Though risky, transplants are crucial treatment interventions for many patients.They can save lives of cancer patients, others with severely ill organs and recently there are trials to make them a mainstream treatment for autoimmune disease patients ( i’ve just read an article about that topic and i’d really love to write about it soon too).
But the major problem with transplants, other than the agonizing wait for the right donor on endless lists for sometimes many years, is that when things go wrong with transplants, the patient’s life becomes at mortal risk. Almost 40% of transplant patients will show rejection episodes within the first year after the operation. The detection of these immunological reactions are usually so late, and the only solution will be to flush the patient’s system with huge doses of immunosuppressive drugs that are toxic themselves and can have debilitating effects on cancer patients for instance. Also, to be able to detect rejection reactions, the doctors should take biopsies of the new organ, a process that can cause damage to the organ itself, let alone the stress and the already fragile patient condition. Transplant patients have to undergo exploratory biopsies monthly for one year after the operation!!!!!
Early detection of these reactions was an interesting topic and a field of research for the cardiologist Hannah Valantine of Stanford University School of Medicine in Palo Alto, California. In 2009, she devised a new test that detects the immunological changes in a transplant patient in an episode of rejection. The test, called AlloMap, became the first of its kind to be approved by the FDA for use in the detection of heart transplant rejections. Yet, it failed to detect the rejections early in about half the patients.This, of course, didn’t satisfy Valantine.
Along with biophysicist Stephen Quake of Stanford, they came out with a much more sensitive test. The idea was that DNA from the new organ constitutes around 1% of the free DNA in blood of transplant patients. This DNA is foreign from the DNA of the patient and using her test, it can be very sensitively detected, despite the fact that it is circulating in minute amounts. To validate their test, they used it on stored plasma samples from transplant patients that later showed rejection signs. It was found that the amounts of the rejected organ’s DNA in such episodes are elevated soon after the surgery and constitutes around 3% of the free DNA in plasma, and of course, will be much elevated later, in the peak of the episode. They reported the results in The Proceedings of National Academy of Sciences.
The good thing about this test, besides its high sensitivity, is that it is much less invasive than a biopsy, and the biopsy will not be needed except for confirmation, in case the test is positive and the DNA % is higher than normal. Also, early detection will allow doctors to use much smaller doses of immunosuppressives to control the case and therefore, less side effects will be experienced. Valantine is a cardiologist, but believes the test can be used with other types of transplanted organs, other than hearts.
Tags: AlloMap, cardiology, FDA, immunosuppressives, organ rejection, transplants