Deformable hydrospheres and cell segmentation report on stresses generated by individual cells in tumoroids

Abstract

The reciprocal interplay between cancer cells and their local environment, mediated by mechanical forces, requires quantitative measurements of cellular forces within the intricate three-dimensional context of the extracellular matrix. In the current study, we introduced an approach that utilizes soft, elastic hydrogel micro-particles, resembling the size of cells, to serve as specific and sensitive traction sensors in three-dimensional cell culture of collagen-embedded tumoroids. Our methodology relies on high-resolution detection of micro-particle deformations, which are subsequently translated into spatially resolved traction fields, reaching micrometer spatial resolution and simultaneously detecting traction forces as low as 30 Pa. Measurements enabled us to explore the relationships between cellular characteristics, extracellular traction fields, and cellular responses. We observed that cellular stresses ranged from 10 to 100 Pa, integrating cellular forces from 0.1 to 100 nN. The interaction of cells with inert microparticles appeared to be governed by contact mechanics resembling that of two soft spheres.