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Asunto:[debunker] Yahoo! News Story - Scientists Turn Stem Cells Into Brain Cells
Fecha:Viernes, 30 de Noviembre, 2001  18:26:55 (PST)
Autor:Yahoo! News <refertofriend>

Luis Gallardo (baalcebub@...)has sent yent you a news article

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Scientists Turn Stem Cells Into Brain Cells

Scientists Turn Stem Cells Into Brain Cells
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Friday November 30 2:14 PM ET Scientists Turn Stem Cells Into Brain Cells

Scientists Turn Stem Cells Into Brain Cells

By Maggie Fox, Health and Science Correspondent

WASHINGTON (Reuters) - Two separate teams of international researchers said on Friday they had found reliable ways to coax human embryonic stem cells into becoming brain cells.

Their work is a step forward in the busy but controversial field of stem cell research, which scientists say holds the promise of treating a range of diseases from brain damage to diabetes, but which critics say kills human embryos.

Stem cells are a kind of master cell that can develop into a variety of tissues. When taken from very small embryos they seem to be even more flexible, with the ability to become any kind of cell in the body at all.

They also seem to live and grow forever in lab dishes, unlike ``differentiated'' cells that have become skin cells, muscle cells and so on, providing a potentially endless source of tissue, and perhaps someday even organs, for transplant.

Both teams, writing in the journal Nature Biotechnology, said they coaxed the stem cells into becoming the three types of brain cells -- astrocytes, oligodendrocytes and mature neurons.

They transplanted the cells into the brains of newborn mice and saw them spread throughout the brains, take up residence and, evidently, start working.

They took stem cells from human embryos -- typically tiny balls of cells left over from IVF or test-tube baby fertility treatments -- grew them in special cultures in the laboratory and then injected them into the brains of the mice.

``These are the cells that will be used, ultimately, to treat Parkinson's and other central nervous system disorders,'' Su-Chun Zhang of the University of Wisconsin, who led one of the studies, said in a statement.

They looked at the mouse brains after a few weeks.

``The neuron that we're seeing after transplant is almost identical to what the neuron should be in the healthy brain,'' Zhang said.

``These transplanted cells had no experience in the brain, and we wanted to see if they would mirror the development of the mouse brain,'' Zhang says. ``And they do.''


Benjamin Reubinoff and colleagues at Hadassah University Hospital in Jerusalem and Monash University in Melbourne, Australia, reported similar results.

Stem cells are difficult to isolate and identify but it is even trickier to direct their development. The particular mix of nurturing chemicals is vital.

Zhang, James Thomson and colleagues at Wisconsin, working with a team at the University of Bonn in Germany, said one step involved starving tumors of a protein called FGF-2.

Sometimes transplanted embryonic stem cells can form tumors, but they did not in these mice, the researchers said.

``We put a lot of cells, in one instance half a million, in a mouse,'' says Zhang. ``The more cells you put in, the more likely you are to have a tumor. The absence of tumors shows our methods for purifying the precursor cells are pretty good.''

Stem cell researcher Lorenz Studer of Memorial Sloan-Kettering Cancer Center in New York said both papers offered insight into how stem cells might be harnessed.

``The list of diseases that may be treatable with human embryonic stem cell research is vast and includes neurological disorders (such as) Parkinson's disease (news - web sites), white-matter loss or spinal cord injury, and many non-central nervous system disorders (such as) juvenile diabetes, muscular dystrophy or cardiac dysfunction,'' Studer wrote in a commentary for Nature Biotechnology.

In a recent interview Curt Freed of the University of Colorado, who experiments with brain cell transplants on Parkinson's patients, said he was looking for such results.

``As soon as a cell comes along that can be mass-produced it will make brain cell repair much more predictable and reliable,'' Freed said.

But he warned that federal approval was a long way off. President Bush (news - web sites) also limited avenues for such research in August when he said federally funded researchers could only work with currently existing supplies of embryonic stem cells.

``It will still be some years before we can even try this in people,'' Zhang said.

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