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Ethics of Cloning Pigs - 2002-02-15


The rapidly expanding science of genetics is leading to breakthroughs in the field of medicine. But many of the advances are also raising questions about the ethics of procedures such as stem cell research and cloning.

The biotech firm PPL Therapeutics celebrated a major milestone late last year. David Ayares, the company's vice president for research, recalls: "On Christmas Day [December 25, 2001] we had the birth of cloned knockout piglets. These were very important in the field of xenotransplantation."

Mr. Ayares explains that xenotransplantation is the theory that organs from mammals can be transplanted into humans. The so-called "knockout technology" to which he refers means that these pigs have been specially cloned so that they lack one of the genes that produces the protein that causes the human immune system to reject pig tissue.

Mr. Ayares says that xenotransplantation has been a medical goal for years. "There's been a number of xenotransplantation trials, dating back to the [19]50s. And they were abysmal failures because these were not genetically modified in any way. But they gave a lot of information regarding rejection issues," he went on to say.

Milestones, such as the birth of the cloned piglets, are nothing new for PPL. In 1996, the company announced the birth of the world's first mammal cloned from an adult cell the sheep named Dolly. In its current project, PPL still needs to "knock out" a second gene before moving on to the next stage: conducting trial organ transplants on primates. The company says this technology can serve several purposes including helping in the development of medicines to treat diabetes, Alzheimer's and Parkinson's diseases.

"We can also take organs from those genetically modified pigs for overcoming the organ shortage crisis," says Mr. Ayares. The organs we would be targeting would be heart and kidney, because they're the most similar in terms of size and function."

For some critics of the technology, using pigs for their organs is inhumane. But Mr. Ayares defends using animals. "Millions of pigs are going onto our tables," he points out. "So what we're talking about is using fifty to a hundred thousand pigs that have been genetically modified so they can cure human disease. I think that in many ways it's a lot more ethical than how they're being used now."

However, some people question whether the technology is even necessary. Professor Harlan Miller is an animal rights expert in the philosophy department at Virginia Tech University, also in Blacksburg. He maintains that the country doesn't need to clone pigs for their organs: that there are many potential human donors whose organs go unused.

"Forty-five thousand people die on America's highways every year," says Mr. Miller. "Many of those people are young, healthy people with plenty of usable, organs. If we spent roughly one-tenth the money we spent on this experiment encouraging more people to be donors, there would be no need for these [cloned] swine."

But Doris Zallen, a professor of Science and Technology Studies at Virginia Tech, disagrees. She says that there are not enough organs available for all the transplants people need. Still, she cautions that researchers must be careful.

"It's often the case that we look at a very serious medical situation and we say, people are suffering, people are dying, we have to do everything possible to help them," said Dr. Zallen. "But we can't do it blindly. "

For Dr. Zallen, xenotransplantation can be dangerous and the benefits must be weighed against the potential risks. "And one of the very serious potential risks is the possible viral infections that could be transmitted from an animal in which they might not be very serious, to humans [in which they might be serious]," she says.

Aside from the potential risk to public health, Dr. Zallen stresses xenotransplantation raises many philosophical questions. She asks, "As you transplant organs into humans from animals, does this in some way devalue the human? Does the human being become less human with each additional animal organ that the person receives?"

All of these questions must be considered, and Dr. Zallen worries that the public might not have a voice in the debate over development of these technologies.

PPL Therapeutics is one of two teams in the world working on this technology. The other is Emerge Biotherapeutics, a company based in Boston, Massachusetts. Ethicists say the public needs to express itself soon on the issue because human trials using cloned pig tissue are likely to begin by 2006.

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