Friday, November 07, 2008

To have the Heart of a Pig

Now this is not a suitable question to discuss over a cooked breakfast, or a bacon 'buttie' at lunchtime. Better over the vegetarian option. Will 'presumed consent' be extended to pigs? Or will it be considered entirely proper for us to breed pigs (in a totally virus-free environment of course) so that we can whip out their vital organs and implant them into human beings in need of an organ transplant. You may think I'm being a little ridiculous here. Been reading some science fiction. But no - not according to today's Telegraph.

Lord Winston, fertility expert at Imperial College, London is developing a GM pig which could be the harbinger of a limitless source of organs for human use - hearts, kidneys, livers etc.. He thinks such a pig will have been created by 2010, and be ready for use in our hospitals within 10 years. I don't think its a wind-up. I'm sure that many people will think that this is a wonderful development. But it causes me disquiet - a lot of it.

14 comments:

Chris Wood (PhD not MD) said...

Glyn> this is new hype over old biotechnology - the kind of hype trick about old stuff that Plaid Cymru has a penchant for.

Such pig->human transplant ideas were in vogue at least 10 years ago. There was a set-up in Northern Illinois (in the DeKalb area if memory serves) where pigs were being genetically engineered with 'clean antigenics' to act as reservoirs for organs for transplantation ('xenotransplantation') into human patients requiring new organs.

The same problem then will present itself now with regard to the Lord Winston porkies. We will be introducing different genes into the human genome; a patient with such an organ will have different cells with different DNA. That in itself is not really the 'bug bear', not so bad as Iceland killing polar bears that swim onto its shores.

No, the real problem is virus genetic code. More particularly, the genetic load/temperate viral particles that are parked in the pig's genome. By transplanting pig organs we will also be transplanting viral genetic material into the human genome.

Putting my microbiology cap on (I have BSc degree in microbiology) Even our old friend Escherichia coli ("E. coli") harbours the odd temperate phage (temperate bacteriophage - virus that infects bacteria like E. coli) - one common example that student microbiologists know so well is Lambda phage.

Lord Winston is not, as far as I'm aware, a microbiologist. You really need to spend a few years playing with microbes and phage that infect bacteria to get an instinct for such things. It can't be understood reading from a book. I loved the microbiology labs and still remember them.

There are very few scientists with microbiology degrees. Cardiff University had a microbiology department ("Department of Microbiology") on Newport Road near Queen Street - that department was shut down, the microbiology single honours degree still lives on, but it is not taught in a dedicated Microbiology Department. I believe there is now only one full-blown Microbiology Department in Wales.

Anyways/milliways, if we put pig genetic material into human there is no way, no how that we will not transfer 'pig temperate virus into the human genome. If one of these temperate viral particles is activated and thereby released from its dormant state, well microbiologists know what happens when phage is triggered - the host bacteria lyses - they disintegrate. We probably don't have immunity to pig phage virus, we may trigger an outbreak that will make the 1918 flu pandemic that killed millions look like a walk in the park.

There is a saying in law, "bad cases make for bad law". I would add that 'bad biotechnology make for disasters of such magnitude that their severity might well challenge man's existence well beyond the threat of nuclear annihilation".

Put another way, to fix a hole use something neutral like a silicone based sealant, not plutonium and certainly not temperate virus.

That line from Frank Herbert's DUNE comes to mind (the movie and/or book), "More worm sign than God has seen." Let's not generate more 'phage' than God has seen in the context of mankind.

nadwin said...

My late brother-in-law collapsed and was rushed to hospital in Toronto Canada with a perforation to his heart wall.

Although close to death, he was offered an 'experimental' procedure which involved surgeons making a 'patch' from pigskin and synthetic materials and attaching it to his heart.

He lasted a further three years of life, for which he was very grateful.

He certainly thought that it was a good idea.

Dylan Jones-Evans said...

This technology is already being overtaken by developments in
Wales

Why heart pumps could kill off the transplant (http://www.timesonline.co.uk/tol/news/uk/health/article5039521.ece)

Just to quote from the piece:

"The British healthcare system is structured and organised in a way which can prove heart-pump technology works,” he says. “You seem to have doctors fighting each other over there, but the reality is that pumps are much less expensive than transplants and they don’t wear out.” Pumps could, according to Frazier, be made very inexpensive indeed. All you need, he says, is one moving part and two small bearings. There is, however, rather more to it than that – not least the problem of how to overcome the weight of the battery and the need for an external power supply. Teams around the world are forging ahead with work on these problems. One of them is led by Marc Clement, director of the Institute of Life Science at Swansea University, which has a £52m budget for interdisciplinary medical research. He was inspired after meeting Peter Houghton at a Downing Street reception for innovators three years ago. Clement, who is widely regarded as one of Britain’s finest physicists, was already interested in the notion of heart pumps, and accompanied Houghton on a trip to Texas, where they visited Frazier and other specialists in the technology. They also went to Nasa, where there are groups of researchers working on nothing but methods of miniaturising pumps for exploration in space, where bulk and weight are as crucial as they are for implants in the human body. It was this experience that gave Clement the idea for his heart pump, which he is hoping will be implantable using keyhole surgery. He has won a £1.3m government grant to work on the invention, which is being developed through a university spin-off company called Calon Cardio-Technology. “We believe we have a unique patent, and a product which will be a major boost for UK plc,” Clement says."

Marc, of course, is the Vice-Chancellor of the University of Wales.

Chris Wood (PhD not MD) said...

Nadwin> there's no problem with 'patches', e.g., heart valve damage is sometimes fixed with tissue from, e.g., horses - the tissue is rendered 'antigenically neutral" by chemical means (e.g., soaking in glutaraldehyde for a predetermined time) to avoid antibody issues (rejection), but that doesn't amount to organ transplant. Transplanting a whole animal organ is a different kettle of fish. The cells that make-up the organ will have cell surface proteins that will be impossible to render antigenically neutral by chemical treatment without harming the living non-human cells. There is a whole lot of difference between, e.g., providing scaffolding for the patient's tissue to grow on verses organ replacement. More specifically, there is a world of difference between xenograft and xenotransplantation of whole non-human organs.

Lord Winston claims his pig organs are virus free - yes, they can be screened for virus that we know of - but it is VERY likely that there are dormant virus in the pigs genome akin to what's found in the unicellular microbiology world In re bacterial temperate phage. So Lord Winston is VERY wrong to claim that his pigs are virus free - they are, but only to the extent of man's current knowledge of viral disease.

Do we really want to risk phenomenal damage to our species to save a fraction of it from premature death? We are talking billions of humans placed at risk of diseases that our outside our biotech/medical knowledge. This issue (along with the antigenic/antibody rejection issue) sunk the previous effort of using pig organs for xenotransplantation to humans). This technology that the media has been hoodwinked into believing is 'new' is actually a rehash of research that was conducted at least a decade ago. I was aware of it, because some friends knew some guys who were looking after the pigs - they were kept in very clean conditions, but that counted for nothing re dormant pig virus that might become activated once placed in the human genome.

In the lab we could trigger activation of temperate bacteriophage using, e.g., UV light. But the mechanisms by which bacteria phage extradite themselves from their host DNA is not fully understood. I haven't read any papers on it for some years now, but I suspect that upon activation the phage includes genetic code to force the host bacterium to manufacture a signal molecule that is secreted from the bacterium, and if there is a critical amount absorbed by other like bacteria this provides the trigger for phage buried in nearby bacteria to emerge from their sleep and multiple to the extent that the host bacteria are lysed and the new phage is free to infect other bacteria and confirm a new cycle.

Savonarola said...

Brings back memories of the earliest heart transplants in Cape Town where Chris Barnard operated at Groote Schuur. I knew his third transplant patient - a youngish nurse in late 20's. Dr Barnard transplanted a pig's heart but the young lady died soon afterwards.
At the time I felt uneasy. Later I came to realise that Mary T was simply a Barnard experiment. Fair enough, I suppose. Barnard was a 'ruthless' surgeon in that his ambitions sometimes comprimised the Hippocratic oath he took. I could be wrong.

nadwin said...

Dr. Wood (phd not md).

Whilst your highly informative explanation would transcend many a brain, I think that I understand your point regarding the difference between a 'patch' and whole organ transplant.

Many thanks.


Word ver: sooth. You couldn't make that one up.

Anonymous said...

Is your disquite around the fact that you may end up having a pigs heart, kidney, liver, pancreas or is the disquite that the pig has been bred to provide organs?

In which case is this any different to breeding pigs for meat, or breeding greyhounds to race and when they get too slow, euthanaising them with a 3lb hammer?

I've got a feeling that within 50 years (if we are around then) then most conceptions will take place in-vitro, and only the viable embrios, post genetic testing for most genetic will be allowed to reach maturity.

Dr. Christopher Wood said...

Artificial pumps no doubt come with some limitations and issues for the patient, but at least they don't harbour dormant virus and are less likely to trigger the patients immune/rejection system. But an artificial pump should pump the patient's blood without harming, e.g., red blood cells, by e.g., shear forces.

Glyn Davies said...

Chris - Lord Winston is a Labour Peer - and a good self publicist. I'll take your word on the microbiological issues. I just know about pigs.

Nadwin - If the choice is death or a pig patch, I'll take the former.

Dylan - Thanks. I didn't know about this specific work, though Marc Clement's reputation is well known.

Savonarola - I too would have been uneasy about the pig's heart transplant. I would still feel uneasy today. But I have not the slightest doubt that if one of my own family memeber's lives could be saved using a pig's organ, I'd be willing to set my concerns aside.

anon - my concern relates to both the disease risks to th ehuman race, and the ethical aspects of such transplants. You are right that it makes no difference to a pig whether its being killed for the breakfast table of te operating table - and that aspect makes no difference to me either.

nadwin said...

Glyn, you said........

If the choice is death or a pig patch, I'll take the former.


You also said.......

But I have not the slightest doubt that if one of my own family memeber's lives could be saved using a pig's organ, I'd be willing to set my concerns aside.

Nadwin says......

This does not compute!!!

Are you saying that you would be prepared to see a whole organ used to save a family member's life but would not use part of an organ, as a patch, to save yours?

Explain please.

Glyn Davies said...

nadwin - Sorry, I meant 'the latter' rather than the 'former'.

Anonymous said...

Glyn

What's your thoughts on Greyhounds being euthanised with a hammer at the end of their very short racing career?

Anonymous said...

To the pig organ, some human genes.

To the human, a pig organ.

To the temperate virus, the human race.

To the human race, a silly end.

Glyn Davies said...

anon - I don't like it. If animals are to be put down, it should be as humanely as possible.