Cornell University Professor C.C. Chu was browsing through Business Week in 1997 when he read about a cardiologist using radioactivity to reduce artery reblockage following angioplasty and stent surgery, a condition called restenosis. Chu called the cardiologist to say he had a better approach.

Now, five years, four U.S. patents and $1.75 million license payments later, Chu has been proven right.

He and researchers in his lab in the Department of Textiles and Apparel in the College of Human Ecology at Cornell have developed a group of biodegradable biomaterials that can deliver nitric oxide (NO) derivatives and other biologically active compounds.

One is an amino acid- (or protein-) based, very elastic biomaterial that can coat stents to deliver NO derivatives to prevent the restenosis of an artery. Elasticity is critical since stents tend to contract and expand significantly. Another class of the patented and licensed biomaterials is star-shaped biodegradable polymers that also can be formulated into jellylike biodegradable materials called hydrogels to improve the delivery in the body of a wide range of bioactive compounds via three-dimensional porous network structures.

"Biodegradable hydrogels also have potential for wound-care products and as substrates for tissue engineering to replace aged or diseased tissues or organs. They may even work for environmentally friendly diapers or for agricultural devices because of their very high water retention capability," says Chu, a fiber and biomedical materials scientist whose inventions have reaped a total of nine patents through the Cornell Research Foundation.

Four of these patents were licensed to MediVas, a privately held San Diego-based company that developed new techniques for coating stents with Chu's biomaterials. The company recently sold the exclusive worldwide license to these new biomaterials to Guidant Corp. for an initial payment of $35 million, of which Cornell received $1.75 million. One-fourth of the payment to Cornell went to the College of Human Ecology, the college's first patent-derived revenue. Additional payments are expected if the U.S. Food and Drug Administration approves the use of Chu's biomaterials.Among the many advantages of Chu's amino acid-based biodegradable biomaterials are their biocompatibility. They also are low in cost, are easily biodegraded and are versatile in biological and material properties so that their design can be film- and fiber-forming, or highly elastic. This allows them to be particularly promising carriers of a wide range of drugs and other bioactive substances. They also are designed to use enzymes, which allows Chu and others to create "self-degradable" polymers with programmable rates and duration. This makes them ideal for bioabsorbable surgical implants and controlled devices for drug delivery. In addition, when used for wound care, they provide nutritional value to local wound sites for facilitating faster healing.

Of the Chu group's new biomaterials, the amino acid-based polymers are the closest to becoming a clinical reality. Chu notes, "Restenosis occurs in as high as 30 to 45 percent of patients after balloon angioplasty procedures and placements of stents to open clogged arteries. The U.S. market size for stents is about $5 billion a year."

To prevent restenosis, current treatments include stents coated with immunosuppressant drugs, cancer drugs or radioactive compounds. "Using NO derivatives allows us to use a biochemical that is naturally produced by the body for the cardiovascular, immune, reproductive and nervous systems," Chu points out. "Research shows that our new NO derivative-coupled biodegradable biomaterials have the same biological function as the NO produced by the body. That means that our approach may have great potential to open a new means to treat those diseases caused by the lack of NO."

Researchers believe NO and NO derivatives can prevent restenosis by preventing the proliferation of smooth muscle cells, which typically block blood vessels after stent implantation. "As our biologically active biomaterials biodegrade, they release the NO derivative," Chu says.

Among Chu's collaborators on various aspects of the research is Ramaz Katsarava of the Republic of Georgia. Katsarava worked with Chu through the Civilian Research and Development Foundation, which helps former Soviet Union weapons scientists to redirect their skills toward peaceful solutions. Other collaborators include Jack Freed, professor of chemistry and chemical biology at Cornell; M.D. Lang, a professor at East China University of Science and Technology, who did postdoctoral research in Chu's lab; and Keun-Ho Lee, Chu's former doctoral student.

The research has been supported largely by MediVas and in part by the College of Human Ecology at Cornell.