Stem cells used to make insulin for diabetic mice

WASHINGTON -- In a possible step toward a new treatment for diabetics, embryonic stem cells were used to produce insulin and keep diabetic mice alive.

Researchers cautioned that the technique was not yet ready for testing in humans.

The researchers at Stanford University nurtured mouse embryonic stem cells until they developed into a tissue that made insulin. Then they put the tissue into diabetic mice and showed that the animals were sustained with the insulin produced by the tissue graft.

Ingrid C. Rulifson, a first author of the study appearing this week in the Proceedings of the National Academy of Sciences, said the research did not grow fully mature, insulin-producing pancreatic islets, which are called beta cells.

Furthest advance so far

"We've made something that shares several important properties with the beta cells, but we have not made beta cells," said Rulifson. "We believe this is the furthest anyone has gone. The fact that we were able to achieve rescue survival in these mice hasn't been demonstrated before in this way."

Dr. Robert Goldstein, chief scientific officer for the Juvenile Diabetes Research Foundation International, said the Stanford finding is "a significant advance" in diabetes research using embryonic stem cells, but he said it will have no immediate human application.

"The principle of being able to take embryonic stem cells and reverse diabetes is an extremely important observation," said Goldstein. He said ultimately researchers hope to use embryonic stem cells to make new beta cells that could be transplanted into diabetics and produce normal levels of insulin.

He called the Stanford study "one of the necessary steps toward achieving this goal," but emphasized that the next steps --translating the mouse data into human therapy --can be a long and difficult process taking many years.

"We can't fix people tomorrow," said Goldstein.

Embryonic stem cells are the ancestral cells from which all the tissue in the body develops. Scientists believe that if they can learn how to direct the transformation of embryonic stem cells they will be able to grow fresh, new cells to replace those that have died or stopped functioning. This could cure some diseases.

Some forms of diabetes are caused by the death or malfunctioning of the pancreatic islet beta cells that make insulin, a hormone essential for regulating sugar in the blood. Some researchers hope to use human embryonic stem cells to grow new beta cells, which could then be grafted into diabetic patients to normalize the metabolism of sugar.

In the Stanford study, researchers used special chemicals to cause mouse embryonic stem cells to transform into cell masses that resembled pancreatic islets. Test-tube experiments showed that the cells made insulin.