Miércoles 1 de Junio de 2005, Ip nº 111

Stem Cells Made to Order
Por Kristen Philipkoski

Korean scientists have used cloned human embryos to derive tailor-made stem cells, a breakthrough with dramatic implications for the development of useful therapies that could help shift the debate over human cloning.

The researchers derived stem cells from patients with spinal cord injury, a congenital immune disorder and juvenile diabetes. The advance, announced Thursday, raises the stakes in the political and ethical argument surrounding embryonic stem-cell research. Once a pie-in-the-sky possibility, human cells now exist that could theoretically be transplanted back into patients without the fear of immune rejection, since as cloned cells they would be a genetic match.

Researchers must test the cells in animals before they can try the therapy in humans. But embryonic stem-cell researchers were shocked and delighted by the advance, which many had referred to as a distant possibility until they saw this study by Woo Suk Hwang and his colleagues at Seoul National University, which appears in the May 20 issue of Science. A little more than one year ago, Hwang and his colleagues derived the first stem cells from a cloned human embryo.

With practical applications coming within reach, proponents of limited human cloning are hopeful that it will become more difficult to ban the science, as some lawmakers and religious leaders have proposed.

"(The research) is going to have an influence on policy because this brings treatments and potential cures decades closer to fruition," said Bernard Siegel, director of the Genetics Policy Institute. "Up until now, it seemed largely like a theoretical exercise, but now with actual stem-cell lines created for individuals suffering with diseases and medical conditions, this takes on a greater significance, and those who would want to ban this research are going to come face to face with millions of patients seeking cures."

A 2001 executive order forbids scientists in the United States from cloning embryos to derive stem cells, a procedure known as therapeutic cloning. Several states outlaw human cloning, but no federal human cloning law has made it past the Senate.

American scientists who believe they can develop therapies using embryonic stem cells face opposition from pro-life and religious groups who believe an embryo should not be destroyed for research (deriving stem cells destroys the embryo). Those groups are lobbying against a bill sponsored by Rep. Mike Castle (R-Delaware) and others that would expand federal funding for embryonic stem-cell research beyond an executive order from President Bush in 2001, which stipulated that only stem-cell lines already derived were eligible for federal funding.

Castle's bill would allow federal funding for research using embryos left over at in vitro fertilization clinics. But it would not allow an embryo to be created for research and therefore would not allow federally funded researchers to take advantage of Hwang's advancement.

Many believe that Hwang's achievement brings therapies much closer to reality, and Congress will have to weigh the increasingly realistic potential benefit to patients when deciding on legislation.

"For the first time (Hwang and his colleagues) have demonstrated that therapeutic cloning can work in a medically useful way," said Robert Lanza, vice president of medical and scientific development at Advanced Cell Technology, a for-profit company working on cloning technology. "Prior to this study, there was a question as to whether it was biologically possible.... The answer is yes, it works. And they did it in a dramatic way -- they used therapeutic cloning to derive stem cells that genetically matched patients who had real diseases that could be treated using this technology."

Other researchers said human clinical trials will be forthcoming if preliminary trials can show that embryonic stem cells are safe.

"Now we're waiting for the clinical trials (using non-cloned embryonic stem cells) to show that they're safe," said Jose Cibelli, a professor at the University of Michigan, where he studies animal cloning because human cloning is forbidden in his state. "We have to make sure embryonic stem-cell therapy will be safe, and then we can start thinking about perfect match cells that are 100 percent compatible with any disease you want to go for."

Hwang and his colleagues created the new stem-cell lines using a technique similar to the one used to produce Dolly the sheep in 1996. One key to their success was using freshly harvested eggs from young, fertile women, rather than embryos left over from fertility clinics. The women who volunteered for the study signed informed-consent agreements, and were not paid.

To perform cloning, scientists remove the nucleus from an egg and replace it with a cell from the person to be cloned, often a skin cell. Typically, scientists suck out the nucleus using a hollow needle, but the Korean team instead made a small tear in the egg and gently squeezed out the nucleus. They inserted a skin cell through the tear, then jolted the cells with an electric shock to fuse the cells and begin cell division.

Another striking aspect of the study, researchers said, is that Hwang was able to significantly increase the efficiency of his technique. Last year, when Hwang derived the first human stem-cell line from a cloned embryo, he failed more than 200 times before he succeeded -- meaning he had to use more than 200 eggs donated from women to create embryos. In his latest study, he brought the average number of tries down to just 20. That means in most cases one woman taking super-ovulating drugs in one menstrual cycle could donate enough eggs to create a stem-cell therapy for one patient.

Some feminist groups worry that women's health will be placed at risk because creating embryos takes many donated eggs.

While the new study decreases the amount of eggs necessary, it brings the technique much closer to reality, which will actually increase demand for eggs, said Nigel Cameron, senior fellow at the Center for Bioethics and Human Dignity.

"It seems to me that even if you don't need as many eggs to do it, you're still going to have women on the line as part of the production process," Cameron said. "It brings the whole thing much closer to reality, and you're still going to need to abuse women to bring this technology into production."

Scientists agree that a method not requiring women to put their health at risk would be preferable, but in some cases, similar to organ donation, the benefits may outweigh the risks.

"One woman suffering is not any different than three or four," Cibelli said. "We still have to come up with a better way of doing it. But if you think in terms of family members we all have -- maybe a daughter or sister or mother that can help out, and if it is only one cycle or two cycles this woman now has to go through (to donate eggs), many people will do it."


  19/05/2005. Wired Magazine.