Embryonic stem cells used to create insulin-producing cells

Scientists in the US have derived insulin-producing cells from human embryonic stem cells (hESCs), and have successfully implanted them into mice. The achievement, reported last week in the journal Nature Biotechnology, could help push forward research into therapies for diabetes.

Type 1 diabetes, and some forms of type 2 diabetes, are caused by a deficiency of pancreatic beta cells. These are cells that produce insulin, the hormone that helps control blood glucose levels, and are part of clusters of hormone-producing cells in the pancreas called the islets of Langerhans. The disease is characterised by a lack of insulin and subsequent misregulation of blood glucose, a condition that can be fatal. Diabetes is currently the seventh leading cause of death in the US, with 200,000 deaths reported per year.

The scientists at Novocell Inc. in San Diego, led by Dr Emmanuel E. Baetge, the chief scientific officer, derived immature precursor pancreatic beta cells from hESCs. They then implanted them into mice whose own beta cells had been destroyed by chemical treatment. After 90 days, the mice had switched the precursor cells into mature beta cells that produced insulin again, which helped control blood glucose. The implanted cells were said to be 'functionally and morphologically similar' to normal beta cells.

Transplanting human islet cells into diabetic patients from donated pancreases has been proven to help treat the symptoms of diabetes, but this technique relies upon donations, of which there is not a consistent supply. There is also a risk of transplanting infected or contaminated cells. The new technology could provide a readily available and renewable bank of clean cells for treatment when the patient needed it.

The scientists say that there is a long way to go before this can be taken into humans. There are safety issues still apparent as some of the mice in the study developed tumours, called 'teratomas'. Some critics are also concerned with whether the transplanted hESC derived cells would be destroyed by the recipient's body, just as their own original beta cells were.

Experts, however, are in no doubt that this is an exciting advancement. 'This for the first time validates that you can use human embryonic stem cells to produce fully functional human islets', says Dr Baetge.