The Differences Analysis Of TPP Cell Culture System And 2L Bioreactor Cell Culture System

After 40 years of development,using animal cell culture technology to produce antibody drugs has become the dominant direction of biological medicine development,its industrialization had rapid development.To enlarge the scale of animal cell culture process,present studies focus on solving the scale-up problems which are caused by the expansion of the bioreactor in pilot scale production and large scale production,but there is less study for the scale-up problems which are caused by the change of cell culture system in the laboratory research stage.In the stage of laboratory process development,the TPP and 2 L bioreactor are two commonly used cell culture system,when scaling up the fed-batch culture process which established in TPP to 2 L bioreactor,inconsistent phenomenon of the cell growth,metabolism and product expression was found.In this study,the research object was the fed-batch culture process of CHO cells which express the IgG antibody,by using the same fed-batch culture process,the cell culture experiments were performed in TPP and 2 L bioreactor,results showed that the maximum viable cells density in TPP was 22.78%lower,but the specific antibody production rate and the antibody titer were 75.54%and 41.16%higher than that in 2 L bioreactor.The metabolism of lactate,ammonia and partial amino acids had large difference in TPP and 2 L bioreactor.By using the same fed-batch culture process,other types of cells were cultured in TPP and 2 L bioreactor,results showed that cell growth,cell metabolism,products expression had some difference.To explore which reasons caused antibody titer difference in TPP and 2 L bioreactor,the cell culture process parameters-pH,osmolality,pCO2,DO,moisture volatilization quantity,mixing time,gas-liquid mass transfer and the shear stress in TPP and 2 L bioreactor were compared and analyzed in this paper,results showed that pH,DO,pCO2,osmolality had much difference.In 2 L bioreactor,the change of pH,pCO2 and osmolality are adjusted by pH control,the change of DO are adjusted by DO control,therefore,the potential key reasons which caused the antibody titer difference in TPP and 2 L bioreactor are pH and DO control.Further,the orthogonal experiments of pH and DO control were performed in 2 L bioreactor,results showed that under the same pH control,when the DO was controlled at 50%and 20%,the antibody titer had no significant difference.Under the same DO control,when the pH was controlled at 6.85±0.2,antibody titer was higher than that the pH was controlled at 6.85±0.1.When the pH and DO were controlled at 6.85±0.2 and 50%,the antibody titer in 2 L bioreactor was 3.24 g/L which increased by 16.9%comparing with the antibody titer in 2 L bioreactor under the original control condition,the antibody titer difference between TPP and 2 L bioreactor decreased from 1.14 g/L to 0.67 g/L.This study raises understanding of the differences between TPP and 2 L bioreactor cell culture system,provides a train of thought for the research of laboratory process scale-up problems and lay the foundation for the industrialization application of cell culture process.