Posted on Mon, Feb. 28, 2005
Researchers report gains with stem cells
By JACOB GOLDSTEIN
Miami Herald
MIAMI - University of Miami researchers may have discovered a shortcut for turning embryonic stem cells into the insulin-producing cells destroyed by Type-1 diabetes.
The technique, described in a paper published in the March issue of the journal Diabetes, could ultimately contribute to a cure for the disease by creating a limitless supply of the insulin-producing cells known as islets.
But researchers cautioned that day is far off.
The new study "gives you a really great system," said Arun Sharma, a scientist at the Joslin Diabetes Center at Harvard University. "But there are still challenges."
Doctors have begun to treat Type-1 diabetes by transplanting islets from organ donors into diabetes patients, alleviating the patients' need to inject themselves with insulin. But donors will always be vastly outnumbered by potential recipients.
"We need to find alternative sources of islets," said Juan Dominguez-Bendala, the University of Miami scientist who authored the paper.
One strategy being pursued by Bendala and his colleagues at the Diabetes Research Institute: Use embryonic stem cells to create a limitless supply of islets for transplantation.
Embryonic stem cells are widely studied because they can propagate themselves indefinitely and can turn into any cell in the body. (They are also mired in controversy - because they come from human embryos, some ethicists believe it is wrong to study them, and the Bush administration has put limits on federally funded stem cell research.)
Left to their own devices, stem cells will turn into a wide variety of cells and tissues; if the cells are to prove useful, scientists must learn how to coax the cells in particular directions. In Bendala's case, that means figuring out how to turn stem cells into islets.
For a stem cell to become an islet, the cell must create a series of proteins in a specific sequence. In the last decade, scientists have developed a good understanding of the sequence. But they have not yet learned to prompt the cell to create the essential proteins.
The new study bypassed this problem by using a technique that delivers the essential proteins directly to the cell. The stem cells treated with this technique "massively turned into islet cells," Bendala said.
The study was done with mouse stem cells. The next step is to try similar experiments on human cells - something already underway in Bendala's lab.
"This technology is a first step that allows us to think we are closer today than we were yesterday," Bendala said.
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