I’ll Take a Burger With Everything — Except the Animals
We’ve heard it time and time again: growing our food from animals is inefficient. The problem is beyond cows emitting methane or the transmission of e-coli from livestock to our dinner plates. In the next 30 years, we will have to feed a planet of 10 million people. That means a 50% increase in demand for agricultural production of products like meat, eggs, and dairy, and a 15% increase in water removal. And that’s simply a rate of demand we cannot sustain — especially if in the next 50 years, we must raise more food than we have produced in the last 10,000 years, combined.
We have been producing animal-based food using detrimental and wasteful methods for too long while slaughtering billions of livestock in the process.
- 25% of our planet is dedicated to farming livestock
- 70% of all land on Earth and 30% of all freshwater is used for agriculture purposes
- Food production accounts for 1/4 of global warming
- 14.5% of all anthropogenic greenhouse gases are due to agriculture
- 80% of our antibiotics are sold to the agriculture industry
- An 8-ounce steak requires 1.6 kg of feed and 3,515 L of water
It is a way bigger issue than cows emitting CH4 or transferring diseases like e-coli. In fact, not only should we change our ways, we must.
So imagine instead, you could slice into a steak from a Petri dish, or enjoy sashimi from a test tube. Leveraging the emerging technologies of the future, a slew of startups have already made this a reality. Enter, yet again, a solution to one of the greatest problems of our lifetime: Cellular Agriculture.
Cellular Agriculture: A biological technique that harnesses stem cells, tissue engineering, fermentation, and gene editing to create real products from cell cultures.
The field of cellular agriculture is designing new methods of producing proteins, fats, and tissues that otherwise would come from traditional agriculture. Through this, we can produce anything from meat tissues and milk proteins to animals skins and leather.
Like every organism, cows and other livestock, are meant to reproduce and survive. That’s simply the principles of evolution. Cows are not meant to be injected with a bunch of hormones, forced to eat tons of feed, or experience countless other harmful and unnatural practices. In fact, cows are not built to endure these processes. However, there are already quite a few tools that can usher us into an entirely revolutionized food system.
Tools like algaculture, which uses algae as a primary food source, mycoprotein, which uses fungi to make meat, or entoculture, which derives proteins from insects. Although these are all possible solutions for combatting global warming, arguably the two most important technologies for widespread food distribution are bioprinting and cell culture. In cellular agriculture, bioprinting utilizes biological cell-based materials such as 3D printing ink to print edible objects like meat. Cell culture grows foods like meat and dairy products from stem cells.
So let’s dive right into how we can culture meat using cells.
In Vitro Meat production starts with a cell culture
Cell cultures refer to a technique of growing cells in a controlled environment — like in a laboratory — outside of where the cells would normally be found.
This controlled environment must have:
- Regulated pH
- Regulated temperature
- Regulated humidity
- Regulated movement
- Limited interference
Although the cells are removed from their original microenvironment — inside the body of an animal — the process occurring in the lab is indeed authentic.
Methods of Production
The idea of producing meat artificially can be traced back for decades.
“Fifty years hence we shall escape the absurdity of growing a whole chicken in order to eat the breast or wing by growing these parts separately under a suitable medium.” — Winston Churchill
Since then, there are two primary methods developed for the actualization of this idea. These biotechnological approaches broadly involve cell cultures and tissue cultures/tissue engineering techniques —and they are also commonly known as ‘Scaffold-based’ and ‘Self-organizing techniques’.
Self-organizing technique
The first potential method of creating in vitro meat involves the use of explanted muscle tissue from an animal donor — a more ambitious approach to producing highly structured meats. Explants possess the advantage of containing the cells necessary to make up muscle in corresponding proportions and essentially mimic in vivo structure. Researchers propose that the tissue formed through the explant method will closely resemble meat, as they contain muscle cells, fat, and cells in familiar proportions present naturally. However, lack of blood circulation within the explants can make substantial growth impossible, as cells become separated from the nutrient supply. The problem remains that proliferation potential is limited and new biopsies of donor animals will be required regularly.
Scaffold-based technique
The second method of culturing meat requires stem cells, which can be taken painlessly from live animals through biopsies. In this technique, embryonic myoblasts or adult skeletal muscle satellite cells are proliferated, attached to a carrier called a scaffold, and then are perfused with a culture medium in a bioreactor. This culturing results in myofibers that can be harvested, cooked, or consumed as meat or other meat-based products.
The question now is: Which types of cells should be used? The answer is stem cells — undifferentiated cells with the inherent capability to self renew, that is, to develop and divide into various types of cells. Stem cells are the basic anchor cells from which all the cells in the human body originate. This ability to differentiate into specialized cells types — like muscle or skin cells — is a unique characteristic called potency.
There are three types of stem cells based on potency:
- A fertilized egg is composed of totipotent cells, which have the ability to be programmed into any cell type, even embryonic and placental cells.
- Second are pluripotent cells, which have more restrictions with their capability to divide as compared to totipotent cells. These stem cells have the capacity to form over 200 different cell types in the adult body and are found in the embryo.
- Multipotent cells are the third type of stem cells that are already committed to developing into a certain cell lineage type. These types of cells are usually found in many issues, such as adult bone marrow, skin, and cord blood.
In research, the generation of totipotent cells requires the harvest of human embryos which has triggered controversy in stem cell research. Due to this, scientists instead turn to the use of adult multipotent stem cells as they offer much more advantages — more availability, improved safety, and ease of culturing.
In regards to producing cultured meat, there are two main types of stem cells utilized: Myosatellite cells and Embryonic cells.
Myosatellite skeletal muscle cells are adult stem cells derived from the muscle of an animal. When these adult stem cells are proliferated or grown, they can only regenerate more muscle cells. The myosatellite skeletal muscle cells lack unlimited regenerative power.
On the other hand, embryonic cells essentially can regenerate indefinitely since they are pluripotent stem cells. They possess the capacity to become any cell in the body of an animal — but, that’s not necessary for producing clean meat. We simply need muscle cells, nothing else.
Harnessing Myosatellite Muscle Cells
Now, how do we actually get these myosatellite cells? First, a sample of the muscle is required in order to reach the satellite cell — which is essentially just a stem cell programmed to develop into a muscle.
We are able to extract these cells using an enzyme — which helps to speed up reactions. In this case, the enzyme aids in the digestion of an extracellular matrix (ECM). The ECM essentially serves as a biological framework, providing biochemical support and necessary factors for the cells. These factors are simply agents that instruct the cells to do different things, like proliferate or fuse — a mechanism necessary for sustaining developmental growth and for cell shaping. The lack of this biochemical structure support can cause the muscle tissues to release myosatellite cells. One such enzyme capable of doing this is protease, a proteolytic enzyme or enzyme that breaks down proteins.
Once we have the stem cell sample, the cells are developed from potential muscle cells into intermediate muscle cells called myoblasts. This occurs when the myosatellite cells are placed in a growth medium that provides the cells with the essential nutrients needed for growth — as if this process took place within the body of an animal. As the stem cells proliferate they produce more and more muscle cells; eventually, growing into myoblasts.
Then the myoblasts form multinucleated myotubes a type of muscular tissue — in a process called myogenesis. Essentially, the myotubes are a rigid form of myoblasts and are crucial in the formation of muscle. The myotubes, when placed in a bioreactor tank, will differentiate into myofibers. Remember myofibers — the final product of this technique — can be harvested, cooked, or consumed as meat.
But, how do we promote proliferation and the continuance of growth, from a petri dish? The answer: through a growth medium.
Growth Media + Factors for Cell Development
As mentioned previously, in order for the original stem cell sample to develop into myoblasts and eventually into muscle, a medium is needed. This medium proliferates the cells by providing the essential nutrients. However, current techniques of producing cultured meat are reliant on the use of fetal bovine serum. This is growth media is extremely expensive and is unethically produced by drawing blood from a fetus inside of a mother bovine. In other words, it’s the blood from an unborn cow.
Although the use of fetal bovine serum doesn't literally kill any fully formed organism, it is still lethal to potential lifeforms and can kill the fetus bovine. Also, due to the expenses of the growth medium, use of it can inhibit the scaling of cell culture. However, researchers have found promise in growth media derived from plants — at cheaper prices and without the expense of using animal blood.
But what is the point of using fetal bovine serum at such a great cost?
It provides one of two necessary aspects for cell survival: factors. The fetal bovine serum contains factors that promote proliferation, development, and growth, as well as differentiation, in stem cells.
Fetal bovine serum contains a large number of nutritional and macromolecular factors essential for cell growth. It also contains a variety of small molecules like amino acids, sugars, lipids, and hormones. Another key component is the bovine serum albumin — a protein concentration standard — which functions as a cell nutrient and has the ability to stabilize enzymes. These growth factors found in the serum facilitate cell survival and proliferation.
Now you might be asking what’s the second necessary aspect for cell survival; its surface.
The Surface — Bioreactors
So we know what cultured meat is being grown on — surfaces. But, how can we expect to produce meat at scale using small Petri dishes? Now the question becomes what are we growing meat in? We’ve got that one answered too: bioreactors.
Essentially, bioreactors provide the space for the cultured cells to continue growing and developing with the growth media. Through fluctuations in environmental factors, a system is created and maintained.
- 🌡 Temperature. The average kinetic energy of all the atoms or molecules of the substance.
- 💨 Oxygen Transfer. The rate of oxygen delivery from the surrounding atmosphere into a liquid.
- 🥣 Agitation Rate. Helps maintain chemical and physical conditions in the medium by continuous mixing.
- 🧪 pH. A scale to specify the acidity basicity of a substance or solution.
- 😩 Pressure. The measure of the force applied over the cells.
The bioreactor system is able to effectively control these crucial factors using a variety of tools such as sensors, thermal technology, and a feeding pump that pours the growth medium. Additionally, bioreactors contain a filtration system and aerators to maintain the liquid and deliver oxygen to cells — a critical aspect of optimizing cell culture in a bioreactor. Using sensor technologies, scientists are able to manage the conditions within the bioreactor, ensuring that the environment remains constant.
Scaffolding
When we produce lab-grown meat, stem cells are cultured to become muscle cells and eventually form muscle as if they would inside an animal. Using tissue engineering methods, we are simply mimicking the process used as embryonic cells develop and form organs.
Tissue engineering is employed for various uses — creating new, functioning organs, bone production, or advanced drug testing. However, in the case of in-vitro meat production, tissue engineering is important for creating tissues that behave and taste like meat, rather than functioning as an organ.
Tissue engineering is pretty groundbreaking in the field of cellular agriculture and beyond. However, culturing meat requires an additional tool that was briefly touched upon earlier: scaffolds.
Now you might be asking, what exactly is a scaffold? They’re simply replacements for extracellular matrix (ECM). Before we get into the integral role scaffolds play in in-vitro meat production, let’s summarize what exactly the ECM does.
Cells attach to ECMs. Here cells migrate, receive cell support, regulate intercellular communication, and grow and proliferate. Thus, without ECMs, cells wouldn’t be able to go through key processes of mitosis or meiosis, communicate, or even move around.
Now, back to scaffolds. Scaffolds are permeable materials that play an integral role in guiding the growth of cells and use collagen microspheres to transform stem cells into myotubes. Without the scaffold, the meat cells in the bioreactor are a pile of mush — no shape or structure. Therefore, the scaffold also serves as a mold of the object cells will shape into, instead of flat, deformed pieces of meat.
More recently, there have been a variety of materials used to create scaffolds — each with there own potential applications and limitations. Scaffold production is very elaborate, especially when customizing it for specific products. This is overcome on a smaller scale, but it’s just not feasible for the commercial level, which is where the industry is aiming.
By mushing the meat cells, matrices, and nutrients all together, we are left with a liquid called bioink. Therefore, instead of relying on traditional scaffolds, we can use 3D printing to bioprint one. Bioprinting is based on extruding cells layer by layer until a specific shape is formed — a process also known as additive manufacturing.
It is important to recognize one necessary factor of why we need scaffolds in the first place. In order for cells to stay alive and grow, they need to be given these nutrients. In animals, like humans, we possess circulatory systems that do this — this system must be reinvigorated for cell culture outside the animals.
Feeding the cell requires a key process: diffusion. Essentially, in the cell culture, the particles move from an area of high concentration to low concentration.
Diffusion isn’t effective when companies make meat, especially considering that with a thicker structure it becomes challenging for diffusion to work. So, what if we can utilize a mechanism that’s guaranteed to work: the circulatory system? Actually, Humacyte is already working on this technology to create synthetic blood vessels to work in conjunction with the scaffolds.
With diffusion serving as the primary mechanism for macromolecular transport in cell culture fields, providing an adequate supply of nutrients using diffusion is necessary for cell proliferation and production of ECMs. However, we’ve already established that this is not going to work right now.
Oh, and there’s one another problem with scaffolds: elastin. ECMs contain a protein called elastin that is crucial for providing flexibility and durability. Right now, scaffold technologies fail to include elastin and their mimicry of cell shells is flawed.
Scaffolds are decent, but they’re not great for in vitro meat production. And there’s no doubt that if we’re going to culture more complex types of meat like pork chops and filet mignon, current tissue engineering is going to get way better.
Regardless, once the myofibers are grown, other cells — mainly fat cells — are added and we’re left with a piece of meat.
Recap
By growing meat in labs, consumers are promised a future of tasty dishes without making billions of animals suffer in the process. Rather, a slew of startups is making cultured meat starting with a biopsy of animal muscle tissues. Once stem cells are collected from the tissue, the cells are multiplied dramatically allowing them to differentiate into fibers that will eventually form muscle tissue.
Voila, sirloin without a slaughterhouse!
Well, not yet.
Current deterrents of in-vitro meat production:
- Source of stem cells
- Scaling up production + bioreactors
- FBS serum
- Diffusion + current scaffolds
- Consumer perception + acceptance
- Price + bringing to market
Companies are focusing on ground products — like chicken nuggets, hamburgers, and sausages — for now. These primary offerings will most likely contain flavors, additives, and fillers to create the look, taste, and feel expected by consumers. However, scientists must address the key challenges presented above and learn how to design and replicate blood vessels before we can have lab-grown pork chops and filet mignon.
That’s pretty much a wrap on how to go from a cell sample to the meat we know and love. The process isn’t perfect but there are several advancements in the field to improve cultured meat production and introduction into the market.
And before you leave…
My name is Isabella Jabbour and I am a 15 y/o, activist, researcher, innovator, exploring cellular agriculture, cancer, and AI 🧬 Current projects include: Innovating @ TKS; Leading Students Against Nicotine & Youth For Climate Refugees; Researching technologies of the future; Writing and educating on Medium
Check me out here:
🔗 LinkedIn: https://www.linkedin.com/in/isabella-jabbour-795bb81b3/
💌 Email: isabellajabbour21@gmail.com
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