February 13, 2004

Heredity disorders, genetic and congenital defects, to biodegrade, to propagate, to be fraught with (ethical and moral controversy), a matter of considerable public concern and debate, to be vocal against, to condone, to pave a path that may lead to a regrettable destination, to defy established views, a slippery slope, to eradicate, to stumble upon, insidious, room for abuse, to perpetuate, well-balanced legislation

14. Read the text and do the follow-up activities.

CLONING AND STEM CELLS: THE RESEARCH; Medical and Ethical Issues Cloud Cloning for Therapy

By ANDREW POLLACK; CORNELIA DEAN AND CLAUDIA DREIFUS CONTRIBUTED REPORTING FROM SEATTLE FOR THIS ARTICLE.

In cloning human embryos and extracting universal stem cells, scientists in South Korea have taken a big step toward a tantalizing goal: growing tailor-made replacement tissues for people who are sick or injured. Imagine new cardiac muscles to restore a heart after a heart attack, insulin-producing cells for diabetics or neurons to stave off Parkinson's disease.

But significant scientific barriers lie between this accomplishment and any actual therapy, experts said. Moreover, ethical objections have put such research off-limits to some scientists -- including the many in the United States who rely on federal money -- and lack of investment has felled many companies trying to develop cell-replacement therapies.

The South Korean work is a step toward what is called ''therapeutic cloning.'' The work so far is ''proof of concept of cloning but it's not therapeutic yet,'' said Dr. Steven A. Goldman, chief of the division of cell and gene therapy at the University of Rochester Medical Center.

It is likely to be several years before tissues derived this way could even be tested in patients, he and other experts said. The South Korean scientists have produced only the raw material, the stem cells, which must be turned into more specific cells like heart cells or brain cells.

Some researchers hope that new work will galvanize support for similar research in the United States, by showing that therapeutic cloning is not merely a pipe dream. They argue that the fact that this work was done in South Korea shows that the United States is in danger of falling behind other countries in what could become a major new medical field.

The idea behind therapeutic cloning is to create tissues or cells that are genetically identical to those of a patient. That way, when the cells are implanted into a patient they will not be rejected like many transplants are. The term ''therapeutic cloning'' is also used to distinguish it from reproductive cloning, in which the goal is to make a baby that is identical to the parent.

The South Korean scientists created embryos that were genetic copies of women who donated cells. After a few days, some of the embryos had grown to a stage when embryonic stem cells could be extracted, and the scientists created one culture of such stem cells. The stem cells have the ability to turn into any other kind of cell in the body.

Dr. Hwang and Dr. Moon said their research team and the university were seeking to patent the techniques and the stem cells produced from the cloned embryos. They said they would be happy to share the cells with other researchers, but probably on condition that the patent holders would share in any profits.

To make those embryonic stem cells useful for therapy, scientists would then have to turn them into particular types of cells like heart cells or neurons that could be injected into people. Scientists have already learned how to do that for some cells, but not all. But the cell populations to be implanted must be pure, said Dr. Goldman of Rochester, who is also a professor of neurology. It is essential, he said, that the cells contain no residual embryonic stem cells, because when implanted in the body they tend to form tumors called teratomas that consist of a mix of tissue types including hair, skin and teeth.

Moreover, Dr. Goldman said, for certain applications, like treating neurologic diseases, implanting the wrong type of nerve cell could cause side effects like seizures.

But the work is advancing. ''With adequate funding, there's no question we could be in clinical trials in two or three years,'' said Robert P. Lanza, medical director of Advanced Cell Technology Inc., a Worcester, Mass., company that has been pursuing therapeutic cloning but now has only a handful of scientists. ''The question is are we going to be around to be doing this work.''

Dr. Thomas B. Okarma, president and chief executive of the Geron Corporation of Menlo Park, Calif., a leader in embryonic stem cells, said his company hoped to ask the Food and Drug Administration to approve a clinical trial in 2005, using cells derived from embryonic stem cells to treat spinal cord injuries. Such treatment has restored mobility in some paralyzed rats, he said.

''We've gone way beyond the academic world and where most of the pundits think the field is,'' Dr. Okarma said. Geron does not do therapeutic cloning but uses human embryonic stem cells derived from embryos left over from fertility clinics, created by the fertilization of egg by sperm. Dr. Goldman, who once collaborated with the Geron Corporation, said he doubted that a trial could begin that soon, saying it would be ''irresponsible'' to try.

There are ethical objections to work with human embryonic stem cells, because it involves the destruction of embryos, which some people view as human life. Therapeutic cloning is also controversial because, critics say, it involves creation of life solely for research or treatment. Supporters argue that therapeutic cloning is distinct from reproductive cloning, which even many of them find objectionable.

The ethical question, scientists say, has slowed progress. Some scientists stay away from such research to avoid the debate. Federal money for research on human embryonic stem cells is limited, they say, and scientists who receive such financing are allowed to work with only a small number of cell lines.

Companies and venture capitalists have also been reluctant to invest in the field, partly because of the ethics debate, but also because investors perceive it will take a long time for such therapies to reach the market and provide a return. Moreover, injecting cells, particularly if they are customized to each patient, is perceived as a less attractive business proposition than mass-producing a pill that everyone can take.

Many companies pursuing cloning and cell replacement therapies, not all from embryonic stem cells, have gone out of business. PPL Therapeutics, the Scottish company that helped clone Dolly the sheep, is being dismantled. Infigen, a pioneering cloning company in Wisconsin, recently laid off all of its employees.

''The landscape is just littered with dead companies,'' said Linda Powers, managing director of the Toucan Capital Corporation, a venture capital firm in Bethesda, Md., that, she said, is one of the few investing actively in cell therapies. ''You can spend so much money so quickly and end up dead before you know it,'' she added. ''I think that's been the story with so many companies in this space. That's had a chilling effect on investors.''

Even among those pursuing cell replacement treatments, many say that therapeutic cloning would be too inefficient to be practical. The South Korean scientists, for instance, started with 242 human eggs donated for the cloning. They got about 20 embryos from which they tried to extract stem cells and managed to produce only one stem cell line.

Moreover, those scientists managed to produce embryos only when the person to be cloned was also the donor of the egg used. They could not clone men or women who were not egg donors. If that remained the case, it would mean that therapeutic cloning would not be of benefit to men, or to women past menopause.

Dr. Okarma of Geron said his company was using more generic stem cells that could make large amounts of tissues at a lower cost. There is no need to create tissue matched to each patient because there are other ways to fight rejection, he said.

Some scientists say it would be more practical to use stem cells from adults. While some experts say these cells cannot be grown outside the body as easily as embryonic stem cells and may not be as versatile, they are more predictable in what kind of cells they turn into. Use of adult stem cells is not ethically objectionable, avoiding ''all the hand-wringing and explanations and gnashing of teeth,'' Ms. Powers of Toucan Capital said.

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