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HomeNewsScientists Clone First Human Embryo

Scientists Clone First Human Embryo

Genetically Identical Cells May One Day Cure Disease

Researchers in South Korea say they are the first to successfully clone a human embryo and use it to create stem cells that may one day provide the foundation for curing diseases from diabetes to Parkinson’s.

“We are the first to report the development of cloned human embryonic stem cells, potentially capable of becoming any cell in the body,” says researcher Woo Suk Hwang of Seoul National University in South Korea.

Hwang presented the results of the study today at a meeting of the American Association for the Advancement of Science (AAAS) in Seattle. The results also appear in today’s issue of Science Express, the online version of the journal Science.

Researchers stress that this breakthrough is intended to pave the way for new custom-made medical treatments, not for human cloning.

Embryonic stem cells are the building blocks of life and the basis from which all other tissue cells are formed. The cells are found in the embryo only during the earliest stages of development and eventually diversify into millions of different cells.

By cloning human embryonic stem cells, researchers hope to replace damaged cells in the human body with genetically identical healthy cells to cure disease.

Embryonic stem cells have been created in the past using cells from mice and other animals, but achieving the same feat with human cells has proved too problematic until now.

“People have tried and utterly failed in the last couple of years to do it with human cells or primer cells, and they succeeded,” says Rudolf Jaenisch, MD, professor of biology at the Whitehead Institute of the Massachusetts Institute of Technology. “That’s an important step.”

First Cloned Human Embryo Clears Major Hurdle

In the study, researchers collected 242 eggs and a sample of ovarian cells from 16 unpaid female volunteers. The scientists then removed the genetic material — which contains the nucleus of each egg — and replaced it with the nucleus from the donor’s ovarian cell.

Then, using chemicals to trigger cell division, the researchers were able to create 30 blastocysts — early-stage embryos that contain about 100 cells — that were a genetic copy of the donor cells.

Next, the researchers harvested a single colony of stem cells from the blastocysts. These stem cells have the potential to grow into any tissue in the body. Because they are the genetic match to the donor, they aren’t likely to be rejected by the patient’s immune system.

Many Hurdles Left

Experts say practical use of stem cell transplants using cells derived from human embryos is still a long way off.

“In a real sense, it’s still going to be years before we affect the treatment of a patient with this,” says stem cell researcher John Gearhart, PhD, the C. Michael Armstrong Professor of Medicine at John Hopkins University.

Gearhart says there are still many problems that need to be solved. One of the biggest problems will be making the process more efficient. In this case, researchers used 242 eggs from 16 donors to obtain a single embryonic stem cell.

Researchers will also need to make sure that they can make embryonic stem cells effectively into Functional cells, which can be transplanted to treat diseases.

But Gearhart says the findings of this study may also help further scientific research in other areas by providing valuable new information on what is so unique about a human embryo.

For example, Gearhart says, “What is it about the egg that permits these nuclei from specialized cells to be reprogrammed? Wouldn’t we love to know how that occurs at the molecular level?”

If researchers can answer that question, he says they may eventually learn how to reprogram cells without using an embryo.

Breakthrough Stirs Stem Cell Debate

The first successful cloning of a human embryonic stem sell is already stirring up an international ethical debate. Hwang and colleagues say they have enough stem cells in reserve and are willing to collaborate with any scientist who wishes to join them.

But the practice of using stem cells taken from human embryos is considered ethically sensitive because the embryo is destroyed once the stem cell is removed.

Current Bush administration policy forbids federally funded research on stem cells derived from human embryos destroyed after Aug. 9, 2001. Privately funded research on human embryonic stem cells is not restricted.

Jaensich says the federal limitations on embryonic stem cell research may impede the pace of progress of science in this area.

“The National Institutes of Health doesn’t pay for it, and, therefore, the premier academic institutions here will not be able to do this research,” says Jaenisch. “This really important research will be done in other countries, and it is a very troubling situation.”

The Korean researchers attributed their success to using extremely fresh donor eggs, but they say this study was supported by private funds.

Some have questioned whether the publishing of the study in a medical journal amounts to providing an instruction book for others on how to create a cloned baby.

Donald Kennedy, editor-in-chief of Science, says the techniques laid out in the paper are designed for use only in developing new treatments for disease.

“It is a recipe only in the sense that ‘catch a turtle’ is the recipe for turtle soup,” says Kennedy. “There is much difficulty that would remain for anybody who tried to use this technology as a first step toward reproductive cloning.”

Human cloning is against the law in South Korea and some other countries. Most major medical organizations in the U.S., including the AAAS, have expressed opposition to reproductive cloning.

SOURCES: Hwang, W. Science Express, Feb. 12, 2004. Woo Suk Hwang, Seoul National University. Rudolf Jaenisch, MD, professor of biology, Whitehead Institute, Massachusetts Institute of Technology. Donald Kennedy, editor-in-chief, Science. John Gearhart, PhD, C. Michael Armstrong Professor of Medicine, John Hopkins University. News release, American Association for the Advancement of Science. WebMD Medical News: “Cloning FAQs and Fiction.” WebMD Medical News: “Most Americans Against Human Cloning.”

By Jennifer Warner
WebMD Medical News

Reviewed By Michael Smith, MD
on Thursday, February 12, 2004

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