Self-Assembly and Stability of 3D Printed Cell Structures in Jammed Microgel Media*

Materials made from jammed microgels are emerging as popular delivery vehicles for living cells and as a support media for 3D-printed cell populations in engineered cell microenvironments. In these applications, cells are dispersed among packed microgel particles at different number densities. The aggregation and self-assembly of cells seeded onto culture surfaces have been studied, but we have a limited understanding of the corresponding behavior in soft, porous 3D environments like packed microgels. Prior work showed that cells randomly dispersed in 3D microgel culture media aggregate into multicellular clusters, forming large system-spanning networks at high cell densities where the transitions between different states of assembly are controlled by cell-cell cohesion and the yield stress of the microgel environment. However, these processes of self-assembly have not been studied in structured populations relevant to 3D bioprinting applications. In this talk, we will present work on the spatiotemporal evolution of 3D-printed Madin Darby Canine Kidney (MDCK) cell populations in a microgel support medium. Preliminary data on bioprinted cell populations with varying cell volume fractions and microgel packing fractions will be presented. The various states of cell reorganization and assembly will be mapped onto a phase diagram in this space. Our results will provide a fundamental basis for selecting appropriate cell density and microgel yield stress for specific bioprinting and cell delivery applications.