title: Intrinsically radiopaque hydrogels for nucleus pulposus replacement.
abstract: Degeneration of the intervertebral disc is the most common cause of back pain. In case of early stage degenerative disc disease or traumatic herniations, a suitable treatment may be to replace the nucleus pulposus, preserving the annulus fibrosus. Eight new hydrogel biomaterials were prepared and studied for their potential as a nucleus replacement. The hydrogels were designed according to the following criteria: (i), they should exhibit adequate radiopacity; (ii), they should be non-cytotoxic; (iii), implantation in the dry state and subsequent swelling in situ to fill the entire nucleus cavity; (iv), after swelling they should match the physical-mechanical properties of the native nucleus. The approach was to use copolymers consisting of 2-(4'-iodobenzoyl)-oxo-ethyl methacrylate (4IEMA) and a hydrophilic building block (either N-vinyl-2-pyrrolidinone (NVP) or 2-hydroxyethyl methacrylate (HEMA)); 4 copolymers of NVP/4IEMA and 4 copolymers of HEMA/4IEMA in different compositions (5, 10, 15 and 20 mol% 4IEMA). The study comprised 1H-NMR analysis of the copolymerization reaction NVP+4IEMA. Furthermore, the copolymers were studied with respect to their swelling behavior, mechanical properties, cytotoxicity in vitro and X-ray contrast. Hydrogels with 5 mol% 4IEMA appear to meet all criteria: they are non-cytotoxic, have adequate physical-mechanical properties and feature sufficient radiopacity in a realistic model. The potential implications of these new results with respect to treatment of degenerative disc disease are discussed briefly.
authors.affiliation: Center for Biomaterials Research, University of Maastricht, P.O. Box 616, 6200 MD Maastricht, The Netherlands. E.Boelen@bioch.unimaas.nl
authors.forename: Erik J H
authors.initials: EJ
authors.lastname: Boelen
authors.forename: Catharina S J
authors.initials: CS
authors.lastname: van Hooy-Corstjens
authors.forename: Sjoerd K
authors.initials: SK
authors.lastname: Bulstra
authors.forename: André
authors.initials: A
authors.lastname: van Ooij
authors.forename: Lodewijk W
authors.initials: LW
authors.lastname: van Rhijn
authors.forename: Leo H
authors.initials: LH
authors.lastname: Koole
mesh_terms: D016475:3T3 Cells; D000818:Animals; D001672:Biocompatible Materials; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D005898:Glass / Q000737:chemistry; D020100:Hydrogels / Q000737:chemistry; D007403:Intervertebral Disc / Q000378:metabolism / Q000473:pathology*; D007455:Iodine / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008689:Methacrylates / Q000737:chemistry; D051379:Mice; D008956:Models, Chemical; D011108:Polymers / Q000737:chemistry; D012212:Rheology; D013314:Stress, Mechanical; D013696:Temperature; D013997:Time Factors; D014965:X-Rays
chemical_list: D001672:Biocompatible Materials; D020100:Hydrogels; D008689:Methacrylates; D011108:Polymers; C005044:hydroxyethyl methacrylate; D007455:Iodine