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Description
The reconstruction and replacement of musculoskeletal tissues have been extensively investigated in the last decades. Trauma injuries and degenerative diseases are the most common causes reported worldwide. Stem cells play an important role in tissue regeneration and have been successfully applied in musculoskeletal research, especially due to the low self-repair capability of tendons, ligaments, and joints. Due to the specialized architecture of native musculoskeletal components, mostly related to the complex interplay between multiple tissues, interface regions between hard (bone) and connective tissues (cartilage) are challenging to be engineered. When it occurs, they often fail during implantation due to the lack of appropriate mechanical properties. This challenge is even more exacerbated in the temporomandibular joint (TMJ), which is composed of several anatomical structures such as the articular disc, jaw, mandible, muscles, and tendons that connect the scapula, sternum, and neck. The TMJ performs complex movements under compression and tension during common activities such as talking, chewing, and biting. In this context, multi-material approaches that combine different manufacturing techniques can be very promising for interfacial tissue engineering of the TMJ. Hence, the objective of this work was to evaluate the integration of polycaprolactone-polylactic acid (PCL-LA copolymer) fibrous scaffolds produced by melt-electrowriting (MEW) with bioprinted constructs made of xanthan gum (XG) hydrogel and mesenchymal stem cells. MEW meshes were manufactured at 10 mm/s, 170 °C, 0.8 bar of pressure, 6 kV and 4 mm of height. Four-layered constructs were bioprinted varying speed from 40-60 mm/s and pressure from 50-70 KPa using smooth flow tapered tip. Morphological aspects regarding filaments size and porosity of both manufacture techniques were quantified through optical and scanning electron microscopes. Stability in culture media for 28 days was also analyzed. Regular and well-defined PCL-LA meshes were obtained using MEW. Constructs with satisfactory shape fidelity were also obtained through bioprinting. To analyze the most appropriate strategy to improve integration, stability, and mechanical properties between PCL-LA meshes and XG bioprinted constructs, a double crosslinking network has been investigated. First, ionic crosslinking of XG using trivalent iron ions, followed by a photocrosslinking step using acrylate groups in MEW meshes. Overall, based on the hybridization between both processing techniques, employing a multi-material approach, as well as including a double crosslinking strategy we hypothesize that promising interfacial tissues with improved mechanical properties can be obtained. The potential application of the multi-material herein explored are analyzed as a replacement for the multi-tissue temporomandibular joint.
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