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Embryo Clones Bear Stem Cells, Controversy

Researchers reach a genetic milestone

THURSDAY, Feb. 12, 2004 (HealthDayNews) -- New research suggests scientists may be closer to a holy grail of genetics -- the development of made-to-order cells that won't be seen as invaders when they enter the human body.

But the discovery is also moving science closer to the prospect of cloned human beings.

South Korean researchers, who released their findings Feb. 12, are apparently the first to develop a kind of embryonic stem cell -- a cell that awaits programming -- from embryos cloned from human cells.

Potentially, the cells could be placed into the body of the original cell donor -- say, an ill person -- and escape the wrath of the immune system. "Our approach opens the door for the use of these specially developed cells in transplantation medicine," study co-author Woo Suk Hwang, of Seoul National University, says in a statement.

People with diseases such as diabetes, Parkinson's disease and even heart disease could benefit from so-called "stem cell therapy."

The findings also open the door to controversy. The scientists have essentially cloned the women who provided the cells used in the process. The embryos, however, reportedly were not implanted in women, and it's possible they were a kind of quasi-embryo that couldn't produce a child.

In the human body, stem cells are empty vessels waiting to discover what part they'll play. When they get the right signal, they take on their role -- a muscle cell, perhaps, or a skin cell or any of many other tissue types.

Scientists can take stem cells from embryos, but a variety of religious groups consider the death of an embryo to be nothing short of murder.

In their study, the researchers harvested 242 eggs from 16 unpaid volunteers. They then developed what is known as a "stem cell line" by inserting the nuclei of cells into eggs that lacked a nucleus.

The researchers report their finding in the Feb. 13 issue of Science. They discussed the study Feb. 12 at the American Association for the Advancement of Science annual meeting in Seattle.

The blending of part of one cell into another allowed the researchers to pull out embryonic stem cells that bore the genetic programming of the woman donor.

Theoretically, the stem cells could be programmed to replace missing cells in the body without risk of rejection. "Just like with organ rejection, the body can detect difference, and would reject the transplanted stem cells. To avoid that, the best thing is to have cells that are genetically identical to the recipient," says Laura Grabel, a professor of natural sciences at Wesleyan University.

As to ethical issues, Science issued a statement saying that neither its publisher nor the researchers support the reproductive cloning of human beings.

"Almost any scientist agrees that human cloning for reproductive purposes should not be allowed," Grabel says. "Aside from the ethical concerns this raises, cloned animals frequently have multiple biological problems. Cloning to create stem cell lines to be used to ease human suffering, it can be argued, is a worthwhile endeavor, though some still find it unacceptable."

Ideally, says pathology professor Dr. Naohiro Terada of the University of Florida, scientists will learn how to make stem cells without entering ethical minefields. "Once we know the molecular mechanism, I hope we can achieve nuclear [nucleus] reprogramming solely biochemically. I predict scientists will achieve this goal within five to 10 years, then we can totally avoid all the controversial steps, considered 'creating' or 'destroying' embryos."

More information

For more on stem cells and what's realistic to expect from them, check out the Batten Support & Research Trust. You can also try the National Institutes of Health or the Society for Developmental Biology.

SOURCES: Laura Grabel, Ph.D., professor, natural sciences, Wesleyan University, Middletown, Conn.; Naohiro Terada, M.D., Ph.D., professor, pathology, University of Florida, Gainesville; Feb. 13, 2004, Science
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