Degradative activities in a recombinant chinese hamster ovary cell culture

Two degradative activities were found in a recombinant Chinese hamster ovary cell culture. These activities became more dominant under high cell density and extended running time, as achieved in a semi-continous perfusion culture. The first, insulin degradative activity caused a growth upset in the 3rd cycle of the perfusion culture and shortened the length of the bioreactor process. The second activity, derived from the neutral pH stable sialidase, was found to affect the integrity of the carbohydrate structure of the recombinant protein, causing increase in heterogeneity in molecular weight and pI of the glycoforms. The most efficient way to overcome these problems may be the use of genetically altered 'designer cells' as the production cell line.