A tissue construct comprising includes a self-assembled, scaffold-free, high-density cell aggregate. The cell aggregate includes a plurality of cells and a plurality of biocompatible and degradable nanoparticles and/or microparticles that are incorporated within the cell aggregate. The nanoparticles and/or microparticles act as a bulking agent and/or provide bioactive agents or signals within the cell aggregate to increase the cell aggregate size and/or thickness and improve the mechanical properties of the cell aggregate and/or regulate cell function within the aggregate allowing the cell aggregate to be readily manipulated and formed into tissue constructs with defined architectures and potential tissue specific functionality.