High-Performance Regenerated Silk Fibers as Building Blocks of Tissue Scaffolds: The European THOR Project

The European Pathfinder THOR project envisages the creation of a vascularized fragment of tissue that can be implanted in a patient using regenerated silk fibers as its building blocks. The selection of regenerated silk as the main building block of the scaffold relies heavily on its outstanding biocompatibility in comparison with either other artificial polymeric fibers or even natural silk fibers. Additionally, regenerated fibers produced through the Dynamic Dope Destabilization Spinning (D3S^TM) process are shown to exhibit high mechanical performance as reflected in values of strain at breaking and work to fracture comparable to those of the natural material. It is further shown that these fibers are endowed with the unique property of self-adhesion whereby hydrated fibers attach to one another and may sustain detachment forces of up to a few tens of MPa, a property that facilitates the generation of the scaffold with the fibers as its basic building block. Lastly, regenerated silk fibers are shown to be efficiently decorated with either peptides or small proteins, such as the vascular endothelial growth factor (VEGF), or with antibodies. The performance of both non-functionalized and decorated silk fibers is assessed in two different in vitro biological systems: (1) endothelial cell cultures, and (2) organotypic brain slice cultures. Together, these results support the use of regenerated silk fibers as versatile building blocks for biofunctional tissue scaffolds and provide experimental validation of the tissue engineering strategy established by the THOR project.