May 03, 2012
By Donna Peck
|M.D.-Ph.D. student Bliss O'Bryhim and Andrew Symons, M.D.|
A University of Kansas Medical Center retina specialist, working with a KU M.D.-Ph.D student, has made some important discoveries that could help more than 4.4 million people in the United States who suffer from diabetic retinopathy and other degenerative eye conditions.
Diabetic retinopathy is the leading cause of blindness in adults. It affects up to 80 percent of all patients who have had the disease for 10 years or more. Poor blood sugar control can be especially detrimental to small blood vessels - such as those in the eye. High blood glucose levels may damage the tiny blood vessels in the retina of people with diabetes, which often leads to vision impairment and blindness.
Andrew Symons, M.D., an assistant professor of ophthalmology, has been researching the process and genetics of retina vascularization since coming to KU Medical Center in 2009. Symons, working with M.D.-Ph.D. student Bliss O'Bryhim, has also been studying another kind of retina vascularization - retinopathy of prematurity - which has some pathological features in common with diabetic retinopathy.
Retinopathy of prematurity is an eye disease that affects babies born prematurely. In this disease, disorganized growth of retinal blood vessels may result in hemorrhage and retinal detachment. In the past, premature infants have been given high levels of supplemental oxygen, is known to be a major factor in retinopathy of prematurity.
"The theory involves the slowing of blood vessel growth when premature infants are exposed to too much supplemental oxygen," Symons says. "When the excess oxygen is eventually removed, uncontrolled growth of the infant's blood vessels can occur, with vessels growing into the vitreous humor of the eye from the retina, which can sometimes lead to blindness."
As part of his research, Symons recreates the conditions for retinopathy of prematurity in the lab. He provides a high oxygen environment that stops retinal blood vessel growth in mice. He then removes the high oxygen conditions to spur the growth of blood vessels.
"It is the regrowth process that interests us most," says O'Bryhim.
Symons has been studying a gene called tyrosinase, which he identified as playing a major role in the rate at which blood vessels grow.
"We believe our gene controls the number of blood vessel progenitor cells in the bone marrow and in the blood, which in turn controls how fast the blood vessels in the retina grow," says Symons.
"If we can figure out how to control the pathway regulated by tyrosinase and thereby control the growth of blood vessels in the retina, it could have major implications for diabetic retinopathy and other diseases of the retina," Symons says.
Symons and O'Bryhim are presenting their research on retinopathy of prematurity at the annual meeting of the Association for Research in Vision and Ophthalmology in Fort Lauderdale, Fl., in May.