By Liz Townsend

Adding to the ever-growing number of scientific studies showing there are ethically acceptable and far more promising sources for stem cells than human embryos, scientists at Harvard Stem Cell Institute wrote in the August 28 issue of Nature that they turned ordinary pancreatic cells into insulin-producing cells, a major step toward a cure for diabetes.

In addition, according to the Associated Press' Malcolm Ritter, " if the experiment's approach proves viable, it might lead to treatments like growing new heart cells after a heart attack or nerve cells to treat disorders like ALS [Lou Gehrig's disease]."

This technique, called direct reprogramming, differs from other recent advances that reprogram adult cells into what are called "induced pluripotent stem" (iPS) cells. Obtaining these cells does not involve the destruction of human embryos and they are almost identical in character to embryonic stem cells.

In fact, the new research bypasses the need for stem cells altogether. According to the  Associated Press, "the new method holds the promise of going directly from one mature cell type to another. It's like a scientist becoming a lawyer without having to go back to kindergarten and grow up again."

Douglas Melton, the study's senior author, told Reuters, "It was easier than one might have thought.

These cells are very stable and live for the life of the mouse."

The Harvard researchers worked with mice that had diabetes. Diabetes is caused when insulin-producing beta cells (only a tiny percentage of all the cells in the pancreas) are absent or are mistakenly destroyed by the body's immune system. Insulin is needed to convert food to energy.

The trick was to figure out which genes are needed to make exocrine cells (which make up about 95 percent of the pancreas) function as beta cells. Through a combination of trial and error and luck, Melton's team found the three necessary genes. They also discovered that an ordinary cold virus could carry the genes to the pancreas.  

According to the Nature article, the genes converted 20% of the normal pancreatic cells into the cells that produce insulin. The mice's blood sugar levels, which had been rising dangerously because of the absence of insulin, began to lower.

The procedure will probably best work with type 2 diabetes, in which the beta cells are absent, according to Reuters. Type 1 diabetes is caused when the immune system attacks the insulin-producing cells, so that immune response would need to be changed or the newly reprogrammed cells would be destroyed by the body.

There are still several years of work needed before human trials can begin, Melton told the Washington Post. The use of a genetically engineered virus may not be safe to use in humans, or be approved by the Food and Drug Administration.

Melton added that the researchers will try to determine if chemicals could be used instead of a virus to transport the genes, and also wish to see if using liver cells to transform into the insulin-producing cells would work better, the Post reported.

Despite the challenges to come, this study is a major advance toward the treatment of diabetes. "It was a mixture of work, luck and guessing," Melton told the Post. "We achieved a complete transformation, or re-purposing, of cells from one type to another. We were delighted."

Opponents of embryonic stem cell research hailed the breakthrough. "This is a 'win-win' situation for medicine and ethics," Richard Doerflinger, associate director of the U.S. Conference of Catholic Bishops' Secretariat of Pro-Life Activities, told the Post.