SPEAKING OF SCIENCE
Making meat in vitro from cells
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There is only a slight difference between making meat in vitro and the way animals do
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SEVERAL NEWS agencies recently carried reports with titles such as `Lab-grown meat for veggies soon', `Now cooking: cultured meat for vegetarians', and `Edible meat can be grown in a lab on industrial scale.'
I found they were stretching the point somewhat when I read the original paper by R. D. Edelman and others in the journal Tissue Engineering that these reports cited.
The authors describe various possibilities of culturing skeletal muscle cells of edible animals such as fish, poultry and turkey, what the difficulties are and what methods might help overcome them.
Steaks, chops, years away
I gathered that culturing these cells to produce a steak or lamb chop is years away, if at all. However, true to the present days of intellectual property rights and WTO, a Dutch group has obtained a patent for a generalised method to culture adult skeletal muscle satellite cells on a collagen mesh to produce fibres that can (hopefully) be harvested, cooked and consumed as meat.
First of all, this kind of lab-made or in vitro cultured meat is still non-vegetarian. A `pucca' vegetarian will not touch it, since the starting material is still from the body of an animal.
Note that while milk too is animal-produced, it is secreted and you do not hurt the animal, or use a knife to get it. Thus, most vegetarians do not have any qualms about dairy products.
Also, some might argue, rightly, that there is only a degree of difference between making meat in vitro from muscle cells, and making it from the egg cell (as animals do, in vivo or ex vivo). Meat from any source is still meat.
I suspect that ovotarians (vegetarians who also eat eggs) too might be somewhat hesitant, at least initially, in including cultured meat in their diet. Why would one want to grow edible meat in the laboratory? The idea came from space scientists. In missions under highly constrained conditions, where room within the craft is at a premium and the duration very long, efforts such as producing food in situ become important.
The food produced must be rich in energy, high in nutrition, fresh if possible, tasty, and bring cheer and relieve boredom.
Experiments from NASA space missions have apparently shown that small amounts of edible meat can be created in vitro. Secondly, even on earth, doing it in vitro means that one does not have to raise livestock, care for them and suffer the pollution they create.
Further, Mr. Jason Matheny, a co-author of the above paper, points out that one could control the nutrients. The high cholesterol-causing components such as Omega-6 fatty acids can be replaced during the culturing process by the healthy fatty acids Omega-3. (Incidentally, that would turn the phrase "neither fish nor fowl" on its head. Omega-3 is far richer in fish, not in poultry, lamb, pork or beef. Adding it would turn them `fishy' in vitro.)
Tailoring to taste
Matheny is also quoted as saying "cultured meat could appeal to people concerned about food safety, the environment, and animal welfare, and people who want to tailor food to their tastes".
What the authors suggest is a cell culture method. When cells are grown in culture, they stop growing after a fixed number of doublings, called the Hayflick limit.
The reason for this limit is that with each doubling, the end portion of the chromosomes (called telomere) in the cell nucleus is clipped off a bit. As a result, cell division stops after 45 rounds or so. The authors surmise that if the cells are transfected with the gene for telomerase (the enzyme that puts back the clipped portion), and if the cell divisions go on for 75 rounds, the amount of meat produced could satisfy the current global demand for meat!
Ideally what one would want is to replicate what the growing animal body does — namely grow the cells into tissues and chunks of muscles.
Currently this can be done in two ways — one is to use a scaffold or a carrier such as collagen (the protein found in skin and tendons), or micro-carrier beads made of cellulose or alginate. Various kinds of growth-aiding molecules and nutrients are added in the culturing liquid (called the medium).
The cells themselves are largely muscle in origin, since that is after all what much of meat is about.
But in order to replicate the taste and texture of real-life meat, other cells such as vascular cells and fibroblasts need to be added and properly organised in a three-dimensional structure.
Fat cells need to be added and co-cultured, as also growth factors to help successful culturing. Yet, the product would be bland, lacking the specific flavours of various types of meat such as those of fish, chicken or beef.
Quite apart from taste and texture, culturing meat must be cost-effective. Cells need nourishment and energy to grow, which are provided by the medium in which they are dipped during the culturing process.
Serum from blood is the usual medium but it can be expensive and so cheaper but effective substitutes must be found.
Technically feasible
Cultured meat, at least of the scaffold-based variety, appears technically feasible. The challenges here are common to skeletal muscle tissue engineering, but since we are not aiming at producing a functionally active muscle for clinical applications but only cultured meat for consumption, the level of complexity is far less.
As Edelman and associates conclude in their paper, "Future research is likely to be most fruitful if focused on developing scaffold-based techniques appropriate for processed meat products, and affordable, nonserum media needed to support them".
D. Balasubramanian
dbala@lvpei.org
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