Francesco Travascio1,2,3, Sabrina Valladares-Prieto1, Alicia R Jackson4. 1. Department of Mechanical and Aerospace Engineering, University of Miami, Coral Gables, FL. 2. Department of Orthopaedic Surgery, University of Miami, Miami, FL. 3. Max Biedermann Institute for Biomechanics at Mount Sinai Medical Center, Miami Beach, FL. 4. Department of Biomedical Engineering, University of Miami, Coral Gables, FL.
Abstract
OBJECTIVE: Articular cartilage is an avascular tissue. Accordingly, diffusivity represents a fundamental transport mechanism for nutrients and other molecular signals regulating its cell metabolism and maintenance of the extracellular matrix. Understanding how solutes spread into articular cartilage is crucial to elucidating its pathologies, and to designing treatments for repair and restoration of its extracellular matrix. As in other connective tissues, diffusivity in articular cartilage may vary depending both its composition and the specific diffusing solute. Hence, this study investigated the roles of solute size and tissue composition on molecular diffusion in knee articular cartilage. DESIGN: FRAP tests were conducted to measure diffusivity of five molecular probes, with size ranging from ~332Da to 70,000Da, in human knee articular cartilage. The measured diffusion coefficients were related to molecular size, as well as water and glycosaminoglycan (GAG) content of femoral and tibial condyle cartilage. RESULTS: Diffusivity was affected by molecular size, with the magnitude of the diffusion coefficients decreasing as the Stokes radius of the probe increased. The values of diffusion coefficients in tibial and femoral samples were not significantly different from one another, despite the fact that tibial samples exhibited significantly higher water content and lower GAG content of the femoral specimens. Water content did not affect diffusivity. In contrast, diffusivities of large molecules were sensitive to GAG content. CONCLUSIONS: This study provides new knowledge on the mechanisms of diffusion in articular cartilage. Our findings can be leveraged to further investigate osteoarthritis and to design treatments for cartilage restoration or replacement.
OBJECTIVE: Articular cartilage is an avascular tissue. Accordingly, diffusivity represents a fundamental transport mechanism for nutrients and other molecular signals regulating its cell metabolism and maintenance of the extracellular matrix. Understanding how solutes spread into articular cartilage is crucial to elucidating its pathologies, and to designing treatments for repair and restoration of its extracellular matrix. As in other connective tissues, diffusivity in articular cartilage may vary depending both its composition and the specific diffusing solute. Hence, this study investigated the roles of solute size and tissue composition on molecular diffusion in knee articular cartilage. DESIGN: FRAP tests were conducted to measure diffusivity of five molecular probes, with size ranging from ~332Da to 70,000Da, in human knee articular cartilage. The measured diffusion coefficients were related to molecular size, as well as water and glycosaminoglycan (GAG) content of femoral and tibial condyle cartilage. RESULTS: Diffusivity was affected by molecular size, with the magnitude of the diffusion coefficients decreasing as the Stokes radius of the probe increased. The values of diffusion coefficients in tibial and femoral samples were not significantly different from one another, despite the fact that tibial samples exhibited significantly higher water content and lower GAG content of the femoral specimens. Water content did not affect diffusivity. In contrast, diffusivities of large molecules were sensitive to GAG content. CONCLUSIONS: This study provides new knowledge on the mechanisms of diffusion in articular cartilage. Our findings can be leveraged to further investigate osteoarthritis and to design treatments for cartilage restoration or replacement.
Entities:
Keywords:
Fluorescence recovery after photobleaching (FRAP); Glycosaminoglycan (GAG); Stokes radius; Water content
Authors: Reza Yousefi; Behnaz Taheri; Parnian Alavi; Mohammad Bagher Shahsavani; Zahra Asadi; Maryam Ghahramani; Ali Niazi; Mohammad Mehdi Alavianmehr; Ali Akbar Moosavi-Movahedi Journal: J Biomol Struct Dyn Date: 2015-06-23
Authors: H T Kokkonen; J Mäkelä; K A M Kulmala; L Rieppo; J S Jurvelin; V Tiitu; H M Karjalainen; R K Korhonen; V Kovanen; J Töyräs Journal: Osteoarthritis Cartilage Date: 2011-07-23 Impact factor: 6.576