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Feliza Mirasol is the science editor for BioPharm International.
Demand for recombinant microorganism-based cell culture supplements is rising on the back of lower contamination risk.
The global market for recombinant cell culture supplements is forecast to grow more than 6% from 2021–2031 as demand rises, and specific demand for microorganism-based recombinant cell culture supplements is expected to grow at an even higher pace, driven by rising demand for animal-free cell culture supplements (1). Microorganism-based recombinant cell culture supplements offer the benefit of eliminating the risk of contamination from cell culture media and are animal-free derived material.
Among the ongoing challenges in commercial-scale cell culture using traditional media and supplements has been a reliance on further supplementing traditional media with material such as human AB serum, human serum albumin, or platelet lysate, says Alexis Bossie, director of Media R&D, Lonza. Often, these undefined supplements are bound to various cytokines, hormones, and other growth factors necessary for primary cell growth and function, but, unfortunately, lot-to-lot variation of these components often leads to differential responses from cells and can produce unwanted side effects, she states.
“Additionally,” Bossie continues, “as the number of cell and gene therapy clinical trials and commercial applications increases, the supply of these critical raw materials is becoming increasingly limited and can cause delays in patient treatments.”
Trissa Borgschulte, head of Bioprocessing Upstream R&D at MilliporeSigma, also points out that having enough capacity to supply critical, high-quality raw materials that are needed for traditional cell culture media and supplements (e.g., animal sera) continues to be a major ongoing challenge. Specifically, COVID-19 has negatively impacted many critical supply chains. “There just aren’t enough materials to supply manufacturers with what they need for their bioprocesses,” she says.
Meanwhile, one of the longer-lasting challenges surrounding traditional cell culture media and supplements is related to patient safety and stems from the potential risk of adventitious agents potentially introduced into bioprocesses from animal-derived raw materials. “To reduce this risk, there is a strong push to remove animal-derived components from modern bioprocesses whenever possible. As a result, today’s standard production processes for recombinant therapeutic proteins are chemically defined and non-animal origin (NAO),” Borgschulte says.
Sonjoy Mukerjee, PhD, principal application scientist, Cell Culture and Cell Therapy, Thermo Fisher Scientific, adds that scale-up, manufacturability, reproducibility, and achieving consistent performance are also among the challenges encountered with using traditional cell culture media and supplements. He explains that this variability in performance can result in sudden spikes in titer, variability in product quality, and difficulties with developing a consistent manufacturing process.
“Additionally,” Mukerjee continues, “there is an increased need to prevent mycoplasma contaminations through the use of 0.2-micron or even 0.1-micron filtration steps at the end of the final formulation. This poses a challenge because it adds additional steps to the process that could be avoided with the use of raw materials that are validated to more stringent bioburden specs.” Finally, variations in glycosylation profiles can limit the ability of quality control (QC) teams to release final batches because it is difficult to set these kinds of limits.
“These challenges highlight the importance of manufacturing supplements and media specifically for biomanufacturing to provide better and more consistent performance,” Mukerjee says.
Several recombinant proteins and peptides are already used in many cell culture media, including, for example, transferrin and insulin, says Bossie, who explains that using defined components in place of the alternative form that is isolated from serum leads to less lot-to-lot variability and can produce more robust cellular responses. “Elimination of human or animal sources for media components reduces the risk of virus or other contaminants and eases the regulatory burden on the final therapeutic product,” she says.
“As mentioned above,” adds Borgschulte, “today’s standard bioprocesses for the production of recombinant therapeutic proteins are chemically defined, NAO, and, in some cases, protein-free. Optimized media formulations and robust bioprocesses have resulted in manufacturing templates that only require low-molecular weight, recombinant peptide growth factors for the cell to thrive.” By contrast, however, the rapidly growing field of novel gene and cell therapies still requires more sophisticated media formulations owing to the diverse nature of cells (i.e., primary cells, embryonic and tissue-specific, regenerative stem cells, induced pluripotent stem cells) used therein, she points out.
Thus, for these close-to-the-patient cell expansions and/or differentiation media, sophisticated supplementation will need to closely mimic the bodily environment from which they are taken, Borgschulte further explains. “Not surprisingly, high-quality bovine and clinical-grade human sera, or fractionated components thereof, are still at the core of these protocols. Replacing sera with supplement cocktails containing only NAO recombinant growth factors and transport proteins is an achievable goal,” she states
Recombinant supplements are already used in commercial cell culture media. Recombinant insulin and transferrin are two examples of widely used recombinant supplements in many cell culture media, Bossie says. She also points out that cytokines and interleukins (e.g., IL-2, IL-7, IL-15) as well as other growth factors (e.g., Rho kinase inhibitor, TGF-) are common recombinant proteins used in cell culture media.
While microorganism-based substitutes for undefined serum-derived components could alleviate some of the challenges associated with commercial-scale cell culture, care must be taken, however, to also supply the additional growth factors that are non-specifically associated with the native forms of these components, Bossie cautions. For instance, trace elements, lipids, interleukins, and as-yet-unidentified other proteins might also need to be added to the cell culture medium when recombinant supplements are used in place of the native form isolated from human serum.
“Determining the optimal concentrations of all of these ingredients can be a time-consuming discovery effort,” Bossie says. Moreover, the costs associated with additional components can result in an extremely expensive medium, resulting in an additional cost burden to the therapeutic product.
Demand for recombinant animal-free components in cell culture media is growing especially on the back of concerns regarding contamination in raw materials. Borgschulte points to the threat to the supply of porcine trypsin (African Swine Fever) and general animal-origin concerns, as well as the current need to accelerate COVID-19 vaccine programs, for example, as driving factors for increased recombinant animal-free cell culture components.
Meanwhile, peptone hydrolysates, specifically manufactured for biomanufacturing, are being widely used in both pre-clinical and all phases of clinical trials as well as many marketed molecules, emphasizes Mukerjee. “Successful applications include monoclonal antibodies, microbial fermentation applications, and various vaccines for both human and animal health,” he says.
In the area of cell therapies, there is need for greater consistency as well as higher regulatory standards, which is also driving the increased use of recombinant growth factors wherever possible, says Bossie. “This trend should be expected to continue,” she continues, adding that “hurdles to greater utilization of recombinant proteins revolve around the need to more completely understand the metabolic demands of the cells to be able to provide all of the necessary ancillary factors bound to or associated with the serum-derived components.”
Once there is greater utilization of the recombinant proteins in place of serum-derived ingredients, however, the economies of scale in their manufacture and increased competition among manufacturers should serve to drive down costs of these materials, Bossie adds. Until then, the high cost of some recombinant proteins might limit their adoption, she says
Furthermore, NAO alternatives reduce the risk of introducing adventitious agents to the biomanufacturing process, Borgschulte confirms. Additionally, recombinant cell culture supplements can offer more consistent purity and activity levels, she explains. “In the growing field of cell and gene therapy, high-quality animal derived supplements are still commonly used. However, replacing these supplements with NAO recombinant growth factors and transport proteins is the direction of the future,” she states.
“Many companies in this space are looking for lot-to-lot consistency for the media and supplements that they use in their processes,” adds Mukerjee. These companies also want full traceability of the components that make up the media and supplements. “These are a couple of the drivers towards microorganism-based recombinant cell culture supplements and media. It’s possible that these type of supplements and media could replace traditional supplements and media, but it would come at a higher cost. The incremental added benefits of these newer supplements might not outweigh this increased cost and given that there are many high-quality options on the market right now, it’s not likely that companies will be making the switch anytime soon,” he concludes.
1. Persistent Market Research, “Recombinant Cell Culture Supplements Market,” www.persistencemarketresearch.com, February 2021.
Feliza Mirasol is science editor for BioPharm International.
Vol. 34, No. 5
When referring to this article, please cite it as F. Mirasol, “Recombinant Supplements Offer Lower Risk of Cell Culture Contamination,” BioPharm International 34 (5) 2021.