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

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, i.e. 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 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/ml, 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 absence and presence of human cells. This article is protected by copyright. All rights reserved.