Stem Cell Hamburgers

August 29, 2013

Reporters watched as Hanni Ruetzler, a food researcher from the Future Food Studio, and food author, Josh Schonwald tasted a hamburger patty that had been cooked by Chef Richard McGeown . . . and synthesized in a lab. The hamburger patty, which came from Mark Post’s lab at Maastricht University, was not the first synthetic food to be taste-tested, but it was the first using current stem cell technology.

According to an article by Post in the Journal of Meat Science, his goal is to make cruelty-free foods that taste like meat, which has earned PETA’s backing for his project, as well as funding from Google co-founder Sergey Brin. Post also hopes to provide an alternative meat source that can help supply an increasing global population with  a meat source containing additional nutritional supplements, while mitigating the adverse effects of livestock meat production on the environment.

Let’s look at how exactly a hamburger is made in the lab, and what bioethics issues the process raises:

The stem cells came from the shoulder of a cow. Originally researchers focused on embryonic stem cells because they could potentially continue to make more and more cells, providing what some touted as an “unlimited supply of food.” However, these cells could not be controlled. Researchers needed to cultivate skeletal muscle cells (that is typically what people eat), but, for example, when pig embryonic stem cells were used they tended to quickly transform into brain cells.

Myoblast cells, which are a type of adult stem cell used to repair muscle tissue, proved more helpful. Using myoblast cells ensures that the stem cells will become the right tissue type. The drawback, however, is their limited ability to continue making cells. They will not provide a “limitless food supply.” For Post’s stem cell hamburger, researchers used myoblast cells taken from a cow’s shoulder – a relatively painless procedure.

Once the stem cells are harvested, the next step is to grow the cells in an appropriate medium. For now, the most efficient and cost-effective medium for growing (and proliferating) these cells is calf serum that is obtained from slaughtering a pregnant cow. This has implications for claims that synthetic foods are animal-friendly and will preserve the limited supply of livestock. Post hopes to find another medium that is animal-friendly, but says that, for now, this process provides proof-of-concept to show that cultivating synthetic meat from stem cells is possible.

For three weeks, the muscles are grown as very small, thin strips. This is necessary for the same reasons scientists cannot yet make life-sized, solid human organs (e.g. liver or kidneys) in the lab.  Tissues need to receive oxygen and nutrients in order to survive. They also need to excrete wastes. Currently synthesized tissues lack the intricate pumping and channeling systems to do this, causing the internal cells to die. Post’s team, therefore, made very small strips, which they grew in the lab for several weeks. According to reports, it takes 20,000 of these small strips to make a single hamburger.

Muscle that has never been used is a bit small and “gooey.” To counteract these effects, Post’s group stretched the thin muscle strips over two pieces of scaffold to simulate tendons. Additionally, the color of the muscle strips was an unappetizing light gray color, which may be nice in oysters but is hardly what one expects when eating a beef hamburger. To make it a more beef-like color, scientists added beetroot and saffron.

Finally, to give the patties some bulk and flavor, Post’s group added chopped onion, free-range egg yolk, salt, pepper, chopped coriander, and breadcrumbs. The stem cell patty lacked fat, which was obvious in the taste test, so it was cooked with butter. Post hopes to eventually add adipose (fat) tissue to the patties using induced pluripotent stem cells.

Bioethics Issues:

With any kind of popular and promising scientific research, we need to consider the relationship between money, science, media, and politics. Sometimes this relationship can become so entangled that it is difficult to tease apart truth from hype in order to discern the key bioethics issues.

Importantly, this is a proof-of-concept experiment, which means it is only at the initial stages in the research process. Research takes a long time, and sometimes progress is over-stated in the popular media to maintain reader attention and excitement over the prospects of the final product. There are still many steps before this can be a viable alternative meat source, including finding a better medium than fetal serum and adding fat cells to enhance the flavor.

Additionally, if synthetic meat cultivation does become a practical, large-scale alternative, will proponents of livestock meat production face social and/or economic pressure to adopt it against their preference? And, if so, would such pressure be appropriate or ethically problematic? For instance, according to a Scientific American article from 2011, some proponents of synthetic meat envision an environmental tax on meat produced from killing livestock. Would such a tax be appropriate?

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