Flying Pigs And Featherless Chickens.
Danny Penman reports on the ethics of using animals for research into genetics.
Imagine a pig with human genes. Or perhaps you’d prefer a featherless chicken, a self-shearing sheep or an animal that doesn’t mind being eaten. All these and more may soon be available – thanks to genetic engineering.
Exploiting and moulding animals for human ends is nothing new; we’ve been doing it for millennia. But what is new is the sheer power science has over the very stuff of life – the DNA that acts as a blueprint for virtually every living thing on the planet.
Although in principle animals could eventually be redesigned for virtually any use, John Webster, Professor of Animal Husbandry at Bristol University in Britain, says that economics will focus the minds of genetic engineers onto a relatively narrow range of options.
He predicts that animals will be engineered to produce more meat, wool, eggs and milk. Their organs will be transplanted into humans, and animals will be re-designed to secrete useful drugs into their blood and milk. In these key areas billions of dollars are at stake.
Xenotransplantation – the transfer of animal organs such as hearts, kidneys and livers into humans – is currently one of the hottest areas of research. A glance at the potential market shows why. The US-based DNX Corporation estimates that the market for human organs may be worth $6 billion per year.
World demand is believed to be in excess of 400,000 organs per year and growing by about 15 per cent annually, whilst organ donations are static at best.
Imutran, based in Cambridge, is one of the world leaders in producing ‘humanized pigs’. These animals have been engineered with human genes to make them more like us so their organs can be used for transplants.
But can genetic engineering deliver the goods? It’s on the verge of doing so. The only thing stopping the first transplant in Britain is gaining regulatory approval – not an easy task after the recent mad-cow disease fiasco and a host of other food crises that have shaken the public’s faith in science and technology.
The task has been made even more difficult following warnings by two British expert committees that xenotransplantation risks spreading epidemic diseases to humanity.
This is not an idle worry. Earlier this century influenza crossed over from pigs to humans and killed 20 million people. And research reported in Nature Medicine in March reveals that a pig retrovirus – a group of viruses that includes hiv – can infect human cells in the lab.
Amidst the hype of genetic engineering some ethicists are beginning to urge caution. Dr Richard Nicholson, editor of the Bulletin of Medical Ethics, questions the safety, value and morality of xenotransplantation. He says: ‘I have a gut feeling that we ought to define the limits to which we manipulate animals for the relatively limited benefits to humans.
‘My own calculations suggest that the whole transplantation program in rich countries adds 0.003 per cent to life expectancy – which amounts to about one day. Even if we begin using xenotransplants to their likely fullest extent, life expectancy will only increase by about 0.02 per cent.’
Dr Nicholson says that the public should also take a more sceptical line about the value of high-tech medicine in general. In rich countries, the greatest improvements in healthcare arose by significantly reducing poverty. Reducing poverty, not increasing the availability of high-tech medicine to the few, is also likely to be the most effective way of increasing life expectancy in the developing world.
The rich OECD (Organization for Economic Co-operation and Development) countries already spend 80 times as much per person on healthcare as the remaining six-sevenths of the world’s population. If xenotransplantation became commonplace the disparities could increase enormously, both within and between countries and regions.
Another hot area of genetic research is molecular pharming: engineering animals to produce pharmaceuticals. In principle, virtually any molecule produced by the human body can be manufactured in an animal.
Genetic engineering makes it possible to hijack an animal’s milk-manufacturing machinery and use it to produce high-value pharmaceuticals. PPL Therapeutics, the company that cloned the now-infamous Dolly the sheep, has done just that.
The company was set up specifically as a molecular pharm specializing in producing the human blood-clotting factor IX and alpha 1 antitrypsin (AAT) in transgenic sheep. A deficiency of AAT can lead to emphysema.
In 1990, Tracey the sheep was born and produced AAT in abundance, giving the company a foothold in a $100 million market.
And this is where Dolly comes in. The technology used to clone her was developed to produce multiple copies of highly valuable animals like Tracey rather than risk diluting her valuable genes through traditional breeding.
Other scientists are working on ways of tricking an animal’s immune system to attack its own fat cells and so produce leaner, ‘healthier’ meat. Featherless chickens, which use all their food-energy to produce flesh, are also being developed. How these developments would affect the creatures’ well-being is open to question.
Australian researchers are trying to engineer sheep that produce wool more efficiently. But perhaps most bizarre of all is the work being done at CSIRO, Australia, which aims to produce sheep that shed their fleeces in harmony, without the need of shearing, all with the aid of a genetically engineered hormone.
Genetic engineers, often with an eye to the stockmarket, are keen to trumpet their self-styled successes. But genetics is a hit-and-miss affair and occasionally stories of their grisly mistakes leak out from the laboratories.
An example of what can go wrong is the infamous experiments conducted by Dr Vernon Pursel of the US Department of Agriculture. He engineered a herd of pigs with a human growth hormone gene to make them grow faster and produce more flesh.
Unfortunately for the pigs, they produced their human growth hormone in the wrong tissues and ended up with crippling arthritis, deformed skulls, poor vision, and unsurprisingly (given their undoubted unhappiness) impotence and a high susceptibility to stress.
Dr Tim O’Brien of the British-based charity Compassion in World Farming says that results of this type are not unusual: ‘I believe that the techniques used by the genetic engineers are fundamentally flawed. The genes that are inserted can go in the wrong way round or in the wrong place, they can be duplicated many times or mutate on insertion into the animal’s own genes.’
But even much of molecular pharming may be unnecessary. In principle, many of the key compounds desired by the genetic engineers could be produced by plants. However, Ron James, of PPL Therapeutics, says that ‘the economics for plants do not look so attractive’.
Danny Penman is the author of The Price of Meat: Salmonella, Listeria, Mad Cows – What Next? He is based in London and writes regularly for the Observer and the Independent.
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