title: Injectable doubly cross-linked microgels for improving the mechanical properties of degenerated intervertebral discs.
abstract: The use of injectable pH-responsive doubly cross-linked microgels (DX microgels) to improve the mechanical properties of degenerated intervertebral discs is demonstrated for the first time. The microgel comprised methyl methacrylate (MMA), methacrylic acid (MAA), ethyleneglycol dimethacrylate (EGD) and glycidyl methacrylate (GM) and was poly(MMA/MAA/EGD)-GM. The GM facilitated covalent interparticle cross-linking. The DX microgels are shown to have tunable mechanical properties. Degeneration of model bovine intervertebral discs (IVDs) was induced using collagenase. When injected into degenerated IVDs the DX microgels were shown to improve the strain, modulus, toughness and resilience. The extent of mechanical property improvement was an increasing function of DX microgel concentration, suggesting tunability. Cytotoxicity studies showed that the DX microgel was biocompatible under the conditions investigated. The results of this study imply that injectable DX microgels have good potential as a future regenerative medicine strategy for restoring the mechanical properties of degenerated load-bearing soft tissue, such as IVDs.
authors.affiliation: Biomaterials Research Group, Manchester Materials Science Centre, School of Materials, University of Manchester, Grosvenor Street, Manchester, M13 9PL United Kingdom.
authors.forename: Amir H
authors.initials: AH
authors.lastname: Milani
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Freemont
authors.forename: Judith A
authors.initials: JA
authors.lastname: Hoyland
authors.forename: Daman J
authors.initials: DJ
authors.lastname: Adlam
authors.forename: Brian R
authors.initials: BR
authors.lastname: Saunders
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000138:chemical synthesis* / Q000494:pharmacology*; D002417:Cattle; D017364:Collagenases / Q000737:chemistry; D003432:Cross-Linking Reagents / Q000737:chemistry; D055119:Elastic Modulus; D004852:Epoxy Compounds / Q000737:chemistry; D005782:Gels; D006863:Hydrogen-Ion Concentration; D007267:Injections; D007403:Intervertebral Disc / Q000187:drug effects* / Q000473:pathology; D055959:Intervertebral Disc Degeneration / Q000188:drug therapy* / Q000473:pathology; D008689:Methacrylates / Q000737:chemistry*; D015394:Molecular Structure; D033081:Shear Strength; D016474:Weight-Bearing
chemical_list: D001672:Biocompatible Materials; D003432:Cross-Linking Reagents; D004852:Epoxy Compounds; D005782:Gels; D008689:Methacrylates; D017364:Collagenases; C007870:glycidyl methacrylate