|
|
 |
ANIMAL
ORGANS HOLD PROMISE FOR HUMANS But Critics Cite Ethical/Safety Issues of Xenotransplantation -- Lincoln Journal Star Three weeks ago, Marcy Weiner was one of 16,000 Americans waiting for a liver. Today, she is recovering from transplant surgery that was performed Dec. 28 at the University of Nebraska Medical Center in Omaha. Weiner, 54, got the liver after 18 months on a waiting list. After 12 years of living with primary biliary cirrhosis, an autoimmune disease in which the body gradually destroys its liver. "There's no cure for this disease," she said. "The only alternative is a transplant." Weiner is now home in Onawa, Iowa, enjoying foods she had to give up before she got a new liver, and feeling more energetic than she has in months. It's all thanks to the generosity of an anonymous family, somewhere outside Nebraska, that donated its loved one's organ. "Whoever my wonderful donor was, they must have had a fantastic liver, and I certainly appreciate their sharing it with me," she said. For the first few weeks, she'll make the 50-mile trip to Omaha each day so doctors can monitor her progress. And she'll be on anti-rejection drugs, which increase susceptibility to other diseases, for five to seven years. But while her story has a happy ending, the sad fact is this: Of the 73,000 Americans who need organ transplants, 12 die each day waiting for the hearts, livers, lungs or kidneys that may have saved their lives. A ready source of organs - an organ farm, so to speak - could eliminate many of those deaths, and much of the trauma of waiting for organs. That possibility is the driving force behind research into xenotransplantation - transplanting organs from one species to another. But with any revolutionary idea comes conflict - and promises.
The University of Nebraska Medical Center is on the cutting edge of xenotransplant research. Its focus: using pigs as a source of organs for humans.
The research has great potential, said Dr. Alan Langnas, chief of transplantation at the Medical Center. About 20,000 organ transplants of all kinds are performed each year throughout the United States, he said. If animal organs were readily available and safe to use, he predicted that figure could mushroom to 100,000 or more. "Organ transplants only occur when there's a 90 percent or better chance of success," he said. "If we had an unlimited supply of organs, we could broaden our organ transplant therapy." That means cancer patients and others who aren't eligible for transplants now could be treated through organ transplant therapy, he said. While earlier xenotransplant research focused on primates, it has switched to pigs in recent years for a number of reasons, said Beschorner. The potential for disease transmission is lower because pigs and humans have fewer pathogens in common. In addition, pigs' organs are similar in size to those of humans. And, researchers believe, there would be less public opposition to harvesting organs from domestic animals already raised for food than from the much more human-like primates. But opponents fear xenotransplantation could unleash new plagues. "Xenotransplantation is something that should never be done," said Alan H. Berger, executive director of the Animal Protection Institute in Sacramento, Calif. "The No. 1 issue is the potential spread of infectious disease. That threat is real. It's very real." He and other opponents, like Alix Fano, director of the Washington, D.C.-based Campaign for Responsible Transplantation, argue that even if doctors are able to screen for known viruses or bacteria, there's no way to avoid the possibility of an unknown virus being transmitted to a human recipient. Once there, they say, a benign pig virus could mutate into something lethal to humans. "There are lots of legal ramifications," she said. "Who's responsibility is it if a disease breaks out?" Xenotransplantation research has faced strong opposition in England and on the European continent, where mad cow disease is a threat. Others point to the deadly Ebola virus and HIV/AIDS, which may have originated in monkeys. But researchers say pigs used as human organ donors would be raised in a germ-free environment and screened for all known pathogens.
"Even doing clinical trials, you have a potential for spreading a disease," said Berger. Seven years ago, Dr. Jay Fishman, head of the Infectious Disease Department at Massachusetts General Hospital in Boston, was one of the first doctors to raise the question of porcine retroviruses. Since then, lab experiments have confirmed retroviruses can transfer from pig tissues to human tissues in a laboratory culture. However, there has been no proof the viruses will reproduce or cause disease, he said. "People tend to look at sensational possibilities like AIDS and Ebola, but so far there is no evidence that such a risk exists," Fishman said. "We need to focus on safety and developing good diagnostic tools." Since 1997, clinical trials of xenotransplants using human subjects have been placed on hold by the FDA pending development of reliable methods to test for and monitor changes in porcine endogenous retrovirus in recipients of pig organs. New federal guidelines require researchers to disclose full information about potential disease risks to students. Recipients of animal organs must agree to be monitored for the rest of their lives and inform all people with whom they have close contact of the possibility of an unknown infection. "It's ludicrous to believe you can track every sexual partner and every other close contact a person has for life," said Dr. Murry Cohen, a spokesman for the Physicians Committee for Responsible Medicine. "Can you imagine someone being monitored for 50 years? It has to be voluntary. There's no way to enforce it." A 17-member national committee of health professionals and citizens begins meeting this month and will monitor progress in the field and advise the U.S. Secretary of Health and Human Services. The Animal Protection Institute's Berger, who will be on the national committee, represents animal-rights activists who say xenotransplantation exploits animals. "Millions of people don't want to see animals used in research," he said. "We should spend more money on prevention and public health programs, rather than researching transplants, which only benefit a minority who can afford them. If a person blows out his liver by being an alcoholic, should he be able to get a pig's liver and blow it out, too?" "All animals have rights," said Kathy Guillermo, a national spokeswoman for People For the Ethical Treatment of Animals. "Our objection is that it's not right to take another being against their will for experimentation." Researchers argue that experimental animals have been used for centuries and that many medical advances would have been impossible without them. "At this point we can't move forward in science to make life better for human kind without using some live animals," UNMC's Langnas said. All animal experimentation at the Medical Center must be approved by its Institutional Animal Care and Use Committee, an 18-member board from several scientific and medical disciplines, plus two nonmedical community representatives. The board made sure all the sheep and pigs used in Beschorner's research were well cared for, that they received proper anesthesia and pain-killers as needed, and, when necessary, were euthanized in a humane and painless manner. "The use of animals in this country is highly, highly regulated," said Dr. Ernest Prentice, associate vice chancellor at UNMC. "Xenotransplantation is the most regulated procedure of all." Animal rights people like to claim the societal risk is greater than the benefit, but that hasn't been proven, he said. "You're really talking about taking the life of a person versus the life of a pig." And then there is the belief that research in xenotransplantation is motivated not by altruism but by money. "It's a matter of competing to be No. 1 - both in terms of profits for individual companies, and also attracting grants for medical institutions," said Cohen of the Physicians Committee for Responsible Medicine. According to some estimates, if xenotransplantation works, it could be a $6 billion industry by the end of the next decade. Dr. Andrew Jameton, an ethicist with the Medical Center in Omaha, acknowledged the lure of fame and fortune is always a temptation, especially when the cost of research requires seeking funds from private stockholders. But, he added, scientists in all fields must guard against letting profit get ahead of scientific method and accuracy. "I don't have any reason to think the problem of scientific integrity would be any worse in this area than in any other," he said. In making a decision to pursue xenotransplantation, society has to strike a balance between the risks of a new procedure and the desire for investment and a need for speedy development, Jameton said. "People don't want to wait 30 years to know whether xenotransplantation works before investing in it." In general, Jameton said, he believes most researchers are pursuing xenotransplantation because they think people will benefit. "There's an organ shortage and people are desperately ill. I think (physicians) have a very deep commitment to care for people." Weiner is among those who said she would have considered accepting a pig's liver, if one were available. "I'm a big believer that somebody has to try it, whether it's a new drug or a new procedure. But I'd want assurance that I wouldn't wake up oinking," she joked. Reach Bob Reeves at breeves@journalstar.com or 473-7212.
|
 |
 |
