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Of the 48,000 corneal transplants performed each year in the United States, 10 percent end up in rejection, largely due to poor medication compliance.

“About 60 to 80 percent of patients don’t take medicine the way they are supposed to,” notes Walter Stark, chief of the Division of Cornea, Cataract and External Eye Diseases at Johns Hopkins. That’s because the follow-up regimen—often requiring multiple doses of medicine per hour—can be hard to manage.

He and a team of researchers from Johns Hopkins’ Wilmer Eye Institute believe they may have found a way to improve compliance—and thus prevent rejection—by using biodegradable nanoparticles that release needed medication into the eye after surgery. The drug delivery system, the scientists say, could be paired with other drugs and used to treat other conditions as well, such as glaucoma, macular degeneration and corneal ulcers, among others.

In an animal study published in March in the Journal of Controlled Release, rats that underwent a corneal graft surgery were randomly divided into four groups and were given various treatments. One group was injected weekly for nine weeks with a safe, biodegradable nanoparticle loaded with corticosteroids for timed release of medicine. The other three groups received weekly injections of saline, placebo nanoparticles and free dexamethasone sodium phosphate aqueous solution after surgery, respectively.

Two weeks after surgery, rats that received the placebo nanoparticle and saline injections had severe swelling, opaque corneas and unwanted growth of new blood vessels, all indicating graft failure. After four weeks, rats that received free dexamethasone sodium phosphate aqueous solution all had graft failure as well. The only group that showed successful corneal transplant was the group of rats that received the corticosteroid-loaded nanoparticle injections. The grafts were still viable in all of these rats.

“That’s 100 percent efficacy, a very promising finding,” says Justin Hanes, director of Wilmer’s Center for Nanomedicine. “This type of treatment may also help prevent corneal transplant rejection in humans while making medicine adherence much easier on patients and their families.”

“Corneal grafts are not easy to come by, and a lot of testing and time goes into ensuring the safe use of a graft for cornea transplant,” says Qingguo Xu, a research associate at the Center for Nanomedicine. “This is why we want to do a better job at making sure corneal transplants don’t end up in rejection, and our study illustrates a potentially better way.”

Walter Stark and a team of researchers from Johns Hopkins’ Wilmer eye Institute believe they may have found a way to prevent rejection of corneal transplants
by using biodegradable nanoparticles that release needed medication into the eye after surgery.