Molecule Helps Turn Regular Cells Into Stem Cells
Discovery is important, but clinical success could be years away, experts say
WEDNESDAY, June 14, 2006 (HealthDay News) -- An embryonic stem cell's magic lies in its ability to grow into any type of cell in the body, offering a potential means of replacing or repairing damaged tissues.
Now, scientists say, a molecule called Nanog may someday allow ordinary cells to borrow that magic.
"Ultimately, we may be able to directly reprogram an adult cell [from a patient, for example] into embryonic stem cells, and from these obtain the cells needed to treat the disease," said lead researcher Jose Silva, of the Institute for Stem Cell Research at the University of Edinburgh in the United Kingdom.
Silva cautioned that, "there is, however, a long way to go -- we have identified Nanog as a major player, but it does not act alone."
His team published its findings in the June 15 issue of Nature.
The clinical promise of embryonic stem cells, which give rise to all cells in the human body, is potentially limitless.
Dr. Robert Goldstein, chief scientific officer for the Juvenile Diabetes Research Foundation, believes these cells might someday be used to help replace insulin-producing cells in the pancreas that are destroyed in type 1 diabetes. "We would like to have an alternate supply, other than people donating their pancreas after death," he said.
However, ethical concerns on the therapeutic use of embryonic stem cells have left scientists in the United States and elsewhere looking for alternatives.
In its research, Silva's team focused on mechanisms that give embryonic stem cells their "pluripotency" -- their ability to develop into any of the body's 200-plus cell types. "Nanog was first identified in 2003," he said. "It is a protein that acts in embryonic stem cells [and in the early embryo] to keep cells pluripotent."
But its true significance hasn't been understood until now. In the latest study, Silva's team fused embryonic mouse stem cells with nerve-cell stem cells and with ordinary cells from the thymus -- a technology called "cell fusion." During this process, the hybrid cell that is produced is essentially "reprogrammed" with a different set of instructions, including just what type of cell it can develop into once it divides.
Suspecting that Nanog was key to this process, the U.K. team genetically engineered the new cells to produce extra Nanog. The result: "Up to 200 times more hybrid cells were formed," Silva said.
"This is a clear indication that Nanog is acting in the reprogramming process," he said.
However, he stressed that the discovery won't, on its own, revolutionize stem cell research.
"At the moment, it is not yet feasible to turn an adult cell into an embryonic stem cell simply by introducing Nanog," Silva said. Many other molecular players are likely to be involved and "there is still much more work to be done to unravel the whole process of reprogramming," the Edinburgh expert said. He said research aimed at answering those questions is currently under way.
"Stem cell research is arguably one of the most exciting fields of biomedical research today, but, as with all scientific endeavors, it advances step by step, at times apparently gently, but always surely," Silva said.
Goldstein, too, stressed that more research is needed.
"It's not like you can go from A to B, and restore [pluripotency] just with Nanog," he said. "This is extremely complicated biology and one little piece of information -- even if it's extraordinarily important -- does not give you the whole answer."
And the diabetes expert said efforts to find viable alternatives should not keep advocates from continuing to lobby for the medical use of embryonic stem cells.
"We have studied the embryonic stem cell, we know what it can do," he said. "We don't want to give up on that."
Find out more about stem cells at U.S. National Institutes of Health.