21st Century: Living Laboratory

Scientists from Duke University predict that within the next few decades joint replacement will be performed with laboratory-grown cartilage and bone. They caution however, that better understanding of the complex cell regulation involving chemical signals and responses is necessary.

Their research involves trying to understand how load causes degenerative joint disease such as arthritis. By placing living cartilage in a computer-controlled stress chamber, they can observe the breakdown and release of inflammatory factors which cause degenerative joint disease. They have seen that the tough fibrous collagen matrix surrounding chondrocytes (cartilage cells) influences how the cells may respond to a chemical signal.

Their search for cartilage replacement also involves growing other living tissues in an incubator for reimplantation into the body. Stem cells from fat tissue can be triggered to mature into many different tissue cells, including cartilage. Eventually, it may be possible to use such donor stem cells or cells from a patient's own body for reimplantation to grow artificial joints. See:   Researchers Turn Fat Cells Into Cartilage  at   Duke University Medical News.

Further Progress in Cartilage Development

At an annual meeting of the Biomedical Engineering Society, bioengineers from the University of California in San Diego, reported that they have grown a biological tissue which closely mimics normal cartilage. (Cartilage is the spongy cushioning material at the bone ends in the joint. It acts as a shock absorber during movement.)

After developing a template to resemble the organizational structure of cartilage tissue, the researchers then took cells from juvenile cartilage and grew them in the laboratory. The cells were suspended in a gel until they began to form their own matrix or scaffolding. After the gel was removed, a new biological tissue remained. This tissue demonstrated structural and functional properties of normal cartilage: superficial cells were able to secrete a key protein necessary for joint lubrication, while the tissue near the surface was soft, and the deeper regions more dense and stiff.

These latest results advance the possibility of implanting the immature cartilage into the joint to grow as normal cartilage. The researchers hope that the implanted cartilage will grow to conform to the geometry of the specific joint.

Their next step is to conduct animal trials to determine the efficiacy of such an implant. For a full report, see  UCSD Bioengineers Fabricate Joint Cartilage Which Mimics Structure and Function of Natural Tissue  at,  University of California, San Diego, Jacobs School of Engineering