the maximum IgG concentration by 37.6% via increasing the specific production rate and cell longevity. Cell cycle analysis showed that violacein induced G1 and G2/M phase arrest. However, the G1 arrest was observed only on day 1, while G2/M arrest lasted more than 3 days, suggesting that G2/M arrest mediated the violacein-induced enhanced IgG production. Moreover, in line with the increased protein expression, the expression levels of IgG mRNA and nutrient metabolic rates were also increased. N-Linked glycosylation and charge variant profiles were barely affected by violacein treatment. Our results indicate that violacein affects the cell cycle of CHO cells and increases IgG production without changing product quality, showing promise as a mAb production enhancer in CHO cells. The study provides insight into violacein utilization in industrial mAb manufacturing and can help develop advanced, effective mAb production technologies using CHO cell cultures.