Impact of Cell Loading of Recombinant Spider Silk Based Bioinks on Gelation and Printability

• Published in: Macromolecular bioscience 2022-03, Vol.22 (3), p.e2100390-n/a
• Main Authors: Lechner, Annika, Trossmann, Vanessa T., Scheibel, Thomas
• Format: Article
• Language: English
• Subjects: Accuracy; Aorta; Aortic valve; Bioengineering; biofabrication; Bioprinting; Cell viability; Extrudability; Extrusion rate; Gelation; gelation kinetics; Heart valves; Hydrogels; physical crosslinking; Printing, Three-Dimensional; Proteins; Rheological properties; Rheology; Silk; Spiders; Three dimensional printing; Tissue Engineering; Tissue Scaffolds
• ISSN: 1616-5187; 1616-5195
• DOI: 10.1002/mabi.202100390

Printability of bioinks encompasses considerations concerning rheology and extrudability, characterization of filament formation, shape fidelity, cell viability, and post‐printing cellular development. Recombinant spider silk based hydrogels might be a suitable material to be used in bioinks, that is, a formulation of cells and materials to be used for bioprinting. Here, the high shape fidelity of spider silk ink is shown by bioprinting the shape and size of a human aortic valve. Further the influence of the encapsulation of cells has been evaluated on spider silk hydrogel formation, hydrogel mechanics, and shape fidelity upon extrusion based bioprinting. It is shown that the presence of cells impacts the gelation of spider silk proteins differently, depending on the used silk variant. RGD‐modified spider silk hydrogels are physically crosslinked by the cells, while there is no active interaction between cells and un‐tagged spider silk proteins. Strikingly, even at cell densities up to ten million cells per milliliter, cell viability is high after extrusion‐based printing, which is a significant prerequisite for future applications. Shape fidelity of the printed constructs is demonstrated using a filament collapse test in the absence and presence of human cells. Spider silk based bioinks show high potential for biofabrication combining high biocompatibility with gentle cell encapsulation and reliable extrusion printing. In this study, valuable insights are gained concerning gelation and rheology of spider silk bioinks dependent on cell densities. Printability is optimized by understanding temperature‐dependency of rheological behavior, used nozzle, and applied pressure.