Bovine muscle designed to produce its own growth signals

Cellular agriculture – producing meat from cells grown in bioreactors rather than harvested from farm animals – is making technological advances that make it a more viable option for the food industry. Such progress has been made at the Tufts University Center for Cellular Agriculture (TUCCA), led by David Kaplan, Stern Professor of Engineering, in which researchers have created bovine (beef) muscle cells that produce their own growth factors, a step which can significantly reduce production costs.

Growth factors, whether used in laboratory experiments or for cultured meat, bind to receptors on the surface of cells and provide a signal for cells to grow and differentiate into mature cells of different types. In this study published in the journal Cell reports sustainabilityResearchers modified the stem cells to produce their own fibroblast growth factor (FGF) that triggers the growth of skeletal muscle cells, like those found in a steak or hamburger.

“FGF is not exactly a nutrient,” said Andrew Stout, scientific director of the Tufts Cellular Agriculture Commercialization Lab and principal investigator on the project. “It’s more like an instruction for cells to behave in a certain way. What we did was engineer bovine muscle stem cells to produce these growth factors and activate the signaling pathways themselves. “

Until now, growth factors had to be added to the liquid or the surrounding environment. Made from recombinant proteins and sold by industrial suppliers, growth factors contribute to the majority of the cost of producing cultured meat (up to 90% or more). Since growth factors do not last long in cell culture media, they also need to be replenished every few days. This limits the ability to provide an affordable product to consumers. Removing this ingredient from the growing medium results in huge savings.

Stout leads several research projects at Tufts University’s Cellular Agriculture Commercialization Lab, a technology incubator created to take the university’s innovations and develop them to the point where they can be applied on an industrial scale in a business environment.

“Even though we have significantly reduced the cost of media, there are still some optimizations that need to be made to make it industry-ready,” Stout said. “We saw slower growth with the engineered cells, but I think we can overcome this problem.” Strategies may include altering the level and timing of FGF expression in the cell or altering other cell growth pathways.

“In this strategy, we don’t add foreign genes to the cell, we simply modify and express genes that are already present” to see if they can improve the growth of muscle cells for meat production. This approach could also lead to simpler regulatory approval of the final food product, since regulations are stricter for the addition of foreign genes than for native gene editing.

Will the strategy work for other types of meat, such as chicken, pork or fish? Stout thinks so. “All muscle cells and many other cell types generally rely on FGF to grow,” Stout said. He envisions the approach being applied to other meats, although there may be variability in the expression of the best growth factors across species.

“Work continues at TUCCA and elsewhere to improve cultured meat technology, including exploring ways to reduce the cost of nutrients in growth media and improving the texture, taste and nutritional content of meat” , Kaplan said.

“The products have already received regulatory approval for consumption in the United States and internationally, although costs and availability remain limited. I believe advancements like this will bring us much closer to seeing affordable, cultured meat in our local supermarkets in the coming years. »