Characterization of the mechanical properties of microgels acting as cellular microenvironments

Abstract

There is an increasing effort in the search and characterization of materials that can function as artificial three-dimensional cellular microenvironments. In particular, the encapsulation of cells in micrometer-size hydrogel particles (microgels) offers the ease of cell visualization, the transport of nutrients, and the ability to generate large combinatorial libraries of cellular microenvironments. In the present work, we report an atomic force microscopy (AFM) method for the characterization of an average Young's modulus and the stress relaxation time of micrometer-size polymer microgel particles. We studied the mechanical properties of agarose microgels with different polymer concentration at room temperature and 37 °C (the temperature of cell culture). We examined the temporal variation in the Young modulus of cell-free and cell-laden microgels under physiological conditions. Furthermore, we correlated the mechanical properties of the microgels laden with a single carcinoma associated fibroblast (CAF) cell with the spatial distribution of collagen around the cell. This work is potentially useful for studies of changes in cellular microenvironments, when cells locally degrade the matrix or secrete molecules that change the mechanical properties of the matrix.