Synovial fluid is slime with a serious purpose: Protecting shoulders, hips and other joints from wear, reducing the likelihood of injuries and arthritis.
Scientists have long believed that synovial fluid gets its surface-slicking, shock-absorbing properties from the “goo molecule” hyaluronate. But new research led by Brown University physician and engineer Gregory Jay, M.D., shows that the protein lubricin is also a player, not only lubricating cartilage but also giving synovial fluid its spring.
“Protein components like lubricin are just as key as hyaluronate for protecting joints,” Jay said. “What we hope to get out of this knowledge is better treatments for arthritis, one of the most common chronic health problems and the biggest cause of disability in the nation.”
Jay’s research, published online in the Proceedings of the National Academy of Sciences, is clinically relevant. People with osteoarthritis in their knees can now get viscosupplementation, a medical procedure that involves an injection of hyaluronate directly into knee joints in an effort to reduce pain and improve movement. The new research shows that it might be beneficial to add lubricin into these injectable fluids, Jay said.
“Adding this protein to supplements could restore elasticity in synovial fluid and prevent damage to cartilage inside the joint,” he said. “These supplements could be an effective preventive treatment for arthritis or for sports injuries.”
Jay, a Rhode Island Hospital emergency physician and Brown associate professor of emergency medicine and engineering, has studied joint mechanics for 20 years. His lab spearheaded research into lubricin’s role as a “boundary lubricant” by reducing friction between opposing layers of cartilage inside joints.
In this new work, Jay and his team show how lubricin and hyaluronate work together to give synovial fluid its elastic property. The team found that these molecules act as weaver and wool: Lubricin gathers the long, thin, stiff polymers of hyaluronate together, creating structures that the researchers believe create shock-absorbing structures inside synovial fluid.
To study this molecular interaction, researchers put microscopic, fluorescent beads into two samples of synovial fluid. One sample was normal. The other came from a patient whose body doesn’t produce lubricin. This rare condition, called CACP syndrome, causes premature joint failure, often prompting the need for joint replacement surgeries for patients in their 20s.
Using a camera and a microscope, the research team observed how these beads moved through the fluid. Those movements were measured and – using a theory espoused by Albert Einstein – used to calculate viscosity and elasticity. The result: Synovial fluid that lacked lubricin wasn’t elastic – and wouldn’t be able to protect cartilage.
“Elasticity is distinct from boundary lubrication,” Jay said. “It’s a different protective feature.”
The research team included Kenneth Breuer, professor of engineering at Brown, Jahn Torres, a former engineering graduate student at Brown, Matthew Warman, associate professor in the Departments of Genetics and Pediatrics at Case Western Reserve University School of Medicine, and Matthew Laderer, a former undergraduate student at Brown.
The National Institute of Arthritis and Musculoskeletal Diseases funded the work.
Editors: Brown University has a fiber link television studio available for domestic and international live and taped interviews and maintains an ISDN line for radio interviews. For more information, call the Office of Media Relations at (401) 863-2476.
Wendy Lawton | EurekAlert!
Atomic-level motion may drive bacteria's ability to evade immune system defenses
24.04.2017 | Indiana University
Two-dimensional melting of hard spheres experimentally unravelled after 60 years
24.04.2017 | University of Oxford
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
24.04.2017 | Physics and Astronomy
24.04.2017 | Materials Sciences
24.04.2017 | Life Sciences