Artificial beef jerky, do you dare to try it?

Produced by: Science Popularization China

Author: Denovo Team

Producer: China Science Expo

As global beef consumption continues to grow, how to meet people's demand for meat has become an important issue.

Behind this problem, an emerging field is emerging, it is called cellular agriculture. With this technology, in the future we may no longer need real farms to raise beef cattle, we can taste delicious beef jerky - this sounds like a plot of a science fiction movie, but in fact, cellular agriculture is gradually becoming a reality.

beef

(Photo credit: Photo taken by the author)

What is cellular agriculture?

Cellular agriculture is a revolutionary way to produce food directly using cell culture technology. By growing and multiplying animal cells in the lab, we can produce food that is similar to traditional meat without the farming and slaughtering process.

Through cellular agriculture technology, there is no need to raise a whole animal. It is enough to cultivate the part we eat. For example, when we just want to eat steak, there is no need to go through the trouble of cultivating bones, horns, hooves and other tissues or organs.

Schematic diagram of the process of cellular agriculture, which does not involve animal farming, but an industrialized cell culture process

(Image source: Reference [3])

What is the process of culturing beef cells?

If you want to eat artificial beef jerky, you have to start with the cultivation of bovine muscle stem cells. The entire process of cultivating bovine stem cells is very complex, precise and energy-intensive.

First, muscle cells extracted from bovine tissue are cultured in the laboratory. In a small flask, these cells are cultured in a special nutrient solution that provides the growth factors, hormones, recombinant proteins and other substances that regulate cell growth necessary for cell growth. Over time, the initial seed cells will begin to multiply and gradually form larger bioreactors. This process requires maintaining a specific ratio of cells and nutrient solution to meet the growth needs of the cells.

Petri dishes and nutrient solution for cell culture

(Image source: Wikipedia)

However, scientists still face a challenge: bovine muscle stem cells extracted from living animals can usually only divide about 50 times during the culture process, and then they will enter an aging state and can no longer survive.

This threshold of 50 doublings is called the Hayflick limit. The Hayflick limit refers to the limited number of divisions of most mammalian somatic cells. This concept was proposed by Leonard Hayflick in the 1960s. The cell division limit is due to the shortening of telomeres, a special structure at the end of chromosomes, every time a cell divides. Each time a cell divides, the telomeres shorten to a certain length. When the telomeres shorten to a certain extent, the cell can no longer divide and enters a state of stagnation or apoptosis (cell death).

During cell division, the telomeres (red parts) at the ends of chromosomes will continue to shorten, eventually causing the cell to be unable to continue dividing.

(Image source: Wikipedia)

To address this problem, researchers at the Tufts University Center for Cellular Agriculture developed immortalized bovine muscle stem cells (iBSCs) that can grow rapidly and divide hundreds of times, potentially even indefinitely.

Will these immortalized bovine muscle stem cells become cancer cells?

In a study published in ACS Synthetic Biology, researchers at Tufts University engineered bovine stem cells to continuously rebuild their telomeres, effectively keeping the chromosomes "young" and preparing for a new round of replication and cell division. These cells achieved more than 120 divisions.

Screenshot of the ACS Synthetic Biology article

(Image source: author)

The researchers note that one concern about the development of immortal cells is that they could develop into cancer cells, because cancer cells are cells that proliferate and divide abnormally, bypassing the normal cell's regulatory mechanism for the Hayflick limit.

However, according to their research, these immortalized bovine muscle stem cells did not exhibit carcinogenic properties. When the researchers injected the cells into mice, they did not find that the cells were able to form tumors or spread in the mice (which are usually the characteristics of cancer cells). In addition, they also observed the cells in a laboratory environment for a long time and did not find any aberrations or abnormal growth characteristics of the cells.

How will meat production change in the future?

With the development of technology and the popularization of cellular agriculture, we can foresee that meat production methods will become further diversified in the future.

One of the advantages of cellular agriculture technology is that it can greatly improve the efficiency of meat production. For example, according to a report by Open Philanthropy, a mature and scaled-up cell-cultured meat industry may eventually achieve the goal of using 3-4 calories of energy to produce 1 calorie of edible protein. If animals are raised, this ratio is 1 calorie of edible protein for every 10 calories consumed in chicken and 25 calories for beef.

Of course, consumers may be more concerned about two other points: price and taste. Although artificial meat is currently expensive and tastes significantly different from real meat, there may be room for improvement in the future.

In terms of taste, we have already seen the dawn of artificial meat: in 2019, Israel's Aleph Farms announced that they had successfully used cell culture technology to produce a steak with good color, aroma and taste. This product has been verified in an actual restaurant environment and has received positive feedback from consumers.

In general, although cellular agriculture faces many challenges, it has certain potential and may become one of the important ways of food production in the future.

References:

【1】Stout, Andrew J., et al. "Immortalized bovine satellite cells for cultured meat applications." ACS Synthetic Biology (2022).

【2】Hayflick, Leonard. "The limited in vitro lifetime of human diploid cell strains." Experimental cell research 37.3 (1965): 614-636.

【3】Reiss J, Robertson S, Suzuki M. Cell sources for cultivated meat: applications and considerations throughout the production workflow[J]. International Journal of Molecular Sciences, 2021, 22(14): 7513.