In an article recently published in the journal Biomaterials, researchers discussed the creation of cultured meat from palatable microcarriers using emulsion-templated microparticles with variable stiffness and structure.
Study: Emulsion-templated microparticles with tunable stiffness and topology: Applications as edible microcarriers for cultured meat. Image Credit: dropStock/Shutterstock.com
For the future of food systems, it will be crucial to diversify protein production techniques. While livestock is a significant source of dietary protein, novel protein production systems will be necessary to meet future human consumption and nutritional needs due to the world's expanding population and vulnerability to climate variability. Reducing the industrial-scale production of meat could enhance environmental and public health by lowering greenhouse gas emissions and animal waste discharge. The industry for plant-based meats has seen rapid growth and demand, yet the bulk of consumers still prefer to eat genuine meat. The quickly emerging field of cultured meat, which tackles the difficulty of producing muscle ex vivo, might offer an alternative strategy for meat manufacturing.
When compared to industrial meat production, life cycle analyses (LCAs) have demonstrated that cultured meat production has the potential to produce significant reductions in the emissions of greenhouse gas and land use. But it will be crucial to create cultured meat with the desired nutritious and sensory characteristics that consumers demand. For decades, tissue engineering and biomaterial methods, such as 3D printed scaffolds or nanofiber sheets, have made it possible to grow skeletal muscle tissue in vitro at the laboratory scale. Adapting cells to grow in suspension in a bioreactor is one strategy, but in vivo, muscle tissue cells are connected to the extracellular matrix (ECM). Edible scaffolds offer a viable method for improving process efficiency, which is crucial for large-scale cultures.
About the Study
In this study, the authors discussed the utility of palatable microcarriers that could facilitate myogenic cell proliferation and differentiation in a single bioreactor system. They demonstrated the development of gelatin microparticles from water-in-oil emulsion templates to produce edible microcarriers in a scalable manner. In order to investigate whether edible microcarriers with striated surface textures could stimulate myoblast proliferation and differentiation in suspension culture, a unique embossing process to imprint edible microcarriers with grooved topology was also created.
For cells cultivated on both smooth and grooved microcarriers, the development of cell-microcarrier aggregates or "microtissues" during the expansion phase was monitored.
The team created edible microcarriers with adjustable surface topology and dynamics for use with cultured meat. Microcarriers were created out of gelatin and microbial transglutaminase (MTG), a food-grade crosslinking enzyme, as proof of concept for the proposed strategy.
The usage of artificial polymers, extra small molecule chemical crosslinkers, or chemical modification of protein side groups was not necessary with the proposed method. A scalable method was developed for the creation of edible microcarriers out of water-in-oil emulsions, which made it simple to create hydrogel microparticles with a smooth surface and a spherical form.
The researchers developed an embossing technique to imprint grooved surface topology on the edible microcarriers in order to test the hypothesis that microcarrier surface topology improved myogenesis. This method was developed in light of previous research that showed that striated substrates encourage myoblast proliferation and myotube formation. This study's major objective was to evaluate the usefulness of spherical, rounded, and grooved edible microcarriers for supporting the development of myogenic tissue for culinary purposes.
Math suggested that a 40 L bioreactor might generate 1 kilogram of meat. In comparison to undifferentiated cells cultured on tissue culture plastic, cells on both types of edible microcarriers displayed equal 102–104-fold increases in Mef2c and Myh4 expression.
The statistical significance of this increase was comparable to cells differentiated on tissue culture plastic. The microcarriers made up 46 ± 13 vol% of the sMC and 35 ±18 vol% of the gMC microtissues, with cellular matter filling the remaining spaces. The percentage of myotubes in the cellular volume component of microtissues was 39 ±13% for sMCs, 33 ± 7% for gMCs, and 7 ± 6% for Cytodex, which demonstrated that edible microcarriers supported a substantially greater myotube fraction than the Cytodex carriers.
The average length of myotubes in the 3D volume of the microtissues was 118 ± 63 μm for sMC, 126 ± 58 μm for gMC, and 32 ± 19 μm for Cytodex. Aggregates with cells and sMCs had an average diameter of 755 ± 257 after 7 days in culture, while aggregates with cells and gMCs measured 601 ± 169 μm. Using widefield and confocal microscopy, cells were adhered to various kinds of microcarriers at 1, 4, and 7 days after seeding.
The gelatin solution between the molds displayed liquid-like behavior, and the droplets tended to fuse to one another when there was no pre-crosslinking or when the partial crosslinking time was less than 5 minutes. This led to embossed microcarriers with irregular shapes and sizes that were consistently larger than 1 mm in diameter. It was demonstrated that mouse myogenic C2C12 cells could proliferate and differentiate when placed on edible microcarriers with either smooth or grooved surface topologies. The myogenic cells produced on grooved edible microcarriers were compared to those cultured on smooth, spherical microcarriers, and it was determined that the proliferation and alignment of myogenic cells exhibited a small increase.
Myotube length, myotube volume fraction, and the expression of myogenic markers were identical in myogenic microtissues grown with smooth and grooved microcarriers. It was demonstrated that edible microcarriers supported the production of myogenic microtissue from C2C12 or bovine satellite muscle cells, which were harvested by centrifugation into a cookable meat patty that maintained its shape and demonstrated browning during cooking. This proved the viability of edible microcarriers for cultured meat. The results showed the potential of scalable cultured meat production in a single bioreactor using edible microcarriers.
In conclusion, this study provided edible microcarriers that could support the suspension culture of myogenic microtissues from bovine and murine sources. The authors investigated the grooved topology of edible microcarriers as a method to encourage the creation of myogenic microtissue. It was discovered that sMCs and gMCs had substantially comparable impacts on cell growth, differentiation, and the production of cultured meat.
The team mentioned that the proposed method for producing edible microcarriers on a large scale and the resulting muscle microtissues has the potential to aid in the production of cultured meat that is both effective and affordable. They also mentioned that this could offer a complementary alternative for the production of protein, which could ultimately help to increase the resilience of future food systems.
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Norris, S. C. P., Kawecki, N. S., Davis, A. R., et al. Emulsion-templated microparticles with tunable stiffness and topology: Applications as edible microcarriers for cultured meat. Biomaterials 121669 (2022). https://www.sciencedirect.com/science/article/abs/pii/S014296122200309X