One of the many challenges facing cell-cultured meat companies is producing an affordable animal-free growth medium (early prototypes of cell cultured beef, for example, used fetal bovine serum, the liquid part of blood, a byproduct of the livestock industry, which somewhat defeats the purpose of cell-cultured meat).
Formulas are a closely guarded secret, but cell culture medium typically contains some combination of water, amino acids, sugars, salts, vitamins, buffering agents, recombinant proteins and growth factors – signaling proteins that encourage cells to proliferate and differentiate.
Growth factors can cost thousands of dollars a gram
While amino acids such as lysine, methionine and glutamate are already made in large quantities (often via fermentation for the animal feed industry) at a dollar or so a kilo, growth factors can cost thousands of dollars a gram, which is fine if you’re using them to culture cells in a laboratory, but presents something of a problem if you’re using them to produce tons of meat.
As Memphis Meats’ VP process development Dr KC Carswell noted at last year’s Cultured Meat Symposium, researchers in the nascent cell-cultured meat industry “may be ordering components for their cells in 500g bottles, but eventually we need to be talking about rail cars and barges to get the raw materials we need to make meaningful amounts of meat.”
Cambridge, UK-based CellRx – which has been supplying growth factors for technical research and bioprocessing markets for a few years – has developed a proprietary version of insulin-like growth factor-1 - ‘Short AE-IGF-1’ - at half the price of competitive products, claims Jane Lam, VP global business development & alliances, although for large scale cell-cultured meat production, prices will have to come down still further, she told FoodNavigator-USA.
“We’re 50% less compared to everyone else, but we do appreciate that the price has to be significantly less for cultured meat.”
Growth factor pricing: ‘It’s not the only limiting factor [to the commercial viability of cell-cultured meat] but it’s definitely a bottleneck that needs to be addressed’
CellRx’s Short AE-IGF-1 – which is produced via a strain of E. Coli - is 100 times more potent, in-vitro, than insulin, and matches or outperforms other market-leading IGF-1 growth factors in productivity (recombinant protein production) and viability (reduced cell death and higher cell density), claimed Lam, who said all mammalian cell expression systems that have a functional Type-1 IGF receptor will respond to it.*
“Some IGF-1 comes in a powder format, which needs to be reconstituted into a liquid that is only stable for a short time – 2-3 weeks, so to prevent degradation, manufacturers have to add stabilizers and excipients and they need to aliquot it into small quantities and freeze it at low temperatures, so it’s time consuming and there is variability.”
By contrast, CellRx’s Short AE IGF-1 is available as a stable liquid formulation and does not require reconstitution or the use of carrier proteins, excipients and additional stabilizers. It can then be added directly into formulation without further handling or risk of influencing cell culture pH and osmolality, claimed Lam.
‘Everyone keeps their media formulations very close to their chest’
But what about other growth factors beyond IGF-1?
“There is always a cocktail of growth factors that’s needed, and our expression platform lends itself to manufacture other growth factors [in addition to IGF-1],” said Lam, who has signed CDAs and NDAs with some players in the field. “Everyone keeps their media formulations very close to their chest. It would be good if there could be more transparency, but [as these startups are all competing with each other] in reality that isn’t going to happen.”
Going forward, she said, “The purity does not necessarily have to be so high for cell-cultured meat production, as long as the efficacy is there, hence we know that we can use the same process but perhaps have a different model specifically for cultured meat.
“We’ve spoken to several companies in cell-cultured meat production, and they all say the cost of growth factors is prohibitively high – plus there’s only a handful of companies producing them using a certified animal-free process.
“It’s not the only limiting factor [to the commercial viability of cell-cultured meat] but it’s definitely a bottleneck that needs to be addressed, so let’s work together to see what is possible.”
* She cited commercially available cell lines such as CHO, PER.C6, BHK, HEK 293, embryonic stem cells, mesenchymal stem cells, hematopoietic stem cells, fibroblasts, and hybridomas.
Cell-cultured meat could be cost competitive with some forms of conventional meat within a decade, according to two new studies from Dutch consultancy CE Delft using data from 16 companies* active in the field including five startups, although the authors acknowledge that data gaps exist and assumptions will change as the industry matures. (Picture credit: Aleph Farms.)
There are now several companies such as TurtleTree Labs (Singapore and San Francisco), Future Fields in Canada, and ORF Genetics in Iceland focusing on growth factors for cell cultured meat, using a variety of expression systems.