title: Covalent attachment of a three-dimensionally printed thermoplast to a gelatin hydrogel for mechanically enhanced cartilage constructs.
abstract: Hydrogels can provide a suitable environment for tissue formation by embedded cells, which makes them suitable for applications in regenerative medicine. However, hydrogels possess only limited mechanical strength, and must therefore be reinforced for applications in load-bearing conditions. In most approaches the reinforcing component and the hydrogel network have poor interactions and the synergetic effect of both materials on the mechanical properties is not effective. Therefore, in the present study, a thermoplastic polymer blend of poly(hydroxymethylglycolide-co-ε-caprolactone)/poly(ε-caprolactone) (pHMGCL/PCL) was functionalized with methacrylate groups (pMHMGCL/PCL) and covalently grafted to gelatin methacrylamide (gelMA) hydrogel through photopolymerization. The grafting resulted in an at least fivefold increase in interface-binding strength between the hydrogel and the thermoplastic polymer material. GelMA constructs were reinforced with three-dimensionally printed pHMGCL/PCL and pMHMGCL/PCL scaffolds and tested in a model for a focal articular cartilage defect. In this model, covalent bonds at the interface of the two materials resulted in constructs with an improved resistance to repeated axial and rotational forces. Moreover, chondrocytes embedded within the constructs were able to form cartilage-specific matrix both in vitro and in vivo. Thus, by grafting the interface of different materials, stronger hybrid cartilage constructs can be engineered.
authors.affiliation: Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences (UIPS), Faculty of Science, Utrecht University, PO Box 80082, 3508 TB Utrecht, The Netherlands.
authors.forename: Kristel W M
authors.initials: KW
authors.lastname: Boere
authors.affiliation: Department of Orthopaedics, University Medical Center Utrecht, PO Box 85500, 3508 GA Utrecht, The Netherlands.
authors.forename: Jetze
authors.initials: J
authors.lastname: Visser
authors.affiliation: Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences (UIPS), Faculty of Science, Utrecht University, PO Box 80082, 3508 TB Utrecht, The Netherlands.
authors.forename: Hajar
authors.initials: H
authors.lastname: Seyednejad
authors.affiliation: Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences (UIPS), Faculty of Science, Utrecht University, PO Box 80082, 3508 TB Utrecht, The Netherlands.
authors.forename: Sima
authors.initials: S
authors.lastname: Rahimian
authors.affiliation: Department of Orthopaedics, University Medical Center Utrecht, PO Box 85500, 3508 GA Utrecht, The Netherlands.
authors.forename: Debby
authors.initials: D
authors.lastname: Gawlitta
authors.affiliation: Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences (UIPS), Faculty of Science, Utrecht University, PO Box 80082, 3508 TB Utrecht, The Netherlands.
authors.forename: Mies J
authors.initials: MJ
authors.lastname: van Steenbergen
authors.affiliation: Department of Orthopaedics, University Medical Center Utrecht, PO Box 85500, 3508 GA Utrecht, The Netherlands; Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, PO Box 80163, 3508 TD Utrecht, The Netherlands.
authors.forename: Wouter J A
authors.initials: WJ
authors.lastname: Dhert
authors.affiliation: Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences (UIPS), Faculty of Science, Utrecht University, PO Box 80082, 3508 TB Utrecht, The Netherlands.
authors.forename: Wim E
authors.initials: WE
authors.lastname: Hennink
authors.affiliation: Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences (UIPS), Faculty of Science, Utrecht University, PO Box 80082, 3508 TB Utrecht, The Netherlands.
authors.forename: Tina
authors.initials: T
authors.lastname: Vermonden
authors.affiliation: Department of Orthopaedics, University Medical Center Utrecht, PO Box 85500, 3508 GA Utrecht, The Netherlands; Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, PO Box 80163, 3508 TD Utrecht, The Netherlands. Electronic address: j.malda@umcutrecht.nl.
authors.forename: Jos
authors.initials: J
authors.lastname: Malda
mesh_terms: D002152:Calorimetry, Differential Scanning; D002356:Cartilage / Q000737:chemistry*; D002478:Cells, Cultured; D002648:Child; D005780:Gelatin / Q000737:chemistry*; D006801:Humans; D020100:Hydrogels
chemical_list: D020100:Hydrogels; D005780:Gelatin
keywords: 3-D fiber deposition; Cartilage; Fiber reinforcement; Hydrogel; Polymer grafting