By Karla Gale

NEW YORK (Reuters Health) - Unfertilized eggs could represent a useful source for stem cells that avoids the ethical issues associated with embryo sources, new research suggests.

Embryonic stem cells have shown promise as a treatment for a variety of diseases. However, some people have objected to their use because they are obtained from the destruction of embryos that could have developed into a living human being. These ethical issues have hindered research with such cells and have lead to a search for other sources.

To bypass the ethical issues of using embryonic stem cells, Dr. Kent E. Vrana, from Wake Forest University in Winston-Salem, North Carolina, and associates studied stem cells derived from the unfertilized eggs of female monkeys.

The new findings are reported in the Proceedings of the National Academy of Sciences (news - web sites).

After more than two years of growth and development, the authors found that their stem cells looked and acted like those derived from embryos. Moreover, when treated with the proper chemicals, these cells were able to become a variety of other cells types, such heart muscle cells and nerve cells--an ability that is critical for possible therapeutic uses.

The "gold standard" for stem cells that can become other cell types is the embryonic stem cell, senior author Dr. Jose B. Cibelli, from Michigan State University in East Lansing, told Reuters Health. "Of course, we have to test whether these (unfertilized egg)-derived cells will cure disease in animals" before concluding that the two cell types are interchangeable. He noted that such experiments are already underway.

US law prohibits use of government funding "to generate a human embryo," Cibelli noted However, he said, religious groups are receptive to the use of unfertilized eggs for stem cell research, because a human being cannot be produced from them.

SOURCE: Proceedings of the National Academy of Sciences, September 30, 2003.