Approaches to Optimizing Animal Cell Culture Process: Substrate Metabolism Regulation and Protein Expression Improvement

Abstract

Some high value proteins and vaccines for medical and veterinary applications by animal cell culture have an increasing market in China. In order to meet the demands of large-scale productions of proteins and vaccines, animal cell culture technology has been widely developed. In general, an animal cell culture process can be divided into two stages in a batch culture. In cell growth stage a high specific growth rate is expected to achieve a high cell density. In production stage a high specific production rate is stressed for the expression and secretion of qualified protein or replication of virus. It is always critical to maintain high cell viability in fed-batch and perfusion cultures. More concern has been focused on two points by the researchers in China. First, the cell metabolism of substrates is analyzed and the accumulation of toxic by-products is decreased through regulating cell metabolism in the culture process. Second, some important factors effecting protein expression are understood at the molecular level and the production ability of protein is improved. In pace with the rapid development of large-scale cell culture for the production of vaccines, antibodies and other recombinant proteins in China, the medium design and process optimization based on cell metabolism regulation and protein expression improvement will play an important role. The chapter outlines the main advances in metabolic regulation of cell and expression improvement of protein in animal cell culture in recent years.

Process development for an inducible rituximab‐expressing Chinese hamster ovary cell line

“…This suggests some form of competitive relationship between cellular growth and productivity and indeed many studies have reported an inverse correlation between the cell specific growth rate and the cell specific productivity. 12,32,33 Hence, the potential to control the onset of antibody production is advantageous for minimizing the metabolic burden imposed on the cells. The general approach for an inducible system should thus consist in allowing the cells to grow rapidly to a desired density, and then maintains a prolonged production phase by slowing/halting cell growth to favor the expression of the recombinant product.…”

Transient transfection of CHO cells using linear polyethylenimine is a simple and effective means of producing rainbow trout recombinant IFN-γ protein

“…Incubation temperature has also been shown to be an important factor affecting the expression of recombinant proteins in mammalian cells, with lower temperatures increasing the cell percentage in G0/G1 phase and decreasing in G2/M phase as well slowing down the cell growth (Galbraith et al 2006;Schatz et al 2003;Zhang 2009). Despite reduced protein synthesis rates at lower temperature, the increased stability of the mRNA encoding the recombinant protein leads to an increase in their cellular abundance (Galbraith et al 2006).…”

“…Daggers indicate significant differences between 32 and 37°C on the same day ( P \ 0.05; P \ 0.01) of cells to maintain active anabolic processes without cell proliferation (Hwang et al 2011;Zhang 2009), actually leads to an increase in recombinant protein production. In this study, the transient transfected CHO cells cultured at 32°C produced 121-fold more rIFN-c than cells incubated at 37°C where the FCS concentration was 0.5 % in both samples.…”

Concise Review: Process Development Considerations for Cell Therapy

“…A balance between delivery of required nutrients and the removal of waste, governed by the perfusion rate and even material distribution, is predicted by mass balance calculations based on specific consumption and generation rates and cell densities. To minimize the costs associated with resultant medium consumption, the perfusion rate is often set near the minimum amount to maintain nutrients and eliminate waste at steady state, as predicted by the mass balance approach [14].…”