STORY SOURCE:Robert Boucek Jr., M.D., All Children's Hospital (727) 892-8984
Media contact: Anne Delotto Baier(813) 974-3300[email protected]
USF/ALL CHILDREN'S RESEARCHERS STRIVE TO ELIMINATE IMMUNOSUPPRESSIVE DRUGS IN TRANSPLANT PATIENTS
TAMPA, Fla. (Oct. 26, 2000) -- If a transplanted heart was 100-percent compatible with the patient receiving it, the patient would be cured -- not just treated for symptoms of heart disease, said the director of the Pediatric Heart Transplant Program run jointly by All Children's Hospital and the University of South Florida.
"This is the goal we are striving to attain in organ transplantation total tolerance: The state in which the donor heart is recognized no differently than a fingernail or a toenail or any other part of the body," said Dr. Robert Boucek Jr. "We're not there yet."
More than 80 percent of children who undergo heart transplants survive many years taking medications to suppress the body's natural tendency to reject the transplanted organ.
That's good, Boucek said, but not as good as if physicians could eliminate the long-term need for immunosuppressive drugs, which can have toxic side effects and make transplant patients more susceptible to infections.
Boucek, professor and chief of the USF Division of Pediatric Cardiology, and his team are trying to identify biomarkers that would reliably indicate when a recipient's body has learned to tolerate a donor heart. They are also investigating how certain substances, such as cancer drugs, can trigger heart damage.
Their research is supported in part by the $2-million Steven and Sonia Raymund Endowment in Pediatric Cardiology.
Since the pediatric transplant program began five years ago, 38 children ranging from nine days old to 15 have received new hearts at All Children's Hospital. Last year, the U.S. Department of Health and Human Services ranked the All Children's Hospital/USF heart transplant program fourth best in the nation -- placing it on top of a long list of prestigious programs.
Refinements in surgical technique and advances in post-transplant surveillance using non-invasive technology, such as ultrasound, have made transplants possible for the tiniest of newborns. These very young children tend to require less immune suppression than older children and adults who undergo transplants, Boucek said. "We're trying to determine whether immaturity has anything to do with achieving a state of tolerance, and if so, how can we duplicate that process in all patients?"
Boucek is examining how white blood cells in the lymphatic tissue of very young transplant recipients relate to the foreign white blood cells from transplant donors. If the donor and recipient cells coexist in harmony, he said, it may be a sign that the transplanted heart has been accepted as the recipient's own, and immunosuppressive drugs can be safely withdrawn.
Other research focuses on preventing conditions that may result in transplantation, such as cardiomyopathy, a serious weakness of the heart muscle. Twenty percent of children who receive chemotherapy for leukemia, lymphomas or other cancers develop cardiomyopathy eight to 10 years following their successful cancer treatments.
Researchers are unsure why this late-onset cardiomyopathy has not been identified as often in adult cancer survivors, but they suspect the demands of new and rapid growth may lead to the progression of the disease in children.
Using an animal model, Boucek's team is studying how prior exposure to the cancer drug doxorubicin may lead to late-onset cardiomyopathy and testing drugs that may counteract doxorubicin's damaging effects on the heart. "We hypothesize that the drug somehow alters the DNA, which initiates an enduring change in the heart muscle cells so that they die prematurely," he said.
- USF -
RSS