Mesenchymal Stem Cells Enhance Lubrication of Engineered Meniscus Through Lubricin Localization in Collagen Gels

This study evaluated the role of cell source in the boundary lubrication of engineered meniscus tissue. To accomplish this, both primary meniscal fibrochondrocytes (FCC) and bone marrow-derived mesenchymal stem cells (MSC) were obtained from neonatal bovine, seeded in high density collagen gels (20 mg/mL collagen with 25 × 106 total cells/mL) at various MSC:FCC ratios, and cultured for two weeks. After culture, the boundary friction coefficient, mechanical properties, surface roughness, and lubricin localization were all evaluated for engineered constructs. A strong correlation between MSC content and boundary friction coefficient was found (R2 = 0.948). Aggregate modulus, permeability, and surface roughness revealed insignificant trends with MSC content; however, lubricin localization was highly correlated with increasing MSC content (R2 = 0.902). Similarly, boundary friction coefficient had no significant trends with modulus, permeability, or roughness, but lubricin localization was significantly correlated with the boundary friction coefficient (R2 = 0.800). Collectively, these data revealed a structure-function relationship in meniscus tissue engineering that is dictated by cell source. Specifically, the connection between MSC content, lubricin localization, and boundary friction coefficient reveal a method through which tuning the lubricating properties of engineered tissue is possible.