Mouse Skin Cells Engineered to be Identical to Embryonic Stem Cells

Associated Press, June 6, 2007

The equivalent of embryonic stem cells have been produced in mice with the use of skin cells. This advance in stem cell research does not entail the controversial destruction of embryos. The findings were reported Wednesday be three independent teams of scientists.

Without the controversial political and ethical debates surrounding the use of embryos, the method could show the way to breakthrough medical treatments if it can be duplicated in humans. However, that would be a considerable leap.

None the less, the achievement impressed many experts.

“I think it’s one of the most exciting things that has come out about embryonic stem cells, period,” said researcher Dr. Asa Abeliovich of Columbia University in New York, who didn’t participate in the work. “It’s very convincing that it’s real.”

But there will be a wait to see if the finding will impact human therapies, a detail which Dr. Abeliovich and others stressed. Mouse skin cells would of course be incompatible for human use so human skin cells would have to go through the same conversion for therapeutic treatment development to begin.

“We have a long way to go,” said John Gearhart of Johns Hopkins University, a stem cell researcher who also wasn’t involved in the new work.

Some scientists say that embryonic stem cell harvesting should persist regardless of the advance.

“We simply don’t know which approach ... will work the best,” said researcher Konrad Hochedlinger of the Harvard Stem Cell Institute, who led one of the three teams.

For the development of transplant therapies for patients suffering from Parkinson's disease, diabetes, paralysis, etc, embryonic stem cells are prized since they can develop into all types of tissue.

But many oppose the practice since human embryos must be destroyed in the process. Opponents also point to adult stem cells and amniotic stem cells which have proven themselves to be equally capable of transformation, without destroying any embryos.

To avoid using embryos all together, scientists have tired to make ordinary cells act like stem cells using an assortment of methods. Tampering with eggs or embryos was necessary with previous methods, and was deemed unacceptable. The mouse study seems to have achieved what the other experiments were attempting to accomplish.

The second team of researchers and Hochedlinger said their goal was to learn how cell reprogramming works, not to dodge ethical objections towards embryo destruction.

But the new achievements were welcomed on ethical terms by a prominent critic of embryonic stem cell research.

“This is what we were looking for people to explore because it may provide all the advantages of embryonic stem cells without the moral problem,” said Richard Doerflinger, deputy director of pro-life activities for the U.S. Conference of Catholic Bishops. “So I’m very encouraged.”

The inaugural issue of the Cell Press publication Stem Cell has published Hochedlinger and his colleagues’ results.

The journal Nature published the reports from the other two teams on Wednesday in their online edition. The work behind one paper was led by Shinya Yamanaka of Kyoto University in Japan and the other was completed by senior author Rudolf Jaenisch of the Whitehead Institute in Cambridge, Massachusetts.

Last August, Yamanaka found that he could make altered cells behave much like embryonic stem cells in lab tests if he slipped four genes into mouse skin cells called fibroblasts. The current work builds upon Yamanaka's landmark paper.

But embryonic stem cells were still considerably different from the so called "iPS" cells that Yamanaka found. The three new papers show that through a variety of lab test, the new "iPS" cells prove to be virtually identical to embryonic stem cells.

Researchers emphasized that a new approach that avoids risk would have to be developed since the technique used in the mouse studies could promote cancer in any patients getting therapy based on iPS cells.

That major issue remains to be resolved said Gearhart. Also, researchers must show that they can coax the cells to become any type of cell in the body just like embryonic stem cells.

And since introducing genes into human cells is a significant challenge, the task of duplicating the study results with human cells will be difficult.

The iPS cells and the tissue they develop into would provide a genetic match to the person who donated the skin cells if the technique can be harnessed for people. Then without any fear of rejection, the cells would be suitable for transplant to that person.