Tuesday, September 23, 2008

Stem cells open door for studying human disease By Julie Steenhuysen

Stem cells open door for studying human disease
By Julie SteenhuysenMon Sep 22, 10:05 PM ET
Advances in stem cell research offer a new way of studying human disease, allowing scientists to move beyond fruit flies and lab mice to see how human cells go awry and how drugs and other therapies might help, U. S. researchers said on Monday.
They said human embryonic stem cells and a newly invented type of cell called induced pluripotent stem cells or iPS cells -- made without the use of human embryos -- are helping to transform how researchers develop and test therapies.
"We've almost worn out what we can do with animals in disease biology such as fruit flies and mice," Lawrence Goldstein, a researcher at the University of California-San Diego, told about 900 scientists and stem cell advocates at the World Stem Cell Summit in Madison, Wisconsin.
"The problem at the end of the day is that humans are not just big mice."
Researchers such as Goldstein hope to use stem cells not only to create a new field of medicine called regenerative medicine -- and grow tissues, organs and blood for transplant -- but also to study diseases as they specifically affect humans.
Embryonic stem cells are the body's master cells, giving rise to all of the tissues in the body, and iPS cells, made using genes to transform ordinary cells, appear to have similar powers.
Stem cells made from people with various diseases can be used to grow batches of living tissue in the lab -- tissue with the same genetic defects that cause or are caused by the disease.
"Scientists have never had access to human tissue before," said James Thomson of the University of Wisconsin, who was first to derive embryonic stem cells from a frozen human embryo a decade ago.
Some people, including President George W. Bush, oppose experimenting on human embryos and Bush has allowed only restricted federal funding for this type of research.
Earlier this year, research teams in Japan and the United States found a way to coax ordinary skin cells into becoming induced pluripotent stem cells.
"We now have a way to genetically modify adult cells out of your body to have the same properties embryonic stem cells have," Thomson told the meeting.
"That will lead to better, faster cheaper drugs in a way that won't make the cover of The New York Times, but will very much affect patients," he said.
Scientists said both types of stem cells will offer a better way to understand human disease.
Goldstein's lab is studying diseases of the nervous system, such as Alzheimer's disease and amyotrophic lateral sclerosis or ALS, also known as Lou Gehrig's disease.
For Alzheimer's, Goldstein said there are very few approved drugs and a few in the discovery pipeline. "The reason is we fundamentally do not understand what is wrong in the nerve cells in that disease," he said.
His lab is gathering skin cells from people with a genetic form of Alzheimer's disease. "We've captured in these cells the quintessential aspects of the disease," Goldstein said. They want to use them to test new drugs.
Thomson said similar research will take place in cultures of heart cells and efforts are already underway to use stem cells to make human blood, which might be used to supplement the blood supply.
He said other stem cell therapies, including transplants to replace damaged or destroyed cells, are farther off, and will likely come within 5 to 10 years.

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