Restoring Joint Lubrication: The Development of a Biomimetic Lubricin Peptidoglycan to Reduce Friction at the Articular Carilage Surface

Osteoarthritis (OA) is a painful and debilitating disease affecting 27 million people nationwide and is often characterized by the degradation of articular cartilage. The loss of lubrication in synovial joints is a major contributor to cartilage damage, and damage can be prevented if proper lubrication is restored through supplemental lubricant treatments. Hyaluronic acid (HA) injections are on the market today, but there is little clinical evidence to support that these products are effective in treating the long-term effects of osteoarthritis. Lubricin, a lubricating proteoglycan found in the human synovial fluid, has become a potential alternative to HA injections. Overall, lubricin has proven to be more efficient than HA as a lubricant. However, as a native molecule, it is still susceptible to enzymatic degradation and depletion factors that are over expressed within OA joints. Synthetically derived molecules show the possibility of resisting these enzymatic degradations. Here, we engineered a biomimetic lubricin proteoglycan mimic that is designed to imitate the lubrication effects of native lubricin but withstand enzymatic degradation. The lubricin mimic was synthesized using a chondroitin sulfate backbone with collagen II and HA binding peptides to promote adhesion to the cartilage surface and interaction with the synovial fluid components. Our synthesized molecule was shown to reduce the kinetic coefficient of friction at the articular surface to a level comparable to that of native synovial fluid. Confocal imaging of the articular cartilage surface after lubricin mimic treatment showed binding of the molecule at the surface even after friction testing. Overall, our biomimetic lubricin shows potential as a long-term supplemental lubrication treatment for OA patients.