by Ndifor Abongnifor

Created on: December 09, 2008

TRANSPLANTING ORGANS FROM ANIMALS TO HUMANS.HAS XENOTRANPLANTATION GONE TOO FAR?

In January 2002,Dr Sochs, a professor of surgery and immunology at Harvard school of medicine with his colleagues reported that they had successfully made a clone of pigs in which one copy of a particular gene had been "knocked out" of their DNA. This "knocked out" gene codes for a sugar molecule called galactose alpha (1-3-galactose) found on the cells of the pig. This molecule is recognized as foreign by the human immune system. During evolution, humans and primates like monkeys and apes lost the enzyme that makes this molecule. The presence of this gene made it impossible to transplant organs from pigs to humans.

The cloned pigs missing one copy of this gene can breed and produce offspring with just one copy of the 1-3-galactose gene. Scientist will then breed those offspring producing a litter in which one out of four piglets will lack both copies of the gene. Organs from an offspring lacking both copies of this gene can now be transplanted to human patients with ought rejection. If all goes well, scientist say this will help most patients on the organ waiting list.
The above finding sounds promising but this has not gone down well with some critics on the grounds of ethics.
The ethical concerns.
There are two major concerns by critics.
- The risk of transferring pig retroviruses to humans.
- It is unethical to raise animals strictly as a means of harvesting their organs.
Concerning the issue of pig retroviruses, Dr Sachs shares this concern with critics, but he says "to date there is no evidence that pig retroviruses have caused human disease."
A study of 160 cases of involving humans who had either received transplants or had been exposed to pig tissues or cells, there was no evidence of viral transmission after years. These people were stroke survivals and people with Parkinson's disease who had neural swine cells implanted; those whose livers had failed and were hooked up with an external pig liver that filtered their blood while they waited for a human liver transplant.
Another concern by critics is that it is not ethical to raise animals strictly as a means of harvesting their organs. Next to non human primates such as chimps (some are endangered and some are too small to provide suitable organs),pigs have the greatest physiological similarities to humans and are abundantly available.
This makes them very suitable for xenotransplantatin. To say that pigs should not be raised solely for their organs to be harvested and transplanted does not sound like an issue of ethical concern to me.
Take for example, in the USA100 million pigs are slaughtered each year for food.
If it is ethical to have pigs raised solely for food, why is it unethical to raise pigs solely for harvesting their organs which is going to bring relieve and save the lives of thousands of people needing organ transplant?

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