Human Embryonic Stem Cells -- Without an Embryo

Nov. 20, 2007 — -- Scientists have imbued ordinary human skin cells with the versatile qualities of embryonic stem cells -- what some doctors call a scientific breakthrough that could change the tone of the ongoing stem cell research debate.

The advance was published in two independent studies reported in the journals Cell and Science on Tuesday.

The findings on the technique, known as "direct reprogramming," follow a study published last week in the journal Nature that reported the extraction of stem cells from cloned monkey embryos, which contained genetic material from adult monkey skin cells. And they come five months after a similar feat was accomplished in mice.

The technique has big implications for human stem cell research, as it sidesteps many of the ethical and political pitfalls that have dogged the field for years.

Now that the research has been done in human cells, the excitement in the stem cell community is mounting. And while it may not be the perfect solution, many say it's a major advance.

"The discovery that it is possible to reprogram adult human cells to pluripotency using a simple combination of genes is an important breakthrough," said Sean Morrison, director of the stem cell biology research center at University of Michigan, Ann Arbor.

"It represents a phenomenal breakthrough, more important than cloning … or the discovery of human embryonic stem cells," said Dr. Markus Grompe, director of the Oregon Stem Cell Center in Portland. "This is a Nobel Prize worthy advance."

Researchers led by Shinya Yamanaka at the Kyoto University in Kyoto, Japan, generated cells called "induced pluripotent stem cells" by inducing four different genes to hitch a ride into human skin cells within specially designed viruses. These genes incorporated themselves into the skin cells, transforming them.

The new cells displayed several characteristics of embryonic stem cells, including the ability to grow into nerve and heart cells.