Raiding the piggy bank for organs

Right now, about 400 New Zealanders know that whether they live or die this year depends on gaining access to donated human organs.

About 350 people, including a growing number with severe diabetes, are waiting for new kidneys. A further 50 or so are waiting for hearts, livers and other organs.

But there are nowhere near enough donors - either friends willing to give one of their two kidneys, as Grant Kereama did for Jonah Lomu, or people who are declared 'brain-dead' but their kidneys and other organs are still in good working order and next-of-kin can be persuaded to give consent.

That means only 25 to 30 per cent of the people waiting for kidney transplants - about 100 of the 350 on the waiting list - will receive one this year.

Some of those who miss out may still be well enough for a transplant next year.

Others will be too sick by then - or dead.

This is not just a local problem. In the United States, 48,000 people are on waiting lists for transplants and 3000 of them die annually.

American experts say a maximum of 7000 suitable US brain-dead donors are available each year, supplying up to 14,000 kidneys. That is less than the number of new patients starting on artificial dialysis because of kidney failure.

So, only a few decades after human organ transplants became widespread, there is now immense pressure to find a new source of spare body parts.

Huge effort is going into developing mechanical organs, and into the use of "stem cells", taken from human embryos or from parts of a patient's own body, and cultured to grow replacement organs.

But both are still highly uncertain technologies. So it is no surprise that many researchers are looking at an obvious source of bodily organs - animals.

The Bioethics Council, recommended by the Royal Commission on Genetic Modification in 2001, publishes a 43-page discussion document today on The Cultural, Spiritual and Ethical Aspects of Xenotransplantation: Animal-to-Human Transplantation.

Restrictions on xenotransplantation (literally, transplanting "foreign" material) were imposed in 2002 with a three-year "sunset clause" because the Government "did not want to limit New Zealanders' access to xenotransplantation if it could be shown that the technology was acceptable, safe, and offered the ability to improve health outcomes".

The law expires in June.

The Bioethics Council is seeking public views on the cultural, spiritual and ethical aspects of the technology, while the Health Ministry reviews its safety.

"New Zealand needs to make decisions about xenotransplantation during 2005," the council says.

Member Anne Dickinson, whose day job is managing the Catholic Bishops' Conference in Wellington, says the two reviews are independent.

"While the public of New Zealand may decide that it's culturally, ethically and spiritually acceptable, it still has to be acceptable from a safety perspective," she says.

"Or if New Zealanders decided that they really didn't want it for cultural, ethical or spiritual reasons, that by itself could impose a longer moratorium or even a prohibition."

But inevitably the two reviews are related, because the decision on whether animal-to-human transplants are morally right depends at least partly on whether they can actually save - or endanger - human lives.

Auckland kidney transplant surgeon Stephen Munn points out that human use of animal tissue for medical treatment is hardly new. The insulin that diabetics inject to maintain their blood-sugar levels was originally extracted from the pancreas of pigs and cattle.

Pig heart valves are widely used to patch up human hearts, and crushed cow bones sometimes provide a "scaffold" for human bones to regrow on after an accident.

But Dr Stewart Jessamine, of the Health Ministry regulatory agency Medsafe, in a paper for the Risk Management Association, says these body parts are "dead". In contrast, whole organs such as kidneys would "actively secrete hormones and substances" inside the body of the person who receives them.

The human body's immune system is geared to destroy any such intruder.

To trick the immune system, scientists have genetically modified pigs to take out the substances that trigger rejection in human bodies.

Last year, South Korea announced a 10-year plan to mass-produce genetically altered pig organs for human transplants.

But Dr Jessamine says this has failed to solve other ways in which the human body rejects foreign organs.

Animal organs may also carry "retroviruses" - tiny particles that can get inside the genetic material in the cells of the human recipient and are passed on to partners and descendants.

"History demonstrates that virulence of a pathogen may be increased if it adapts to infect a species other than the natural host," Dr Jessamine warns.

"Influenza, hantavirus infection, Ebola haemorrhagic fever and, most probably, HIV/Aids are powerful examples of the same phenomenon manifested in human disease."

More than 200 humans have received transplanted pig tissues, including a small group of New Zealand diabetics who received insulin-producing cells from the pancreas of pigs from the Auckland company Diatranz in the late 1990s.

None of them has been infected with a detectable pig retrovirus.

But Dr Jessamine says laboratory experiments have shown that pig retroviruses can be transmitted to human cell lines.

Transplants may also cause "reverse zoonosis", producing a disease in the original host species or another animal through the process of genetic alteration that is involved in transmitting a virus to humans.

"While the risk of reverse zoonosis may be acceptable to an urban New Yorker, it may be totally unacceptable to a pastoral trading nation such as New Zealand," he says.

For these and other reasons, a Health Ministry discussion document on human tissue regulations, issued last year, concluded that xenotransplantation should be prohibited, "pending further work on the public acceptability and safety issues".

Most of the 125 submissions in response to that document supported the prohibition, and next month the Cabinet will consider policy options.

Last year, Australia banned all clinical trials of animal-human transplants for five years. Canada and other countries have imposed similar bans.

But this may only be a short-term position because the Bioethics Council says animal-human transplants are already being trialled or planned in the US and eight European countries.

Diatranz, now called Living Cell Technologies (LCT), plans to seek US Food and Drug Administration (FDA) approval this year for trials of pig-to-human transplants of both insulin-producing pancreatic cells and other cells from the brain or the liver to treat Parkinson's disease or haemophilia.

"The US Government and all the major pharmas [pharmaceutical firms] in the US are moving towards xenotransplantation," says LCT director David Collinson.

Dr Jessamine's paper calls for "guidance on policy and guidelines from organisations such as the FDA before we even begin to consider whether xenotransplantation can occur in our country".

Even then, the Bioethics Council says, we will need to think about whether it is morally right to take body parts from animals.

Everyone agrees, it says, that apes and monkeys should not be used because they are such close cousins that we should treat them morally as akin to us.

But most people are not so worried about rearing pigs as spare parts warehouses. After all, if we are happy to eat them, why not chop out their hearts and kidneys?

LCT New Zealand managing director Paul Tan says his pigs are "far more humanely bred" than farm animals. Their pens are much roomier and the conditions cleaner.

But Dr Jessamine says some veterinarians consider that the clean, sterile conditions of pigs bred to be organ donors may increase the risk of infection by producing less-robust and sicker piglets.

"Piglets will be derived by hysterectomy or medicated early weaning and reared on artificial foods containing no animal protein," he writes.

The Bioethics Council says we also need to think about whether it is right to genetically modify pigs to make our bodies think their organs are human, and also whether it is right to mix up our own identity as humans by installing hearts or kidneys from pigs.

It quotes Pope John Paul II, who has ruled that an animal-to-human transplant is acceptable as long as it "does not affect the psychological or genetic identity of the person who receives it".

In particular, the Pope considered the head and sexual organs to be "indissolubly linked with the personal identity of the subject". But no one is proposing to transplant those organs - yet.

The council's discussion document is open for submissions until May 20. People can also register on the council's website to attend a "dialogue" event or hui, and may join an online discussion group after March 1.

Xenotransplantation

* Means transplanting body parts from one species into another.

* May save the lives of some of the 250 New Zealanders now waiting for kidney transplants and unlikely to get one this year.

* Risks letting new animal viruses similar to HIV into the human population.

* Requires moral judgments about whether we should treat animals as our "spare parts warehouses" and mix up the identity of each species.