By Valerie Schmalz

The potential of embryonic stem cells, especially their capacity to subdivide and create all the organs that make up a human being, enthralls many scientists. However, the 100-150 cells from "left-over" embryos created via in-vitro fertilization have not, so far, lived up to scientists’ expectations. The technology of using embryonic stem cells has yet to produce a cure.

One of the biggest problems is that the little test-tube babies have their own unique DNA and the human body is programmed to reject foreign matter. And so recipients of transplanted organs spend a lifetime on anti-rejection drugs and the same issues apply to treatments devised with embryonic stem cells.

In addition to organ rejection, there are other problems, among them: mice injected with embryonic stem cells to cure one disorder have developed tumors in other parts of the body and died.

"For over twenty years they have been working with embryonic stem cells. No patient has been treated with them because they can’t get them to work," says David Prentice, Ph.D., science advisor to Sen. Sam Brownback, R-Kansas, the prime sponsor of a bill to ban human cloning nationally. Prentice is also science advisor for the Family Research Council and former biochemistry professor at Indiana State University.

"At the same time we have thousands of live patients successfully treated with adult stem cells," says Prentice. "It’s like night and day when you look at the actual results."

Some successful treatments using these flexible adult stem cells include partially regenerating spinal cord damage, rebuilding corneas to restore sight, and alleviating the symptoms of Parkinson’s disease and diabetes. Other diseases whose symptoms have been successfully treated with adult stem cell therapies include multiple sclerosis, lupus, Crohn's disease, heart disease, leukemia, non-Hodgkin's lymphoma, aplastic anemia, and sickle cell anemia, according to this article on the Family Research Council website.

But the promise of embryonic stem cells beckons to many scientists. They believe if they can successfully clone an embryo using the cells and thus the DNA of the person needing treatment, they can circumvent the body’s rejection mechanism. With cloning, the scientists would take the DNA material from the person to whom the "cure" was to be directed and implant it into an "emptied" egg or ovum and then build an embryo from it.

Cells from cloned embryos–broken apart to retrieve the cells–could theoretically be used to build new organs, create cures to auto-immune diseases such as diabetes and arthritis, and to regenerate new nerve systems to repair damaged spinal cords.

"When you listen to these stories think about how many times you hear 'potential'," says Prentice. Researchers are also running into rejection problems with cloned mice because there are many technical issues with the injection of one person’s DNA into the "emptied" egg taken from a woman, he says.

Most important–cloning for cures, even if there are any–still means killing.

"A lot of people want to keep away from the 'C' word, so they use the term ‘somatic cell nuclear transfer to obtain stem cells’," says Prentice. "They are playing with words to kind of sanitize it--so people don’t know you made an embryo to destroy and you are actually doing cloning."