Harnessing shear stress preconditioning to improve cell viability in 3D post-printed biostructures using extrusion bioprinting

Extrusion-based three dimensional bioprinting has emerged as a promising fabrication technique in the field of tissue engineering. However, it still suffers from reduced cell survival post-printing due to process-induced shear stress. Great research efforts have been made to reduce such an effect, yet none have investigated the ability of preconditioned cells to tolerate stress induced by printing. In this study, we investigated the effect of shear stress preconditioning of C2C12 murine myoblasts on post-printing cell viability using a custom-built device to induce shear stress. Here, we present the first study investigating the link between shear stress preconditioning, cellular protective mechanisms and cell survival post-printing. We hypothesized that moderate shear stress preconditioning increases the ability of cells to tolerate bioprinting induced stress, thus improving their viability after printing. We used HSP70 expression as an indicator of cellular stress and of the activation of cell adaptation/repair mechanisms. Our results showed an increase in level and a translocation of HSP70 in shear stress preconditioned cells compared to non-conditioned cells. In addition, our results demonstrated that exposure to shear stress prior to printing enhances viability of cells after printing. In particular, viability of preconditioned cells printed via a nozzle was 7.8% higher than that of non-conditioned cells while viability of preconditioned cells printed via a needle was 6.6%, higher than that of non-conditioned cells. Taken together, these findings indicate that shear stress cell preconditioning is a promising method to enhance cell viability post-printing, which is of vital importance in tissue engineering applications.