Skin cells made to mimic embryonic stem cells.

The breakthrough announcement of early June came wrapped  in excitement and caution.

The big news was that three independent research groups had caused mouse skin cells to mimic embryonic stem cells.

Scientists got excited because it furthered the understanding of early stem cells.

Embryonic research opponents got excited because they hoped it would open a path to the benefits of stem cell research without the need to destroy human embryos.

“The Nebraska Coalition for Ethical Research has been saying for two years that researchers have been trying to manipulate genes in mature cells to turn them into the equivalent of embryonic stem cells,” coalition Director Chip Maxwell said in a prepared statement. “It’s more evidence that ethics and progress can proceed hand-in-hand in stem cell research.”

Scientists cautioned they didn’t know if the technique would work with human cells, which are very different.

And they warned that the technique that worked with mouse cells resulted in cancer one-fifth of the time.

David Crouse, associate vice chancellor for academic affairs at UNMC, cautioned that the technique used viruses to insert genes into skin cells, which comes with its own ethical and scientific baggage.

He predicted the use of viruses to alter cells will be the center of controversy in the future.

The new breakthrough built on last August’s landmark paper by Shinya Yamanaka of Kyoto University in Japan. His paper suggested that inserting just four of 20 genomes active in embryonic stem cells could reprogram ordinary cells to act like stem cells.

As in that experiment, the three groups inserted four genomes — Oct4, Sox2, c-Myc and Klf4 — into mouse cells, causing them to genetically reset themselves. In the later experiments, researchers also demonstrated that the resulting cells had the ability to give rise to many other types of cells — just like embryonic stem cells.

The viruses used in the experiment randomly inserted genomes into the cells. Between each step, researchers chemically neutered or removed cells that did not respond.

The process required several days, indicating a gradual realignment of proteins within the affected cells.

To prove the cells had potential similar to that of to embryonic stem cells, the altered cells were inserted into an early stage embryo and placed in a female.

The resulting offspring were chimeras, a single being comprised of cells with two different sets of DNA. Human chimeras, while rare, occur naturally when the embryos of fraternal twins fuse to create one person.

Regarding the incidence of cancer that appeared one-fifth of the time, researchers traced the tumor formation to the c-Myc gene, notorious for its involvement in cancer creation.

Outside researchers commented that the breakthrough confirms the principal that ordinary cells can be made to behave like embryonic stem cells.

The methodology remains problematic.

Reach Mark Andersen at 473-7238 or mandersen@journalstar.com.