(806b) Quantifying the Contribution of Structural Proteins to Cell Mechanics With a Live Cell Monolayer Rheometer

Cell mechanical properties depend primarily on the cytoskeleton, a multifunctional network which plays a key role in cell shape, motility, and intracellular transport.  Additionally, the cytoskeleton is one of the first cell components to be modified by disease.  Therefore a number of biological fields would benefit greatly from a device capable of rapidly measuring cell mechanical properties.  However, most existing technologies for analyzing cell mechanics are either low throughput single-cell measurements or complicated by the presence of a three-dimensional cell culture gel.  Our research addresses this need through the construction of a device capable of rapidly measuring the average mechanical properties of an entire cell monolayer.  In this device, a confluent monolayer of cells cultured on collagen-coated glass is gently compressed by a coverslip lowered down to contact the monolayer.  After a wait period to allow attachment of the cells to the top coverslip, this top plate is sheared while a sensitive force transducer measures the applied stress, thereby allowing rapid measurement of average mechanical properties across the cell monolayer.  The entire apparatus is mounted on a DIC microscope, allowing visualization of the cell deformation during these mechanical measurements.  We have applied this cell monolayer rheometer to study the relative impact of several cytoskeletal structural proteins on undifferentiated and differentiated adipocyte cell mechanics.  Step-strain experiments using this device show differences in relaxation modulus in cells with disrupted microtubules and actin filaments, as well as cells knocked out for the intermediate filament vimentin.  These results indicate that the cell monolayer rheometer may be used to quantify the contribution of various cytoskeletal structural proteins to cell mechanical properties in a way that is relatively high throughput and allows for cells to maintain cell-cell contacts and their adherent morphology throughout the experiment.