Surface Active Phospholipids as Cartilage Lubricants

Efficient lubrication and extremely low friction are essential for proper functioning of synovial joints. Various joint dysfunctions were described in direct association with increased friction or adhesive forces. Surface-active phospholipids (SAPLs) are well known to reduce friction in synovial joints. This study demonstrates, using a novel human-sourced cartilage-on-cartilage setup, the potential of multilamellar vesicles (MLV) composed of the SAPL dimyristoyl phosphatidylcholine (DMPC) to act as effective lubricants, reducing static and dynamic friction-coefficients to levels of healthy synovial joints. Furthermore, MLV composed of DMPC, in sizes ranging from 0.8 to ∼3.5 μm, were found to be more effective lubricants than histidine buffer, saline, or synovial fluid. The ability to test new cartilage lubricants, simulating, to a great extent, natural conditions, using the setup presented herein is discussed.