(Republished with permission from the St. Louis Post-Dispatch. This article originally ran on the front page on Wednesday, Sept. 13, 2006.)
By Tina Hesman Saey
Washington University researchers have developed a potential cure for Type 2 diabetes.
The treatment has already cured rats, and it could eventually mean a second chance at health for the almost 200 million people worldwide with Type 2 diabetes, the most common form of the disease.
The researchers took tissues from pigs – tissues that would have become pancreases – and implanted them into rats. The tissues helped control blood sugar, curing the rats’ diabetes for life.
The team has started trials in primates. Human studies are probably years away.
Dr. Raffaello Cortesini says the work is exciting because it opens up a new area of research in the fight against diabetes. Cortesini is a transplant surgeon at Columbia University in New York, and editor in chief of the journal Transplant Immunology, where the new study appears.
The researchers, led by Sharon A. Rogers and Dr. Marc R. Hammerman, found that when they transplanted the embryonic pig pancreases, the rats didn’t need immune-suppressing drugs to keep their bodies from rejecting the pig organs.
The organs are taken from pig embryos just before they become pancreases – a stage known as primordia. Those tissues have “immune privilege,” a type of diplomatic immunity that keeps them from being attacked when placed in a host organism.
The research is particularly exciting because it means that doctors could give patients new pancreases with few or no immune-suppressing drugs, Cortesini said.
The Washington University team showed last year that the tissue could cure Type 1 diabetes in rats. Type 1 diabetes results when the pancreas stops making insulin. It is sometimes called juvenile diabetes.
Type 2 diabetes is far more common – about 20 times more prevalent, affecting almost 15 million people in the United States. People with the disease have high blood sugar because their pancreases make too little insulin and the body ignores the insulin that is made, a condition known as insulin resistance.
Obesity, genetics, age and high-fat diets all contribute to the development of the disease, and the number of people diagnosed with Type 2 diabetes is on the rise. The disease used to be known as adult-onset diabetes but large numbers of young people now are developing the disease.
Hammerman said he wasn’t initially sure what would happen when the researchers transplanted the pig organs into rats with Type 2 diabetes. Because the diabetic rats are resistant to insulin, just as people with the disease are, new insulin-producing cells might have had no effect.
The researchers used rats that lack a receptor for leptin, a hormone that helps control feeding. The rats become obese and males spontaneously develop diabetes. Females with the same mutation get diabetes after eating a high-fat diet.
The different responses mirror the development of diabetes in humans, Hammerman said.
“These rats have a family history” of diabetes, he said. The males might represent people of normal weight who get diabetes because of a genetic predisposition. The females are more like people who set off the genetic time bomb with unhealthy diets and body weight.
When the researchers implanted the tissues in the diabetic rats, the males were cured completely. Their blood sugar returned to normal and their resistance to insulin also went away. The females were a tougher case. The transplants also worked for them, but their diabetes was cured only once they stopped eating fatty foods. The females remained slightly insulin-resistant, but their blood sugar was normal.
Using pigs also solves another problem with transplanted organs – the supply. Pig embryos could provide a nearly endless supply of primordial organs, Hammerman said.
The research:
- Scientists transplant embryonic tissues from pigs into rats that have Type 2 diabetes.
- Rats accept the organs without immune-suppressing drugs.
- Transplanted tissues control rats’ blood sugar and erase insulin resistance.
- The cure lasts the rest of the rats’ lives.
Copyright 2006 St. Louis Post-Dispatch, Inc.