"Test Tube Steaks," M.E. Online Exclusive, July 2008

July 2008

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Test Tube Steaks

Some researchers are trying to grow meat in vats rather than on the hoof. But how far are bioengineers from making a collection of muscle cells pass for a sirloin?

by Jeffrey Winters, Associate Editor

Technology prize competitions are all the rage. The X Prize Foundation, which awarded millions to the company that sent SpaceShipOne to the edge of space, has ongoing contests for everything from landing a rover on the moon to building an ultra-efficient car. The mania has even entered the presidential campaign: Senator John McCain has proposed giving $300 million to the company that can build a rechargeable battery suitable for use in long-range electric cars.

But perhaps the strangest technology prize is being offered by the most unlikely source. People for the Ethical Treatment of Animals, the Norfolk, Va.-based advocacy group, announced in April that it was going to award a million dollars to the first company to produce a commercially viable food made from artificial meat.

"Scientists have been studying this for years," said Lindsay Rajt, manager of Vegan campaigns at PETA. "By providing funding, we hope to help speed along the process of getting this choice to consumers."

Animal-rights groups aren't known for promoting technology—indeed, some activists in that field have been arrested for sabotaging scientific research-but what makes PETA's artificial meat prize so interesting is that it highlights an area that has garnered considerable attention in that past few years. The idea of meat grown in a vat may sound like something from a bad science fiction movie, but bioengineers in the U.S. and Europe are taking strides to make it a reality.

"I am 100 percent sure that tissue engineered meat is inescapable," said Vladimir Mironov, director of the Bioprinting Research Center at the Medical University of South Carolina in Charleston.

People have been eating animal flesh as long as records have been kept. Meat consumption is part of most human cultures, with ritual celebrations tied closely to specific types of meat (the Thanksgiving turkey) and taboos established to forbid other meats, such as the prohibition against pork in Islam or against beef in Hinduism.

For many Americans, eating meat is an every-meal occurrence, with annual U.S. consumption of beef, pork, and poultry at more than 200 pounds per person. Livestock competitions are a centerpiece of rural county fairs and, at the other extreme, meatpacking 9 billion farm animals consumed each year makes for an estimated $200 billion dollar business.

While vegetarians began questioning the central place of meat in our diets as far back as the 19th century, recently researchers have examined whether the current practices for providing this influx of animal protein is sustainable. The resources taken to produce one pound of meat, for instance, could produce four pounds of, say, soybeans, with an equivalent nutritional value. In the U.S., farm animals produce some 1.4 billion tons of waste each year, not counting the greenhouse gases—especially methane—that are an outcome of raising livestock.

In addition, fish stocks from Atlantic cod to yellow fin tuna are either depleted beyond commercial levels or are heading toward that state.

In 2003, a team of scientists including Mironov, a cell biologist, and public health researcher Jason Matheny published a paper that looked at potential alternative means of meat production. Taking a cue from Winston Churchill, who felt that it was absurd to raise a whole chicken just to get a breast or leg, the team surveyed the state of the art in tissue growing techniques with an eye toward putting them to work in meat production.

"The level of functionality needed for most clinical applications of muscle tissue engineering," the team concluded, "exceeds that needed to produce cultured meat with nutritional and aesthetic properties sufficiently similar to those of conventional meat." In other words, if you could grow an artificial heart or leg muscle, you would be able to grow a steak in a vat.

Meat is, at its core, a collection of cells—mostly muscle cells, although some people prize the meat of livers, kidneys, and brains. Since early last century, scientists have been able to grow individual cells in a Petri dish filled with agar or some other growth medium. Naively, then, one could imagine that making artificial meat would be a simple process of growing individual muscle cells in a vat.

But the experience of eating meat is more than consuming the individual cells, or else "meat shakes" would be widely popular. Flavor, texture, and consistency are crucial elements to the acceptance of a cut of meat as food. Cells grown individually don't possess the cohesive physical qualities most people desire in meat.

The state of the art of tissue engineering involves growing a patch of cells in two dimensions and attaching the cells to a scaffold made of biodegradable polymers or natural substances such as collagen. In 2006, researcher Anthony Atala at Wake Forest University in Winston-Salem, N.C., created artificial bladders that could be implanted into children with severe urinary disorders.

Patches of other kinds of tissue can be made in this way, but the technique is time-consuming and expensive.

A recent conference in Norway, where some 50 research scientists attended three days of talks, was a good snapshot of current activity in the field. Presentations ranged from modeling muscle tissue and designing media for growing cells to marketing artificial meat to vegetarians.

One of the talks focused on the economics of in vitro meat production. Stig Omholt of the Norwegian University of Life Sciences reported that a fully operational artificial meat factory could churn out fake beef or poultry for about $2.30 a pound, well above the wholesale price of chicken. Other estimates put the costs much higher. One researcher, using data based on state-of-the-art tissue cultures, claimed that the cost of one pound of artificially grown beef was in the neighborhood of $10,000.

But groups of scientists are pushing ahead with research, confident that, between optimizing current practices and breakthroughs yet to be discovered, industrially grown meat can be both cost-effective and edible.

In Europe, the idea has gotten a bit of serious attention. In 2005, the Dutch government awarded a $3 million research grant to the University of Amsterdam, Eindhoven University of Technology, and the University of Utrecht to develop artificial meat. Private efforts have been established in Norway and Germany.

In the U.S., in vitro meat research is funded privately, either through commercial ventures or nonprofit organizations, such as New Harvest, the Baltimore-based organization founded by Matheny in 2004. Lack of funding may hurt the effort in the U.S., Mironov said. "It will probably take 10 years and as much as $100 million to develop this technology at an industrial scale."

The relatively small bits of tissue that have been cultivated in the lab so far wouldn't be mistaken for anything edible— although a collaboration of artists and biologists did once serve bits of cultured frog muscle to arts patrons. The two main strategies for making artificial meat that bioengineers have envisioned can be thought of as the two-dimensional approach and the three-dimensional approach.

The 2-D approach would grow a flat sheet of tissue on an edible membrane, infusing it with nutrients supplied from top or bottom to simulate the flow of blood. When harvested, the tissue and membrane could then be rolled up to produce something like a meat strudel.

More ambitious is the 3-D approach, which would seed a spongy scaffold of collagen or chitosan with muscle cells. As the cells grow within the matrix, the scaffold would be periodically stretched mechanically or through electric jolts to simulate the movement of a muscle inside an animal. When mature, the meat would be removed from the bioreactor and be ready to consume.

But while some researchers are making up in vitro menus, others aren't so sure that this line of investigation is going to lead anywhere. Bob Dennis, a biomedical engineering professor at the University of North Carolina in Chapel Hill, said the difference between a fully functioning animal organ and the techniques being talked about in artificial meat circles is vast.

"We are not even close to starting with cells and ending up with a whole organ in vitro," he said. "What passes for in vitro organs is something very different: either small bits of tissue or cells cultured on a scaffold that is shaped like an organ. I call this 'tissue topiary.' "

Dennis is a leader in tissue research, and has spent more than a decade in the field. His main focus is on biomedical applications: the potential of replacement parts for people grown in a self-organized way—that is, without the scaffolding most other groups use. Dennis attended the in vitro meat conference, but his message may not be one that proponents wanted to hear.

"Muscle precursor cells grown is a gelatinous scaffold is really just steak-flavored Jell-O," he said. To reach something that would have real consumer appeal would require stepping back and approaching the question from a fundamentally new direction.

If Dennis is right, it may take a fundamental rethinking of the bioengineering of culturing tissue before the necessary breakthroughs needed to make artificial meat viable can occur. What some people think is the next obvious step in providing food to the world's hungry may stay just out of grasp.

If so, the PETA prize may be unclaimed. As it is, the likelihood of any group meeting its goals would be small: The winner must have a commercially viable in vitro meat product in widespread distribution by the end of 2012. Given the considerable time lags in getting any product to market, someone would probably have to make a breakthrough of near-historic proportions by year's end to have a chance.

"We do hold out hope that we can see the emergence of artificial meat in the next few years," PETA's Rajt said. She added, "We are ready for science to deliver a methadone to treat our society's addiction to meat heroin."