Engineering mammalian cells in bioprocessing – current achievements and future perspectives

Abstract

Over the past 20 years, we have seen significant improvements in product titres from 50 mg/l to 5-10 g/l, a more than 100-fold increase. The main methods that have been employed to achieve this increase in product titre have been through the manipulation of culture media and process control strategies, such as the optimization of fed-batch processes. An alternative means to increase productivity has been through the engineering of host cells by altering cellular processes. Recombinant DNA technology has been used to over-express or suppress specific genes to endow particular phenotypes. Cellular processes that have been altered in host cells include metabolism, cell cycle, protein secretion and apoptosis. Cell engineering has also been employed to improve post-translational modifications such as glycosylation. In this article, an overview of the main cell engineering strategies previously employed and the impact of these strategies are presented. Many of these strategies focus on engineering cell lines with more efficient carbon metabolism towards reducing waste metabolites, achieving a biphasic production system by engineering cell cycle control, increasing protein secretion by targeting specific endoplasmic reticulum stress chaperones, delaying cell death by targeting anti-apoptosis genes, and engineering glycosylation by enhancing recombinant protein sialylation and antibody glycosylation. Future perspectives for host cell engineering, and possible areas of research, are also discussed in this review.

Annotation of additional evolutionary conserved microRNAs in CHO cells from updated genomic data

“…Over the last 25 years, the optimization of growth, product quality and titer was mainly driven by the modification of media, feeding strategies, and biotechnological processes. More recently, with the availability of genomic sequences, cell engineering strategies have emerged as an alternative route to improve cell line performance (Lim et al, 2010; Xiao et al, 2014), although deeper insight into genetic, transcriptional and translational regulation is required to obtain full control over cellular metabolism (Jadhav et al, 2013; Kildegaard et al, 2013). …”

Exploring Packaged Microvesicle Proteome Composition of Chinese Hamster Ovary Secretome

“…Though CHO cells have been successfully scaled up to produce 5-10 g/L biologics [3], further improvements in the production are of eminent importance to meet the global demand at affordable cost. This could be achieved mainly by three ways; 1-improve production capability of cells in culture (improved cell specific productivity, cell density and culture longevity), 2-minimize product degradation and heterogeneity, 3-improve product purification process.…”

Global metabolic effect of manipulating pyruvate dehydrogenase complex activity in mammalian cells

“…higher glucose concentration, higher oxygen concentration and all substrates in excess. They exhibit aerobic glycolysis resulting in an undesired high glucose and glutamine consumption in combination with high lactate and ammonia production leading to shorter culture periods and possible negative effects on cell growth, productivity, and product quality (Dietmair, Nielsen & Timmins 2011;Lim et al 2010). Lactate is the main waste product that highly accumulates in both, batch and fedbatch processes, which can inhibit cell growth and protein production (Glacken, Huang & Sinskey 1989;Lao & Toth 1997).…”

“…Culture conditions can impact productivity and antibody quality (Lao & Toth 1997;Li, J et al 2012;Lim et al 2010;Pacis et al 2011). The cell specific productivity during exponential growth was the same in control and DCA cultures with 8.81 ± 0.05 pg/(cell*day) (p > 0.05, t-test).…”

“…inefficient energy metabolism, characterized by increased glucose consumption and lactate production (Warburg, Wind & Negelein 1927). Rapid lactate accumulation adversely effects culture performance and productivity (Dietmair, Nielsen & Timmins 2011;Gambhir et al 2003;Lao & Toth 1997;Lim et al 2010). In fermentation, pH is controlled and growth inhibition has been attributed to the concomitant osmolality increase (Cruz et al 2000).…”