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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 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
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
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
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.
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