Diabetes affects millions of Americans who must monitor their blood sugar closely for life and often undergo frequent insulin injections to avoid undue health complications. So far, cell replacement therapies to reinstate insulin-producing tissue have been limited by the availability of donor cells and the need for lifelong immunosuppression. But the results of a recent study offer new hope for novel treatment options. Scientists have successfully modified liver cells to produce insulin that, when transplanted into mice, brought the disease under control.

Sarah Ferber of the Endocrine Institute in Israel and her colleagues modified adult human liver cells (AHL) to express the pancreatic and duodenal homeobox gene 1 (PDX-1). A quarter of the AHL cells transformed in this manner produced insulin, the researchers report in a paper published online this week by the Proceedings of the National Academy of Sciences. The team then transplanted the treated cells into diabetic mice and determined that the insulin-producing AHL cells store the hormone in granules in much the same way that regular beta-cells in the pancreas do. (In the image of AHL cells above, insulin is shown in red.) Over time, insulin was secreted and subsequently controlled the glucose levels in the animals' bloodstream. Treated diabetic mice reacted to an influx of sugar in the same manner as healthy control animals, suggesting the PDX-1-treated liver cells can stand in for of beta-cells.

The success reveals a tantalizing way to avoid complications caused by transplantation of donor tissue in the future: diabetics could conceivably be the donors of their own insulin-producing tissue.