New route to insulin-making cells

The pancreas has a second way to make cells that produce the hormone insulin, new research on mice confirms. The discovery could eventually lead to new therapies for diabetics.

Scientists have known that insulin-producing cells, called beta cells, create copies of themselves by dividing. But whether beta cells also arise from pancreatic stem cells has been more contentious.

Many organs contain stem cells that serve as factories, churning out new cells to replace old or damaged ones. But evidence in the past few years has suggested that the pancreas is an exception, and that new beta cells come only from existing ones (SN: 6/2/07, p. 350).

In the new experiments, researchers led by Harry Heimberg of Vrije University in Brussels, Belgium, induced damage in mouse pancreases. Afterward, the team detected activity of a gene called Neurogenin-3 (Ngn-3), a telltale marker of cells in embryos that develop into beta cells, the researchers report in the Jan. 25 Cell. Ngn-3 is not normally active in the pancreases of adults.

The cells with Ngn-3 activity became new beta cells in much the same way stem cells would. But true stem cells replenish themselves to maintain their numbers; the Ngn-3 cells did not and so were used up.

If this embryonic route for making beta cells also exists in humans, as the scientists suspect, developing drugs that activate Ngn-3 could offer a new way to boost insulin production in people with diabetes.

“It’s a stunning result,” comments Jake Kushner of the Children’s Hospital of Philadelphia, who has performed related research. But Kushner cautions that therapies that exploit this discovery are still many years away.

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