Using cell size kinetics to determine optimal harvest time for Spodoptera frugiperda and Trichoplusia ni BTI-TN-5B1-4 cells infected with a baculovirus expression vector system expressing enhanced green fluorescent protein

Infecting insect cells with a baculovirus expression vector system (BEVS) is an increasingly popular method for the production of recombinant proteins. Due to the lytic nature of the system, however, determining the optimal harvest time is critical for maximizing protein yield. We found that measuring the change in average diameter during the progress of infection with an automated cell analysis system (Cedex HiRes, Innovatis AG) could be used to determine the time of maximum protein production and, thus, optimal harvest time. As a model system, we use insect cells infected with a baculovirus expressing enhanced green fluorescent protein (EGFP). We infected two commonly used insect cell lines, Spodoptera frugiperda (Sf-9) and Trichoplusia ni BTI-TN-5B1-4 (Hi5) with an Autographa californica nuclear polyhedrosis virus (AcNPV) encoding EGFP at various multiplicities of infection (MOI). We monitored the progress of infection with regard to viability, viable cell density and change in average cell diameter with a Cedex HiRes analyzer and compared the results to the EGFP produced. Peak protein production was reached one to two days after the point of maximum average diameter in all conditions. Thus, optimal harvest time could be determined by monitoring the change in average cell diameter during the course of an infection of a cell culture

Bioreactor technology for sustainable production of plant cell-derived products

The successful cultivation of plant cell and tissue cultures for the production of valuable chemical components requires the selection of an appropriate bioreactor. Selection criteria are determined based on a number of factors that are intrinsic to particular plant cell or tissue cultures and are influenced by the process objectives. Due to the specific properties of plant cell and tissue cultures, bioreactor systems may differ significantly from those used for microorganism or animal cell cultures. Furthermore, the differences from one plant culture to another can be immense; it is obvious that the optimal bioreactor system for a plant suspension cell culture is different to one for a plant tissue culture in many ways. General considerations are presented, and based on these key points, selection criteria are used to establish a “bioreactor chooser” tool. The particular details of the most relevant bioreactor types for plant cell and tissue cultures are listed and described. To produce valuable products, the process also needs to be scaled up to an economically justifiable size, which is usually done either by scaling up the size of the bioreactor itself or by bioreactor parallelization. Therefore, the most significant influencing factors are also discussed