How Movement Lubricates Bone Joints

Taking a cue from machines that gently flex patients knees to help them recover faster from joint surgery, bioengineering scientists at UC San Diego have shown that sliding forces applied to cartilage surfaces prompt cells in that tissue to produce molecules that lubricate and protect joints.

The results reported in Osteoarthritis and Cartilage are important in the ongoing efforts of the group led by Robert Sah, a Howard Hughes Medical Institute (HHMI) professor at UCSDs Jacobs School of Engineering, to grow cartilage in the laboratory that can be used to replace patients injured or diseased joint surfaces.

We have shown that shear forces on cartilage prompt chondrocyte cells in it to produce proteoglycan 4, said Sah. This is an important step toward our goal of eventually growing joint tissue for transplantation.

Proteoglycan, a name that reflects its protein and polysaccharide components, is a basic building block of connective tissue throughout the body. The chondrocyte cells of cartilage make several forms of proteoglycans, including several that build up in cartilage and contribute to its stiffness. However, proteoglycan-4 is primarily secreted into the joint fluid where it coats and lubricates cartilage surfaces.

Researchers have known for years that defects in a gene for proteoglycan 4 result in a type of childhood joint failure that resembles osteoarthritis in the elderly. Sahs goal is to stimulate healthy chondrocytes in cartilage tissue grown in the laboratory to form robust tissue that makes proteoglycan 4 and has a smooth, well-lubricated surface.


Posted by: Mark    Source