SCIENCE IN THE NEWS - Progress Made in Stem Cell Research（在线收听）

SCIENCE IN THE NEWS - Progress Made in Stem Cell Research
By Caty Weaver, Jerilyn Watson, ...

Broadcast: Tuesday, May 31, 2005

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This is SCIENCE IN THE NEWS, in VOA Special English. I'm Barbara Klein.

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And I'm Bob Doughty. On our program this week, we talk about a way to help lung cancer patients. We also report on a treatment that may return sight to damaged eyes.

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But first, we tell about a method to produce stem cells that could be used for disease research.

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Scientists in South Korea have reported major progress in their efforts to copy human embryos. The scientists say they have used the method to produce embryonic stem cells. Stem cells have the ability to grow into other cells, such as heart, nerve or brain cells. So they might offer new ways to treat injury and disease.

The Korean scientists say their recent work resulted in eleven stem cell groups or lines. Each stem cell line is an exact genetic copy of a human patient involved in the experiments.

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Seoul National University professor Hwang Woo-suk
Hwang Woo-suk and Moon Shin-yong led the research effort at Seoul National University. Maybe you recognize those names. We reported on the two men last year. At that time, they were the first scientists to report success in producing a stem cell line from a human embryo they had copied, or cloned.

Cloning is reproduction by one parent in which an exact genetic copy is created. A similar process happens in nature. It is called asexual reproduction.

In the laboratory, such a process begins with egg cells. Scientists remove the nucleus from each cell. The nucleus contains the complete genetic plan for an organism. The last step is to place the nucleus of an adult cell into the egg.

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The South Korean study last year involved eggs from sixteen women. The same women also provided the adult cells to be placed into each of their eggs.

Recently, the scientists used eggs from eighteen women. But, the skin cells they placed into the eggs came from eleven other people. Nine of them have spinal cord injuries. Another has the disease diabetes. And the eleventh has a genetic disorder. The group included men, women and a child as young as two years old.

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The scientists developed new methods for their experiments. For example, this time they did not use a needle to pull the nucleus from the egg.

 
 
Instead, they reportedly made a small cut in the egg and pressed the genetic material out through the opening. They used the same hole to place the skin cell into the egg.

The result was eleven stem cell lines from the nine of the people who provided skin cells. Scientists have never before produced stem cells that are genetic copies of people with diseases or injuries. Scientists hope stem cells will be helpful in the treatment of diseases and injuries because they can grow into any kind of cell.

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Gerald Schatten is a reproductive biologist at the University of Pittsburgh. He advised the Korean scientists and helped to prepare the English language version of their report. He says the study brings science much closer to use of stem cells in medical treatments. He says the scientists showed that stems cell lines can be established through the use of people of different ages, sexes and health conditions.

Not everyone is as happy about the study. There are many political and moral questions about experiments involving cloning. Lawmakers in many areas are not sure how to supervise such science.

Last week, the United States House of Representatives passed a bill that would ease restrictions on government aid for embryonic stem cell research. President Bush has threatened to veto the bill. He says an embryo is human life and should not be destroyed.

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Some people have expressed fear that cloning could one day be used to produce babies. Some scientists have already created animals this way. But, most scientists, politicians and clergy say the idea of reproductive cloning of humans is un-acceptable.

Doctor Hwang says the goal of his experiments is limited to finding cures for disease and injury. He says it must continue for this reason only. He says his team has no plan of using the new method for making babies.

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An American research center has reported studies that may some day help return sight to damaged eyes. Scientists at the Schepens Eye Research Institute say they have repaired a damaged optic nerve connection in mice.

Dong Feng Chen reported on the study. She teaches at Harvard Medical School in the state of Massachusetts. The study was published in the magazine, Journal of Cell Science.

The optic nerve connection links the eye to the brain. It makes sight possible. The optic nerve contains millions of nerve cells. When healthy, the cells carry sight messages from the eye to the brain. The brain makes it possible for a person or animal to see the image sent by the eye.

The eye and the optic nerve are part of the central nervous system. Many body parts are able to repair themselves after injury. But this is not true for nerve cells in the central nervous system.

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Doctor Chen and her team want to know why tissue from the central nervous system stops repairing itself. A scientist in Doctor Chen's laboratory tested two ways to re-start the process in the optic nerve. One way involved a gene called BCL-two. BCL-two normally is not active. The scientists thought this lack of activity was blocking nerve restoration. So they developed a mouse in which the gene is always active.

The scientists also believed scar tissue on the brain helped stop a damaged nerve from repairing itself. The scar was created from a healed wound soon after birth. Specialized cells called glial cells create the scar.

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The scientists found that the animals with the active BCL-two gene could quickly repair damaged optic-nerve tissue. But this could happen only when the mice were very young. It could happen only before their glial scars developed. Then the scientists carried out another experiment with mice. They again used animals with active BCL-two genes. But they added a process to the experiment. They reduced the ability to develop a glial scar in these mice. The optic nerves were restored in the mice, even when they were older.

Doctor Chen said the scientists observed that at least forty percent of the optic nerve in the animals had been repaired. But she said a higher percentage probably was repaired than they could observe. They will now attempt to learn if the restored nerves can operate like undamaged nerves. Doctor Chen says she believes their methods might repair optic nerves and other tissue of the nervous system.

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A new study suggests that sunlight and vitamin D may help some people with lung cancer live longer. Lung cancer is the most common cancer around the world, with more than one million new cases each year. It kills more people than any other cancer. About sixty percent of those who get lung cancer die within a year. The major preventable cause is the use of tobacco.

Vitamin D helps build strong teeth and bones. Foods such as oily fish and egg yolks are high in vitamin D. But not many foods naturally have high amounts of the vitamin. So extra vitamin D is often added to milk products. Some people take vitamin D pills. Another way to get vitamin D is from sunshine. The body produces it through the skin from the ultraviolet radiation of the sun.

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Scientists from Harvard University led a study of more than four hundred fifty people. These men and women had been treated for lung cancer in Massachusetts. Doctors operated to remove their tumors.

Scientists asked the people what they ate, what vitamins they took and what time of year their operations had taken place. Some took high levels of vitamin D and had their operations during the summer, when there is lots of sunshine. Others had low levels of the vitamin, and were operated on in winter.

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The scientists found that thirty percent of the people in this second group were alive five years after their operation. Forty-six percent were disease-free. But patients with the highest vitamin D intake and summer operations had higher survival rates. Seventy-two percent were still alive after five years. And eighty-three percent were disease-free.

The findings were presented at a meeting of the American Association for Cancer Research. Other studies are needed to confirm them.

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This program was written by Cynthia Kirk, Jerilyn Watson and Caty Weaver. Cynthia Kirk was our producer. I'm Barbara Klein.

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And I'm Bob Doughty. Join us again next week for SCIENCE IN THE NEWS, in VOA Special English.

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