Lab-grown fish fillets promise to save yellow croaker fish from extinction

Can lab-grown fillets replace real fish meat?

Besides its sweet taste, yellow croaker is known for its high protein, micronutrients, and omega-3 fatty acid concentration. Moreover, about 80 percent of the fish’s body mass is made up of fat and muscles. The Chinese researchers claim that their lab-grown fillet has similar nutritional value to a real croaker fish fillet. 

When they compared the lab-grown fillet with the original fillets, they found that both had the same muscle-to-fat cell ratio, water percentage, and other physical attributes. However, the lab-grown fillets required less chewing when consumed. 

The researchers also detected noticeable differences in how water was distributed in their muscle cells. They hope to overcome such small differences with further research and believe, “This technology may provide support for addressing the supply of meat and animal protein for human beings.” 

“It also has important implications for the conservation of marine fish stocks,” Liu Donghong, one of the study authors from ZJU, told SCMP. 

So how did they create lab-grown fish fillets?

The study authors collected stem cells from a yellow croaker fish's muscle and fat tissues and cultured them in a medium. Initially, they noticed slow growth in muscle stem cells, so they studied different genetic pathways to trigger their growth. 

They examined several factors that could affect the cells, “Among them, two signaling pathways, Notch and TGF-β, attracted our attention in particular. A balance between Notch and TGF-β signaling regulates the proliferation of satellite cells (give rise to skeletal muscles), and attenuation of TGF-β restores regeneration in old, injured muscle,” the researchers note. 

When they inhibited both these pathways, the muscle cells in the culture also started growing and multiplying at a normal pace. The fish meat also began to take shape but even until this point it was loose. It lacked the tissue formation to be considered similar to real meat.

To provide the meat a proper structure and texture, the researchers shifted the culture into a 3D scaffold made out of satellite cells and gelatin-based gel. Finally, the fillets were ready, 

The cell culture took 17 days to turn into real-like lab-grown fish meat. Hopefully, these lab-grown fish fillets will play a significant role in restoring the yellow-croaker population, and their success will also open doors to other kinds of lab-grown marine meat products. 

The study is published in the journal Science of Food.

Study Abstract:

Tissue-like cultured meats of some livestock have successfully been established by different approaches. However, the production of a structure similar to fish fillets is still challenging. Here, we develop tissue-like cultured fish fillets by assembly of large yellow croaker muscle fibers and adipocytes with 3D-printed gel. Inhibition of Tgf-β and Notch signals significantly promoted myogenic differentiation of piscine satellite cells (PSCs). The mixture of fish gelatin and sodium alginate combined with a p53 inhibitor and a Yap activator supported PSC viability and proliferation. Based on the texture of fish muscle tissue, a 3D scaffold was constructed by gelatin-based gel mixed with PSCs. After proliferation and differentiation, the muscle scaffold was filled with cultured piscine adipocytes. Finally, tissue-like fish fillets with 20 × 12 × 4 mm were formed, consisting of 5.67 × 107 muscles and 4.02 × 107 adipocytes. The biomanufacture of tissue-like cultured fish fillet here could be a promising technology to customize meat production with high fidelity.