By Pat Anson, Editor

An experimental stem cell treatment that grows new cartilage could someday help millions of arthritis patients avoid joint replacement surgery.

Researchers at Washington University School of Medicine in St. Louis and Cytex Therapeutics in Durham, N.C. have developed a 3-D, biodegradable synthetic scaffold that is molded into the precise shape of a patient’s hip joint.

The scaffold, which is covered with cartilage made from the patient’s own stem cells, is designed to be implanted onto the surface of an arthritic hip.

Resurfacing the hip joint with this “living” tissue could ease arthritis pain, and may delay or even eliminate the need for hip replacement surgery, according to researchers.

Joint replacement surgery is usually performed on the elderly to relieve pain from osteoarthritis, a painful and disabling condition caused by a loss of cartilage and the degradation of joints. Over a million hip and knee joint replacement surgeries are performed annually – a number expected to surpass four million by 2030 due to the aging of the U.S. population. 

“We’ve developed a way to resurface an arthritic joint using a patient’s own stem cells to grow new cartilage, combined with gene therapy to release anti-inflammatory molecules to keep arthritis at bay. Our hope is to prevent, or at least delay, a standard metal and plastic prosthetic joint replacement,” said Farshid Guilak, PhD, a professor of orthopedic surgery at Washington University.

After inserting a gene into the newly grown cartilage and activating it with a drug, researchers say the gene will release anti-inflammatory molecules to fight arthritis.

“When there is inflammation, we can give a patient a simple drug, which activates the gene we’ve implanted, to lower inflammation in the joint,” said Guilak. “We can stop giving the drug at any time, which turns off the gene.”

By adding gene therapy to the stem cell and scaffold technique, Guilak and his colleagues believe it will be possible to coax patients’ joints to fend off arthritis, preserve cartilage, and function better for a longer time.

The 3-D scaffold is built using a weaving pattern that gives the device the structure and properties of normal cartilage. It is made with hundreds of biodegradable fiber bundles that are woven together to create a high-performance fabric that functions like normal cartilage.

“The woven implants are strong enough to withstand loads up to 10 times a patient’s body weight, which is typically what our joints must bear when we exercise,” said Franklin Moutos, PhD, vice president of technology development at Cytex.

Scientists have tested the tissue engineering in cell culture, and some customized implants are being tested in laboratory animals. If all goes well, such devices could be ready for testing in humans in three to five years.

Currently, there are about 30 million Americans who have osteoarthritis. That number includes a growing number of younger patients — ages 40 to 65 — who have limited treatment options.  Doctors are often reluctant to perform hip replacement surgery on patients under age 50 because prosthetic joints typically last for less than 20 years. A second surgery to remove a worn prosthetic can destroy bone and put patients at risk for infection and other complications.

“We envision in the future that this population of younger patients may be ideal candidates for this type of biological joint replacement,” said Bradley Estes, PhD, vice president of research and development at Cytex.

The research findings, which are published in the Proceedings of the National Academy of Sciences, are supported by the National Institute of Arthritis and Musculoskeletal and Skin Diseases and the National Institute on Aging, which are both part of the National Institutes of Health (NIH).