Experimental procedure designed to control blood sugar level, wean patients off insulin
The University of Maryland Medical Center in Baltimore has performed its first islet cell transplant to treat type 1 diabetes, making the center one of only a handful of facilities in the country to offer the procedure.
The transplant was performed last month as part of a federally funded study to gauge the method's effectiveness as a less-invasive alternative to pancreas transplants. The patient is Laura Bolling, a 34-year-old research laboratory technician from Wilmington, Del.
In the procedure, islet cells from a donor pancreas are injected into the patient's liver in the hope that the cells will live there and produce insulin. Patients with type 1 diabetes, who usually develop the disease as children, produce no insulin and have to manage their blood sugar through insulin injections and a controlled diet.
Alan C. Farney, M.D., Ph.D., a transplant surgeon, director of the Islet Transplant Program at the University of Maryland Medical Center and an assistant professor of surgery and pediatrics at the University of Maryland School of Medicine, says the procedure does not require major surgery and poses fewer complications than transplanting the entire pancreas.
But he cautions: "It is not a cure. It is a treatment. Patients will still have to take medicine to prevent rejection of the transplanted cells."
"The ultimate goal of islet cell transplantation is to normalize blood glucose levels and prevent secondary complications of diabetes, such as kidney failure, heart disease, nerve damage and loss of vision," says Dr. Farney.
In Ms. Bolling's case, her new islet cells are producing insulin, but she will require a second infusion of cells before her body can make enough to wean her off insulin injections entirely.
"At this point, she needs to take only half as much insulin as she did before. There is also less fluctuation of her blood sugar level, which makes her diabetes easier to control," says Kristi D. Silver, M.D., an endocrinologist and an associate director of the Joslin Diabetes Center at the University of Maryland Medical Center, who is monitoring Ms. Bolling's progress.
Still considered experimental, islet cell transplants are performed at only a handful of hospitals in the United States, according to Dr. Farney. A group of doctors from the University of Alberta in Edmonton, Canada, which recently improved the method, has performed the most - 20 transplants, with 70 percent to 80 percent of the patients not needing insulin after a year.
Type 1 diabetes destroys insulin-producing beta cells in the pancreas, which are located in nests of cells called the islets of Langerhans. About 2 million to 3 million people in the United States have this type of diabetes.
In the procedure, doctors use an enzyme to break down the donated pancreases to retrieve as many islet cells as possible. Guided by X-rays, they inject the cells into the patient's liver through a major blood vessel, the portal vein, and wait to see if the transplanted cells start to produce insulin.
"It may take several weeks or a few months before patients are able to stop taking insulin, and more than one injection of islet cells may be needed," Dr. Farney says.
The transplant apparently works best in the liver because of that organ's ability to regenerate itself and produce new blood vessels that envelope the islet cells.
Dr. Farney says that the best candidates for the procedure are people with type 1 diabetes who have "very poor blood sugar control," despite their best efforts to manage their disease with insulin and good nutrition. They are the people most at risk for life-threatening complications from diabetes, such as kidney failure or heart disease.
The procedure may be better for some patients than a whole pancreas transplant because it requires no incision and has few complications. In pancreas transplants, the surgery takes several hours, requires several days of hospitalization and carries the risk of infection and blood clots.
Dr. Farney said that as part of the study, patients will be closely monitored before and after the transplant, and doctors will also try to address such quality-of-life issues as, "Are the anti-rejection drugs that transplant patients must take worse than taking the insulin?"
Before islet transplants can become a viable treatment for most patients with type 1 diabetes, however, doctors will have to address the shortage of donated tissue. Doctors at the University of Maryland Medical Center are also looking at ways to increase the supply, such as growing insulin-producing cells from stem cells or pancreatic ductal tissue.
The medical center has the nation's second-largest pancreas transplant program, performing about 60 transplants a year. Last year, Dr. Farney and another surgeon, Benjamin Philosophe, M.D., an assistant professor of surgery at the University of Maryland School of Medicine, also performed an islet cell transplant on a patient with chronic pancreatitis. The only cure for the man's severe condition was to remove his pancreas and transplant islet cells from the pancreas into his liver to prevent him from becoming diabetic.
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