Researchers at Tufts University have made bovine muscle cells produce their own growth signals, eliminating costly ingredients from the production process.
Growth factors, whether used in laboratory experiments or in cultivated meat, bind to receptors on the cell surface and signal cells to grow and differentiate into mature cells of various types. In the current study, published in the journal Cell Reports Sustainability, researchers engineered stem cells to produce their own fibroblast growth factor (FGF), which triggers the growth of skeletal muscle cells – the kind you find in a steak or hamburger.
“FGF isn’t exactly a nutrient,” says Andrew Stout, then the project’s principal investigator and now scientific director of the Tufts Cellular Agriculture Commercialization Lab. “It’s more of an instruction to the cells to behave in a certain way. We got bovine muscle stem cells to produce these growth factors and activate the signaling pathways themselves.”
Until now, the growth factors had to be added to the surrounding liquid, the medium. The growth factors produced from recombinant protein and sold by industrial suppliers account for a large proportion of the production costs of cultivated meat (up to 90% or more). Since the growth factors in the cell culture media do not last long, they must be replenished every few days. This limits the ability to offer the consumer an affordable product. Removing this component from the growth media results in huge cost savings.
Stout leads several research projects in the Tufts University Cellular Agriculture Commercialization Lab, a technology incubator that takes innovations at the university and develops them to the point where they can be deployed on an industrial scale in a commercial setting.
Approach could mean easier regulatory approval
“Although we have significantly reduced the cost of the media, there is still a need for optimization to make it industrial-grade,” says Stout. “We have noticed slower growth with the genetically modified cells, but I think we can overcome that.”
Possible strategies include altering the amount and timing of expression of FGF in the cell or altering other cell growth pathways. “In this strategy, we do not add foreign genes to the cell, but rather edit and express only genes that are already there to see if they can improve the growth of muscle cells for meat production. This approach could also lead to easier regulatory approval of the final food product, as regulations for adding foreign genes are more stringent than for editing native genes,” says Stout.
Stout believes this strategy could also work with other types of meat, such as chicken, pork, or fish. “All muscle cells and many other cell types typically rely on FGF to grow,” says Stout. He imagines that the approach could also be applied to other types of meat, although there may be differences in the best growth factors to express between different animal species.
“Work continues to improve cultured meat technology at TUCCA and elsewhere,” said research leader David Kaplan, “including exploring ways to reduce the cost of nutrients in growth media and improve texture, flavor, and quality nutritional content of the meat. The products are already approved for consumption in the United States and other countries, although cost and availability are still limited. I think advances like this will bring us much closer to finding affordable cultured meat in our supermarkets in the next few years.”
More information: cellularagriculture.tufts.edu