Multiscale measurements of mechanical stress in 3D co-cultures using a deformable micro-device

A wide range of methods are available to measure cellular mechanics, with a view of differentiating cancerous vs. normal cells. However there is a lack of a high-throughgput methods to measure the mechanics of multi-cellular aggregates, even though these provide much better models of health and disease. In addition to single-vell mechanics, understanding the tissue levels mechanical properties must account for cell-cell contacts, extra-cellular matrix, geometric factors, etc. Here we present a method to actuate and observe many multicellular aggregates, such as spheroids or organoids, within a single deformable micro-device. Heterogeneous mechanical properties within each tissue can be quantified by analyzing the deformation field of the tissue under stress and comparing with Hertzian mechanics. The variations in local properties can be related to the cellular parameters by analyzing the actin organization and nuclear shapes at the single-cell level. Then using confocal microscopy it is possible to construct a 3D graph of the deformation field, under mechanical forcing, with a sub-cellular resolution. Cellular rearrangements and re-orientation can be observed, as well as local membrane elongation and nuclear deformation. These measurements allow us to link the global deformations with the mechano-biological response of individual cells and to contrast the response of cancerous vs. non-malignant cells to mechanical forcing.