Numerical analysis of bioprinting-related shear stress and hydrostatic pressure during acoustic droplet ejection method versus microvalve-based technique and experimental investigation of their effects on epithelial and endothelial cells

Nasehi, Ramin; Fischer, Horst (Thesis advisor); Behr, Marek (Thesis advisor); Leube, Rudolf (Thesis advisor)

Aachen : RWTH Aachen University (2023)
Dissertation / PhD Thesis

Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2023

Abstract

The aim of this work was to explore the mechanobiological effects of the bioprinting process on cells. It was hypothesized that the bioprinting-induced mechanical signals affect the cellular behavior. To test this hypothesis, finite volume-based numerical simulation and experimental measurements were utilized. A custom-made pressure setup was used to examine the cellular response to hydrostatic pressure. Viability analysis, immunohistochemistry and qRT-PCR were used for experimental evaluation of cellular responses. Numerical simulation revealed that the maximum shear stress in acoustic droplet ejection is one third of the maximum wall shear stress in microvalve inkjet bioprinting. The impingement shear stress is in the same range as the nozzle wall shear stress. The viability analysis of cells after ejection from the microvalve confirmed that nozzle-to-platform distance is an additional parameter to be optimized for cell-friendly bioprinting. No change in cytoskeletal organization of actin filament, intermediate filament, focal adhesion and cell-cell contact were detected. However, in the case of stimulation with pulsatile hydrostatic pressure, a proinflammatory response of HUVECs was observed by an increase of interleukin 8 and a decrease of thrombomodulin transcripts. In a next step, the inflammatory response of the cells to bioprinting-induced shear stress should be further explored.

Institutions

• Division of Materials Science and Engineering [520000]
• [542000-3]