Use of novel cystine analogs to decrease oxidative stress and control product quality

•Replacement of cysteine with cystine analogs can improve product quality.•N,N′-diacetyl-l-cystine dimethylester (DACDM) reduce charge variants and protein coloration without negative effect on titer.•DACDM can be used as a cysteine sources by CHO cells.•DACDM contribute to the cellular defense against oxidative stress by increasing the intracellular glutathione pool. Continuous improvements of cell culture media are required in order to ensure high yield and product quality. However, some components can be instable and lead to detrimental effects on bioprocess performances. l-cysteine is an essential amino acid commonly used in cell culture media. Despite its beneficial effect on recombinant protein production, in some cases, this component can be responsible for product microheterogeneity. In this context, alternative components have to be found in order to reduce product variants while maintaining high productivity. In this study, we have assessed the performance of different cysteine and cystine analogs : N-acetyl-cysteine, s-sulfocysteine, N,N′-diacetyl-l-cystine and the N,N′-diacetyl-l-cystine dimethylester (DACDM). Replacement of cysteine by cystine analogs, and especially DACDM, has shown positive impact on charge variants level and recombinant protein coloration level. Moreover, this molecule contributed to the increase of the intracellular glutathione pool, which suggests a close relationship with the oxidative stress regulation.