On-Line Monitoring of Protein Product Formation in Mammalian Cell Culture System

Recombinant protein therapeutics are the most important new therapeutic entities developed in the past twenty years. In the processes of cell line development for producing these proteins, on-line and in situ monitoring the product titer is crucial. In this work, we report a novel on-line monitoring method to predict the monoclonal antibody (mAb) titer in a Chinese hamster ovary (CHO) cell bioreactor based on mass balance of amino acids. By measuring a few parameters beforehand and conducting simple optical readings in situ, we were able to promptly predict the mAb titer in bioreactors at any specific fermentation time with high accuracy. This rapid and low-cost method could be extremely useful for clone selection and process development in the bio-pharmaceutical industry.