Scientists, politicians and conservative activists have been fighting over stem cells, which can morph into any type of cell in the body, with the right coaxing. Some activists objected to how scientists harvest the cells they use in much of the most promising research — from human embryos. Researchers argued that embryonic stem cell science has incredible promise to alleviate suffering caused by disease and organ failure. Until now, the scientists didn't have many big payoffs to tout.

Last week, a group of Harvard researchers announced that they had effectively cured diabetes in lab mice using human embryonic stem cells. The team painstakingly exposed stem cells to various chemicals until they figured out which ingredients to use and in which order, finally inducing undifferentiated stem cells to become beta cells, which specialize in detecting rises in blood sugar and releasing insulin in response. Beta cells are nature's natural insulin pumps — much better at finely tuning blood sugar than artificial insulin-delivery methods. The scientists transplanted the beta cells into diabetic mice, which were asymptomatic within 10 days.

This dramatic result is particularly promising for victims of type I diabetes, in which the body's immune system kills off all of its beta cells, but it also potentially offers relief to those suffering with type 2, or adult-onset, diabetes. Many lab discoveries take years or decades to yield therapies, but the Harvard scientists are more optimistic — they hope to begin human trials within three years.

After the Harvard team reported its findings in the journal Cell, its leader, Doug Melton, pointedly thanked the philanthropists who donated to his project. The George W. Bush administration, he noted, had ruled out federal funding for embryonic stem cell research except on a few lines of cells that were already in use. The Obama administration correctly reversed that policy shortly after taking office. Without private support in the interim, this advance on diabetes would have been significantly delayed, if not stopped altogether.

Embryonic stem cells have been the "gold standard" in research to date, lead study author Felicia Pagliuca said. So it is crucial that scientists preserve the flexibility to explore the huge potential of stem cell research.