Monday, July 11, 2005

Hamburger saviour?

Here's a solution to the bird flu problem. Not right away, perhaps, but maybe in the near future. A paper in the June 29 journal Tissue Engineering describes new techniques to grow meat in the laboratory--that is, to culture meat.

It turns out this isn't new. Similar small scale experiments have been going on for some time, although only three research groups are reported engaged in the effort. Perhaps the current concern about the food chain--including Mad Cow (BSE) and now avian influenza--will raise its profile. Should this mode of industrial food production come to pass there are sure to be pluses and minuses, but with a hungry globe and increasingly inhumane methods of animal "husbandry", it seems on first look, to be a net plus. I'm guessing that we will soon be thinking about some of the negative aspects if we get into this more (consider the effects on traditional societies). But for now, it is interesting to see what might be.

The basic idea is to grow meat (muscle) cells from animals in tissue culture, i.e., in vats or bottles supplied with essential nutrients. One of the authors of the paper, Jason Metheny, described some of the benefits:
"There would be a lot of benefits from cultured meat," says Matheny, who studies agricultural economics and public health. "For one thing, you could control the nutrients. For example, most meats are high in the fatty acid Omega 6, which can cause high cholesterol and other health problems. With in vitro meat, you could replace that with Omega 3, which is a healthy fat.

"Cultured meat could also reduce the pollution that results from raising livestock, and you wouldn't need the drugs that are used on animals raised for meat."
In an informative Commentary to the paper (full text here), however, we learn of the formidable technical obstacles and difficulties of producing cultured meat on an industrial scale. One of the older techniques, scaffold-based, uses skeletal muscle satellite cells on a scaffold or carrier in a bioreactor. Skeletal muscle satellite cells are muscle cells capable of producing new muscle cells, sort of tissue-specific stem-cells. While there is a limit to how often such a cell can divide (the so-called Hayflick limit) some estimates suggest that in theory a single such cell could satisfy the current annual global demand for meat (such is the power of exponential growth). So this part of the underlying biology doesn't seem to present an insurmountable problem.

On the other hand, finding the techniques, nutrients, co-factors and other requirements to make cells divide and actually produce what we would call meat is another matter. The scaffold-based techniques might work for processed foods (hamburger, sausage, chicken "nuggets") but not actual steaks or cuts of meat as we think of them now. Meat is a not just muscle but has connective and vascular tissue and other components that contribute to its "mouth feel" and texture, not to mention its taste. So there is much work to do.

Growing "meat" industrially in vats and factories (instead of sentient and intact animals) is the stuff of many science fiction scenarios. Like many such things, however, it is reasonable to think it will come to pass and perhaps before not too long.

Let's assume for the moment some untoward consequence doesn't come along to spoil the party. Will future generations look back on the twentieth century and early twenty-first as a time of high barbarism where gigantic industrial killing machines ("the food industry") were used to feed the ravenous maw of a world population out of control, spawning the seeds of mass extinction by zoonotic disease? Or will mass extinction via a "natural" population crash make the point for us?