There is promising news today for those who hope to turn the potential of undifferentiated stem cells into medical miracles: Researchers are reporting a way to produce insulin-producing cells from mouse embryonic stem cells. Millions of diabetes patients could benefit if researchers can achieve such alchemy with human cells.
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ILLUSTRATION: CAMERON SLAYDEN |
Doctors have reported promising results in transplanting pancreatic cells from cadavers into diabetic patients, enabling a handful of recipients to stop insulin injections indefinitely. But the demand for cells is far greater than the supply, and an unlimited source of cells that could produce insulin would be a hot commodity. So far, success at growing such cells from stem cells has been limited.
Ron McKay and his colleagues at the National Institute of Neurological Disease and Stroke in Bethesda, Maryland, usually focus on brain development, but they were intrigued by recent papers reporting that some pancreas cells express nestin, a protein typical of developing neural cells. The scientists already knew how to encourage mouse embryonic stem cells to express nestin, and they wondered if they could coax their nestin-positive cells to take on more characteristics of pancreas cells.
When they briefly exposed nestin-positive cells to a growth factor, the cells differentiated not only into neural cells but also into clusters that resemble the insulin-producing islets in the pancreas. The clusters' inner cells produced insulin, while outer cells produced glucagon and somatostatin, two proteins typical of pancreas cells, the team reports in a paper published online today by Science.
"The percentage of cells that become insulin positive is remarkable and way above what others have reported," says developmental biologist Palle Serup, who studies pancreas development at the Hagedorn Research Institute in Gentofte, Denmark. Yet important caveats remain. The clusters produce only about 2% as much insulin as normal islets and failed to make insulin in response to a glucose level that typically triggers a response in normal cells.
That does not discourage researchers like molecular biologist Ken Zaret of the Fox Chase Cancer Center in Philadelphia. "The glass is 1/50th full," says Zaret, who predicts that refinements in the culture technique or drug manipulations will boost insulin production.
--GRETCHEN VOGEL
Related sites
Information on islet transplants
The Juvenile Diabetes Foundation
