By Steve Elliott our Science-Health correspondent
With an ever increasing world human population on Earth, currently estimated to be 6.94 billion (by the United States Census Bureau as of July 1, 2011) we need to find ways to feed them protein.
It is estimated that there are approximately 1.5 billion cattle in the world today, over 1 billion domestic sheep and more than 24 billion chickens. Some estimates say each human consumes on average 40 kilograms of meat annually, we collectively eat about 250,000,000 tonnes of meat annually worldwide and that amount is growing by about five million tonnes per year. That’s an awful lot of meat, getting pricier, less healthy and one day the human population might well outstrip its physical capacity to feed itself meat.
People like their meat protein, red and white, so researchers around the world are trying to produce ‘artificial’ meat in culture (cultured meat) and the first lab-grown sausage might be ready to eat in about six to twelve months.
Mark Post, Maastricht University in the Netherlands, has developed a technique for growing pig muscle cells in culture in the lab. By supplying pig stem cells with horse fetal serum Post has managed to create strips of muscle-like flesh measuring about 2.5 centimetres long and 0.7 centimetres wide. Animal muscle being what meat is, means that simply joining the strips pig stem cell protein together produces a slice of cultred ‘ham’.
Easy to say, but producing artificial meat requires a certain amount of tinkering and tailoring. The muscle tissue strips need daily exercise to make them develop the same constitution as real muscle meat – Post anchors them onto Velcro then stretches the cells away from the surface.
This kind of research has been somewhat of a holy grail for animal welfare activists who find farming of livestock to be animal cruelty, cow pens equivalent to bovine concentration camps. One group PETA (People for the Ethical Treatment of Animals) has offered $1m to any professional group that can put an ‘in vitro chicken’ onto shop shelves by June next year. With funding from an unnamed philanthropist, Post is now ready to produce ‘beef’ from cow muscle cells, so a ‘beef’ burger may be in a fast food outlet near you soon.
Scientists say there are advantages to eating cultured meat: in vitro meat, once perfected, would eventually be free of hormone, additives, E. coli bacteria and deadly prions. In vitro meat would require 99 per cent less land than beef farming (Environmental Science and Technology, DOI: 10.1021/es200130u) and consequently fewer farm animals would produce 95% less greenhouse gas (agriculture actually produces more carbon gas emissions than transportation https://www.cdproject.net/) and require 95% less energy and water.
Interestingly, for meat aficionados, in vitro cultured meat opens up the possibility of making all kinds of previously very rare meat available to eat. Meat choice is most usually dictated by the animals that are relatively easy to domesticate rather than by those offering the tastiest meat. With synthetic meat, this no longer applies since there is no need to domesticate a petri dish, all that would be required for meat production are muscle stem cells. Fancy munching into a kangaburger, a whale steak or even a panda bear fry up, it would only require getting stem cells from these relatively exotic animals and culturing them in the lab – no need then to kill such rare creatures anymore to satisfy human appetites.
One problem currently slowing Post’s technical development is an upper limit on muscle stem cell division. Pig muscle stem cells can only divide a maximum of 20 to 30 times in culture, making it necessary to regularly return to the pig to extract fresh stem cells, a time consuming process. However, Bernard Roelen of Utrecht University in the Netherlands, is tasking himself with finding pig stem cells that will be capable of dividing for months at a time. He has isolated a subset of stem cells called muscle-derived progenitor cells (MDPCs) which look promising. “If we start with 1000 cells, after three months we have billions upon billions,” he says (Journal of Cellular Biochemistry, DOI: 10.1002/jcb.21921).
The ‘meat’ strips are described as having a ‘squishy’ texture and look rather anaemic and unappetizing.
Dr Post: “It’s white because there’s no blood in it, and very little myoglobin, the iron-bearing protein. We are looking at ways to build up the myoglobin content to give it colour. I’m hopeful we can have a hamburger in a year.”
In theory it’s a fine idea but no one has actually eaten the strips of pig muscle cells yet due to strict lab regulations which prevent the consumption of lab-grown tissue fed on calf fetal serum (there is a small risk it may contain contaminants such as prions).
Post is effectively producing ‘meat’ protein but is it as nutritious as ‘natural’ meat? There are many other labs currently pursuing in vitro meat. Joost Teixeira de Mattos at the University of Amsterdam, the Netherlands, aims to develop cyanobacteria meat protein – naturally rich in the amino acids, sugars and fats that the animal cells require and on paper more nutritious.
Nutritious possibly, but is it delicious? Will the public eat such meat? Researchers know this work can be considered ‘unnatural’ and attracting funding for such research can be hard to do. Researchers respond, saying the true irony is that ‘natural’ livestock meat is produced from animals often kept in unnatural conditions and dosed with hormones and antibiotics. Hardly an entirely natural process – far from it, considering that ‘Mad cow disease’ was created by feeding recycled cow tissue to herbivores that should only eat grass.
Would you eat it?