Pioneering cell-based player Mosa Meat has published a peer-reviewed paper revealing how it achieves muscle differentiation in cultured meat without the use of fetal bovine serum (FBS) and without genetically modifying the cells in any way.

FBS has conventionally been used in cultured meat production as a supplement for cell feed – also known as cell culture media – due to its richness in nutrients and growth factors.

In 2019, Mosa Meat successfully removed fetal bovine serum and other animal components from its entire process. 

However, this solution has been flagged as unsustainable, unethical and not scalable, due to its process of being harvested from the blood of fetuses taken from pregnant cows slaughtered in meat or dairy supply chains.

“Our cell feed uses non-animal components or ingredients to stimulate differentiation of the cells into muscle,” Maarten Bosch, CEO of Mosa Meat, tells FoodIngredientsFirst. “Although the decision to publish this information could be seen as competitively sensitive, we highly value openness and transparency for the advancement of the entire cellular agriculture field.”

Growth medium proteins are not widely available in the market today and represent one of the most prohibitive expenses in scaling up cultivated meat.“We studied the natural growth process extensively (including with RNA sequencing) and discovered which ingredients to use in which step to enable cells to become muscle fibers without FBS,” he details.

When is cultured meat truly slaughter-free?
In 2019, Mosa Meat shared a significant milestone with industry – successfully removing FBS and other animal components from its entire process. 

The company’s nclick="updateothersitehits('Articlepage','External','OtherSitelink','Mosa Meat eliminates fetal bovine serum from the cultivated meat equation','Mosa Meat eliminates fetal bovine serum from the cultivated meat equation','325812','https://www.nature.com/articles/s43016-021-00419-1', 'article','Mosa Meat eliminates fetal bovine serum from the cultivated meat equation')">newly published paper in Nature Food includes descriptions of processes and differentiation medium ingredients that have worked well in its cultivation process.

In the paper, Mosa Meat’s researchers describe changes that occur to stem cells when they turn into muscle through a process known as serum-starvation, a process of abruptly reducing FBS in the cell feed.

Muscle cells differentiating into fibers are responsible for the structure and chew of meat, and within muscle fibers the proteins and rich color of meat are produced.

“We were particularly interested in proteins on the surface of cells that increase during differentiation. By specifically activating these proteins (known as ‘receptors’), we are now able to recreate the same transition in the absence of any fetal bovine serum,” explains Tobias Messmer, first author and PhD candidate at Mosa Meat.

Using a method called RNA sequencing, the researchers can study the changes in gene expression that the cells undergo when they differentiate into muscle.

“This is really a milestone for us and for the cultivated meat field, because there’s no method out there that describes the differentiation of primary satellite cells if you don’t want to use fetal bovine serum or genetically modify your cells,” remarks Mosa Meat scientist and corresponding author on the publication, Dr. Joshua Flack.

Proprietary but accessible
Bosch shares that the company doesn’t have any growth medium cost numbers to share with its recent announcement, because its article is a scientific proof of principle, not a commercial one. 

“The described medium formulation is used in our R&D setting which is not representative of cost structure in scaled production,” he notes. “We are constantly bringing the costs down.”

The continued use of fetal bovine serum in cultured meat production would arguably pose an ethical dilemma for adherents of the halal and kosher diets.Mosa Meat has filed a patent for its cell feed formulation, meaning it is publicly available but protected for commercial use for a limited amount of years.

The absence of fetal bovine serum was part of the company’s latest funding round agreements as a hard requirement, signed by all participating shareholders. 

“We highly value openness and transparency for the advancement of the entire cellular agriculture field,” says Bosch. “Academic researchers are free to use this methodology, and we look forward to sharing more peer-reviewed work in the future.”

Addressing a prohibitive expense
Growth medium proteins are not widely available in the market today and represent one of the most prohibitive expenses in scaling up cultivated meat. And while this is a key consideration, curbing the cell-based industry’s reliance on fetal bovine serum is pivotal to its “cleaner meat” philosophy.

In a study published in Biochemical Engineering Journal, Liz Specht, senior scientist at the Good Food Institute, estimates that a standard 20,000 liter batch of cells cultured using fetal bovine serum, would yield between 1,800 and 4,500 kg of meat.

Over recent months, early movers in the cell-based arena have been ramping up investments in the science of fetal bovine serum substitution. For instance, Aleph Farms partnered with protein tech supplier Wacker last December to develop new fermentation-based growth medium proteins. 

The continued use of fetal bovine serum in cultured meat production would arguably pose an ethical dilemma for adherents of the halal and kosher diets. “There doesn’t seem to be broad consensus yet, as the exact processes of different companies are still under development,” comments Bosch.

In a recent interview, FoodIngredientsFirst spoke with Israel-based start-ups Aleph Farms and SuperMeat, as well as experts from the UK’s United Synagogue and the Islamic Chamber of Halal Certification Services (ICHCS) about how modern cultivation can be reconciled with ancient traditions and rituals.