Viscoelastic microbead stress sensors and validation based on organoid mechanobiology

• Applicants: Professor Dr.-Ing. Daniel Balzani; Dr. Nicole Fertala
• Subject Area: Biomaterials
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 467937258

Mechanical stress exerted and experienced by cells plays an important role for tissue morphogenesis and organ formation. While techniques to quantify mechanical stresses are established, their study in living tissues and organisms remains challenging. Recently introduced hydrogel-based microbeads represent a new type of stress sensors. These deformable, spherical, cell-sized probes are injected into the intercellular space of cell aggregates or tissues and allow the direct interaction with neighboring cells. On the basis of the resulting deformations of these microbeads, stresses can be quantified at the cellular level. However, current sensors exhibit elastic material properties which, after introduction into a viscoelastic tissue environment, can influence the cellular behavior and thus lead to measurement artifacts. Furthermore, the rate-dependent interaction of the cells can not be captured. In addition to that, additional functionalization, e.g., regarding incorporation of fluorescent position and orientation markers, is hardly possible in available sensors. Therefore, we plan to develop novel microbead stress sensors in this project based on a viscoelastic hydrogel material which is highly flexible with regard to cell responsive functionalization. These microbeads will be produced by a microfluidic device and precisely characterized in terms of their mechanical properties at the micro- and macroscale. Furthermore, they will be incorporated into pluripotent stem cell-derived kidney organoids to explore their potential to quantify cellular stresses at different developmental stages of organoid growth. An already established method called “Computational Analysis of Cell Scale Stress Sensing” (COMPAX), which will be extended to the application of the viscoelastic stress sensors, will be used for the subsequent analysis of the microbeads. In this context, a new simulation setup for the stress calculations will be developed and validated. With this novel type of stress sensors, we expect an expansion of the range of mechanobiological tools as well as new spatiotemporal insights into the developmental processes during organoid formation enabling a better understanding of cellular processes.

• DFG Programme: Research Grants