|10-14-2002, 11:39 AM||#1|
Stem Cell Science Offers New Hope to Diabetics
Stem Cell Science Offers New Hope to Diabetics
Mon Oct 14,11:04 AM ET
By Deena Beasley
LOS ANGELES (Reuters) - Type 1 diabetes patients may be able to avoid the need for daily insulin shots through transplants of insulin-producing stem cells, but the procedure faces some hurdles including finding the cells and dealing with immune-system rejection, researchers said.
"We have done 38 islet cell transplant procedures since 1999--87 percent of those patients are free of insulin therapy a year after transplantation," said Dr. Jonathan Lakey of the University of Alberta in Edmonton.
Research from Edmonton and other islet stem cell transplantation centers was presented last week at a diabetes conference in Anaheim, California.
Diabetes, which can lead to heart and circulatory disease, kidney failure and blindness, is caused by a shortage of insulin, a hormone that regulates blood sugar levels, or by the body's failure to respond to it.
In Type 1 diabetes, the body's immune system attacks cells in the insulin-making parts of the pancreas, called the islets of Langerhans. The body is then unable to control blood sugar levels and insulin must be injected daily.
Type 2 diabetes, which is more common, arises when the body becomes resistant to insulin, often as a result of obesity.
Researchers have sought for decades to prove that islet cell transplantation could be a cure for Type 1 diabetes, said Taylor Mayo, a spokesman for the City of Hope Cancer Center in Duarte, California, one of 10 research centers chosen by the US National Institutes of Health (news - web sites) to conduct studies aimed at duplicating on a larger scale the islet cell transplantation done in Canada.
CELLS CULLED FROM DONATED ORGANS
The goal is to transplant stem cells into a patient's body where they can produce their own insulin. Research so far has been with purified pancreatic islet cells salvaged from donated organs, but experts acknowledge that there are not enough.
"Spain is the No. 1 country in terms of organ donors, but even we would only be able to cover 1 to 2 percent of the need," said Dr. Bernat Soria, of the Universidad Miguel Hernandez in Alicante, Spain.
His group is working on ways to generate insulin-secreting cells from embryonic stem cells and has succeeded in deriving, and successfully transplanting into mice, cells from mouse embryonic stem cells.
In the United States, there are 5,000 to 6,000 donated pancreases available each year, compared with 37,000 new cases of type 1 diabetes and the 1.5 million Americans already diagnosed with the disease, according to City of Hope.
Experts have been able to coax islet stem cells--precursors of insulin-producing cells--to mature. Stem cells are the body's master cells, and the embryonic versions are considered especially powerful.
Stem cell researchers can use adult stem cells found in the blood or other tissue, but they are rare and difficult to work with; they can try to transform normal adult cells; or they can use stem cells from embryos, which have the potential to become any kind of cell in the body at all.
Some groups oppose using this last group of cells, at least from humans, on ethical grounds, and the debate is only partly settled in the United States and some other countries.
"One of the critical problems is the islet shortage and the need to explore new sources," said Dr. Craig Smith, associate professor of transplant surgery at the University of California at Los Angeles School of Medicine and associate director of the Southern California Islet Cell Resource Center.
Ultimately, an individual's own genes will likely be cloned and inserted into an egg which is then allowed to develop as an early stage embryo, producing the crucial stem cells, said Dr. Fouad Kandeel, director of the department of diabetes and endocrinology at City of Hope.
This method would solve the problem, seen with any transplant of foreign tissue, of immune system rejection.
There are drugs now available to suppress the immune systems of organ transplant patients, but they are expensive and have side effects, Kandeel said.
"There are a multitude of ways to reprogram the immune system to accept a transplant. But we have an existing treatment for this disease--insulin--that is not toxic and not expensive and a new treatment cannot be more daunting than the existing one," the City of Hope scientists explained.
"This dilemma is forcing scientists to think very hard about strategies for immune tolerance without having to go to the big guns."
The multicenter trial of the islet cell transplants, sponsored by the NIH Immune Tolerance Network, is currently underway, with enrollment expected to complete this year.
"Our goal is to facilitate the efforts...to provide human islets and figure out the best way to generate functional islets," said Richard Knazek, a medical officer at the NIH National Center for Research Resources.
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