Xenotransplantation

Even the name sounds sci-fi. Xenotransplantation is the process of taking organs from donor animals, and transplanting them to humans. It hasn't been successful in the past, but genetic engineering just might make it work.

The idea isn't a new one. Some of the first known operations were actually performed all the way back in 1906. French surgeon Mathieu Jaboulay implanted a pig's kidney into one woman, and a goat's liver into another. Both patients died.

Fast-forward to a world famous case. In 1984 a team of surgeons implanted a baboon heart into an infant in desperate need of a new heart. "Baby Fae" died after 20 days but the idea didn't.

Why is the idea still being pursued? The alarming shortage of donor organs. Many people suffer for years, or even die, while waiting for a suitable donor organ. In order to increase the supply of organs available, science is trying to produce animal organs that won't be rejected by human bodies.

Rejection is one of transplantation's biggest hurdles. Whether the donor organ comes from a person or an animal, the recipient's immune system is likely to reject it. To overcome that hurdle, genetic engineering can adjust the genetic makeup of donor animals, adding or subtracting specific genes, to make the organs compatible to humans.

In 2002 PPL Therapeutics, the company that created Dolly the cloned sheep, announced new "knock-out" pigs. These cloned piglets had specific genes "knocked-out" - removed from their DNA. The genes produce a substance that guarantees rejection. Without the genes, the substance is gone, increasing the odds that the organ is accepted.

Critics of xenotransplantation charge that not nearly enough is known about the process. Viruses that are normally carried only by animals could cross the species boundaries causing problems for people. There are also serious ethical objections to the process. Should animals be bred as organ factories for humans?

Thought Questions

Is genetic engineering the only answer to the organ shortage? Is it ethical to change the genetic makeup of animals to take their organs?

Sources

Williams, Rebecca D. Food and Drug Administration. "Organ Transplants from Animals: Examining the Possibilities." (Online.) http://www.fda.gov/fdac/features/596_xeno.html September 2002.

CNN.COM. "Pig-to-Human Transplant Hopes Rise." (Online.) http://www.cnn.com/2002/TECH/science/01/02/genetics.pigs/index.html September 2002.

Henderson, Mark. News.Com.Au. " Pig-organ Transplants Closer." http://www.news.com.au/common/printpage/0,6093,4960482,00.html September 2002.