Using a $2.5 million, three-year grant from the Juvenile Diabetes Research Foundation (JDRF), Emory transplant researchers plan to develop pig islets as an alternative to human islets for transplant into patients with Type 1 diabetes. If their research is successful, clinical trials of the porcine islet transplants into humans could begin within the next three years. Christian P. Larsen, MD, DPhil, director of the Emory Transplant Center, is principal investigator of the grant.
Individuals with Type 1 diabetes, which usually develops early in life, are unable to produce their own insulin because their pancreatic islets do not function. In 2000, researchers in Edmonton, Alberta, first reported that islet transplantation can produce a high rate of insulin independence with excellent metabolic control. This was followed over the next several years by a series of clinical trials focused on improving the islet transplant procedure. Emory was the first, and is still the only, center in Georgia thus far to transplant human islets. Emory physician/researchers have performed 16 islet transplants into nine patients since 2003.
Despite some success in helping patients forgo or cut down on insulin injections, the islet transplant procedure still faces significant challenges. Transplant recipients must take toxic immunosuppressant drugs to improve long-term survival of the islets. Emory scientists, based on research begun at the Yerkes National Primate Research Center and continued in human clinical trials, are leaders in a national effort to develop less toxic drugs for islet and solid organ transplants.
At the same time, researchers have realized the vast gap between the number of human islets available from current sources and the millions with Type 1 diabetes who could potentially benefit from safe and effective islet replacement therapy. Xenotransplants, which are transplants between two different species of animals, have been considered as an alternative that could provide much larger quantities of islets for human transplant.
"While support from the JDRF has allowed us to make considerable progress in improving immunosuppressant drugs and in refining the islet transplant procedure, a significant problem remains with the available supply of islets," says Dr. Larsen. "There simply will never be enough islets available for transplant if we must rely on human deceased donor pancreases. We are very optimistic that porcine islets may provide the answer to this difficult challenge."
With the JDRF grant, the Emory scientists will use a nonhuman primate model at the Yerkes Research Center to develop their porcine islet transplant strategy. This will include successfully preparing the porcine islets for transplant; circumventing the potent rejection barriers to acceptance of the xenograft; and understanding and minimizing the risk of transmission of porcine pathogens to human transplant recipients and the general population.
In 2002, the JDRF awarded Emory scientists $4.1 million to create the Emory JDRF Center for Islet Transplantation to address large-scale strategies for islet replacement. One of only a handful of such centers, it was renewed with an additional five-year grant of $8.5 million in 2006 with the goal of advancing islet transplantation to a mainstream therapy for Type 1 diabetes. More information about JDRF is available at www.jdrf.org
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