October 14, 2008
Kidney Transplant List Undergoing Renovations
Every one in three patients needing a kidney transplant may never receive one because their bodies are unusually conditioned to assault a donated organ. Doctors are now trying to outsmart the immune system and save more "highly sensitized" patients.
These patients often have kidneys donated by living donors, thought to be the best kind.
"I feel very lucky. Our son saved my life," said Cynthia Preloh, after a curious mixture of blood cleansing and a cancer drug permitted her to accept a kidney from her son that her body ordinarily would have ruined.
This promising work arrives as the nation's kidney distribution system is receiving important renovations. They are trying to prevent the years of waiting it can take to find a kidney transplant match.
This is terribly important, because "your chance of getting successfully transplanted decreases with time," says Dr. Keith Melancon of Georgetown University Hospital. Melancon is Preloh's surgeon and head of the mounting field of incompatible kidney transplant research.
About 77,000 people are currently on the national waiting list to obtain a kidney from a departed donor. However, fewer than 17,000 transplants a year are actually performed.
Approximately 10,500 of these performed transplants are from deceased donors and a little over 6,000 are from living donors, relatives and friends who donate their organs to a specific patient. The time on a waiting list can last from four to five years, and 4,000 patients pass away while waiting annually.
The United Network for Organ Sharing is taking into consideration some changes being proposed to the system. While there are no formal suggestions yet, there are topics and options being discussed.
One suggestion is that waiting periods could be determined by kidney deterioration instead of how early on someone is put on the transplant list.
Additionally to revamping wait time, matches could take into consideration both patient and kidney age as well as medical conditions. The ages are reviewed in order to make the most of "life years from transplant."
One kidney could be successful over a longer period of time in an elderly person without diabetes than in a younger diabetic, explains Dr. Kenneth Andreoni of Ohio State Medical Center and the vice chair of the UNOS kidney committee.
"It's trying to get the balance between having a person live longer because they have the transplant over dialysis, and also looking at how many years in total they would live," Andreoni says.
Positioning the value of donated kidneys could allow patients to prefer one of lesser quality if it means a briefer waiting period, or allow the patients the option of waiting for a better one.
These kinds of changes will not enhance available kidneys. The benefit of the changes made to the systems will target patients like Preloh who otherwise might not get a chance at a new organ.
To receive a transplant, doctors must match patient and donor kidneys by blood and tissue type. The anti-rejection drugs used today are so effective that tissue-typing can afford to make mistakes.
There is a different concern called antibody-mediated rejection, where patients become progressively more "sensitized." Their bodies produce antibodies that attack kidneys.
Several things such as pregnancy, blood transfusions, a previous transplant, and prolonged time on dialysis can cause bodies to become sensitized. Waiting on the kidney transplant list can also cause this to happen.
The more antibodies that the body produces, the harder it becomes to find a compatible kidney. The primary focus becomes to rid the patients of antibodies and prevent them from making new ones.
To do this doctors can filter a patient's blood prior to a transplant. Another way to fight this is through intravenous immune globulin, or IVIG, a mixture of antibodies that fights infection. They force out the bad antibodies that the kidney produces with regular types.
The treatments established at hospitals like Los Angeles' Cedars-Sinai Medical Center and Baltimore's Johns Hopkins University are slowly becoming mainstream.
It is still not soon enough for many incredibly sensitized patients, so a new experiment is evaluating the lymphoma drug Rituxan, which combats the immune-system cancer by destroying specific antibody-producing cells.
Melancon hopes that Rituxan would give the patient Preloh enough desensitization to attempt a prolonged, successful transplant. Her latest kidney began working on the operating table, "which was the best thing you could hope to hear," she stated during her recovery.
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