“Bammetjes” that was what researcher Anon van Essen called the structures that he has been trying to improve for the last four years. To learn more about the technology behind in vitro meat I spoke with Anon van Essen, a technician in the research group concerned with in vitro meat at Maastricht University and with Peter Verstrate, co-founder of MosaMeat, one of the first companies that aim to develop in vitro meat. The goal of this article is to make you acquainted with the technology behind in vitro meat. First, I will familiarise you with the basic concept of in vitro meat in a 5-step crash course. Then, I will discuss the current research to in vitro meat and the major technological challenges that it still faces.
1.The right cell
The first step of producing in vitro meat is taking some cells from a living animal (or from one that recently died) using biopsy. For these cells, there are essentially two options: you can either take embryonic stem cells (stem cells are cells that still have the capacity to become any type of cell) from an animal embryo or you can use the so-called satellite cells. Embryonic cells have the advantage that they can reproduce (a single cell forms two new cells by division) themselves indefinitely. So theoretically, you can produce the whole world’s demand for meat with one single cell! However, embryonic stem cells of farm animals have not been found yet – only human and rat embryonic stem cells are currently available.
Satellite cells are produced by a tissue when it is damaged and although they cannot reproduce themselves indefinitely, they are able to reproduce themselves enough times to make them useful for the production of in vitro meat. An advantage of satellite cells is that they are already differentiated (i.e. they are specialised cells, for example muscle cells) which saves you the effort to let them differentiate to muscle cells which is a rather difficult process. Another advantage of these satellite cells is that we already have the knowledge to work with them and use them to grow muscle tissue.
Although the technology of in vitro meat allows you to grow meat from all animal species – “you could even produce a Justin-Bieber-steak” as Peter Verstrate put it – it is most sensible to start producing non-human meat. So at least for now satellite cells are the basis of in vitro meat production.
2.Grow a cell culture
When you have isolated the right cells, you have to let them reproduce. The basic way to do this is putting these cells in a medium with all the necessary nutrients (including minerals, vitamins etc.) and then these cells will start to multiply themselves. Right now, a bioreactor seems the most efficient method for this.
3.Grow muscle tissue
Depending on the method you use, bioreactors give you thin layers of cells or loose cells. Because this is not a finished product yet that resembles meat, there are some more steps to take. Muscles (the main component of meat) consist of muscle cells that are organised in muscle tissue. There are several ways to let individual muscle cells form muscle tissue. One way is to inject a large number of muscle cells into a gel. These gels contain a structure (a so-called scaffold) to which muscle cells attach themselves. Then, muscle cells are activated and form muscle fibers that connect to each other and form muscle tissue around the scaffold. By scientists in Maastricht, these gels with growing muscle tissue inside are called “bammetjes”. With this bammetjes-technique – which is the most-used at the moment – it is only possible to grow very thin layers of muscle tissue. The reason for this is that the tissue does not contain veins with blood that transports nutrients and oxygen to the cells and waste away from the cells. The tissue can thus only exchange these substances with the environment at the tissue’s surface. Cells that are far away from the surface do not have access to nutrients and oxygen and therefore “suffocate”. Another possible method to create muscle tissue out of individual cells is 3D-printing these cells in a tissue-structure.
4.Exercise the muscle tissue
The product of the previous step are layers of muscle tissue. For muscle tissue to become a mature muscle, it needs to exercise (with “exercise” I mean: contraction. Like all muscles, in vitro muscles need to contract to become “strong”). Again, there are several ways to do this: one way is to let the tissue grow on a scaffold on which it can exercise itself. You can also let the tissue contract by stimulating it electrically (applying electric pulses) or chemically (this is also what happens in the muscles in our bodies).
5.Make a meat product
The next step is to use the exercised muscles that you have grown to make a meat product. Because the muscles from step 4 are generally very thin when you use the common 2D-scaffolds, it is easiest to make a processed meat product (e.g. a hamburger). To make a hamburger, a large number of these thin muscles are put together. The first in vitro meat hamburger was presented to the public in 2013.
Now that you know more about the production process of in vitro meat, you will understand that the basics of in vitro meat production are the same as that of normal (in vivo) meat production but then not inside but outside an animal’s body. Also, the basic component of both types of meat is the same: a real animal muscle cell. In this sense in vitro meat is very natural: there is no manipulation involved whatsoever.
The whole process is clearly explained in the figure below:
A short history of In Vitro Meat: a Dutch project
Decades ago, people already speculated about the possibility of producing animal meat outside of a living animal’s body, amongst these speculators was for example Winston Churchill. In the years 2004-2008, a large research programme funded was started in the Netherlands. The project was initiated by the Dutch “father of in vitro meat” Willem van Eeden and several universities and also a private party (Stegeman) were involved. After this project Mark Post and his research group continued their research to in vitro meat which was now also funded by some private investors (e.g. Sergey Brin, co-founder of Google). Since they presented world’s first in vitro meat hamburger in London in 2013, research has continued at a slower pace. The research is currently centred at Maastricht University and I spoke with Anon van Essen, who works in Post’s research group, to find out what they are currently doing research to.
Where are we now?
Van Essen himself is trying to optimise the 2D growth structures of muscle tissue (bammetjes) by using different types of cell cultures, different scaffold-shapes and also different growth media (the gels). Growth media need to contain the necessary nutrients and also the right regulating substances (e.g. growth factors). Most growth media that are used nowadays still contain several animal-products. This is a problem because the whole idea and advantage of in vitro meat is that it can produce real animal meat without needing actual living animals (except for the initial biopsy). An example is Fetal Bovine Serum (FBS) which comes from a cow’s fetus. It has been found that in synthetic media without FBS, muscle cells have difficulties growing on a scaffold. Better synthetic media thus still need to be developed. Other researchers in Maastricht focus on fat cell cultivation. The taste of meat is largely determined by its fat and that is why it is necessary to develop cultivation techniques that produce in vitro meat that contains fat cells that give it a real “meat-taste”. Soon, a new project will will start in Maastricht that aims to investigate the cultivation of meat cells on the surface of small plastic beads inside bioreactors. This approach to produce thin layers in bioreactors of meat cells has the potential to be more efficient than the production of these layers on 2D structures.
Van Essen is positive about the future of in vitro meat and believes it can produce commercial products (first: processed meat) in 8 to 10 years. He thinks that the biggest plus of in vitro meat is the fact that you know exactly what is inside: in vitro meat is produced in a sterile, controlled environment. He thinks that recent scandals in the meat industry (antibiotics, horse meat being sold as beef) work in the advantage of in vitro meat. According to van Essen the biggest advantage of in vitro meat over other meat substitutes is the fact that it is very much like (or even: identical to) conventional meat which would make the transition easier for meat-eaters. However, he thinks that other meat substitutes (insects in particular) have a future as well in a world where we eat substantially less meat: it will depend on the person which meat substitute he/she will consume in the future. At the end of our conversation, van Essen stressed that a lot of money is still needed to develop the technology of in vitro meat.
Major technological challenges
In this paragraph I will discuss the major technological challenges as I understood them from the literature and my conversations with Anon van Essen and Peter Verstrate. Taste, Colour, Structure, Growth Medium and Up-scaling
1.Taste
In the first in vitro meat hamburger there was hardly any fat and that is why some of the people who tasted this burger reported that although it was very similar to conventional meat, the burger was somewhat dry (The Guardian, 2013). As I mentioned before, fat cells can be co-cultured in in vitro meat and are then also included in the meat product. The concentration of all substances in in vitro meat can very precisely be controlled as it is grown in a completely controlled environment. In theory you can grow in vitro meat with any taste, colour and nutritional content you want (imagine a pink dolphin steak with a liquorish taste). This also gives us the possibility to produce in vitro meat with a better nutritional value (fats, proteins, vitamins, iron etc.) compared to normal meat (Jimenez-Colmenero, 2007). However, current focus lies on producing in vitro meat with exactly the same taste as conventional meat and more research needs to be done to fat cells and also to other substances that contribute to a meat product’s taste.
2.Colour
Meat tissue is in principle grayish and gets its red colour mainly from the hemoglobin in the blood that flows through the muscle and the myglobin in the muscle tissue. Colourants (beet juice) were added to the first in vitro meat hamburger to give it a red colour. It is possible to add myglobin and/or (off course cultivated) blood cells to in vitro meat or even to grow blood veins in the muscle tissue. Research has to prove which approach is best to give in vitro meat an attractive colour.
3.Structure
I explained that it is relatively easy to produce processed meat products using in vitro meat because this can be a combination of several thinner structures. It is harder to create larger and thicker structures of in vitro meat because this thickness limits the supply of nutrients and oxygen to the underlying cells during the growing process. It is a nice first goal to use in vitro meat instead of conventional meat in all processed meat products as processed meat products make up 40% of the meat market (Verstrate, 2016). However, in vitro meat would become even more interesting when it could be used to produce other meat products (e.g. steaks). There are several ideas on how to realise this. One of the ideas is to let the muscle tissue grow on a 3D scaffold. This 3D scaffold can be 3D-printed and could even be biodegradable (so that the muscle that grows on the scaffold “eats” its own scaffold. The 3D scaffold can have channels for the supply of nutrients and oxygen built in so that cells that are far away from the surface can also “breathe”. A lot of research has to be carried out still to this promising approach. Another approach would be to grow real blood veins in the muscle tissue. This second approach comes with several difficulties, for example: how to pump the blood through the veins (there is no real heart) and Verstrate indicated that the 3D-scaffold approach seems the most promising.
4.Growth Medium
As mentioned before, most media still contain animal products. Also, antibiotics are sometimes added to the media. It has to be said however that when the cultivation process happens on a larger scale, this can happen without the use of any antibiotics; this is in fact already being done in England (Verstrate, 2016). To make in vitro meat less dependent on livestock and indeed a healthier and more sustainable alternative for conventional (livestock-based) meat production, new synthetic media have to be developed which do not contain any animal products and no antibiotics. The nutrients that are required for the in vitro meat production should also be produced in a sustainable way. Microalgae are seen as a potentially sustainable nutrient-source for in vitro meat production. Microalgae have a higher productivity (in biomass per year) per acre than conventional terrestrial crops and would thus use less land (land-use is an important aspect of sustainability).
5.Up-scaling
At this moment, in vitro meat has only been produced at a very small scale in laboratories. However, to make commercial products, larger production facilities with bioreactors have to be designed and built and costs have to be reduced significantly. This up-scaling will bring its own challenges, for example: creating and maintaining optimal conditions for cell cultivation, cheap and sustainable supply of nutrients, making the meat “exercising”process more energy-efficient. Fortunately, other industries have a lot of experience with bioreactors and process technology and this knowledge can help the up-scaling process of in vitro meat.
I want to point out that the technology behind in vitro meat shows a lot of parallels with modern health care (e.g. regeneration of damaged tissue) and that research to in vitro meat can also be very advantageous for developments in health care and vice versa. For governments, this can be an extra stimulus to fund research to in vitro meat.
I hope to have given you a clear understanding of the technology behind in vitro meat and a nice overview of the technological challenges that it still faces. The next article will be about the consumer perspective of in vitro meat: who would eat it? what would be the identity of in vitro meat? what are the objections of the public to in vitro meat?
When you have questions about this article or your own ideas about in vitro meat, do not hesitate to contact me by commenting on this article or sending me an e-mail (s.p.j.koenis@student.utwente.nl)
Sources
Anon van Essen. Interview on February 17 2016.
Haagsman, H. P., Hellingwerf, K. J., & Roelen, B. a. J. (2009). Production of Animal Proteins by Cell Systems. Desk Study on Cultured …, 60. Retrieved from http://new-harvest.org/wp-content/uploads/2013/03/production_of_animal_proteins_1207.pdf
Jiménez-Colmenero, F. (2007). Healthier lipid formulation approaches in meat-based functional foods. Technological options for replacement of meat fats by non-meat fats. Trends in Food Science & Technology, 18(11), 567-578.
Leersum, K. Van. (2014). High Tech , Human Touch, 2014.
Next Nature Network, Bistro In Vitro (featured image)
Peter Verstrate. Interview on February 19 2016.
The Guardian. 2013. The Guardian. [ONLINE] Available at:https://www.theguardian.com/science/2013/aug/05/world-first-synthetic-hamburger-mouth-feel. [Accessed 29 February 16].
Meat of the Future? 