The Hindu : International : South Korean team of scientists develops patient-specific stem cells

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Saturday, May 21, 2005

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International

South Korean team of scientists develops patient-specific stem cells

Gareth Cook

Breakthrough will help the study of degenerative diseases; experiments to continue

NEW YORK: A team of South Korean scientists announced on Thursday that they had discovered a highly efficient way to clone human cells, an advance that could alter the scientific and political debate over the procedure.

The researchers said they have created 11 new lines of cloned human embryonic stem cells, including, for the first time, two that are genetically matched to patients with a disease.

This is the first step necessary for therapeutic cloning, a procedure in which patients might one day be treated with healthy nerve, blood, or other cells cloned from their own skin.

The two disease-carrying cell lines, cloned from patients with juvenile diabetes and an inherited blood disorder, will offer researchers new ways of studying those maladies.

Impact of work

But the most immediate impact of the work, scientists said, was to establish the cloning of human cells as a robust, surprisingly reliable procedure.

The team, led by Woo-Suk Hwang at Seoul National University, for the first time cloned skin cells from men and from patients with a wide range of ages, from 2 to 56.

The South Koreans announced the first successful cloning of human cells last year, but it required 242 egg cells, which are used to make microscopic embryos, to create a single batch, or "line,'' of cells.

By refining its laboratory techniques, the team made 11 new lines of embryonic stem cells using only 185 egg cells, more than a 10-fold improvement in efficiency.

"This is a very important paper,'' said Douglas Melton, a Harvard University biologist who is preparing an effort to clone human cells. "I am very impressed by the speed with which they have done this.''

Critics of cloning research have argued that treating patients will require large numbers of women to donate eggs, and egg donation carries some risk. The paper, published online on Thursday by the journal Science, may dampen this concern, because the new research shows it is often possible to create a line of cloned embryonic stem cells using only the eggs gathered from a single cycle of fertility treatment in one woman.

But the advances are likely to intensify another concern about the science: That the United States is falling increasingly behind.

"We are going to be playing catch-up,'' said Kevin Eggan, a Harvard scientist who works with Mr. Melton and who recently visited the South Korean team. "They are the masters.''

Embryonic stem cell research in the United States has been slowed by a political fight with roots in the abortion debate. Some critics of the research charge that destroying a human embryo, which researchers do to create embryonic stem cells, means taking a human life. On August 9, 2001, U.S. President George W. Bush announced that the Government would not fund research using human embryonic stem cells created after that date, because he did not want the Government to encourage embryo destruction.

The new cell lines in South Korea, which were created with money from the Government there, fall under that ban, but American scientists could study them using private funds or, in some places, state money.

Dissatisfaction with the President's policy has been mounting in Congress, fuelled in part by announcements like Thursday's. The U.S. House of Representatives is scheduled to vote next week on a measure that would allow scientists to work with newer lines of embryonic stem cells, though not stem cells created by cloning.

Hybrid process

What the South Korean team has been able to do is create human embryonic stem cells with the genetic material of particular patients.

With cloning, also called nuclear transfer, the scientists take a cell from a patient, remove the cell's nucleus containing the genetic material, and place this nucleus in an egg cell that has had its own nucleus removed. This hybrid cell is then stimulated to grow, until it becomes a nearly featureless ball of about 200 cells, a type of embryo known as a blastocyst. The first application of this technology is the creation of cells to study diseases. South Koreans created a human embryonic cell with the DNA of a 6-year-old girl who suffers from juvenile diabetes.

Now scientists can observe how these cells develop into specialised cells and compare this with the development of embryonic cells that do not have the genes that contribute to juvenile diabetes.

This could show them where the first problems arise that lead to the disease.

The other principal application is therapeutic.

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