Expression Platforms

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…

Technology to Transform AAV Manufacture

Adenoassociated virus (AAV) vectors are a popular choice for modern gene therapies because of their favorable safety profile, low immunogenicity, and the ease with which they can be transduced into different cell and tissue types. An AAV genome is a single strand of DNA comprising a replication (rep) gene, which encodes regulatory proteins involved in genome replication, and a capsid (cap) gene, which produces three capsid proteins. However, AAVs cannot replicate alone. In nature, AAV shares an exquisite relationship with…

Optimizing Cell Line Development for High-Quality Biologics

For a host-cell system to generate high yields of recombinant proteins and other entities, cells must be derived from optimized and stable cell lines. However, cell line development (CLD) can be tedious and time-consuming work, and every stage in the CLD workflow has its limitations and challenges. Researchers are creating advanced strategies and tools to overcome those challenges, especially for complex biologics such as bispecific antibodies (BsAbs) and difficult-to-express (DTE) proteins. Online presentations from the CLD track of the BioProcess…

Plant-Cell Cultures and Cell Lines for Recombinant Protein Expression

Cell cultures derived from mammalian and bacterial cell lines are the conventional production systems in bioprocessing. But they also have their limitations. Media for mammalian cultures in particular are notoriously expensive, and traditional cell cultures can be highly sensitive to growing conditions. During the late 1980s and into the 1990s, plants and plant-derived cell cultures were introduced as alternative cell-culture systems (1, 2). Although transgenic plants (genetically modified) once looked promising in the early 2000s, the cost and manufacturing complexity…

Toward a Roadmap for Cell-Free Synthesis in Bioprocessing

Cell-free synthesis (CFS), also known as cell-free transcription and translation, supplements cellular components (either a cell lysate or purified recombinant elements) with nucleotides, amino acids, metabolic intermediates, and salts to produce a nucleic acid or protein from a genetic template added to the reaction. This exciting technology has seen a substantial increase in both academic and commercial interest over the past decade (1). Interest stems in large part from the potential to democratize access to the machinery of biology by…

Microbial Expression and Purification: One Company’s Historical Perspective

Since the dawn of the recombinant DNA era in the 1970s, New England Biolabs (NEB) has been integrally involved in expressing and purifying proteins, both for its own research interests and for biomanufacturing processes. In 1978, the company began screening microorganisms for restriction enzymes. Our scientists remember the challenges met in purifying limited amounts of restriction enzymes and other proteins from native organisms isolated from the environment. The efforts of those scientists to clone, overexpress, and purify restriction enzymes from…

eBook: Expression Systems — Innovative Techniques for Conventional Cell Lines

Although Chinese hamster ovary (CHO) and Escherichia coli cells have become the biopharmaceutical industry’s preferred platforms for producing recombinant proteins, perennial challenges have limited the capabilities of those expression systems. New CHO lines and improved upstream methods steadily are increasing expression titers, yet researchers continue to decry CHO’s relatively low growth rate. E. coli exhibits strong growth kinetics but cannot perform posttranslational modifications necessary for complex therapeutic proteins. Researchers need advanced technologies and analytical methods to overcome such limitations. This…