title: Novel bioadhesive polymers as intra-articular agents: Chondroitin sulfate-cysteine conjugates.
abstract: The aim of this study was to generate and characterize a chondroitin sulfate-cysteine conjugate (CS-cys) as a novel bioadhesive agent for intra-articular use. Mucoadhesive properties of synthesized CS-cys were investigated by rheological measurement of polymer-mucus mixture and rotating cylinder method, while bioadhesive features of CS-cys on porcine articular cartilage were evaluated via tensile studies. Thiolation was achieved by attachment of l-cysteine to CS via amide bond formation mediated by carbodiimide as a coupling reagent. The conjugate exhibited 421.17±35.14 μmol free thiol groups per gram polymer. The reduced CS-cys displayed 675.09±39.67 μmol free thiol groups per gram polymer after disulfide bonds reduction using tris(2-carboxyethyl)phosphine hydrochloride. The increase in dynamic viscosity of thiolated CS due to oxidative disulfide bond formation was demonstrated using capillary viscometer. The combination of CS-cys and mucus led to 4.57-fold increase in dynamic viscosity in comparison with mucus control. Furthermore, adhesion time to porcine mucosa of CS-cys-based test disk was enhanced by 2.48-fold compared to unmodified CS as measured by rotating cylinder method suggesting the interaction between thiomers and mucus gel layer via disulfide bonds formation. Tensile studies of thiolated CS on porcine articular cartilage showed 5.37- and 1.76-fold increase in the total work of adhesion and the maximum detachment force, respectively, in comparison with unmodified CS indicating bioadhesive features of CS-cys. Cytotoxicity of CS-cys was assessed in Caco-2 cells and rat primary articular chondrocytes using MTT and LDH release assay, thereby showing the safety of CS-cys at a concentration of 0.25% (w/v) in Caco-2 cells. Furthermore, 0.1% of CS-cys was found non-toxic to rat primary articular chondrocytes. According to these results, CS-cys provides improved bioadhesive properties that might be useful as an intra-articular agent for treatment of osteoarthritis.
authors.affiliation: Department of Pharmaceutical Technology, Institute of Pharmacy, University of Innsbruck, A-6020 Innsbruck, Austria.
authors.forename: Wongsakorn
authors.initials: W
authors.lastname: Suchaoin
authors.affiliation: Department of Pharmaceutical Technology, Institute of Pharmacy, University of Innsbruck, A-6020 Innsbruck, Austria.
authors.forename: Sonja
authors.initials: S
authors.lastname: Bonengel
authors.affiliation: Department of Pharmaceutical Technology, Institute of Pharmacy, University of Innsbruck, A-6020 Innsbruck, Austria.
authors.forename: Julia Anita
authors.initials: JA
authors.lastname: Griessinger
authors.affiliation: Department of Pharmaceutical Technology, Institute of Pharmacy, University of Innsbruck, A-6020 Innsbruck, Austria.
authors.forename: Irene
authors.initials: I
authors.lastname: Pereira de Sousa
authors.affiliation: Institute of Analytical Chemistry and Radiochemistry, University of Innsbruck, A-6020 Innsbruck, Austria.
authors.forename: Shah
authors.initials: S
authors.lastname: Hussain
authors.affiliation: Institute of Analytical Chemistry and Radiochemistry, University of Innsbruck, A-6020 Innsbruck, Austria.
authors.forename: Christian W
authors.initials: CW
authors.lastname: Huck
authors.affiliation: Department of Pharmaceutical Technology, Institute of Pharmacy, University of Innsbruck, A-6020 Innsbruck, Austria. Electronic address: andreas.bernkop@uibk.ac.at.
authors.forename: Andreas
authors.initials: A
authors.lastname: Bernkop-Schnürch
mesh_terms: D000269:Adhesives / Q000008:administration & dosage / Q000737:chemistry*; D000818:Animals; D018938:Caco-2 Cells; D002358:Cartilage, Articular / Q000187:drug effects*; D045744:Cell Line, Tumor; D019902:Chondrocytes / Q000187:drug effects*; D002809:Chondroitin Sulfates / Q000008:administration & dosage* / Q000737:chemistry*; D003545:Cysteine / Q000008:administration & dosage / Q000737:chemistry*; D004220:Disulfides / Q000737:chemistry; D016503:Drug Delivery Systems / Q000379:methods; D006801:Humans; D008297:Male; D009092:Mucous Membrane / Q000187:drug effects; D010084:Oxidation-Reduction; D010720:Phosphines / Q000737:chemistry; D011108:Polymers / Q000008:administration & dosage / Q000737:chemistry*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012212:Rheology / Q000379:methods; D013438:Sulfhydryl Compounds / Q000737:chemistry; D013552:Swine; D014783:Viscosity
chemical_list: D000269:Adhesives; D002809:Chondroitin Sulfates; D003545:Cysteine; D004220:Disulfides; D010720:Phosphines; D011108:Polymers; D013438:Sulfhydryl Compounds; C080938:tris(2-carboxyethyl)phosphine
keywords: Bioadhesive polymers; Chondroitin sulfate; Disulfide bonds; Intra-articular agent; Mucoadhesion; Thiomers