title: Isolated effects of external bath osmolality, solute concentration, and electrical charge on solute transport across articular cartilage.
abstract: The metabolic function of cartilage primarily depends on transport of solutes through diffusion mechanism. In the current study, we use contrast enhanced micro-computed tomography to determine equilibrium concentration of solutes through different cartilage zones and solute flux in the cartilage, using osteochondral plugs from equine femoral condyles. Diffusion experiments were performed with two solutes of different charge and approximately equal molecular weight, namely iodixanol (neutral) and ioxaglate (charge=-1) in order to isolate the effects of solute's charge on diffusion. Furthermore, solute concentrations as well as bath osmolality were changed to isolate the effects of steric hindrance on diffusion. Bath concentration and bath osmolality only had minor effects on the diffusion of the neutral solute through cartilage at the surface, middle and deep zones, indicating that the diffusion of the neutral solute was mainly Fickian. The negatively charged solute diffused considerably slower through cartilage than the neutral solute, indicating a large non-Fickian contribution in the diffusion of charged molecules. The numerical models determined maximum solute flux in the superficial zone up to a factor of 2.5 lower for the negatively charged solutes (charge=-1) as compared to the neutral solutes confirming the importance of charge-matrix interaction in diffusion of molecules across cartilage.
authors.affiliation: Department of Orthopedics, UMC Utrecht, Heidelberglaan100, 3584CX Utrecht, The Netherlands; Department of Biomechanical Engineering, Faculty of Mechanical, Maritime, and Materials Engineering, Delft University of Technology (TU Delft), Mekelweg 2, 2628CD Delft, The Netherlands. Electronic address: b.pouran-2@umcutrecht.nl.
authors.forename: Behdad
authors.initials: B
authors.lastname: Pouran
authors.affiliation: Department of Orthopedics, UMC Utrecht, Heidelberglaan100, 3584CX Utrecht, The Netherlands; Department of Biomechanical Engineering, Faculty of Mechanical, Maritime, and Materials Engineering, Delft University of Technology (TU Delft), Mekelweg 2, 2628CD Delft, The Netherlands; Department of Mechanical Engineering, University of Birjand, 61597175 Birjand, Iran.
authors.forename: Vahid
authors.initials: V
authors.lastname: Arbabi
authors.affiliation: Department of Biomechanical Engineering, Faculty of Mechanical, Maritime, and Materials Engineering, Delft University of Technology (TU Delft), Mekelweg 2, 2628CD Delft, The Netherlands.
authors.forename: Amir A
authors.initials: AA
authors.lastname: Zadpoor
authors.affiliation: Department of Orthopedics, UMC Utrecht, Heidelberglaan100, 3584CX Utrecht, The Netherlands; Department of Biomechanical Engineering, Faculty of Mechanical, Maritime, and Materials Engineering, Delft University of Technology (TU Delft), Mekelweg 2, 2628CD Delft, The Netherlands; Department of Rheumatology, UMC Utrecht, Heidelberglaan100, 3584CX Utrecht, The Netherlands.
authors.forename: Harrie
authors.initials: H
authors.lastname: Weinans
mesh_terms: D000818:Animals; D001692:Biological Transport; D002358:Cartilage, Articular / Q000166:cytology / Q000000981:diagnostic imaging / Q000378:metabolism*; D003287:Contrast Media / Q000378:metabolism; D004058:Diffusion; D004560:Electricity; D006736:Horses; D009994:Osmolar Concentration; D055114:X-Ray Microtomography
chemical_list: D003287:Contrast Media
keywords: Articular cartilage; Cartilage zones; Iodixanol; Ioxaglate; Micro-computed tomography; Non-Fickian diffusion; Solute's charge; Steric hindrance