Coloured Xray of the knees taken by Dr. P. MARAZZI/SCIENCE PHOTO LUBARY
Injections of a fluid similar to the natural one found in joints could help relieve pain in arthritic knees. It helps the joints heal and boosts cartilage regeneration in rats.
Osteoarthritis is a result from wear and tear on bones as we age. A scan of an arthritic joint can reveal bits of cartilage that have separated from the main cartilage tissue.
This causes friction to increase inside the joint and a feedback loop, according to Chuanbin Mao, University of Oklahoma in Norman.
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Surgery can be performed to remove any remaining debris and smoothen the cartilage. However, this is not a very effective option. One experimental approach is to inject stem cells from the person's blood or fat.
Mao and his team instead focused on synovial fluid. A large molecule known as a lubrication compound is found in healthy joint fluid. It is composed of a backbone made of hyaluronic acids that contains feathery subunits called Lubricin as well as lipids.
The subunits that are feathery bind to water molecules while the whole lubrication complex binds with cartilage. This results in a watery layer over the cartilage that reduces friction when joint movements are performed.
Mao and his collaborators created an artificial version the lubrication compound by linking another feathery molecule called PAMPS to the same hyaluronic acids backbone. This reduced friction was demonstrated in laboratory tests when it was applied to human cartilage.
Researchers also administered the substance to rats suffering from early arthritis in their legs. The joints of the rats looked almost normal after eight weeks. This was measured using a common arthritis-grading scale. Mao says that the cartilage appeared to have grown back. It was surprising to discover that tissue regeneration can be helped by lubrication.
The team will then test the artificial fluid on larger animals, with joints more like those of humans.
Journal reference: Nature Biomedical Engineering, DOI: 10.1038/s41551-021-00785-y
