Expression Platforms

Pseudomonas fluorescens: Cell-Line Development of a Commercially Proven Platform for Biopharmaceutical Manufacturing

A number of factors contribute to delivering a robust, highly productive, and reliable process for manufacturing a therapeutic protein. They begin with a cell-host system and a gene-expression strategy that determine a developer’s ability to optimize growth and expression titers. But for many therapeutic proteins, initial attempts to develop a production process are based on evaluation of limited factors and tend to yield only small quantities or poor product quality. Automation can enable parallel building and expression screening of diverse…

Plant-Based Protein Expression: Emerging Systems Bring Viable Approaches to Biopharmaceutical Manufacturing

The application of plant-based systems to produce biopharmaceuticals for human and veterinary indications is a rapidly expanding field. Available systems range from stable transgenic root-cell culture to transient expression in whole plants. Products that have been expressed include monoclonal antibodies (MAbs) (1), subunit vaccines (2), virus-like particles (VLPs) (3), specialty enzymes (4), and structural proteins such as collagen (5). “Traditional” bioproduction platforms such as Chinese hamster ovary (CHO) cells, Escherichia coli, and Pichia pastoris have long histories of patient safety…

Posttranslational Modifications and Their Control in CHO Culture

The Chinese hamster ovary (CHO) cell line was first established by Theodore Puck in the 1950s and was used mainly for cytogenetics studies (1). Since the 1990s, CHO cells have increased in popularity as expression host cells because they can be adapted easily into suspension culture and genetically modified. The CHO cell line also has a human-like glycosylation profile (2–4). Therapeutic proteins undergo different posttranslational modifications (PTMs) during manufacturing. Some modifications can lead to undesired effects such as decreased stability,…

Ask the Expert: A Novel Escherichia coli System for Controlled Release of Difficult-to-Secrete Proteins

Although Escherichia coli often enables dependable, highly productive expression of nonglycosylated recombinant proteins, the efficiency with which it secretes a target protein into culture supernatant can depend greatly on that molecule’s physicochemical properties. Some proteins remain trapped in periplasm, thus diminishing process yield and productivity. In June 2021, Marcel Thoen (head of Wacker Biotech’s Global Competence Center for Cell Line Development) described how his company’s improved ESETEC (E. coli secretion technology) solutions can address productivity challenges raised by difficult-to-secrete recombinant…

Avenues for Innovation: The Latest in Cell-Line Engineering and Development

Plato wrote in ancient Greece that “our need will be the real creator,” which transformed over time into the English proverb, “Necessity is the mother of invention.” Advancements in medicine and biomanufacturing technology in 2020 have epitomized that idea. Even as technologies such as mRNA vaccines have rocketed into the public’s awareness, biomanufacturing experts have worked behind the scenes with renewed vigor spurred on by hard lessons from the pandemic. Cell-line development and engineering are no exception. Already undergoing a…

Increasing Expression Titers: New Technologies Could Help Other Cell Lines Catch Up to CHO

Fang Tian is a lead scientist and head of cell biology research and development at the American Type Culture Collection (ATCC) in Manassas, VA. She is a member of both the International Cell Line Authentication Committee (ICLAC) and the US technical advisory group for the ISO/TC276 technical committee. At ATCC, she oversees preparation, authentication, characterization, quality control, and cryopreservation of more than 3,400 accessioned animal cell lines and hybridomas in the cell biology general collection. She holds a PhD in…

Engineering Alternatives: Modern Technology Enables Expression System Developers to Think Beyond CHO Cells

Major biopharmaceutical companies are teaming up with academics and the Bill & Melinda Gates Foundation to develop new biomanufacturing cell lines and methods. The project — known as the AltHost Consortium — is exploring innovative ways to produce biologics and vaccines for clinical usage in diseases from diabetes to cancer. Lead researcher J. Christopher Love at the Massachusetts Institute of Technology (MIT) likens this precompetitive, open-access collaboration to the early days of the biopharmaceutical industry. “When biomanufacturing first emerged as…

Cell-Free Expression: A Technology with Truly Disruptive Potential

Bioprocess engineer Beatrice Melinek is a postdoctoral research fellow at University College London’s Future Targeted Healthcare Manufacturing (FTHM) Hub, where she focuses on the use of cell-free protein synthesis (CFPS) as a platform for distributed production of stratified biotherapeutics. Previously Melinek specialized in purification of viral vectors and vaccines, with an engineering doctorate (EngD) in biochemical engineering and postdoctoral experience in UCL’s hematology department developing a new chromatography-based analytical method for measuring empty and full adenoassociated virus (AAV) capsids. She…

Technologies and Innovations: A Discussion with Selexis SA

Pierre-Alain Girod is chief scientific officer (CSO) for Selexis SA. He holds a PhD in plant biochemistry from the University of Lausanne in Switzerland and completed a postdoctoral fellowship at the University of Wisconsin in Madison, WI, on the degradation of proteins by the ubiquitin pathway. Girod returned to Switzerland in 1993, where he discovered a family of sequences that are involved in the epigenetic regulation of genes. That discovery subsequently has been used to express therapeutic proteins in the…

Oxygen Control Strategy and Yield of Recombinant Antibody Fragments Produced in Fermentation

Immunoglobulin molecules are used extensively in therapeutic treatments, diagnostic applications, and fundamental academic research. Traditionally, full-length antibodies and smaller fragments such as the recombinant antigen-binding fragment (rFab) are produced through mammalian cell culture. rFabs also are small enough to be produced in Escherichia coli through fermentation (1, 2). Because disulfide bonds cannot be formed efficiently in the reducing cytoplasm of E. coli, rFabs are supplemented most commonly with a signal sequence that directs them to the more oxidizing bacterial periplasm…