title: Fibronectin mediates enhanced wear protection of lubricin during shear.
abstract: Fibronectin (FN) is a glycoprotein found in the superficial zone of cartilage; however, its role in the lubrication and the wear protection of articular joints is unknown. In this work, we have investigated the molecular interactions between FN and various components of the synovial fluid such as lubricin (LUB), hyaluronan (HA), and serum albumin (SA), which are all believed to contribute to joint lubrication. Using a Surface Forces Apparatus, we have measured the normal (adhesion/repulsion) and lateral (friction) forces across layers of individual synovial fluid components physisorbed onto FN-coated mica substrates. Our chief findings are (i) FN strongly tethers LUB and HA to mica, as indicated by high and reversible long-range repulsive normal interactions between surfaces, and (ii) FN and LUB synergistically enhance wear protection of surfaces during shear, as suggested by the structural robustness of FN+LUB layers under pressures up to about 4 MPa. These findings provide new insights into the role of FN in the lubricating properties of synovial fluid components sheared between ideal substrates and represent a significant step forward in our understanding of cartilage damage involved in diseases such as osteoarthritis.
authors.affiliation: Department of Materials Science and Engineering and ‡Department of Biomedical Engineering, Cornell University , Ithaca, New York, United States.
authors.forename: Roberto C
authors.initials: RC
authors.lastname: Andresen Eguiluz
authors.affiliation: Department of Materials Science and Engineering and ‡Department of Biomedical Engineering, Cornell University , Ithaca, New York, United States.
authors.forename: Sierra G
authors.initials: SG
authors.lastname: Cook
authors.affiliation: Department of Materials Science and Engineering and ‡Department of Biomedical Engineering, Cornell University , Ithaca, New York, United States.
authors.forename: Cory N
authors.initials: CN
authors.lastname: Brown
authors.affiliation: Department of Materials Science and Engineering and ‡Department of Biomedical Engineering, Cornell University , Ithaca, New York, United States.
authors.forename: Fei
authors.initials: F
authors.lastname: Wu
authors.affiliation: Department of Materials Science and Engineering and ‡Department of Biomedical Engineering, Cornell University , Ithaca, New York, United States.
authors.forename: Noah J
authors.initials: NJ
authors.lastname: Pacifici
authors.affiliation: Department of Materials Science and Engineering and ‡Department of Biomedical Engineering, Cornell University , Ithaca, New York, United States.
authors.forename: Lawrence J
authors.initials: LJ
authors.lastname: Bonassar
authors.affiliation: Department of Materials Science and Engineering and ‡Department of Biomedical Engineering, Cornell University , Ithaca, New York, United States.
authors.forename: Delphine
authors.initials: D
authors.lastname: Gourdon
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry*; D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D005353:Fibronectins / Q000737:chemistry*; D006023:Glycoproteins / Q000737:chemistry*; D033081:Shear Strength; D000099158:Proteoglycan 4
chemical_list: D000538:Aluminum Silicates; D020099:Coated Materials, Biocompatible; D005353:Fibronectins; D006023:Glycoproteins; D000099158:Proteoglycan 4; C011934:mica