Seeing clearly

Assistant professor develops fiber that could help fight blindness in diabetics

Kevin Nelson is interested in his rats, especially when they have surgery. Ophthalmic surgeons make tiny incisions in the rats' eyes and insert a special fiber into the eyeball that Dr. Nelson, a biomedical engineering assistant professor, developed. The fiber is attached to the inside of the eyeball and delivers medication directly into the rats' eyes.

The fiber is a new treatment for retinopathy, a condition that causes blindness in people with diabetes.

"The next step is to try the procedure on larger animals, such as dogs or pigs," Nelson said.

He said a beagle's eyes are the closest match to a human's.

It's all part of research into finding a cure for one of the most debilitating symptoms of diabetes. Diabetic retinopathy is the most common cause of blindness in the United States.

Nelson is working in conjunction with Nadir Alikacem, an ophthalmology assistant professor at the University of Texas Southwestern Medical Center at Dallas, and he is trying out his procedure on the center's diabetic rats. Nelson has developed a way to load drugs or any other kind of biological molecules into a fiber the size of a human hair and use the fiber to deliver medication to the eye of a diabetic rat.

Nelson is seeking a patent on his revolutionary way to help stop, and even reverse, the symptoms of retinopathy.

He says his work is an example of the ground-breaking research conducted here that will bring prestige and will establish a national reputation for the university.

Nelson said he hopes that this research can be translated someday to humans and cure the blindness associated with diabetes.

Diabetes is a disorder in which cells in the body are unable to use blood sugar, resulting in an excess. Retinopathy is one of the most serious complications of the disorder. The excess sugar causes a chain reaction making the blood vessels in the retina form incorrectly and dilate. The blood begins to leak from the vessels and seeps into the eye. Without treatment, this leakage can cause blindness.

Nelson said he began working on his project about four years ago.

"We just got it to the point last summer where we had all the loose ends tied up so we could submit it as a patent," he said.

Part of the patent is the ability to release drugs from a fiber. Working with Dr. Alikacem, Nelson can release those drugs directly into the eyes of diabetic rats via a fiber.

Alikacem said that traditionally, drugs have been administered by pills or injected to stop the malformation of the blood vessels in the eye. These drugs are toxic, and to achieve the therapeutic levels necessary in the eye, large amounts of the drug have to be in the body. The toxicity can cause serious side-effects.

"With Kevin here, we are thinking about reapplying localized treatment to the eye," he said.

Nelson said that many over-the-counter drugs are comprised of microspheres inside a capsule that deliver medication during a period of time.

"You open them up, and there's all the millions of beads inside them," he said. "People have been using those kinds of beads for a long time to deliver medication, but nobody has ever looked at a fiber. We thought this was a beautiful application of the patent."

By making a tiny incision in the eye, Nelson and his colleagues place a drug-loaded fiber into one of the rats' eyeballs and a plain fiber in the rats' other eye. Nelson said the plain or "dummy" fiber was implanted to be sure that the fiber itself had no effect.

He said the procedure is simple and takes about ten minutes. The fiber can deliver the drug for about a year.

"The hope is that the process would be reversed and the blood vessels would shrink down to their normal size and retract back into their normal shape and that would stop the progress of blindness associated with diabetes," he said.

He said that in 100 percent of the cases, the rats' eyes with the drug-loaded fiber did not develop cataracts, which are the first stages of blindness. The rats' eyes that had the dummy fiber implanted in them did develop cataracts.

Because the drug is delivered directly into the eye, the drug is not systemic, meaning it affects only the eye.

The fiber, which is biodegradable and therefore doesn't have to be surgically removed, is made of polymerized lactic acid. Nelson said the human body produces lactic acid abundantly.

"Like when you lift weights and you're sore the next day, the reason your muscles are sore is the lactic acid built up in your muscles," he said.

Nelson said that as the lactic acid in the fibers break down, the cells in the eye metabolize the molecules. Each molecule becomes carbon dioxide and water and gets washed away in the blood.

Alikacem said the fact that the fiber doesn't need to be removed is important to the study.

"Diabetic people have a tendency not to heal very well," he said. "A second surgical procedure to extract the fiber could be problematic."

Nelson said people have never before been able to use a fiber to deliver a drug.

"Up until now, whenever somebody has made fiber for clothes or carpet, the processing conditions were very harsh," he said. "The temperature and the solvents used made the environment very caustic. Sensitive biological molecules would never survive the processing."

Nelson said he has modified the way in which the fibers are spun so that biological molecules will still maintain their activity.

Engineering Dean Ron Bailey said this type of research is important to the Engineering College.

"Our faculty needs to be on the leading edge of technology. Otherwise, before long, they will be teaching the history of engineering," he said.

He said that professors like Nelson are creating knowledge for students.

"The calling of engineering is to harness the forces of nature for the benefit of mankind," he said.

Dr. Nelson said he is hoping to do just that.

Sally Claunch

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