VOA慢速英语20060830a

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HEALTH REPORT - Scientists Develop Stem Cells Without Loss of EmbryosBy Caty Weaver³

Broadcast: Wednesday, August 30, 2006

This is the VOA Special English Health Report.

Researchers say they have found a way to produce stem cells from human embryos² without harm to the embryo¹.


Image from Advanced Cell Technology shows a single cell being removed from a human embryo

The technology uses a single cell taken from an eight-cell embryo known as a blastocyst. The researchers say that from among the cells they removed, they developed two stem cell lines that were genetically⁵ normal.

Company scientists at Advanced Cell Technology in Worchester, Massachusetts, did the experiment.

Nature magazine published the study online last week.

Current technology uses cells from blastocysts that are more developed. But the process destroys the ability of the embryo to continue to grow.

Embryonic⁶ stem cells are able to develop into all of the different kinds of cells in the body. Many scientists believe embryonic stem cells could be used to develop new treatments for diseases.

But the scientific use of embryos is an issue of debate. Some people, including President Bush, say destroying the embryo destroys life.

The removal of a single cell from a blastocyst is not a new idea. It is often done when people go for reproductive assistance at fertility clinics. The process is called preimplantation genetic⁴ diagnosis⁷, or P.G.D. A cell is removed to test for genetic disorders⁸. The cell is destroyed in the process. But the blastocyst from which it came can continue to develop into an embryo and then a fetus⁹.

Robert Lanza of Advanced Cell Technology was the senior author of the new study. In a statement he said it demonstrates that stem cells can be produced without interfering¹⁰ with the embryo's potential for life. Doctor Lanza said that to date, more than one thousand five hundred healthy children have been born following P.G.D.

The company's chief executive officer, William Caldwell, tells us there is no evidence that the removal of a single cell has any effect on the embryo.

Some people say this method could end the moral debate over the use of embryonic stem cells. But other people think that is not likely.

The Bush administration, in a statement, said: Any use of human embryos for research purposes raises serious ethical¹¹ concerns. But a presidential spokeswoman said the study does hold some promise, and that the president believed it should get a good look.

And that's the Special English Health Report, written by Caty Weaver. You can read transcripts¹² of our reports and download audio files to listen on an MP3 player, at www.unsv.com. I'm Barbara Klein.