The new gene-editing technique CRISPR/Cas9 could remove one of the toughest barriers to the transplantation of pig organs to humans (see BioNews 824). It has been suggested that the production of genetically modified (GM) pig organs could end the anguish of those waiting for suitable donors. Currently in the UK there are well over 6500 people on the waiting list to receive an organ transplant. Last year, 1300 people died waiting for a transplant or became so sick that they were no longer eligible to receive one. The shortage is in part because only a small percentage of people die in circumstances that enable them to become donors (most organs are harvested from patients in intensive care units who are being ventilated).
The potential of GM pig organs to eradicate transplant waiting lists would depend in part on the scalability of the process. Might we one day see industrial-scale factory farming of GM pigs and a conveyor belt of organs as cheap and plentiful as budget supermarket sausages? This seems unlikely for several reasons.
Despite the relatively low cost of CRISPR itself, the process of creating and rearing GM pigs is likely to be expensive. They would be valuable animals, whose security would be a matter of concern for their breeders. The widespread European objections to GM crops may also an indication that we are unlikely to see bucolic fields of GM pigs alongside our conventional bred cows and sheep. Moreover, there would be risks that the animals might ingest toxins, or be exposed to pathogens that would jeopardise their organs. High security – and highly expensive – controlled laboratory facilities are a more realistic prospect.
Genetically modified pigs farmed for their organs would be subject to at least the same regulatory welfare controls as those that apply to ordinary farmed animals. They might also fall within the regulatory frameworks for research animals, meaning that large-scale production would be limited by animal-welfare requirements.
At least, it might be thought, wastage would be very low in comparison with human donors. Poor organ quality resulting from accidents, old age, disease and unhealthy lifestyles would all be forestalled. Yet harvesting pigs' organs would still require a porcine version of intensive care, including ventilation, in order to ensure that the organs are cleanly excised and adequately oxygenated till the very last minute. These procedures will not be cheap.
The cost of GM pig organs themselves is also a concern. Human organs cannot legally be bought or sold anywhere in the world except Iran (although there is a multi-billion pound black market in trafficked organs). Altruistic donation has a significant economic benefit for health services who acquire these valuable commodities free of charge. A report published in 2010 states that 'the UK transplant programme realised annual gross savings of £316,000,000 to the NHS'. Producers of GM pig organs will not be donating them altruistically to the NHS. Health services will have to pay for them, just as they pay for other medical products and services.
Rapid medical advances in modern times have been matched by a rise in the public's expectation of medicine. Given the high emotive appeal of organ transplants, there will be heavy pressure on the NHS to offer GM pig organ transplants as soon as they are proved safe, even if they are expensive. If the cost of GM pig organs proves too steep to be affordable on the NHS, it could trigger the kind of battle that we currently see between healthcare providers, pharmaceutical companies, NICE, patient lobby groups and the media.
Perhaps more likely is the prospect that healthcare providers would undertake limited quantities of GM pig transplants in order to conserve their budgets, as they do with other costly interventions. It is easy to foresee a scenario in which patients have to fulfil stringent eligibility criteria, and remain on lengthy waiting lists for one of the few GM pig transplants that the NHS can afford in that particular year. Increasing the supply of human organs as an alternative to costly GM pig organs would then be an even stronger imperative than it is now.
If organ waiting lists, and donor-recruitment campaigns are not then to become a thing of the past, this raises the question of whether GM pig organs should be pursued at all. Given the cost-effectiveness of human donation, and the fact that only around one-third of the UK population currently are on the donor register, perhaps this is where we should be focusing our efforts.
Successfully growing organs safe that are for human transplantation would undoubtedly be one of the greatest achievements of medical science. But, exciting though they are, victories over biology do not invariably translate into human benefit. Only those who are in denial about the ethical, political and economic complexities of our health services will expect GM pig organs, or any other scientific development, to be a panacea for human miseries.