GAITHERSBURG -- Using light waves, polymers and a nuclear reactor, researchers here are investigating a superstrong, experimental gel that might some day turn into a novel treatment for millions of people who suffer from arthritis.
Scientists at the National Institute of Standards and Technology have spent two years shooting neutron beams at the mysterious hydrogel, trying to determine why it is almost as strong, flexible and resistant to friction as the cartilage in the human knee.
The polymers in the gel - formed when synthetic molecules are struck by ultraviolet light - were developed by researchers at Hokkaido University in Japan in 2003. The report of their discovery intrigued Wen-li Wu, a materials scientist at the NIST, who began testing them shortly afterward.
His goal: a gel that could serve as both a coating for the materials used in knee and hip replacements and as a kind of caulk to plug holes in damaged cartilage.
"The idea is to give time for the body to heal so cartilage can grow," Wu said.
Wu and other scientists are part of a small but intense community developing biomaterials that can mimic or supplement what our bodies do every day: repair and replenish the cartilage in our joints. If they can inject these synthetic repair materials into aching, arthritic joints, it could reduce the need for many of the 1 million knee and hip replacement surgeries performed each year, experts say.
"It's pretty amazing stuff. I think it's something definitely worth exploring," said Dr. John Hardin, chief scientific officer of the Arthritis Foundation and a professor of orthopedic surgery at the Albert Einstein Medical College in New York.
To figure out what was going on inside the Japanese polymers, scientists used NIST's Small Angle Neutron Scattering Instrument, which was able to decipher the molecular structure of the polymers as they were hit with neutrons created by the agency's small research reactor.
They announced their findings in a paper earlier this month at the American Physical Society meeting in New Orleans.
At the molecular level, they concluded, the two polymers that make up the gel join together in tightly linked chains when hit with ultraviolet light. The result is a substance with the consistency of a slightly stale gummy bear that might ultimately increase the lifespan of joints that are wearing out.
"The smaller the surgery, and the less pain, the better, so if you can delay your implant for 10 years or so, that's a good thing" said Jennifer Elisseeff, an associate professor of biomedical engineering at Johns Hopkins University who is also developing biomaterials that could help arthritis patients.
Unfortunately, suitable substances are elusive because the joints in our bodies are particularly hostile environments for synthetics.
"Cartilage loss is the No. 1 unsolved problem in orthopedic medicine today," said Dr. Norman Marcus, an orthopedic surgeon in Springfield, Va.
When cartilage in a knee is damaged, it forms a kind of pothole, said Marcus, who has joined with Elisseeff to form a company called Cartilax, which is seeking FDA approval of a hydrogel to treat arthritis.
Cartilax's hydrogel, now undergoing clinical trials in Europe, stimulates the repair process by getting stem cells from a patient's bone marrow to act as a kind of catalyst in helping damaged cartilage to heal.
There's a critical need for such hydrogels because the alternative treatments for severe arthritis - which include knee replacement and microfracture surgery - are expensive and not always successful. According to the Arthritis Foundation's Hardin, a typical knee replacement costs about $25,000.
In microfracture surgery, often performed on athletes, tiny holes are punched into the bone so that stem cells in the marrow can stimulate growth of repair tissue, Marcus said. But that approach is successful only about 60 percent of the time, he said, and with an aging population of baby boomers, the industry foresees an increasing demand for knee and joint repairs.
"Younger people today don't want to become old before their time. They don't want to give up their active lifestyle," Marcus said. "What we're trying to do is invent the new bricks and mortar for cartilage repair."
For those prone to such problems, tiny holes in the cartilage are warning signs of joint damage and are often the first indication of the need for a future knee replacement. "By the time they appear, the cartilage isn't going to heal by itself," Hardin said.
As the cartilage degrades, the knee deteriorates to the point that it becomes nearly impossible to walk.
Lane Weinzweig, 66, a retired physicians assistant from Randallstown, knows that from experience. She had both knees replaced at Sinai Hospital in May 2006.
"[Arthritis] holds you back from doing the things you want to do," she said.
Before that, she tried a wide range of treatments, including cortisone shots, acupuncture, glucosamine tablets, physical therapy and arthroscopic surgery. But her knees continued to deterioriate to where she could no longer handle her grandchildren, now ages 9 and 4.
"It got to a point where I didn't feel safe holding them because of the pain in my knees," she said.
Since the replacement surgery, her legs have been better. But she is now troubled by arthritis in her shoulder and in her fingers. She takes medication for the pain and makes sure to get into a swimming pool near her home twice a week for aerobic therapy.
"Arthritis isn't fun," she said. "What's really important is to keep moving."