Q&A | Solutions To Questions On Lactate Metabolism Regulation Strategies in Cell Culture

Q&A on Lactate Metabolism Regulation Strategies in Cell Culture

Last week, BioEngine launched a live webinar series themed "Intelligent Manufacturing in China" focusing on serum-free cell culture media, with the session titled Lactate Metabolism Regulation Strategies in Cell Culture. Manager Su Shuang first introduced common lactate metabolism issues in cell culture-abnormal lactate metabolism may lead to cell apoptosis, reduced cell viability, process scale-up failure, and decreased product titer, among other problems. She then elaborated on the regulatory mechanisms and strategies for lactate metabolism, whose core lies in directing carbon flux toward the aerobic respiration pathway. A variety of regulation strategies were proposed from the perspectives of medium composition and culture process parameters. Finally, she presented BioEngine's comprehensive CHO cell culture solutions covering R&D to large-scale production, including the RapidTrans CHO Kit for transient CHO transfection, the Eden Series Medium Kit for stable CHO protein expression, Tuner Modulators for metabolic and glycosylation regulation, and custom medium development services.

 

The live webinar was rich and insightful, with a host of giveaways for participants. The audience engaged actively in the lively interactions, creating a strong learning atmosphere. Regrettably, due to time constraints, some questions from participants remained unanswered during the live session. We have therefore compiled all the questions and provided unified answers, hoping to be of great help to you. If you have any needs or inquiries regarding cell culture, please feel free to contact us.

 

Below are the compiled answers to the questions raised during the webinar:

 

Q: In the late stage of cell culture, lactate levels do not increase but pH decreases. What could be the possible reasons?

A: A variety of factors can cause pH decline, and other free acids are also produced in the late culture stage. Literature reports indicate that pH drop in the late stage is induced by acetic acid accumulation.

 

Q: Using the same materials and process, some batches exhibit a certain degree of lactate accumulation in the late stage of cell culture. Although lactate levels are not high, pH drops rapidly. What might be the causes?

A: This may be attributed to batch-to-batch variations in certain raw materials, or ion precipitation occurring during medium preparation, which leads to changes in culture performance.

 

Q: What are the possible reasons for the increase in cell diameter during culture, and how to address it?

A: In the fed-batch culture process of CHO cells, cells grow rapidly in the logarithmic phase in the early culture stage. In the middle and late stages, cell proliferation slows down and antibody/protein production is ramped up, during which cell diameter increases. Therefore, in most cases, an increase in cell diameter during the antibody/protein production phase is a normal phenomenon.

 

Q: Is the selection of temperature shift time in cell culture related to lactate metabolism? For example, is it more appropriate to perform temperature shift before or after the lactate peak?

A: Temperature shift can help reduce the peak of lactate accumulation in cells during the logarithmic growth phase (mainly by affecting the glycolysis rate and thus lactate accumulation). However, it has little effect on lactate accumulation in the stationary and late culture stages.

There is no uniform answer to whether temperature shift is better before or after the lactate peak, as it depends on your specific culture process.

 

Q: Can reducing pH in the early stage of cell culture alleviate the accumulation of cellular metabolites in the late stage?

A: It can alleviate the issue to a certain extent. In addition, reducing pH can decrease the amount of base supplementation, thereby lowering the osmotic pressure of the culture environment and reducing the risk of adverse effects of high osmotic pressure on cellular metabolism.

 

Q: In some projects, significant lactate accumulation occurs in the late stage, but cell growth and antibody quality remain normal. Is it necessary to regulate lactate levels?

A: It is necessary to combine the pilot scale-up data. If cell growth and product quality remain normal during large-scale culture, lactate regulation is not required. If you have higher requirements for product titer, you can try to improve antibody/protein titer by regulating lactate metabolism.

 

Q: Using the same culture process, the pCO₂ in shake flasks is higher than that in bioreactors. What could be the possible reasons?

A: It is related to the pH control strategy, mass transfer efficiency and other factors of the bioreactor.

 

Q: Does severe lactate accumulation have a significant impact on the glycosylation of different products?

A: It may have an impact, but the factors affecting product glycosylation profiles need to be judged based on more process parameters.

 

Q: Is there a direct relationship between lactate levels and antibody titer?

A: Based on existing data, lactate accumulation has a certain impact on antibody titer, and improving abnormal lactate metabolism can help increase product titer.

 

Q: Does pH affect lactate metabolism? For lactate-consuming cells, will artificial lactate addition change antibody titer?

A: The pH control strategy may affect lactate metabolism. Artificial lactate addition to lactate-consuming cells may have an impact on antibody titer, but the specific effect needs to be analyzed in combination with actual cases.

 

Q: When the partial pressure of carbon dioxide is too high, can organic acids be used to control pH?

A: Yes.

 

Q: Do organic acids have an impact on cell growth, metabolism and product quality?

A: The addition amount needs to be controlled, and organic acids generally have little impact on cell growth, metabolism and product quality.

 

Q: Is copper ion precipitation likely to occur during medium storage?

A: Ion precipitation generally occurs before medium filtration; it is uncommon during storage after filtration.

 

Q: Questions related to Tuner-Lac Lactate Modulator

A: Tuner-Lac Lactate Modulator is designed for lactate metabolism regulation in the late stage of cell culture and is composed of multiple components. The addition of Tuner-Lac has no adverse effects on critical quality attributes (CQAs) of antibodies such as charge heterogeneity and glycosylation profiles. It is beneficial for lactate metabolism regulation, cell viability maintenance and protein titer improvement in the late stage of cell culture.