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Growing replacement cartilage in the lab

Heath and student Scott Carver hold the high-pressure perfusion reactor uesed for cultivatin the cells in a porous resorbable polymer.

Astronauts and earth-bound persons with painful joints may benefit from NASA-sponsored research being conducted by ChemE Associate Professor Carole Heath.

NASA is interested in ways to keep astronauts' joints healthy in the low-gravity conditions of space travel. Heath hopes her work will also ease the suffering of people with joint diseases and injuries.

Cartilage is a tough tissue that covers the ends of bones in joints. Produced by cells called chondrocytes, cartilage provides the nearly frictionless surface that distributes the body's weight as bones interact at the joints. When cartilage is injured and gradually degenerates, osteoarthritis often develops, leaving only painful and limited joint movement.

Cartilage has little ability to repair itself, Heath says. Once cartilage deteriorates the damage is irreversible-not a promising outlook for the more than 30 million people in the United States who have osteoarthritis. Moreover, neither of the current treatments, surgically replacing the entire joint with a prosthesis or transplanting healthy cartilage tissue from donors, is entirely satisfactory.

Heath thinks a better approach is to grow replacement cartilage from chondrocyte cells in the laboratory and implant the living cartilage in the joint. Cartilage could be grown to the exact specifications needed within a three-dimensional polymer mesh that the body could reabsorb.

Heath's challenge is to duplicate the unique three-dimensional structure of cartilage that allows it to repeatedly withstand and distribute the forces of compression, shear, and gravity that can equal several times the body's weight.

Previous research has focused only on compression forces exerted over short periods of time. Heath and her research team are using a new device called a microgravity reactor to subject chondrocyte cells to different levels, frequencies, and durations of mechanical stress.

Heath hopes to discover the right conditions needed for cells to produce fully functioning cartilage capable of bearing body weight over long periods of time. She also hopes to determine how low-gravity conditions, such as those encountered in space flight, affect the cells' growth and ability to regenerate cartilage.