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Significance Statement
Osteochondral bone injuries beyond the self-repair threshold represent a great challenge. The combination of stereolithography and 3D fibre deposition modelling represent a valuable tool to manufacture complex scaffolds. Stereolithography allows to produce thin scaffold layer, finely structured, suitable to reproduce the thin cartilage layer. However, this technique prevents to process polymeric materials incorporating a significant particulate reinforcement phase. On the other hand, 3D fibre deposition prevents to finely structure a scaffold, as the stratification thickness depends on the needle diameter. However, this technique allows to process composite materials incorporating a significant particulate reinforcement phase. This requirement is important as bone scaffolds are concerned. Therefore, by combining stereolithography and 3D fibre deposition modelling it is possible to benefit from the advantages of each single technique, and complex multimaterial scaffolds, such as scaffolds for osteochondral tissue regeneration, can be manufactured.
Poly(ethylene glycol) and poly(caprolactone) based nano-composites have been processed through stereolithography and 3D fibre deposition, respectively. Results shows that dynamic mechanical properties (e.g. storage and loss moduli) of the region of the scaffold manufactured through 3D fibre deposition reproduce those of trabecular bone. Instead, dynamic mechanical properties in compression of poly(ethylene glycol) based nano-composite mimic those of the articular cartilage. Also, the Brazilian test suggests a stable interface between the differently processed scaffold regions, and adhesion between these regions relies at least on a micromechanical interlocking.
The incorporation of a superparamagnetic nano-reinforcement phase, based on iron oxide nanoparticles encapsulated in a polymeric shell, allows for further improving the scaffold material design by offering a unique opportunity. Poly(ethylene glycol) and poly(caprolactone) based superparamagnetic scaffolds become magnetised as an external magnetic field is applied, and magnetization goes to zero as the external field is turned off. This peculiarity of superparamagnetic nanocomposite scaffolds allows to attract magnetically functionalised bioaggregates using and external magnetic field, and to release these bioaggregates on demand. This opportunity represents an important tool to guide the regeneration process of complex tissues like the osteochondral defect.
Non-degradable prosthesis based on metals, polymers and ceramics, represent the available solution to restore joint disorders. However, the life span of such approach is very limited, especially when dealing with population aging. Of course, the possibility to regenerate ostechondral bone would be the best solution. By using the reverse engineering approach to define the osteochondral defect and implementing the combination of rapid prototyping techniques, in the future it would be probably possible to manufacture customized polymer based scaffold for joint disorders.
Journal Reference
J Mater Sci Mater Med. 2015;26(10):250.
De Santis R1, D’Amora U2, Russo T2, Ronca A2, Gloria A2, Ambrosio L3.
[expand title=”Show Affiliations”]- Institute of Polymers, Composites and Biomaterials, National Research Council of Italy, V. le J.F. Kennedy 54 – Pad. 20 Mostra d’Oltremare, 80125, Naples, Italy. [email protected].
- Institute of Polymers, Composites and Biomaterials, National Research Council of Italy, V. le J.F. Kennedy 54 – Pad. 20 Mostra d’Oltremare, 80125, Naples, Italy.
- Department of Chemical Science and Materials Technology, National Research Council of Italy, Piazzale Aldo Moro 7, 00185, Rome, Italy.
Abstract
Magnetic nanocomposite scaffolds based on poly(ε-caprolactone) and poly(ethylene glycol) were fabricated by 3D fibre deposition modelling (FDM) and stereolithography techniques. In addition, hybrid coaxial and bilayer magnetic scaffolds were produced by combining such techniques. The aim of the current research was to analyse some structural and functional features of 3D magnetic scaffolds obtained by the 3D fibre deposition technique and by stereolithography as well as features of multimaterial scaffolds in the form of coaxial and bilayer structures obtained by the proper integration of such methods. The compressive mechanical behaviour of these scaffolds was investigated in a wet environment at 37 °C, and the morphological features were analysed through scanning electron microscopy (SEM) and X-ray micro-computed tomography. The capability of amagnetic scaffold to absorb magnetic nanoparticles (MNPs) in water solution was also assessed. confocal laser scanning microscopy was used to assess the in vitro biological behaviour of human mesenchymal stem cells (hMSCs) seeded on 3D structures. Results showed that a wide range of mechanical properties, covering those spanning hard and soft tissues, can be obtained by 3D FDM and stereolithography techniques. 3D virtual reconstruction and SEM showed the precision with which the scaffolds were fabricated, and a good-quality interface between poly(ε-caprolactone) and poly(ethylene glycol) based scaffolds was observed for bilayer and coaxial scaffolds. Magnetised scaffolds are capable of absorbing water solution of magnetic nanoparticles, and a preliminary information on cell adhesion and spreading of human mesenchymal stem cells was obtained without the application of an external magnetic field.
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