Summer 1997 Mission

Transplanting organs—

gaining ground through innovation

Picture When Health Science Center and Air Force transplant surgeons successfully divided and transplanted one donor liver into a middle-aged woman and an infant boy this winter, the families were ecstatic. A few weeks later, Health Science Center surgeons performed the first pediatric liver and kidney transplant in South Texas. Success stories abound for the Health Science Center's organ transplantation program; however, challenges such as a severe shortage of organ donors, organ rejection by some recipients' immune systems, and sometimes unrealistic expectations held by recipients persist.

"We want to be full-service in terms of organ transplantation at the Health Science Center," explained William E. Strodel, MD, professor and chairman of the department of surgery. To that end the transplantation program has been expanded and made more widely available to patients.

"The team here has done a split-liver transplant," he said. "They took a cadaver liver and were able to separate the liver into two pieces, preserve the blood supply and bile duct drainage and then use them in two patients. That is an important interim step in making more organs available to patients.

"A big problem is organ availability. While split-liver transplants will not solve that problem, it will help—more people can benefit," said Dr. Strodel. "Once the team establishes a certain technical level in separating a cadaver liver, then the surgeons can start to think about using living, related patients for liver transplantation," he said. Some kidney patients, he explained, receive a kidney from a living relative. The liver transplant would be similar, in terms of tissue typing and compatibility checks, with the living donor providing a part of his or her liver. He added that this technique is being considered particularly for children with irreversible liver disease. A parent may be a suitable donor, and there's a minimal, defined waiting period for a donor organ.

Another possible way of addressing the donor organ shortage is use of animal organs from animals whose immune systems are genetically altered to decrease the rejection response in the recipient. Studies at Duke University, explained Dr. Strodel, are under way to determine whether or not a pig's heart could be used in humans. Researchers hope that the use of pigs' hearts would have a twofold benefit: a ready supply of donor organs and fewer problems with organ rejection. "Obviously, when we talk about using animal organs, the concern is diseases that might develop down the road, whether they be viral or other types of diseases that we just don't know about, because we're using non-human tissue in a human being," stated Dr. Strodel.

"I think this is certainly futuristic. But more research needs to be done on xenografts—a lot of people feel they'll be of benefit in the future."

In the more immediate future, Dr. Strodel and the transplant team will continue to perform split-liver transplants and investigate new drugs designed to eliminate organ rejection. "Our technical abilities and immunosuppression have moved along quite nicely in terms of producing better results," said Dr. Strodel.

Dr. Glenn A. Halff, MD, associate professor of surgery and director of the organ transplantation program, is interested in preserving harvested organs for longer time periods, noted Dr. Strodel "Once organs are harvested, they have to be used fairly quickly or function starts to deteriorate," he said. Harvested organs are placed in a liquid solution developed by the University of Wisconsin. Twenty-four hours is generally the maximum time the transplant team can perfuse an organ, explained Dr. Strodel. Thus, with the time restraints, there's some pressure to use organs within a certain geographical region because they can be retrieved and delivered for transplant more quickly. Dr. Halff is interested in ways to extend that period of time beyond the 24 hours.

For those patients who receive donor organs, dramatically improved lifestyles are not always forthcoming. "If a young person or middle-aged person develops viral cardiomyopathy—a viral illness that affects mainly the heart muscle—he or she could have a transplant done and probably get up to speed in terms of lifestyle rather quickly," said Dr. Strodel.

For other diseases, regardless of the kinds of replacement parts available, the surgeons cannot restore the lifestyle the patient enjoyed prior to the onset of the illness. "We may palliate them with replacement parts and allow them to survive," said Dr. Strodel, "but we're never going to give them back what it took a long time for them to lose.

"It's not all a perfect world where you come in, get a new organ, take a tablet every day for immunosuppression and think things are going to be like they used to be—there's always a tradeoff," he said.

Investigators also are working on methods to 'bridge' patients to transplant which include artificial livers and hearts. "Physicians try to extend peoples' lives until they find a perfect organ—a good match," said Dr. Strodel. "It's best obviously to do one transplant with a good organ and provide good immunosuppression, so that you maximize the benefits to the patient."

Artificial livers are still in the experimental stage. "So people with really sick livers are in trouble right now without a transplant." Several years ago there was enthusiasm for permanent artificial hearts, explained Dr. Strodel. That enthusiasm has waned, he added; however, artificial hearts are used to bridge patients to transplant.

Heart, liver, lung, kidney and pancreas transplants are all performed by the physicians in the Health Science Center's organ transplantation program. The team includes physicians from the departments of surgery, medicine and pediatrics. "I think we have an exceptional transplant team," said Dr. Strodel. "I'm really proud of all the people who make up that team."

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