Biofabrication of Endothelialized, Intrinsically Vascularized 3D-Printed Recombinant Spider Silk Scaffolds

Tissue engineering aims to create functional tissues for regenerative medicine, where scaffold design and vascular integration remain key challenges. Therefore, the capability to promote vascularization, long-term stability and biocompatibility are important requirements to a scaffold material. One goal is to optimize the cell-to-scaffold material interaction to support vascularization and de novo tissue formation. This study evaluates 3D-printed and non-printed recombinant spider silk protein eADF4(C16)-RGD hydrogels in a rat arteriovenous (AV) loop model. The hydrogels were implanted subcutaneously using polytetrafluorethylene (PTFE) chambers, where the lower half contained an acellular 3D-printed spider silk hydrogel, while the upper half either contained a manually extruded eADF4(C16)-RGD hydrogel without cells (group A) or with T17b endothelial progenitor (EPCs) cells embedded (group B). Constructs were explanted after 2, 4, and 12 weeks. The 3D-printed eADF4(C16)-RGD scaffolds showed good biocompatibility and vascularization. Interestingly, the presence of T17b cells resulted in an increased biodegradation, with the 12 week constructs nearly completely dissolved. The cell-laden constructs showed a significantly increased vascular density per construct area after 4 weeks compared to the cell-free constructs. This study demonstrates that both the scaffold ultrastructure and the integration of T17b cells are effective strategies to enhance the functionality of biomaterials for tissue engineering.