By Pat Anson, PNN Editor

An experimental implant containing cartilage derived from stem cells reduced pain and restored function in dogs with damaged hip joints -- a study that researchers say could be a significant step towards repairing and replacing cartilage in humans with osteoarthritis.

Osteoarthritis is a progressive joint disorder caused by painful inflammation of soft tissue, which leads to thinning of cartilage and joint damage in the knees, hips, fingers and spine.

“One of the holy grails of orthopedics is to replace cartilage, but there hasn’t been an effective way to do it,” says co-author Duncan Lascelles, PhD, a professor of surgery and translational pain research and management at North Carolina State. “Most of the focus is on replacing or restoring the cartilage surface with artificial materials, but regenerating cartilage isn’t possible right now. And many of the artificial products in use don’t integrate with the body.”

Lascelles and his colleagues developed a cartilage repair implant using a textile manufacturing process that utilizes three-dimensional (3D) weaving with composite material. When seeded with a patient’s own stem cells, the “bioartificial” implant is designed to integrate with native bone while preserving the integrity of the joint.

“Combining 3D printing with advanced textiles enabled us to engineer an implant that mimics the function of native, healthy tissues in the joint from day one after implantation,” said co-author Bradley Estes, PhD, President of Cytex Therapeutics, which developed the implant technology. “We also designed it to dissolve over time so that, ultimately, joint function is transferred back to the patient’s own tissues during the healing process.”

The researchers used the implant to resurface damaged hip joints in dogs. Cartilage derived from stem cells was first allowed to grow on the implant for several weeks before surgery, then the implant was placed into the damaged area of the dogs’ joints. Over time, the implant dissolved, leaving only the dog’s own natural tissue in the repaired hip joint.

Four months after surgery, researchers say dogs that received the cartilage implant returned to baseline levels for both pain and function, while dogs in a control group never improved. They also saw evidence that the implant had successfully integrated into the hip joints, effectively resurfacing them.

“We were thrilled that the implant was so effective at restoring the activity levels of the animals,” Estes says. “After all, this is why patients go see their physicians – they want to be able to play tennis, play with their kids, and, in general, re-engage in a pain-free active lifestyle that had been taken away by arthritis.”

While osteoarthritis primarily affects older adults, researchers hope the experimental implant will address some of the problems associated with total joint replacements in younger, active patients.

“There are significant drawbacks to total joint replacements in the young patient,” Lascelles says. “The surgery is more complicated, and the artificial joints are only good for a particular number of years until they must be replaced, often with poorer results each time.

“This procedure is less invasive, and the implant uses the body’s own cells and integrates into the damaged area with little danger of rejection. We believe that it is an early intervention that could be a major advance in postponing joint replacements for dogs and hopefully one day for humans.”

The research findings are published online in Science Advances. The study was funded by Shriners Hospitals for Children, the Arthritis Foundation, the Nancy Taylor Foundation for Chronic Diseases, and the National Institutes of Health.