by Kenneth W. Krause.
Kenneth W. Krause is a contributing editor and “Science Watch” columnist for the Skeptical Inquirer. Formerly a contributing editor and books columnist for the Humanist, Kenneth contributes regularly to Skeptic as well. He may be contacted at firstname.lastname@example.org.
Some ideas make so much sense that you know great minds somewhere must be working on them. The impediments could be political, cultural, technological, or more often some formidable combination of all three. But in extremely rare instances one can’t help but believe that a particularly powerful idea’s time has finally arrived. Biologists, conservationists, and economists around the world are saying precisely that about the commercial production of cultured, or in-vitro, meat.
The facts surrounding “slow-grown” meat are compelling, to say the least. Conventional meat production is a $1.4 trillion industry globally. We consumed 228 million tons of flesh in 2000, and that number is expected to more than double by 2050 as world population swells to 9 billion. Gorging themselves on 40 percent of the planet’s cereal grain, livestock also use and despoil about 30 percent of the earth’s surface, 70 percent of its arable land, and eight percent of its water supply.
The world’s 1.5 billion livestock are responsible for between 15 and 24 percent of all anthropogenic greenhouse gasses—including 68 percent of ammonia, 65 percent of nitrous oxide, 37 percent of methane, and nine percent of carbon dioxide. Beef ranching accounts for 80 percent of Amazon deforestation, and cattle, which poop 130 times more by volume than humans, dump 64 million tons of sewage in the United States alone. Pigs, of course, are no less prolific.
When we use antibiotics on intensively farmed animals, we contribute mightily to the emergence of multi-drug resistant strains of bacteria. Animal diseases—the chicken flu, for example—can lead to novel epidemics or even pandemics capable of killing millions of people. What are the most common causes of food-born diseases in the U.S., EU, and Canada? That’s right—contaminated meats and animal products. And don’t forget that the nutritional maladies associated with animal fats—diabetes and cardiovascular disease, in particular—are now responsible for a full third of global mortality.
In rather stark contrast, meat grown in culture doesn’t poop, burp, fart, eat, overgraze, drink, bleed, or scream in agony—and it’s a great deal less likely to poison, infect, or kill us. In those bright practical and ethical lights, a growing number of scientists are hopping onto the cultured meat bandwagon. The conventional meat industry “no longer makes sense,” according to Zuhaib and Hina Bhat, Indian biotechnologists and authors of an enlightening new study on cultured meat (Bhat 2011). All things considered, they argue, the transition to “an in vitro meat production system is becoming increasingly justifiable.” And although the technology is still in its early stages, adds a seasoned trio of Dutch veterinary scientists, cultured meat “holds great promise as a solution” to reduce livestock’s horrific impact on the environment (Haagsman 2009).
To that noble end, Hanna Tuomisto and M. Joost Teixeira de Mattos from the Universities of Oxford and Amsterdam, respectively, calculated the likely energy use, greenhouse gas emissions, and land requirements associated with large-scale in vitro meat production (Tuomisto 2010). When contrasted with the conventional industry in Europe, cultured meat would involve 35-60 percent less energy use for pork, sheep, and beef, they say, and 80-95 percent lower greenhouse gas emissions and 98 percent reduced land use overall. Although in vitro chicken could require 14 percent more energy, if land use savings were partially converted to bioenergy production, the total energy efficiency of the cultured product would still prevail.
And because most greenhouse gas emissions caused by cultured meat production are associated with fuel and electricity use, such emissions could be further reduced through the application of renewable energy sources. That potential doesn’t exist for the conventional industry, however, because most of its emissions are produced by methane from manure and enteric fermentation and nitrous oxide from the soil.
Cultured meat would also promote wildlife conservation, Tuomisto and de Mattos contend, because it shrinks economic pressure to convert natural habitats to agricultural lands, and because it provides an alternative means of producing meat from rare, endangered, or currently over-hunted or over-fished species. And although neither transportation nor refrigeration expenses were figured into their study, they add that such costs would likely be less with in vitro meat. Whole animals wouldn’t need to be hauled about, after all, production sites could be located closer to actual consumers, and the finished product would present fewer issues relating to microbial contamination.
Not that cultured meat is a new idea. Back in the 1920s, in fact, Winston Churchill predicted its use within fifty years. Following the discovery of stem cells and the development of the in vitro tissue culture, Dutch scientist Willem van Eeelen first patented the idea in 1999. In 2002, NASA financed a study involving the culturing of a goldfish fillet to explore the possibility of growing meat for long-term space flight (Benjaminson 2002).
Since then, most of the research has taken place in the Netherlands. Between 2005 and 2009, the Dutch government funded a study exploring the possibility of culturing skeletal muscle cells from farm animal stem cells. The group was largely successful, but, unfortunately, the US$2.6 million grant has since expired without renewal.
The general process behind in vitro meat is relatively basic. In theory, embryonic stem cells could provide a cheap and unending supply of cultured meat. But scientists have yet to isolate and develop such cell lines from farm animals. Thus, most of the research so far has involved myosatellites, or the adult stem cells that grow and repair muscle.
Myosatellites are extracted from a small biopsy—reasonably painless to the animal—using enzymes or pipetting. A bacterial-based growth serum is applied to multiply the stems. Researchers then coax them to differentiate into muscle cells, which are grown on an edible or biodegradable scaffold to form myofibers. Those, in turn, are exercised under tension—as if in a miniature, high-tech gymnasium—to build bigger muscle tissues. The appropriate level of stress can be achieved in a variety of ways, including electrical impulses, anchor points, or possibly microspheres.
Once produced on a commercial scale using bioreactors, producers could then grind the muscle strips while adding spices, iron, and vitamins to taste. In a nutshell, that’s the proposed method for creating processed meats like sausages and hamburger patties. The fabrication of structured meats like steaks will be more complicated because, as muscle fibers grow larger—more than 200 micrometers thick, they tend to die off as their inner cell layers become isolated from the flow of nutrients and oxygen.
Regardless of the specific goal, scientists face difficult challenges at every phase of production. As African food security expert Phillip Thornton explains, although in vitro meat currently represents a “perfectly feasible” “wildcard” driver of change in the livestock industry—indeed, in world culture more sweepingly, “at least another decade of research is needed” before we can even begin to effectively confront the critical issues of scale and cost (Thornton 2010).
Stem cells, of course, are a bountiful source of both amazement and frustration for everyone who works with them. Scientists would love to culture the embryonic lines from farm animals because of their incomparable regenerative capacity—ten cells, according to the Dutch group, could produce 50 million kilograms of meat within two months. But even if we develop that technology, embryonic stems must be specifically stimulated to produce myoblasts and at present we have no way of guaranteeing they will do so accurately.
Myosatellites, by contrast, have been successfully isolated from the muscle of cattle, chicken, turkey, pigs, and fish. But in addition to their general rarity and severely limited regenerative abilities, myosatellites have different capacities to proliferate, differentiate, and respond to growth factors depending on their specific muscle of origin. Adipose-derived adult stems provide an attractive potential alternative, the Indian team notes, because they can be obtained less invasively from subcutaneous fat and can differentiate into multiple cell lineages, including muscle.
As anchorage-dependent cells, myoblasts require some sort of substratum or scaffold upon which to proliferate and differentiate. The challenge here is to develop structures that mimic the in vivo milieu. They should have large surface areas for growth and be flexible enough to facilitate contraction. And their by-products must be edible, natural, and derived from non-animal sources. Researchers have proposed a number of inventive solutions, including porous collagen beads or meshworks, large sheets or thin filaments, and microspheres made of cellulose, alginate, chitosan, or collagen that fluctuate in size following slight changes in temperature or pH.
To commercialize the process, we’ll need new bioreactors as well—ones that maintain low sheer and uniform perfusion of nutrients at large volumes. Balancing centrifugal, drag, and gravitational forces, rotating bioreactors allow the structures inside to stay medium-submerged in a perpetual state of free fall. In theory, research-size rotating systems can be scaled up to industrial capacity without affecting their physics.
Perhaps most crucial of all, however, is progress toward a cheap, clean, and consistently effective culture medium. At this point, myoblast culturing usually occurs in animal (fetal calf or horse) sera, which are expensive, highly variable in composition, and potentially rife with infectious contamination. They also raise familiar ethical concerns for some, and rather defeat the important point of creating an animal-free protein product.
Serum-free, chemically defined media have already been developed to support turkey, sheep, and pig myosatellites, and one particularly inventive researcher has employed a medium made from maitake mushroom extract. Thus far, however, the price of these media remains inconsistent with mass production. In addition, we need to formulate species- and cell-specific arrays of growth factors to effectively control proliferation and differentiation.
Clearly we have much left to achieve. Then again, as a group of Dutch and American researchers observed six years ago in the very first peer-reviewed paper published on the subject, the technical challenges facing cultured meat producers are far less daunting that those facing scientists pursuing the application of engineered muscle tissue in a clinical setting (Edelman 2005). And maybe the Dutch group put it best two years ago. “It may seem somewhat premature to start a societal discussion,” they advised. “However, food is a subject that evokes many emotions: it is, if we recall the turmoil associated with the introduction of genetically modified foods, a good idea to educate citizens about all aspects” of in vitro meat, and to do so now.
Compared to its conventional counterpart, cultured meat will allow us to lead significantly safer and more sustainable lives. We will be able to control not only its flavor, but its nutritional composition as well. It will free our valuable resources and our land, minimize animal suffering, and satisfy mounting consumer demand for protein across the globe. How can we transform this truly great idea into a reality? At this critical point, the experts contend, we require only the degree of public investment long lavished upon in vitro meat’s dirty, dangerous, inefficient, and plainly outdated predecessor.
Benjaminson, M.A., Gilchriest, J.A., and Lorenz, M. 2002. In vitro edible muscle protein production system (MPPS): Stage 1, fish. Acta Astronaut 51, 879-889.
Bhat, Z.F., Bhat, H. 2011. Animal-free meat biofabrication. American Journal of Food Technology 6(6): 441-459.
Edelman, P.D., McFarland, D.C., Mironov, V.A., and Matheny, J.G. 2005. Commentary: in vitro-cultured meat production. Tissue Engineering 11(5/6), 659-662.
Haagsman, H.P., Hellingwerf, K.J., Roelen, B.A.J. 2009. Production of animal proteins by cell systems: desk study on cultured meat (“kweekvlees”). University of Utrecht, Faculty of Veterinary Medicine.
Thornton, P.K. 2010. Livestock production: recent trends, future prospects. Phil. Trans. R. Soc. B 365, 2853-2867.
Tuomisto, H.L. and de Mattos, M.J.T. 2010. Life cycle assessment of cultured meat production. 7th International Conference on Life Cycle Assessment in the Agri-Food Sector, 22nd-24th September 2010, Bari, Italy.