Imagine if a piece of damaged heart muscle could be replaced with a simple chemical trick that triggered neighboring cells to convert themselves into whatever type of tissue was needed. Scientists at Harvard took a step closer to that possibility with a paper published today in the journal Nature. Doug Melton and his collaborators "transformed mouse pancreas cells that aid digestion into the insulin-producing cells that are destroyed in childhood diabetes, potentially giving stem cell scientists a powerful new way to one day grow replacement tissues for patients," according to the Boston Globe.

The findings follow a whirlwind of new advances in cellular reprogramming, which include creating patient-specific stem-cell lines without the need for human eggs or embryos. The new research differs, however, in that one type of adult cell is converted directly into another type. The process doesn't require that the cells first be transformed into undifferentiated cells before developing into the desired cell type.

According to the Washington Post,

Through a series of painstaking experiments involving mice, the Harvard biologists pinpointed three crucial molecular switches that, when flipped, completely convert a common cell in the pancreas into the more precious insulin-producing ones that diabetics need to survive.

"The feat . . . raises the tantalizing prospect that patients suffering from not only diabetes but also heart disease, strokes and many other ailments could eventually have some of their cells reprogrammed to cure their afflictions without the need for drugs, transplants or other therapies.

"It's kind of an extreme makeover of a cell," said Douglas A. Melton, co-director of the Harvard Stem Cell Institute, who led the research. "The goal is to create cells that are missing or defective in people. It's very exciting."

Melton and others caution that it's likely to take years to translate the advance into useful treatments. From the Washington Post:

"It's an important proof of concept," said Lawrence Goldstein, a stem cell researcher at the University of California, San Diego. "But these things always look easier on the blackboard than when you have do [sic] them in actual patients."

Although the experiment involved mice, Melton and other researchers were optimistic the approach would work in people.

"You never know for sure--mice aren't humans," [Harvard stem-cell biologist George] Daley said. "But the biology of pancreative [sic] development is very closely related in mice and humans."

Melton has already started experimenting with human cells in the laboratory and hopes to start planning the first studies involving people with diabetes within a year. "I would say within five years we could be ready to start human trials," Melton said.