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Islet Transplants

By David Mendosa

Last Update: June 15, 2000

For more than a year they kept their fingers crossed and the news a secret. Not a word of their breakthrough leaked to the press until Dr. James Shapiro of the University of Alberta in Edmonton, Canada, made his stunning announcement on May 17.

Dr. Shapiro, who leads a team of 44 scientists and researchers, told the final session of a transplant conference in Chicago that they had 100 percent success in transplanting islet cells. Even after more than a year their patients no longer needed insulin shots.

The New England Journal of Medicine, one of the world's most respected medical journals, considers their work so important that on June 6 it released its original article on its Web site almost two months early. They can't get it into print until July 27. This "early release" is limited to papers with especially important implications for patients.

The team's preliminary report, an on-line abstract prepared for the Transplant 2000 conference, said that five consecutive patients with type 1 diabetes who received islet cell transplants "attained immediate and sustained independence from insulin...and remain off insulin currently." The NEJM site reports that the number of consecutive patients increased to seven, and as their work has continued most news reports now count eight successful transplants in a row. But as this column goes to press The Toronto Star News says that the number is now 10.

This remarkable success rate contrasts dramatically with previous experience. The team cites The International Islet Transplant Registry. The registry reports that of 267 islet allograft (human to human) transplants in the past decade only 12.4 percent were insulin independent for even one week and only 8.2 percent after one year.

Why has the Edmonton team been so much more successful? They say that there are two reasons. All transplants so far have needed drugs to keep the body from rejecting the transplanted cells. Most previous procedures used steroids to do this, although animal studies suggest that they are toxic to islet cells, Dr. Shapiro says.

Instead, the Edmonton team used a combination of three steroid-free drugs that work in synergy. One of them, Sirolimus , was discovered in the soil of Easter Island more than a quarter century ago, but gained Food and Drug Administration approval only last September. The FDA approved the other two drugs, Tacrolimus and Daclizumab, in 1994 in 1997 respectively.

Like all immunosuppressants, they increase the risk of cancer and infection. Still, the patients so far have suffered only relatively mild side effects from taking them, such as temporary mouth sores. They will have to take them for the rest of their lives, but Dr. Shapiro hopes that in the future they can modify their technique to require few, if any, anti-rejection drugs.

The second big difference in the Edmonton Protocol, as it is now known, is the use of lots of high quality islets. All but one of the patients got islets from two donors, who were matched for blood type. The get almost twice as many islets as someone without diabetes.

The operation itself is simple, typically taking just 20 minutes. They inject about a teaspoon of islets into the blood vessel leading to the liver, where they start functioning immediately. "We want to develop it as an outpatient procedure," says Dr. Jonathan Lakey, one of the Edmonton scientists.

Is this a cure for the one million Americans with type 1 diabetes? While it's not yet being called one, it's the closest the world has come, Dr. Shapiro says. "None of these patients has residual diabetes by American Diabetes Association criteria."

Still, the long-term safety and effectiveness of the Edmonton Protocol needs to be established. And because the long-term effect of immunosuppressants is unknown, for now at least islet transplants will be tested only in adults.

Another concern is that only a few thousand pancreases are donated annually. That will be a limitation until scientists find a way to grow the cells in the laboratory, which is "where the next leap forward in this field is going to be," Dr. Lakey says.

But already plans are in motion to begin a multicenter clinical trial of the Edmonton Protocol. According to the Immune Tolerance Network headquartered at the University of Chicago, beginning this fall up to eight clinical centers in North America and Europe will perform about 32 more transplants.


The American Diabetes Association originally published this article on its Web site as one of my “About the Internet” columns.


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