New gel promotes healing by gluing bone pieces together

A new material that fuses biological and synthetic substances at the molecular level speeds bone and cartilage repair. Its creators at the Technion-Israel Institute of Technology say laboratory studies have shown the new gel promotes healing by gluing bone pieces together and stimulating tissue development.

A report on the work, authored by lead researcher Dror Seliktar of the Technion Department of Biomedical Engineering, who was assisted by graduate student Liora Almany-Levi, was published online in the November 2004 Biomaterials journal. Animal tests are now underway.

"Gelrin is a brand new material engineered molecule by molecule, not just mixed together," Seliktar said, adding that while the two components are relatively cheap and readily available, "it’s the way we engineer them that represents a breakthrough."

Orthopedic surgeons currently use biological materials such as collagen and fibrin to stimulate tissue growth in bone injuries. However, these biological materials tend to leach out of the injury site long before the healing is complete. As a result, the injury may take longer to heal completely.

Seliktar explains that the difference in Gelrin lies in the unique combination of natural and synthetic molecules used to engineer the new material. Synthetic materials provide enough strength to remain in the injury site but are limited in their ability to promote healing. Biological materials are too weak to stay affixed for the duration of the healing process. Instead of using one or the other – as is true with the making of other orthopedic materials -- he used a protein called fibrin, the protein in blood plasma responsible for clotting. To it, Seliktar attached a synthetic material called polyethylene glycol, a plastic used in contact lenses and other biomedical applications.

The result is a three-dimensional material with the biological properties of fibrin and the strength of plastic, providing structural support and encouraging tissue growth. Since the bone cells come in contact with fibrin, they are "tricked" into also accepting its synthetic partner. Gelrin can be adjusted to different strengths and degradation rates according to its intended application.

Injected into the damaged area, the broken bone fuses within the Gelrin, which at that point breaks down and is excreted in the urine. While metallic pins and plates will still be necessary to affix the bone fragments, Gelrin will facilitate bone regeneration so that these metallic parts will remain in place for a shorter duration.

A patent application has been submitted. Since polyethylene glycol and fibrin are both already approved for biomedical use, the U.S. Food and Drug Administration approval process is expected to be relatively quick. Seliktar and his team are currently working on other applications for Gelrin, such as the creation of cartilage tissue outside the human body and the cultivation of artificial heart muscles.

With some 1 million orthopedic bone substitution procedures performed annually in the United States (source: Datamonitor Market Dynamics, Bone Substitutes and Growth Factors, December 2002), Gelrin could have widespread applications. It could reduce the need for bone transplants and heal bone defects caused by cancer, trauma or age related degeneration; it could also be used to treat sports injuries and aid in spinal fusion operations.

The Technion-Israel Institute of Technology is Israel's leading science and technology university and home to the country’s only winners of the Nobel Prize in science. It commands a worldwide reputation for its pioneering work in computer science, biotechnology, water-resource management, materials engineering, aerospace and medicine. The majority of the founders and managers of Israel's high-tech companies are alumni. Based in New York City, the American Technion Society is the leading American organization supporting higher education in Israel, with 19 offices around the country.