Transplants of Cells Aided Diabetics, Doctors Say : Health: Fetal tissue grafts boosted patients’ insulin production. But other researchers call results preliminary.
The first U.S. trial of a Russian technique for transplanting fetal pancreatic cells into diabetics has led to increased insulin production and a marked improvement in the control of blood sugar levels among the 24 patients who received the grafts, according to Santa Barbara scientists.
Virtually all of the recipients received some benefit from the transplants, a marked improvement over previous U.S. trials in which few transplant recipients showed improvements. Other researchers, however, cautioned that the results are very preliminary and have yet to be confirmed elsewhere or published in a scientific journal.
Russian surgeons came to the Sansum Medical Clinic in Santa Barbara in July, 1993, and implanted a curious mixture of human and rabbit fetal cells and fetal hormones, imported from Moscow, into American diabetics. The 24 patients in the trial represent as many fetal tissue transplants for diabetes as have been performed by all other U.S. researchers combined.
In the first year after the surgery, the transplant recipients showed no instances of severe infections, weight gain or hypoglycemic attacks caused by poor blood sugar control; there was a 35% incidence of such effects in a comparable group of patients who received several insulin injections every day, according to Dr. Bent Formby of Sansum. The transplant patients’ blood pressure was also reduced to normal levels.
Researchers hope that this improved control of blood sugar levels will reduce the incidence of diabetes complications, such as blindness, nerve damage and cardiovascular problems, but the patients have not yet been observed long enough to document such an effect. Formby also said there were no adverse effects associated with the surgery.
Buoyed by the results, a U.S. team next month will begin implanting larger quantities of fetal tissue in 72 diabetics at Los Gatos Community Hospital in Northern California.
“The surgery is still experimental, but we have learned a lot,” Formby said. “We feel something has been done to control the disease.”
Formby’s results, which were presented last week at a symposium in Santa Barbara but have yet to be published, “are very encouraging research,” said Dr. Frank Vinicor of the federal Centers for Disease Control and Prevention, president-elect of the American Diabetes Assn. “If it turns out to be valid, it’s a very exciting step.” But he cautioned that until the results are published, it is difficult to evaluate the claims.
“There are a number of factors that need to be looked at to make a more substantial judgment” of success, Vinicor said. Formby refused to discuss details of the research pending publication in a journal.
Other researchers were even more cautious. “Since no one has seen (a report of) what they are doing, there are some hard questions that need to be answered,” said Dr. David Sutherland of the University of Minnesota, who pioneered pancreas transplants for diabetes. “I’m very dubious.”
The fetal cell transplants are aimed at Type 1, or insulin-dependent, diabetics. The disorder, which affects almost 1 million Americans, occurs when insulin-producing cells in the pancreas are destroyed by the immune system, leaving the body unable to regulate the use and storage of sugars in food. The immediate symptoms can be controlled by injections of insulin, but that does not control the long-term complications. Pancreas transplants can cure the disorder in 75% of cases, but they are expensive and fraught with potential complications.
Some researchers believe that transplanting only the insulin-secreting cells, called islets, from the pancreas--especially from fetal pancreases--is a better approach because it requires only minimal surgery and may not require immunosuppressive drugs to prevent rejection. Such drugs have many adverse side effects.
Despite this promise, researchers outside Russia have so far performed only about 200 islet transplants with adult donors, and another 100 using fetal cells. Typically, fewer than half of the recipients have surviving islets one year after surgery.
But Russian researchers have performed many more transplants and claim that most of the transplants survive and provide good blood sugar control. The basis for their success, the Russians say, is the complex mixture of cells that are transplanted.
The technique used at Sansum was developed by researchers at Moscow’s Institute of Transplantology, a division of the Russian Academy of Medical Sciences.
Each patient received pancreas cells from three human fetuses, as well as similar cells from 12 newborn rabbits. Formby believes the role of the rabbit tissue is to release insulin for a short period--before the rabbit cells are rejected--to protect the human islets.
All of the patients had virtually no insulin production at the time of the transplants, and each had “a significant decrease” in the need for injected insulin in the year after the surgery, Formby said. The average decrease was 16%, he said, but some had as much as a 50% decrease. At 16 months after the surgery, the levels are remaining constant, he added.
