Ethical Stem Cell Breakthrough

A new discovery in adult stem cell research may signal the beginning of the end for human embryonic experimentation. Scientists in both Japan and Wisconsin have successfully reprogrammed human adult stem cells to behave like embryonic cells, with the ability to develop into all of the major tissues of the human body. In two studies released simultaneously November 20, the research teams reported on the breakthrough science that has profound implications for the future of stem cell research.

By activating a handful of buried genes that normally remain dormant in adult cells, researchers were able to convince the cells to return to an embryonic like stage of development. Known as “induced pluripotent stem cells,” or iPS cells, the reprogrammed cells were able to grow into all of the major tissue types, including muscle, cartilage, neuron and heart cells. After 12 days of growth in the lab, the heart muscle cells began to beat in unison.

The technique successfully bypasses key problems that have plagued embryonic stem cell research. Condemned for causing the death of human embryos, embryonic stem cell research also requires the harvesting of human eggs, a costly procedure with ethical concerns that is physically dangerous to the woman. The new research technique of causing adult cells to revert back to an embryonic stage offers a potentially unlimited source of “embryonic” stem cells.

The cells are a genetic match to the person they came from, so rejection of tissue grown from the cells would not be a factor in future therapies—also a major obstacle in using cells taken from human embryos.

There are still hurdles to overcome—the dormant genes are “turned on” by the introduction of a retrovirus, which in some cases led to the development of tumors in experiments using mice.
Researchers have said the difficulties are being addressed, however, and do not pose a significant barrier to the advancement of the science.

The research was carried out by two separate teams in Japan and Wisconsin.
Dr. Shinya Yamanaka and his colleagues at Kyoto University initiated the reprogramming technique in mice, reporting success in June 2007. They followed a similar approach using human cells in their new study, published in the journal Cell. A second team at the University of
Wisconsin-Madison, led by Dr. James Thomson and Junying Yu, used a similar technique in a study published in the journal Science.

Cell reprogramming is anticipated to become a focal point of much of the research into stem cells. The consistent failure of attempts to control human embryonic cells in research applications stands in stark contrast to the current developments using adult cells.

The scientist who cloned Dolly the sheep has announced he will no longer pursue the cloning technique he pioneered, saying the recent breakthrough in non-embryonic stem cell research shows greater promise.

Professor Ian Wilmut revealed the world’s first cloned mammal, Dolly the sheep, in 1997 at the Edinburgh University. Two years ago Great Britain awarded Wilmut a license to clone human embryos. In his recent announcement Wilmut said he would abandon research using human embryos to pursue research into cell reprogramming. Wilmut said he made the decision to drop embryonic research for practical considerations, although he admitted that the Japanese approach would be easier for society to accept.