Collective Cell Behavior in 3D Cell Assemblies—3D Printed Structures, Random Aggregates, and Perfectly Precise Arrays

The remarkable differences between cells grown on plates and cells in vivo or 3D culture are well-known. At the physical level, cell shape, structure, motion, and mechanical behavior in 3D are totally different from those in the dish and are far less explored. At the molecular level, cells grown in monolayers exhibit gene expression profiles that do not correlate or are anticorrelated with those of cells grown in 3D culture or xenograft animal models. However, our understanding of cell biology has been heavily shaped by the culture plate, whether viewed through the lens of gene expression profiles, signaling pathways, morphological characterization, or mechanical behaviors. Closing this major gap between 2D in vitro culture and in vivo biology requires a tunable and flexible method for creating 3D cell assemblies and performing experiments on cells in 3D environments. Critically, studying collective cell behavior in 3D assemblies is needed to gain an understanding of the relationship between the detailed cellular structure found within tissues and emergent tissue function. In this talk, I will describe how we use 3D biofabrication tools in combination with a 3D culture medium made from jammed microgels to perform a wide range of 3D experiments. I will demonstrate this experimental platform’s ability to print structures made from multiple cell types or extracellular matrix with predictable feature sizes down to the scale of a few cell bodies. I will also present data from numerous types of experiments performed in 3D, designed to explore collective cell behavior and cell-cell interactions. For example, I will discuss recent results on collectively driven mechanical instabilities in 3D printed structures, collective cell migration in 3D printed immunotherapy models, cell aggregation in random 3D cell dispersions, and biofabrication with single-cell precision.