Cell culture media used in biopharmaceutical production have come a long way over the last few decades. Arguably the single biggest change has been the shift from complex animal-derived compositions to chemically defined media that are safer, more consistent and deliver higher levels of performance. In this interview with Dr. Martin Schilling from Evonik Health Care, key solubility, stability and other challenges that still face many media developers and biopharma companies are reviewed.

“With the further development of cell culture media and processes, the requirements on ingredient purity, consistency and global supply security are further increasing. The use of highly purified amino acids continues to be essential to cell culture media by serving as primary protein building blocks. They are chemically defined and compared to previously used protein hydrolysates provide consistency, however, limitations in stability and solubility of some amino acids can become major barriers to further media and process improvement. At Evonik, we are helping customers to overcome these challenges by offering a range of chemically defined peptides,” Dr. Schilling said.

“cQrex® peptides have been designed to overcome solubility and stability limitations of amino acids in cell culture media. Being natural precursors of amino acids, they are hydrolyzed to free amino acids during the process. They are now well established in the industry and open up a world of new possibilities for process simplification and intensification, such as in the context of fed-batch and perfusion processes . That is why we call them ‘performance boosters’. We have decades of expertise in manufacturing these ingredients at large-scale based on powerful technology platforms to meet the needs of customers around the world. We can also provide customer support that leverages our in-depth product, regulatory and application know-how,” Dr. Schilling said.

“L-tyrosin and L-cystine in particular can exhibit poor solubility in water and media and impose limitations to media and process optimization. They often cannot be prepared at the desired concentration at neutral pH. The use of extreme pH values to increase solubility is often used. But there are many drawbacks to that, including the need for separate feed tanks, pH control, excess salt and the risk of precipitation in the bioreactor. To improve the solubility of L-tyrosine and L-cystine, we offer a selection of peptides. cQrex® GY (glycyl-L-tyrosine dihydrate) and cQrex® AY (L-alanyl-L-tyrosine dihydrate) for example can increase solubility at neutral pH by up to 50 times compared to free L-tyrosine. Because these peptides are efficiently taken up and metabolized by the cell, full replacement of L-tyrosine is also possible. Other solutions are cQrex® AC (N,N'-di-L-alanyl-L-cystine) and cQrex® KC (N,N'-di-L-lysyl-L-cystine dihydrochloride), which increase the solubility of L-cystine by around 30 and 1000 times, respectively. Those peptides can be efficiently taken up and metabolized as a source of cysteine,” Dr. Schilling said.

“L-glutamine is a great example of an amino acid that exhibits limited chemical stability in water or equivalent solutions. This tendency to easily degrade can lead to elevated levels of ammonia and glutamic acid or pyroglutamate, which can have a detrimental impact on cell culture performance. Levels of product quality and long-term stability in liquid media or feeds can also be adversely affected. We offer two peptides to stabilize L-glutamine, cQrex® AQ (L-alanyl-L-glutamine) and cQrex® GQ (glycyl-L-glutamine hydrate), that are used to replace free glutamine in basal media or feeds. Uptake and peptide conversion differ between these glutamine peptides and process performance can be optimized by choosing the right glutamine peptide for the right cell line and application,” Dr. Schilling said.

“Evonik is one of the world’s leading specialty chemical companies. We have teams of experts all around the world that are able to speak to you on the phone for an initial consultation or email exchange. A lot of customers also appreciate the free sample kit of our peptides from which they can conduct initial feasibility studies,” Dr. Schilling said.