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Stem cell transplant 'cures' diabetic mice
08 February 2008
From New Scientist Print Edition.
Andy Coghlan

The prospect of using transplants derived from stem cells to reverse diabetes has come a step closer with the news that the technique seems to work in mice.

A team from Novocell in San Diego, California, told a stem cell conference in Evry, France, last week that this is the first hint therapies derived from human embryonic stem cells (hESCs) might cure type 1 diabetes. The only existing treatments for people with this autoimmune disease are regular insulin, or islet-cell transplants from cadavers.

The Novocell team grew hESCs - the embryonic cells from which all the body's tissues originate - in the lab until they differentiated into insulin-producing islet cells. They then injected these cells into the abdomens or backs of mice whose own islet cells had been destroyed, to see if they could regulate glucose concentrations in the animals' blood.

The transplanted cells produced insulin in response to a high-sugar meal, thus reducing the mice's blood sugar levels. "The treatment worked for several months," says Alan Lewis, chief executive of Novocell.

However, Lewis says the cells may need to be modified further before they can be transplanted into humans, as they may not be fully differentiated and so not work optimally.

Novocell will also need to ensure that the cells aren't rejected by the immune systems of people whose own tissue isn't a match for the stem cells - the mice used in these early experiments didn't have working immune systems. The firm plans to try coating the cells in a permeable form of the polymer polyethylene glycol (PEG) to hide the cells from the immune system. "The polymer lets glucose, nutrients and oxygen in, and hormones such as insulin out, but excludes immune cells that otherwise destroy the islet cells," says Lewis.

Novocell has already shown the trick works in two diabetic people given PEG-coated islet cells from cadavers. In principle, it should also work with the insulin-producing cells from hESCs.

Researchers who heard the presentation in Evry said the company is making good progress. "The data looked pretty convincing to me," says Tim Allsop, chief scientific officer at Stem Cell Sciences of Cambridge, UK.

Two other companies are also developing diabetes treatments from hESCs: ES Cell International of Singapore, and Geron of Menlo Park, California, which is also developing hESC-based treatments for heart and spinal cord repair.

From issue 2642 of New Scientist magazine, 08 February 2008, page 11

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