Insulin-Producing Cell Transplant Research Continues To Show Promise

From CNN Medical Correspondent Holly Firfer

CNN) -- It's been called the biggest breakthrough in diabetes treatment since the discovery of insulin in 1922.

Last month, researchers reported in the New England Journal of Medicine that eight diabetic patients had been able to stop taking injections for a year after transplantation of key pancreatic cells. These vital cells, called the islets of Langerhans, are scattered throughout the pancreas and produce the blood sugar-regulating hormones insulin and glucagon.

The problem, though, is that there are very few available islet cells. Each patient in the study required the use of cells from at least two donor pancreases. Now, researchers at the Joslin Diabetes Center at Harvard University have shown they can spawn new islet cells from leftover pancreatic tissue.

"We take the other tissue, which is mainly ductal tissue of the pancreas, and we put it into a culture," explained Dr. Susan Bonner-Weir of the Joslin Diabetes Center. "(We) give it some growth factors and all the sorts of things it needs, and they will grow and expand."

Using the technique produced a harvest of 25,000 to 35,000 new islet cells, she said.

But that's still only a fraction of what's needed for a successful transplant. Every human pancreas has about 1million islet cells, but only half of them survive transplantation, leaving patients at least a half-million cells short.

"Twenty-five thousand islets does not represent a cure, so they have a long way to go before this is quantitatively meaningful for islet transplantation," said endocrinologist Paul Robertson of the Pacific Northwest Research Institute. "But we have to remember this is a new technology. It will grow and develop."

At the University of California, San Diego, Dr. Fred Levine and colleagues are using a cell-multiplying gene to create millions of human islet cells in a petri dish.

Levine's team genetically modified the cells in a stable environment, he said, adding that "since we've done that they will just grow forever in the laboratory, unlike the cells we started with, that have a very short, well-defined life span."

This therapy has yet to see human testing because scientists have not figured out how turn the cells off. "We have to be really sure that once you put these into humans they don't keep on growing willy-nilly and just sort of take over whatever organ or space they're put into," said Robertson.

Promising as this research is, its application as a viable treatment option may be years away.

So far, testing has been limited to severely ill diabetic patients who had Type 1 diabetes, often called juvenile-onset diabetes. Transplants were done in conjunction with anti-rejection drugs, which have their own long-term risks. And finding donor pancreases remains a problem.

Copyright © 2000 Cable News Network.

This article posted July 8, 2000.