Effects of dissolved oxygen concentration on oxidative stress and recombinant protein production in insect cell cultures

The existing utility as well as the potential benefits of recombinant proteins are considerable. The baculovirus expression vector system (BEVS) has gained worldwide laboratory usage for the production of recombinant proteins. It is a powerful tool for the production of proteins of interest to be used in research and has potential for the production of diagnostics and therapeutics. However, there are currently many aspects of the host insect cell lines that require understanding if the protein production process is to be improved.; The effect of dissolved oxygen (DO) concentration on virally infected Spodoptera frugiperda Sf-9 (Sf9) and Trichoplusia ni BTI-Tn-5B1-4 (Tn5) insect cell lines was studied in 3-liter bioreactor culture. It was found that protein production and cell viability were unaffected by DO concentration over the range from 10% to 190% air saturation in Sf9 cells. In Tn5 cells, increased protein production rate was found at 190% air saturation and viability was found to decline faster as DO increased. There was little evidence of protein oxidation in Sf9 cells; however, it was found to increase at least 2-fold by 72 hours post infection in Tn5 cells. Lipid peroxidation was observed in both lines following infection and was found to increase by ∼50% in Sf9 cells and 2-fold in Tn5 cells, with no clear relationship to DO concentration.; Protein production in the same two cell lines was also studied in high aspect ratio rotating-wall vessel (HARV) bioreactors. Sf9 cells were found to produce similar amounts of protein in HARV vessels as in shaker flask controls. Tn5 cells were found to produce significantly lesser amounts in HARV culture than in controls. Among possible reasons for the different behaviors was the thought that DO concentration in the HARV was inadequate for the Tn5 cell line.; A modified version of the HARV vessel system was designed and built with the capability of measuring and controlling DO inside the vessel. Use of the principle of fluorescence quenching in a metal-ligand indicator molecule was used in the design of the oxygen sensor developed for the system.