Date of this Version
Amir M. Esfahani, A SINGLE CELL PAIR MECHANICAL INTERROGATION PLATFORM TO STUDY CELL-CELL ADHESION MECHANICS, PhD diss, University of Nebraska-Lincoln. 2021
Cell-cell adhesion complexes are macromolecular adhesive organelles that integrate cells into tissues. Perturbations of the cell-cell adhesion structure or relatedmechanotransduction pathways lead to pathological conditions such as skin and heart diseases, arthritis, and cancer. Mechanical stretching has been used to stimulate the mechanotransduction process originating from the cell-cell adhesion and cell-extracellular matrix (ECM) complexes. The current techniques, however, have limitations on their ability to measure the cell-cell adhesion force directly and quantitatively. These methods use a monolayer of cells, which makes it impossible to quantify the forces within a single cell-cell adhesion complex. Other methods using single cells or cell pairs rely on cell-ECM adhesion to find the cell-cell adhesion forces and consequently, they indirectly measure the junctional forces.
In the current study, we designed and developed a single cell-cell adhesion interrogation and stimulation platform based on nanofabricated polymeric structures. The platform employs microstructures fabricated from biocompatible materials using two photon polymerization (TPP), a process that enables direct 3D structure writing with nanometer precision. The microdevice allows a pair of epithelial cells to form a mature cell junction. The single matured cell junction is stretched with controlled strain until cell-cell junction ruptures while the forces within the cell-junction-cell system are recorded. Using this platform, we have conducted mechanical characterization of a single cell junction with strain-stress analysis. The strain dependency of the junction has been investigated through the stretch test with four different strain rates. The results showed that the junction behaves in a strain-rate dependent manner, where high strain-rates lead to decreased viscosity property, a characteristic for a shear-thinning viscoelastic material. This also confirms our hypothesis that strain-rate plays an important role in the cell mechanical behavior, particularly the cytoskeleton dominant cell mechanics. The maturation of this technology can pave the way for the in situ investigation of mechano-chemical signaling pathways mediated by cell-cell junctions and potentially reveal novel disease mechanisms in which defects in cell-cell adhesion play a significant role in the disease pathology.
Advisor: Ruiguo Yang