One of the major bottlenecks in the production of cultivated meat products is the high cost of cell culture media and the animal-derived supplements that are included in that media. Media is essential for the survival, proliferation, and differentiation of cells being cultured. However, cell culture media that is typically used for mammalian cell culture in research settings can cost upwards of $300 per liter (Specht, The Good Food Institute). When calculating how much it would cost to sustain a series of bioreactors (each of which would have multiple liters of media) for cultured meat production, the cost adds up quickly. For example, a bioreactor that is 20,000L would cost upwards of $7 million to fill (not accounting for possible bulk discounts and wholesale prices) (Specht, The Good Food Institute). At this price, it is estimated that it would take around $8,000 worth of media to produce around two pounds of meat. Because this price is unsustainable and not competitive with current meat products on the market, it is essential to bring the cost of cell culture media down.
It is important to note that all the calculations and prices listed are made under the assumption that the cell culture media being used is an animal-free medium, specifically the Essential 8 medium that is made up of: DMEM, ascorbic acid-2-phosphate magnesium, sodium selenium, FGF2, insulin, transferrin, and TGFβ (Chen). While Essential 8 has been shown to be sufficient for the proliferation and differentiation of cells in culture, studies have shown that the use of it results in decreased cell yield compared to other cell culture medias that include serum (O’neill) (Reiss). So what is serum? Serum is the liquid portion of blood that separates from cells, fibrinogens, and proteins through a settling or centrifugation process. It includes many components conducive to cell growth, however, the exact composition of the serum isn’t fully characterized. Some components it may include are growth factors, antibodies, and other macromolecules. For cell culture, serum is added to the culture medium in small volumes to supply growth factors, hormones, and other factors that help with cell viability and growth. Fetal bovine serum (FBS) is the most commonly used serum that is added to basal media. There are several issues with the use of FBS for cultivated meat. The first, and perhaps most obvious, issue is that it is an animal derived product. Additionally, FBS is an undefined reagent making it difficult to rely on as the quality and exact composition may change from batch to batch. Finally, its supply is finite and it is expensive.
Because of these issues with cost and sourcing of cell culture media and its components, the cellular agriculture industry must find alternatives to ensure that their final products will be at price parity with animal-based products on the market. The white-paper published by the GFI titled ‘An analysis of culture medium costs and production volumes for cultivated meat’ nicely highlights several scenarios that could be used to bring down the cost of cell culture media including: reducing the amount of components added to the basal media, increasing production of FGF2 and TGFβ (two of the most expensive components in the essential 8 media), and replacing HEPES which is a pH buffer (Specht, The Good Food Institute).
In addition to the methods outlined by the GFI, there are already several companies that are working to address this issue from multiple angles. These companies can be divided into a couple of groups: companies that are directly making components for cell culture media, and companies that are making tissue products and inherently have come up with animal-free culture systems during their R&D process. I will focus on the companies that are making components for cell culture media. Of these companies, many of them are addressing the need to produce cheaper components of cell culture media (including FGF2 and TGFβ). Enantis, ORF Genetics, and Future Fields already have products on the market for FGF2 that are much more affordable than the FGF2 product used in the GFI predictions. For example, using FGF2 from R&D Systems it would cost upwards of $4 million to provide enough FGF2 for a 20,000 liter bioreactor (Specht, The Good Food Institute). Using Future Field’s Ento-F FGF2 Growth Media Supplement, you could get the same concentration of FGF2 in 20,000 liters of media for only $30,000.
What makes these companies unique and how are they addressing this need for cheaper media components? Many of the companies listed are manufacturing recombinant proteins using novel expression systems. Future Fields uses drosophila (a fruit fly) as their expression system and has termed this new technology ‘EntoEngine’. One of the major benefits of using the fruit fly as their expression system is that fruit flies produce complex protein forms that other expression systems, such as yeast, cannot. A couple of other companies (Bright Biotech and ORF genetics) are using plants as their expression system. Finally, a couple of these companies are focusing on the development of software that will enable them to produce growth factors and growth factor mediums that meet their client’s need. For example, Multus Media uses their machine learning technology to optimize the growth factors in a given media for the end use. A summary of some of the companies in this space can be found in the table below:
While many of these companies are attacking the most pressing issue head on (the cost of cell media components) there are additional layers to this problem that will need to be addressed in the future. For example, when thinking about only one formulation of cell culture media, we are ignoring the fact that certain cells have certain needs. How will these different needs change the problem we are addressing? When formulating a cell culture media, companies will need to consider what their starting material is and what their end goal is, and those two points will undoubtably impact their needs from their media. We know that cell culture media is essential for providing cells with the nutrients they need to grow and survive. It also can provide important information on when to differentiate and what to differentiate too. Are there other ways that we can provide this information to the cells? There is a body of work demonstrating that mechanical queues are also important in influencing a cell’s behavior, specifically it’s differentiation trajectory (Je) (Park). What technologies can be developed that are focused on scaffolds in the proliferation bioreactors? Providing other growth and differentiation stimuli may be another approach to offset the amount of components needed in the media.
The work being done by these companies is essential for the viability of the cellular agriculture field. While it may seem that there are several companies in this space already, there is definitely still room for growth and contributions. What other expression systems exist? How can existing waste products be used as sources for cell culture media? What other cell growth stimuli is there outside of media? Finally, how will the scope of this problem shift as the field of cellular agriculture progresses? Those with experience in protein engineering, synthetic biology, and tissue engineering may be well equipped to jump into this space with new and innovative solutions to this problem.
Sources:
Arora, Meenakshi. “Cell Culture Media: A Review.” Materials and Methods, Labome, 29 Jan. 2022, https://www.labome.com/method/Cell-Culture-Media-A-Review.html.
Chen, Guokai, et al. “Chemically Defined Conditions for Human IPSC Derivation and Culture.” Nature Methods, U.S. National Library of Medicine, May 2011, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3084903/.
Girón-Calle, Julio, et al. “Chickpea Protein Hydrolysate as a Substitute for Serum in Cell Culture.” Cytotechnology, Springer Netherlands, July 2008, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2570005/.
Je, Hyeon-Jeong, et al. “Induction of Myogenic Differentiation in Myoblasts by Electrical Stimulation.” Korean Society of Physical Medicine, Journal of The Korean Society of Physical Medicine, 31 May 2019, http://www.jkspm.org/journal/view.html?doi=10.13066%2Fkspm.2019.14.2.63.
O'Neill, Edward, et al. Considerations for the Development of Cost-Effective Cell Culture Media for Cultivated Meat Production. Comprehensive Reviews in Food Science and Food Safety, https://ift.onlinelibrary.wiley.com/doi/abs/10.1111/1541-4337.12678.
Park, Jennifer S, et al. “The Effect of Matrix Stiffness on the Differentiation of Mesenchymal Stem Cells in Response to TGF-β.” Biomaterials, U.S. National Library of Medicine, June 2011, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3073995/.
Reiss, Jacob, et al. “Cell Sources for Cultivated Meat: Applications and Considerations throughout the Production Workflow.” MDPI, Multidisciplinary Digital Publishing Institute, 13 July 2021, https://www.mdpi.com/1422-0067/22/14/7513.
Spechy, Liz. An Analysis of Culture Medium Costs and Production Volumes for Cultivated Meat. The Good Food Institute , https://gfi.org/wp-content/uploads/2021/01/clean-meat-production-volume-and-medium-cost.pdf.
