Exerting control over the glycan moieties of antibody therapeutics is highly desirable from a product safety and batch‐to‐batch consistency perspective. Strategies to improve antibody productivity ...may compromise quality, while interventions for improving glycoform distribution can adversely affect cell growth and productivity. Process design therefore needs to consider the trade‐off between preserving cellular health and productivity while enhancing antibody quality. In this work, we present a modeling platform that quantifies the impact of glycosylation precursor feeding – specifically that of galactose and uridine – on cellular growth, metabolism as well as antibody productivity and glycoform distribution. The platform has been parameterized using an initial training data set yielding an accuracy of ±5% with respect to glycoform distribution. It was then used to design an optimized feeding strategy that enhances the final concentration of galactosylated antibody in the supernatant by over 90% compared with the control without compromising the integral of viable cell density or final antibody titer. This work supports the implementation of Quality by Design towards higher‐performing bioprocesses.
Exerting control over the glycan moieties of antibody therapeutics is highly desirable from a product safety and batch‐to‐batch consistency perspective. Strategies to improve antibody productivity may compromise quality, while interventions for improving glycoform distribution can adversely affect cell growth and productivity.
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•Pseudo attP sites are transcriptionally active sites for site-specific integration purposes.•Two pseudo attP sites of CHO-K1 cells are successfully targeted via CRISPR/Cas9 and ...compared in terms of level and stability of expression.•The pseudo attP site of chromosome 6 has higher knock-in efficiency and more homogenous expression than the pseudo attP site of chromosome 3.
Chinese hamster ovary (CHO) cells are regarded as a prominent host for manufacturing therapeutic proteins. Although conventional strategies for generating recombinant proteins in CHO cells depend on the random integration of a gene of interest (GOI), these established techniques occasionally result in genetically heterogeneous cell lines, which causes diminished expression of the recombinant proteins in the long run. Production instability can be reduced by SSI and creates stable cell lines with a consistent expression of the GOI. In this experiment, we demonstrate the targeted incorporation of a reporter cassette in two PhiC31 pseudo attP sites of CHO cells exploiting the homology-directed repair (HDR) generated by the CRISPR/Cas9 platform. Genes encoding GFP and puromycin resistance marker were precisely inserted into these loci via CRISPR/Cas9. Stable cell lines were suitably produced following antibiotic selection. Junction PCR and fluorescence assay determined targeted integration and expression homogeneity of the reporter cassette, respectively. Taken together, our results indicate the possibility of these two PhiC31 pseudo attP sites as the target sites for site-specific integration of a transgene mediated by CRISPR/Cas9. Furthermore, higher knock-in efficiency and expression homogeneity was observed in the pseudo attP site associated with chromosome 6 compared to the pseudo attP site from chromosome 3.
Cell line development represents a crucial step in the development process of a therapeutic glycoprotein. Chinese hamster ovary (CHO) cells are the most frequently employed mammalian host cell system ...for the industrial manufacturing of biologics. The predominant application of CHO cells for heterologous recombinant protein expression lies in the relative simplicity of stably introducing ectopic DNA into the CHO host cell genome. Since CHO cells were first used as expression host for the industrial production of biologics in the late 1980s, stable genomic transgene integration has been achieved almost exclusively by random integration. Since then, random transgene integration had become the gold standard for generating stable CHO production cell lines due to a lack of viable alternatives. However, it was eventually demonstrated that this approach poses significant challenges on the cell line development process such as an increased risk of inducing cell line instability. In recent years, significant discoveries of new and highly potent (semi)-targeted transgene integration systems have paved the way for a technological revolution in the cell line development sector. These advanced methodologies comprise the application of transposase-, recombinase- or Cas9 nuclease-mediated site-specific genomic integration techniques, which enable a scarless transfer of the transgene expression cassette into transcriptionally active loci within the host cell genome. This review summarizes recent advancements in the field of transgene integration technologies for CHO cell line development and compare them to the established random integration approach. Moreover, advantages and limitations of (semi)-targeted integration techniques are discussed, and benefits and opportunities for the biopharmaceutical industry are outlined.
Genome-scale metabolic models describe cellular metabolism with mechanistic detail. Given their high complexity, such models need to be parameterized correctly to yield accurate predictions and avoid ...overfitting. Effective parameterization has been well-studied for microbial models, but it remains unclear for higher eukaryotes, including mammalian cells. To address this, we enumerated model parameters that describe key features of cultured mammalian cells – including cellular composition, bioprocess performance metrics, mammalian-specific pathways, and biological assumptions behind model formulation approaches. We tested these parameters by building thousands of metabolic models and evaluating their ability to predict the growth rates of a panel of phenotypically diverse Chinese Hamster Ovary cell clones. We found the following considerations to be most critical for accurate parameterization: (1) cells limit metabolic activity to maintain homeostasis, (2) cell morphology and viability change dynamically during a growth curve, and (3) cellular biomass has a particular macromolecular composition. Depending on parameterization, models predicted different metabolic phenotypes, including contrasting mechanisms of nutrient utilization and energy generation, leading to varying accuracies of growth rate predictions. Notably, accurate parameter values broadly agreed with experimental measurements. These insights will guide future investigations of mammalian metabolism.
•A panel of parameters are evaluated for their importance in model accuracy.•Parameters describing the cellular objective, biomass and time-course metabolic shifts profoundly affect model accuracy.•Conventional and alternative objective functions for CHO metabolism are compared and explored.
Chinese hamster ovary (CHO) cells are a mammalian cell line used in the production of therapeutic proteins. Host cell proteins (HCPs) are process-related impurities that are derived from the host ...cell expression system. During biopharmaceutical drug development, removal of HCPs is required. Enzyme-linked immunosorbent assay (ELISA) is a common technique to quantitate HCPs, but is a labor-intensive process that takes up to 7 h. Ella® is an automated instrument that utilizes microfluidics and glass nanoreactors to quantitate HCPs in 75 min using similar ELISA reagents. The antibodies and antigens are captured on three distinct glass nanoreactors, resulting in sensitive reproducible data. Our results indicate that Ella quantitates CHO HCPs with precision, accuracy, sensitivity and trends comparable with our traditional CHO HCP ELISA.
•Recombinant EBV gp350 aa 1–860 was successfully produced and expressed in CHO-cells.•EBV gp350 aa 1–860 was used as a serological antigen in indirect ELISA.•Serum samples (n = 360) with known IgG ...status against VCA and EBNA1 were analyzed.•EBV gp350 aa 1–860 was a sensitive and specific antigen for detection of EBV-specific IgG.
Epstein-Barr virus (EBV) glycoprotein 350 (gp350) is the most abundant glycoprotein expressed on the EBV envelope, the major target for neutralizing antibodies and also essential for virion attachment to B lymphocytes. Several studies have addressed EBV gp350 as a vaccine candidate, but less commonly as a potential antigen for serological assays. The aim of the current study was to develop a diagnostic tool to quantify EBV gp350-specific IgG in previously EBV-infected individuals. A construct encoding the extracellular domain of EBV gp350 (amino acid (aa) 1–860) was developed for expression in Chinese hamster ovary cells. Serum samples (n = 360) with known IgG serostatus against viral capsid antigen (VCA) and Epstein-Barr nuclear antigen 1 (EBNA1) were divided into three groups based on the differences in their serostatus: VCA + EBNA1+ (n = 120), VCA + EBNA1- (n = 120) and VCA-EBNA1- (n = 120). The samples were analyzed by indirect ELISA using recombinant EBV gp350 aa 1–860 as antigen. A clear majority, 108 of the 120 VCA + EBNA1+ samples, had detectable EBV gp350-specific IgG. Of the 120 VCA + EBNA1- samples, 79 had detectable EBV gp350-specific IgG. Only 2 of the 120 VCA-EBNA1- samples had detectable EBV gp350-specific IgG. The results reported here show that use of the EBV gp350 aa 1–860 ELISA can serve as a sensitive method for EBV-specific IgG detection in serum samples.
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•Half-sandwich organoruthenium compounds are extensively investigated as cancer treatments.•Bidentate bioactive ligands with a wide variety of donor atom combinations are ...investigated.•Bidentate bioactive ligands endow in some Ru compounds multimodal anticancer activity.•The bioactivity of the organometallics is often determined by the bidentate ligands.•The complexes have been categorized into 5 structural design concepts.
The small molecule anticancer agent cisplatin and its Pt(II) analogs carboplatin and oxaliplatin are widely used to treat a variety of tumorigenic diseases. Despite their structural simplicity, side effects and disadvantages, they are cornerstones of cancer chemotherapy. Several strategies have been pursued to enhance the activity and reduce the side effects of metal-based drugs, for example, to use bioactive ligands that equip them with novel modes of action, enhance delivery, allow for selective activation, create synergistic effects or improve tumor accumulation. Many of these strategies have been developed for or adapted in the design of half-sandwich organoruthenium compounds. For such compounds decorated with bioactive ligands that coordinate monodentately to the Ru center, we have identified five design concepts (Coord. Chem. Rev. 2021, 439, 213890): (i) the bioactive ligand coordinates directly to the Ru center or (ii) after functionalization with a coordinating group, (iii) the ligand(s) and the Ru center solely define the overall shape of the molecule, (iv) the bioactive ligand is released, and (v) the bioactive ligand acts as a vector to the tumor (cell). Herein, we use these five concepts and explore their application to half-sandwich organoruthenium anticancer compounds in which the bioactive ligand is coordinated to the Ru center through a bidentate chelating motif.
Large scale biopharmaceutical production of biologics relies on the overexpression of foreign proteins by cells cultivated in stirred tank bioreactors. It is well recognized and documented fact that ...protein overexpression may impact host cell metabolism and that factors associated with large scale culture, such as the hydrodynamic forces and inhomogeneities within the bioreactors, may promote cellular stress. The metabolic adaptations required to support the high‐level expression of recombinant proteins include increased energy production and improved secretory capacity, which, in turn, can lead to a rise of reactive oxygen species (ROS) generated through the respiration metabolism and the interaction with media components. Oxidative stress is defined as the imbalance between the production of free radicals and the antioxidant response within the cells. Accumulation of intracellular ROS can interfere with the cellular activities and exert cytotoxic effects via the alternation of cellular components. In this context, strategies aiming to alleviate oxidative stress generated during the culture have been developed to improve cell growth, productivity, and reduce product microheterogeneity. In this review, we present a summary of the different approaches used to decrease the oxidative stress in Chinese hamster ovary cells and highlight media development and cell engineering as the main pathways through which ROS levels may be kept under control.
Reactive oxygen species are generated during recombinant protein production using CHO cells and can lead to oxidative stress. Consequently, cell growth, productivity and product quality can be negatively impacted. In order to alleviate oxidative stress, two main strategies can be used: media development and cell engineering. This review gives an overview of the different approaches available in literature.
Much of the biopharmaceutical industry's success over the past 30 years has relied on products derived from Chinese Hamster Ovary (CHO) cell lines. During this time, improvements in mammalian cell ...cultures have come from cell line development and process optimization suited for large-scale fed-batch processes. Originally developed for high cell densities and sensitive products, perfusion processes have a long history. Driven by high volumetric titers and a small footprint, perfusion-based bioprocess research has regained an interest from academia and industry. The recent pandemic has further highlighted the need for such intensified biomanufacturing options. In this review, we outline the technical history of research in this field as it applies to biologics production in CHO cells. We demonstrate a number of emerging trends in the literature and corroborate these with underlying drivers in the commercial space. From these trends, we speculate that the future of perfusion bioprocesses is bright and that the fields of media optimization, continuous processing, and cell line engineering hold the greatest potential. Aligning in its continuous setup with the demands for Industry 4.0, perfusion biomanufacturing is likely to be a hot topic in the years to come.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Cell line development (CLD) represents a complex but highly critical process during the development of a biological drug. To shed light on this crucial workflow, a team of BioPhorum members (authors) ...has developed and executed surveys focused on the activities and effort involved in a typical CLD campaign. An average of 27 members from different companies that participate in the BioPhorum CLD working group answered surveys covering three distinguishable stages of a standard CLD process: (1) Pre‐transfection, including vector design and construction; (2) Transfection, spanning the initial introduction of vector into cells and subsequent selection and analysis of the pools; and (3) Single Cell Cloning and Lead Clone Selection, comprising methods of isolating single cells and confirming clonal origin, subsequent expansion and screening processes, and methods for identifying and banking lead clones. The surveys were very extensive, including a total of 341 questions split between antibody and complex molecule CLD processes. In this survey review, the authors interpret and highlight responses for antibody development and, where relevant, contrast complex molecule development challenges to provide a comprehensive industry perspective on the typical time and effort required to develop a CHO production cell line.
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