ARLINGTON, Va., May 13, 2004 -- With an eye toward reducing the need for knee replacement surgery, biomedical engineers have created a dual purpose scaffold that cushions a damaged joint while providing the support that cartilage cells need to generate new tissue.

Whitaker investigator Lori Setton, Ph.D., and collaborator and orthopedic surgeon T. Parker Vail, M.D., both of Duke University, stimulated new cartilage growth in knees using a light-activated polymer hydrogel doped with hyaluronan, a natural component of joint fluid and cartilage.

The hyaluronan-based polymer forms a protective cap over the wound to prevent further damage while the knee stays active. Meanwhile, the polymer provides the structural support and chemical environment necessary for new cartilage tissue to grow into the affected area.

"Cartilage is a tissue that does not have the ability to heal itself, so there cannot be any healing without outside intervention," Vail said. He and Stetton reported their results in the March issue of the Annals of Biomedical Engineering.

The research group began with a sticky, hyaluronan-based solution that can be poured into tears and holes in damaged cartilage. Laser light is applied, turning the liquid into a solid in about 30 seconds.

The approach was tested in a rabbit with joint damage. In the animal study, the implanted hydrogel integrated well with the natural environment. The surrounding natural cartilage infiltrated the hydrogel, growing new tissue.

Hyaluronan injections are typically used to ease joint pain, but the beneficial effects are temporary. Joint repair can also be accomplished through surgery by culturing a patient's cartilage cells in a laboratory, and then sewing a patch of the lab-grown tissue into the wound. This expensive procedure has benefited athletes but is less suitable for osteoarthritis patients. Setton would like to see an alternative treatment that would last for about 10 years.

"If we can heal lesions in joint cartilage with this type of bridge therapy, we could prevent end-stage osteoarthritis that leads to knee replacements," she said.

Further research will seek to optimize the hyaluronan polymer, looking for the best pore size for nutrient diffusion and cell movement and the best timeline for the polymer to dissolve and disappear from the body.

Other collaborators include Dana Nettles from Setton's laboratory, Meredith Morgan from Duke' chemistry department, and Whitaker investigator Mark Grinstaff of Boston University. The research was supported by the National Institutes of Health, the Orthopaedic Research and Education Foundation and a predoctoral fellowship from the National Science Foundation.

In 1995 Setton received a Whitaker Foundation Biomedical Engineering Research Grant for research on articular cartilage.

Contact:
Lori Setton, Duke University
Frank Blanchard, The Whitaker Foundation