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In a major medical breakthrough, the researchers - led by Andrew Posselt, a 27-year-old fifth-year medical student - were able to cure the laboratory rat by transplanting insulin-producing cells, the hospital announced at a press conference this week. Although more research needs to be done, the findings could one day lead to a cure for diabetes in humans. The discovery also has important implications for transplant medicine and the study of organ rejection. Science magazine, the prestigious journal of the American Association for the Advancement of Science, will publish the research team's findings today. Diabetes destroys pancreatic islet cells that produce insulin, which is needed to regulate blood sugar levels. Type-one diabetes, in which the iselt cells do not work at all, effects more than oen million Americans. They must take daily injections of insulin to survive. A far greater number of people suffer from other forms of diabetes in which some insulin is produced, but not enough. Posselt's team was able to reverse induced diabetes in laboratory rats by transplanting healthy pancreatic islet cells into the thymus of the rats. The thymus is an organ located over the heart near the base of the neck. In the past, researchers have succeeded in transplanting islet cells into other organs of diabetic rats and humans and blood sugar levels briefly returned to normal. But the islet cells were always rejected soon afterwards unless massive doses of anti-rejection drugs were administered. In April, researchers at Washington University in St. Louis transplanted islet cells into the liver of a woman. She was able to go for two weeks without insulin shots before the cells were rejected. In the HUP experiment, only one dose of an anti-rejection drug was administered to the rats after the transplant. The rats never rejected the new islet cells. The islet cells produced insulin and returned blood sugar levels to normal. After 200 days, the scientists transplanted a second sample of healthy islet cells into the rats' kidneys. These cells were not rejected either. After 10 more days, the researchers took the thymus, along with the first transplanted cells, out of the rats. The islets in the kidneys were never rejected and maintained normal blood sugar levels. Some of the rats lived with normal blood sugar levels for as long as 17 months after the transplants. Posselt said yesterday that the rats may not have rejected the islet cells transplanted in the thymus because the organ is "immunologically privilidged." White blood cells, which cause rejection, do not enter the thymus easily. He said the experiment only has limited implications for use as a treatment for diabetes in humans because of the way it was conducted. The rats used in the experiment did not spontaneously become diabetic the researchers killed off their healthy islet cells in the first place. This means that further experiments must be done using rats with naturally developed diabetes. The disease in these rats may kill transplanted islet cells in the same process that brings on diabetes in the first place, even if the immune system does not reject the transplant. "In this model that we used, you only look at rejection," Posselt said. "It at least provides a different site that seems to be very good for transplantation. The most interesting finding of this study is that you can induce tolerance ]to transplants]." Currently all transplant patients must take anti-rejection drugs for the rest of their lives, drugs which are very expensive and have many side-effects. "We believe that these new experiments are a method by which rejection can possibly be avoided without [using anti-rejection drugs,]" Surgery Department Chairman Clyde Barker said. Barker co-authored the report of the researchers findings. In the future, doctors may be able to implant a few cells from the new organ into the patient's thymus before a transplant to trick the body into thinking that the new organ is its own. If this works, transplant patients might not need to take anti-rejection drugs. In addition to Posselt and Barker, Associate Professor of Surgery Ali Nagi, HUP Assitant Professor John Tomaszewski, medical student James Markmann and former Surgery Department Resident Michael Choti participated in the research.

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