Computational Fluid Dynamics and Quantitative Cell Viability Measurements in Dispensing-Based Biofabrication

Sammanfattning: Bioprinting is a technique used to create tissue models by deposition of a bioink containing cells on a printing surface using a 3D-printer. To net the highest cell viability, cell throughput and structural rigidity in a bioprinted tissue the characteristics of a bioink such as viscosity and ease of use is of importance. The dispensing process can be simulated using Computational Fluid Dynamics (CFD) to gain information on shear stress and pressure that cells are subjected too and examine cell trajectories in the dispensing system. Cell throughput, cell shear stresses, pressure and origin of cells is individual for each dispensing system and have to be specified for each individual setup and cell type. By analyzing the cell throughput and cell viability of Human Stem Cells from Apical Papilla (SCAP) and Dental Pulp Stem Cells (DPSC), we found approximately 37%-53% cell survival of SCAP cells in the CELLINK Inkredible bioprinter using Bioink (CELLINK). Using CollMaGel (CELLINK) the cell throughput for DPSC cells was found to be approximatly 75% with a 67%-70% cell survival. Simulating cell trajectories in a needle geometry shows that the shear rates, pressures and trajectories can be analyzed for our setup and that it can easily be modified to fit a particular dispensing unit. The results show the importance of cell throughput in bioprinting when a specific cell concentration is required in a 3D printed cell construct. CFD simulations increases the understanding and data received about a system that could not have been acquired using physical experiments or analytical models. When requiring a specific cell concentration in a bioprinted tissue our work regarding SCAP and DPSC cells can be used as a baseline for cell throughput and cell viability. CFD simulations giving information of cell damaging parameters could be used in work involving improvements of bioprinters from a cell viability perspective.