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[IP] Vision: New Therapies Studied New Therapies Studied

Albuquerque Journal


    Sometimes, when blood vessels to the eye suffer damage, the body rushes to
produce others to help the oxygen-low organ.

         Unfortunately, those new vessels can cause a worse problem, blocking
the retina and making a person blind.

         Research at the University of New Mexico is taking an early look at
medications that might stop those misguided blood vessels in their tracks.

         Now, the most common treatment is to destroy the proliferating
vessels with a laser, said Arup Das, assistant professor of surgery. While
that approach might help preserve central vision, it usually wipes out
peripheral vision, he said. Loss of that side vision also can make it
difficult for a person to see at night or in low-light conditions, he added.

         Together with Paul McGuire, associate professor of cell biology and
physiology, Das has been looking for ways to stop the blood vessels from
spreading enough to block vision.

         The process begins because the body gets messages that the eye is not
getting enough oxygen. Eye oxygen levels can run low, for instance, in a
person with diabetes. High blood sugar levels can harm vessels and limit their
ability to carry blood and oxygen, Das said. The growth of new blood vessels
leads to diabetic retinopathy, a common cause of blindness in older people.

         The question is how to stop that blood vessel growth, called

         "Our lab is interested in protease inhibitors," Das said. Protease is
an enzyme that dissolves protein, a step needed to break down blood vessel
walls so new blood vessels can connect with them.

         Das' lab has found higher levels of protease in both animals affected
by the eye problems and in human diabetes patients, he said. Injection of the
protease inhibitor in animals' eyes appeared to slow the blood vessel growth,
Das said, adding that researchers plan to try eye drops rather than injections
on humans.

         "We will have clinical trials soon in diabetic patients," he said.
"We are very excited about that." Approval still is needed from the U.S. Food
and Drug Administration, but UNM researchers hope to start those trials by the
end of the year, according to Das.

         The hope is that such a treatment would be successful without
destroying the peripheral vision that is lost in laser treatments.

         Meanwhile, researchers are getting interested in PEDF  pigment
epithelial derived factor. This molecule, common in cells at the back of the
eye, play a role in growth of the supporting cells of the nervous system, Das
said. "It's an important factor in the maturation of cells," he said.

         Research published last July showed PEDF could inhibit the growth of
new blood vessels, he said. UNM research reported at a conference last October
showed that diabetes patients had lower-than-normal levels of PEDF in the
fluid within their eyeballs, he said.

         That leads scientists to the suspicion that, if you could increase
the PEDF levels in diabetic patients' eyes, then new blood vessels would have
a harder time growing. GenVec Inc., a Maryland biotechnology company, is
funding gene-therapy research at UNM related to PEDF.

         "If you deliver that protein to the back of the eye, can you stop new
blood vessels from growing?" asked Das, who said experiments are under way in
mice. "If we have good results, that could translate into a (human) clinical

         UNM is one of two medical centers in the United States investigating
this gene therapy.

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