(Nanowerk News) A team of researchers from the National University of Singapore (NUS) have successfully used a common plant protein to 3D print an edible cell culture scaffold, enabling more affordable and sustainable laboratory meats to be brought to the table.
As consumers become more aware of the environmental and ethical consequences of their food, laboratory grown meat, also known as cultured meat or cell-based meat, is becoming an increasingly popular source of dietary protein. Cultured meat is produced by taking skeletal muscle cells from animals and growing them on three-dimensional constructs called scaffolds, which provide structural support as cells proliferate and develop into tissue.
However, cell culture scaffolds are usually made from synthetic or animal-derived materials, which are either too expensive or not edible. To find alternatives, the team led by Professor Huang Dejian, Deputy Head of the Department of Food Science and Technology at NUS, turned to plant proteins, which are known to be biodegradable and biocompatible with animal cells. Most importantly, vegetable protein also meets the general requirements for food consumption, making the resulting scaffolds suitable for meat cultivation.
“By using readily available cereal prolamins as a biomaterial for high-precision 3D printing technology, we open up a new method for fabricating structured and edible scaffolds to produce muscular cutlets of fibrous quality,” said Prof Huang.
The team’s work, in line with NUS’ desire to produce cutting-edge sustainability research, is published in a journal Advanced Materials (“3D Printed Prolamin Scaffolds for Cell-Based Meat Culture”).
Manufacture of edible scaffolding
Prolamins are a family of plant storage proteins which, due to their specific amino acid profile, are of low nutritional value. In fact, prolamins are generated as waste in the starch and vegetable oil industries. However, Prof. Huang and his team take advantage of these characteristics of prolamin to produce affordable and sustainable beef cultivation resources.
Specifically, the researchers used a mixture of prolamins derived from corn, barley, and rye flour, also known as zein, hordein, and cecalin, respectively. This mixture then acts as an ink for electrohydrodynamic printing, a high-precision 3D printing technology commonly used in biomedical applications.
To assess whether the prolamin constructs were suitable for meat culture, they were immersed in cell culture media and examined seven days later to check for any structural changes. Under a scanning electron microscope, the scaffolds retain their structure and do not collapse, even though many holes develop on their surface. However, according to the researchers, these pores are more likely the result of enzymes secreted by the cultured cells than evidence of structural weakness.
For the scaffold to be used in cultivating meat, it must be biocompatible with muscle cells from livestock, meaning it must be able to accommodate these cells and support their growth and development.
To test this, Prof Huang and team seeded the prolamin construct with stem cells from pig skeletal muscle and measured cell proliferation over the following days. They found that cells divided extensively on the scaffolds, reaching a maximum number 11 days after inoculation. Stem cells grow well in the zein/hordein and zein/secalin scaffolds.
Of significance, when compared to standard polycaprolactone scaffolds, a common tool in tissue engineering, pig cells seeded to prolamin constructs proliferate more rapidly, indicating that plant protein based scaffolds are more feasible for cultured meat production than standard synthetic polymers.
The scaffolds made from vegetable protein are edible and have multiple and varied peptide sequences that can facilitate cell attachment, induce differentiation, and accelerate growth of meat. In contrast, synthetic scaffolds such as plastic beads used for cultured meat lack the functional groups that make it difficult for animal cells to attach and proliferate. In addition, synthetic scaffolds are not edible and extra steps are needed to separate the scaffolds from the meat culture,” explained Prof Huang.
As a proof of concept, the research team tried to produce an actual piece of meat by culturing pork skin stem cells on a zein/secalin scaffold, and then allowing them to differentiate, or mature, into muscle. Beet extract is used to simulate the reddish color of the meat.
Their experiment turned out to be a success. Within 12 days, the research team was able to culture meat that was similar in texture and appearance to real animal flesh.
“Because the scaffolds are edible, no special or additional procedures are required to extract them from the final product,” said Prof Huang. These results further verify the potential of the proposed prolamin-based scaffolds in cultured meat production.”
Prof. Huang and his team are actively trying to perfect vegetable protein-based technologies. For example, further research is needed to better determine how the particular structures and compositions of prolamin constructs can influence the growth of animal stem cells and how they form muscle tissue.
“In addition, we need to ensure that the resulting meat products are ready for market, with a safety profile that will meet the demands of strict regulations and a nutritional composition that will meet the recommended dietary needs,” said Prof. Huang. “Of course, they also have to be appetizing. Taste, aroma and texture need to be carefully calibrated to compete with traditionally farmed meat products.”