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[IP] Stem Cells Grow Eye Blood Vessels

By RANDOLPH E. SCHMID WASHINGTON (AP) - Stem cells taken from bone marrow can 
grow new blood vessels in the eyes of mice, a development researchers say 
raises the possibility of treating some diseases that often lead to blindness 
in humans.
In tests in mice, the stem cells injected into the eye became incorporated 
into the eye's structure and formed new blood vessels.
If the process turns out to work in humans, the scientists hope to use it to 
treat eye diseases affecting the blood vessels in the retina. They include 
diabetic retinopathy and age-related macular degeneration, two leading causes 
of blindness.
Dr. Martin Friedlander, who headed the research team at the Scripps Research 
Institute in La Jolla, Calif., said it may be possible to use the process to 
rescue sick blood vessels or, in modified form, inhibit the growth of 
abnormal vessels in the eye.
His research will be published in the September issue of the journal Nature 
Peter A. Dudley, director of the retinal diseases program the National Eye 
Institute, said it is ``extremely interesting'' that the team was able to 
take certain precursor stem cells that can form blood vessels and then target 
He said it seems reasonable this could lead to human treatments. But he 
cautioned that the work only involved mice and that many details need to be 
worked out before moving on to humans.
Dr. John S. Penn, who teaches ophthalmology at Vanderbilt University, said 
the work adds to the fundamental understanding of biology, adding that the 
finding that the cells can home in on specific parts of the eye ``is pretty 
cool stuff.''
He also cautioned that the work is in mice and much work needs to be done 
before it can be applied to humans.
Stem cells are a type of cell that can differentiate into many different 
cells depending on what is needed. They form in the embryo and are also found 
in adult bone marrow.
Friedlander's team used a type of stem cell called an endothelial precursor 
cell taken from mouse bone marrow.
When these cells were injected into the eyes of mice, they attached to cells 
in the retina called astrocytes and then formed new blood vessels.
``What's exciting about this, and surprising to us, is they don't target 
mature vessels, they go where vessels are going to form,'' Friedlander said.
Newborn mice, for example, do not have blood vessels in their retina but have 
astrocytes forming a sort of template for future vessels, Friedlander 
In adult mice, he said, if the retina is injured, it encourages the 
development of astrocytes. By injecting the stem cells, the researchers can 
help stabilize a degenerating blood vessel system.
Friedlander said he was ``flabbergasted'' at the improvement when the stem 
cells were injected into the eyes of a type of mice that have eye 
degeneration and normally go blind within 30 days of birth.
Friedlander said he believes that because the stem cells target astrocytes, 
genetically modifying the stem cells before injection may make it possible to 
block the growth of unwanted blood vessels, which are also a factor in some 
eye disease.
He also suggested that the cells could be used as a drug delivery system for 
the eyes, something Penn said would be an exciting development.
Diabetic retinopathy is the leading cause of blindness in working age 
Americans, and almost all people who have had diabetes for more than 30 years 
will show signs of poor eyesight.
Age-related macular degeneration is a common cause of vision loss among 
people over age of 60. Both conditions are caused by damage to blood vessels 
of the retina.

07/28/02 14:13 
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